Technical guide for selection of LT motor

Technical Guidelines
ABB LT Motors

Others
Testing 30
Motor for frequency converter drive 31
Guide and check points for motor selection
(mechanical aspects) 33
Guide and check points for motor selection
(electrical aspects) 34
Ordering Information 35
Frequently asked questions 37
Contents
Product range 3
Features of standard TEFC motors 3
Manufacturing range summary 3
Designs variants 4
Features of standard SPDP motors 4
Standards 5
Tolerances 6
Mounting arrangement 6
Degree of protection 8
Cooling methods 9
Direction of rotation 9
Insulation and insulation class 9
Effect of voltage and frequency variation 10
Permitted output in high ambient temperature
and high altitudes 10
Permitted output for voltage unbalance 10
Motors for 60 Hz operation 11
Winding connection 12
Electrical features 13
Starting method for AC motors 14
Typical motor current and torque curves 15
Comparison between starting methods 15
Starting time 16
Example of starting performance with
different load torques 17
Electrical braking 18
Duty types 20
Protection accessories 22
Guide for fuse protection 22
Voltage drop along cable 23
Negative sequence withstand characteristics23
Power factor improvement chart 24
Mechanical Features 25
Exploded view of HX motors 26
Pulley diameter 27
Permissible radial forces 28
Permissible axial forces 29
General
Electrical
Mechanical

Product Range
! Standard TEFC motor, IS : 325 - 1996
! Crane duty motors
! Non sparking motors Type “EX-n”
! Increased Safety motors Type “Ex-e”
! Flame proof motors Type “Ex-d”
! Variable frequency drive motors
! Ring frame motors, IS : 2972 Part III
! Roller table motors for steel plants
! Auxiliary motors for a.c locomotives
! Custom build motors for textile, machine tools and various other applications.
! Standard SPDP motors, IS : 325 - 1996
Feature of standard TEFC Motors
Range
Type Three phase squirrel cage induction motor
Enclosure Totally - enclosed fan cooled
Voltage ± variation 415V ± 10%
Frequency ± variation 50Hz ± 5%
Combined variation 10% (Absolute Sum)
Mounting reference As per IS 4691
Frame dimensions As per IS 1231; IS 2223
Altitude Up to 1000 M
Relative humidity Up to 100%
Degree of protection IP55
Class of insulation Class F
Ambient temperature / temperature rise 45ºC/75ºC Up to Frame 160
50ºC/70ºC Frame 180 to 400
Duty S1/Continous
Position of terminal box Top at drive end
Connection / No of leads Up to 2 HP - STAR / 3 Leads > 2 HP - DELTA / 6 Leads
Direction of rotation Bi-directional
Grease type Lithium complex grease
Greasing arrangements Online greasing arrangement for 225 and above
Cooling IC 0141 (TEFC)
Paint Polyurethane (Shade: Munsell Blue)

Output 0.18 ...500kW; 0.25 ...675hp; according to IS 325
Voltage 220 ... 660V
Frequency 25 ... 60Hz
Duty S1 ... S8 according to IS:325
Ambient Temperature -20ºC ... 65ºC
3

Design Variants
Electrical Mechanical
Non standard voltage and frequency variations Non standard mounting dimensions
AC variable speed drives Special shaft extension
High torque motors Double shaft extension
High slip motors Separately ventilated motors
Motors for frequent start / stops / reversals Low vibration and noise level
Frequency 25 to 60 Hz Brake motors
Special performance requirements Special bearings and lubrications
Class H insulation Tacho mounting / SPM mounting
Voltage 220V to 550V Non standard paint shade
Alternative terminal box position
IP 56 protection
Special shaft material
Special size of terminal box and terminal arrangements
Surface cooled motors
SS name plate
Non standard keyway
Epoxy gelcoat on overhangs
Space heaters
Thermistors, RTD , BTD
Single compression / double compression glands
Note: Please refer to the company for details of special designs offered.
Feature of standard SPDP Motors
Type Three phase squirrel cage induction motor
Enclosure Screen protected drip proof
Voltage ± variation 415V ± 10%
Frequency ± variation 50Hz ± 5%
Combined variation 10% (Absolute Sum)
Mounting reference As per IS 4691
Frame dimensions As per IS 1231; IS 2223
Altitude Up to 1000 M above MSL
Relative humidity Low / indoor applications
Degree of protection IP 23
Class of insulation F, Temperature rise limited to CL.B
Ambient temperature 40ºC
Duty S1
Position of terminal box Top
Connection / No of leads DELTA / 6 Leads
Direction of rotation Bi-directional
Grease type Li-complex grease
Cooling IC 01
Paint Polyurethane (Shade: Munsell Blue)
4

Standards
ABB Motors are designed to ensure that performance complies with IS:325. HX/M2BA Motors are totally-enclosed three-phase
squirrel cage type complying with relevant Indian Standards.
List of Indian Standards applicable to low-voltage induction motors are as given below:
IS No. Title
IS 325:1996 Three-phase induction motors (fifth revision)
IS 900:1992 Code of practice for installation and maintenance of induction motors (second revision)
IS 1231:1974 Dimensions of three-phase foot-mounted induction motors (third revision)
IS 2223:1983 Dimensions of flange mounted a.c. induction motors (first revision)
IS 2253:1974 Designation for types of construction and mounting arrangement of rotation electrical machines
(first revision)
IS 2254:1985 Dimensions of vertical shaft motors for pumps (second revision)
IS 2968:1968 Dimensions of slide rails for electric motors
IS 4029:1967 Guide for testing three-phase induction motors
IS 4691:1985 Degrees of protection provided by enclosure for rotation electrical machinery (first revision)
IS 4722:1992 Rotating electrical machines (first revision)
IS 4728:1975 Terminal marking and direction of rotation for rotating electrical machinery (first revision)
IS 4889:1968 Method of determination of efficiency of rotating electrical machines
IS 6362:1971 Designation of methods of cooling of rotating electrical machines
IS 7538:1975 Three-phase squirrel cage induction motors for centrifugal pumps for agricultural applications
IS 7816:1975 Guide for testing insulation resistance of rotating machines
IS 8151:1976 Single-speed three-phase induction motors for driving lifts
IS 8223:1976 Dimensions and output ratings for foot-mounted electrical machines with frame numbers 355 to 1000
IS 8789:1978 Values of performance characteristics for three-phase induction motors
IS 12065:1987 Permissible limits of noise level for rotating electrical machines
IS 12066:1987 Three-phase induction motors for machine tools
IS 12075:1986 Mechanical vibration of rotating electrical machines with shaft heights 56mm and higher-measurement,
evaluation and limits of vibration severity (super ceding IS 4729:1968)
IS 12615:1989 Energy efficient three-phase squirrel cage induction motors
IS 12802:1989 Temperature rise measurement of rotating electrical machines
IS 12824:1989 Type of duty and classes of rating assigned to rotating electrical machines
IS 13107:1991 Guide for measurement of winding resistance of an a.c. machine during operation at alternating voltage
IS 13529:1992 Guide on effects of unbalanced voltages on the performance of three-phase cage induction motors
IS 13555:1993 Guide for selection and application of three-phase a.c. induction motors for different types of driven
equipment
5

Item Tolerance
Efficiency (h)
By summation of losses
Motors up to 50kW -15 percent of (1 - h)
Motors above 50kW -10 percent of (1 - h)
By input output method -15 percent of (1 - h)
Total losses applicable to motors above 50kW* +10 percent of total losses
Power factor (cosf) -1/6 of (1 - cosf) min 0.02 and max 0.07
Slip at full load and working temperature ±20 percent of the guaranteed value
Breakaway starting current with the specified ±20 percent of the guaranteed starting current
starting method (no negative tolerance)
Breakaway torque -15 to +25 percent of the guaranteed torque
(+25 percent may be exceed by agreement)
Pullout torque -10 percent of the guaranteed torque except that after
applying this tolerance, the torque shall not be less than
1.6 or 1.5 times the rated torque
Moment of inertia or stored energy constant for ±10 per cent of the guaranteed value
motors above 315 frame
* Upon agreement between manufacturer and purchaser
Tolerances (as per IS:325-1996)
IS:2253 and technically identical IEC 60034-7 specify two
possible ways of describing how a motor is mounted.
Code I covers only motors with bearing end shields and one
shaft extension. The code consists of letters IM, a further letter
and a number.
Code II is a general one applicable to all rotating machines. The
code consists of letters IM and four characteristics numerals as
illustrated below.
Mounting arrangements
IM 1 00 1
Shaft extension, one cylindrical shaft extension
Mounting arrangement, horizontal mounting with
feet downward
Type of construction, foot mounted motor with
two endshield
International mounting
6

Mounting arrangements
Foot-mounted motor, IM B 3 IM V 5 IM V 6 IM B 6 IM B 7 IM B 8
IM 1001 IM 1011 IM 1031 IM 1051 IM 1061 IM 1071
Flange -mounted motor, IM B 5 IM V 1 IM V 3
Large flange IM 3001 IM 3011 IM 3031 IM 3051 IM 3061 IM 3071
Flange -mounted motor , IM B 14 IM V 18 IM V 19
Small flange IM 3601 IM 3611 IM 3631 IM 3651 IM 3661 IM 3671
Foot and flange-mounted, IM B 35 IM V 15 IM V 36
Motor with feet, IM 2001 IM 2011 IM 2031 IM 2051 IM 2061 IM 2071
Large flange
Foot and flange-mounted, IM B 34
Motor with feet, IM 2101 IM 2111 IM 2131 IM 2151 IM 2161 IM 2171
Small flange

Foot-mounted motor, IM 1002 IM 1012 IM 1032 IM 1052 IM 1062 IM 1072
Shaft with free extensions
CodeI/CodeII
7

Degree of protection
Degree of protection for rotating machines are indicated according to IS:4691 using the characteristic letters ‘IP’ followed by two
characteristic numerals for the degree of protection.
The first numeral indicates protection against contact and ingress of foreign bodies.
The second numeral indicates protection against ingress of water.
First characteristic numeral
IP 2 Protected against solid objects greater than 12mm
IP 5 Dust protected motors, Ingress of dust is not fully protected, but dust can not enter in an amount sufficient to interface with
satisfactory operations of the motor.
Second characteristic numeral
0
IP 3 Protected against spraying water, sprayed up to angle of 60from vertical shall have no harmful effect.
IP 5 Protected against water, jets by a nozzle from any direction shall have no harmful effect.
IP 6 Protected against heavy seas, powerful jets from all direction shall have no harmful effect.
Degree of protection - Schematic
No protection
Protected against
solid objects
greater that 50mm
(e.g. hand)
Protected against
solid objects
greater that 12mm
(e.g. fingers)
Protected against
solid objects
greater that 2.5mm
(e.g. tools,
wires)
Protected against
solid objects
greater that 1mm
(e.g. wire or
strips)
Ingress of dust is
not totally
protected, but does
not enter in
sufficient quantities
to harm equipment
No ingress of dust
0
1
2
3
4
5
6
0
1
2
3
4
5
6
No protection
Dripping water
shall have no
harmful effect.
Protected against
dripping water
when enclosure is
0
titled 15
Protected against
spraying water up
0
to 60
Water splashed
from any direction
shall have no
harmful effect
Water hosed
against the
enclosure shall
have no harmful
effect (water jets)
Water from
powerful jets of
heavy seas shall
have no harmful
effects
1st Numeric 1st Numeric
8

Cooling Methods
Cooling methods of HX/M2BA Motors are in accordance with
IS:6362. The motors are cooled by the method IC 0141, i.e.
frame surface cooled, with external cooling fan on motor shaft.
The fan is made of strong engineering plastic for frames upto
200 (aluminum alloy/cast iron option is also available). For
frames 225 and above, aluminum alloy fans are used. Fans of
all motors are bidirectional. The motors are provided with
cooling ribs for increased surface area and improved cooling.
An air gap is left between ribs and fan cover for cleaning
purposes. The ribs are designed so that they keep the flow of
air close to the surface of the motor along the entire length, thus
improving self cleaning and cooling.
The external ventilation of the motors is obtained by means of
the fan mounted to the shaft, which sucks in the ambient air
through the fan cover on the N-end and blows it over the frame
in between the ribs. Fans are axially and radially locked to
prevent vibration. The internal cooling of motors is affected by
the churning action of internal air by the ribs on the die-cast
rotor.
Insulation and insulation classes
Insulation materials are divided into insulation classes. Each
class has a designation corresponding to the temperature that
is the upper limit of the range of application of the insulating
material under normal operating conditions.
The winding insulation of a motor is determined on the basis of
the temperature rise in the motor and the ambient temperature.
The insulation is normally dimensioned for the hottest point in
the motor at its normal rated output and an ambient
temperature of 45ºC/50ºC. Motors subjected to ambient
temperatures above 45ºC/50ºC will generally have to be
derated.
In most cases, the standard rated outputs of motors from ABB
motors are based on the temperature rise for insulation class B.
Where the temperature rise is according to class F, this is
specified in the data tables.
However, all the motors are designed with class F insulation,
which permits a higher temperature rise than class B. The
motors, therefore, have a generous overload margin. If
temperature rise to class F is allowed, the outputs given in the
tables can be increased by approximately 12%.
D-end and N-end
The ends of motors are defined as D-end; the end that is
normally the drive end of the motor and N-end; the end that is
normally the non-drive end of the motor.
Direction of rotation
In conformation with IS:4728, the terminals of the motor are
marked such that when the alphabetic sequence of the
terminals U1, V1, W1: U2, V2, W2 corresponds to the supply
phase sequence L1, L2, L3 the motor runs in a clockwise
direction, when seen from drive end.
For anticlockwise operation of the motor, any two of the supply
phase connections (L1, L2, L3) are exchanged to obviate the
need for change of the terminal markings.
Temperature limits are according to standards. The extra
thermal margin when using class F insulation with class B
temperature rise makes the motors more reliable.
180
130
155
120
45
45
B
130
0
C
F
155
H
180
10
Hotspot temperature
margin
Permissible temperature
rise
Maximum ambient
temperature
Insulation class
Maximum winding
temperature
75
45
15
95
45
15
120
9

Effect of voltage and frequency variation
Almost without exception, the starting current decreases slightly more in proportion to the voltage. Thus for example 90% of rated
voltage the motor will draw slightly less than 90% of the starting current, approximately 87 to 89%. The starting torque is
proportional to the square of the current, the torque delivered at 90% of rated voltage is therefore only 75% to 79% of the starting
torque. Particular attention should be paid to these points if the electrical supply is weak and when starting techniques based on
current reduction are being used. The pull out torque is roughly proportional to the voltage.
If the saturation of the magnetic circuit is neglected, then the general effect of variation in voltage and frequency on the
characteristics of induction motor can be given as per the table below.
Table - Effect of variation of voltage and frequency on the characteristics of induction motor*
Characteristics Voltage Frequency
110% 90% 105% 95%
Torque Increased by 21% Decrease 19% Decrease 10% Increase 11%
Starting & maximum
Speed
Synchronous No change No change Increase 5% Decrease 5%
Full load Increase 1% Decrease 1.5% Increase 5% Decrease 5%
Slip Decrease 17% Increase 23% Little change Little change
Current
Rated Decrease 7% Increase 1% Slight decrease Slight increase
Starting Increase 10-12% Decrease 10-12% Decrease 5-6% Increase 5-6%
No load Increase 10-15% Decrease 10-15% Decrease 5-6% Increase 5-6%
Overload capabilityIncrease 21% Decrease 19% Slight decrease Slight increase
Temperature rise Decrease 3-4% Increase 6-7% Slight decrease Slight increase
Magnetic noise Slight increase Slight Decrease Slight decrease Slight increase
Efficiency, full loadIncrease 0.5-1.0% Decrease 2% Slight increase Slight decrease
Power factor, full loadDecrease 3% Increase 1% Slight increase Slight decrease
*These variations are indicative in nature and are not uniformly applicable to all the designs.
Permitted output in high ambient temperature and high altitudes
Motors of basic design are intended for operation in a maximum ambient temperature of 45°C and at maximum altitude of 1000
meters above mean sea level. If a motor is to be operated in higher ambient temperature or at higher altitude, it should normally be
derated according to the following table.
Ambient temperature (°C) 40 45 50 55 60* 65* 75* 85*
Permitted output (% of rated output)107 100 96.5 93 90 86.5 79 70
Height above sea level (M) 1000 1500 2000 2500 3000 3500 4000
Permitted output (% of rated output) 100 96 92 88 84 80 76
*changes in the type of lubricant and lubrication interval required.
Permitted output for voltage unbalance
The phase unbalance for voltage is calculated as follows:
% voltage imbalance = 100 x
If this unbalance is known before the motor is purchased it is advisable to apply derating as per following table.
Unbalance 1% 2% 3% 4% 5%
Derating 100 95 90 83 76
Rerating S1 duty motors to S2 and S3 duty motors
Standard motors can be used for S2 and S3 duties with increased outputs. However, the starting torque and pull out torque as a
percentage of the full load torque would be reduced.
S2 S3
60 min 30min 10min 60% CDF 40%CDF 25% CDF
100% 115% 120% 100% 105% 120%
maximum difference in voltage compared to average voltage value
_____________________________________________________
average voltage value
10

Motors for 60 Hz operation
Motors wound for a certain voltage at 50 Hz can be operated at 60 Hz, without modification, subject to the following changes in their
data.
Motor Connected Data at 60 Hz in percentage of values at 50Hz
wound for to 60 Hz
1)
50 Hz and and Outputrpm I I/I T T/T T/T
N SN N SN max N

220 V 220 v 100 120 98 83 83 70 85
225 v 115 120 100 100 96 95 98
380 V 380 V 100 120 98 83 83 70 85
415 V 110 120 98 95 91 85 93
440 V 115 120 100 100 96 95 98
460 V 120 120 100 105 100 100 103
400 V 380 V 100 120 100 80 83 66 80
400 V 100 120 98 83 83 70 85
415 V 105 120 100 88 86 78 88
440 V 110 120 100 95 91 85 93
460 V 115 120 100 100 96 95 98
480 V 120 120 100 105 100 100 100
415 V 415 V 100 120 98 83 83 70 85
460 V 110 120 98 95 91 85 94
480 V 115 120 100 100 96 95 98
500 V 500 V 100 120 98 83 83 70 85
550 V 110 120 98 95 91 85 94
575 V 115 120 100 100 96 95 98
600 V 120 120 100 105 100 100 103
Efficiency, power factor and temperature rise will be approximately the same as at 50 Hz.
1) I = rated current
N
I/I = starting current/rated current
SN
T = rated torque
N
T/T= maximum torque/rated torque
max N
T/T = starting torque/rated torque
SN
11

Winding Connection
Single speed
Star connected windings for motors upto 2 hp and delta connected windings for motors above 2 hp are standard features. The
connection diagrams for single speed motors are given below:
D - connection Y - connection
Double speed
The difference in winding configuration and application necessitates different winding connections so as to accommodate maximum
power in a given frame.
-Motors with two separate windings are normally Y/Y connected upto frame size 160, larger motors are D/D, Y/D or D/Y
connected
-Motors with Dahalander connection, are in D/YY when they are designed for constant torque drives and Y/YY when they are
designed for fan drive.
The connection diagram for different combinations are given below:
1. Two separate
windings Y/Y
Low speed High speed Low speed High speed
2.Two separate
windings D/D
Low speed High speed Low speed High speed
3. Dahlander-
connection D/YY
Low speed High speed Low speed High speed
4. Dahlander-
connection Y/YY
Low speed High speed Low speed High speed
12

1.Voltage
Rated voltage is the voltage between line terminals for
which the motor is designed.
Standard voltage for motors is 415V. Motors can, however,
be made available for any supply voltage between 220V
and 660V. Motors for two different supply voltages have
non standard windings and are available on request.
2.Frequency
Rated frequency is the frequency of the voltage for which
the motor is designed.
The basic design of the motor is suitable for a rated supply
frequency of 50 Hz. HX/M2BA motors can be offered for
any frequency in the range 25 Hz to 60 Hz, however, for
supply frequency other than 50 Hz, they are made
available on request.
3.Voltage and frequency variation
Motors can be operated continuously at rated output, with a
long term voltage variation of
4.Number of poles
Number of poles of the motor determine the basic speed
(synchronous speed) of the motor. Standard motors are
available in the configuration of 2,4,6 and 8-poles.
5.Power
Rated power is the shaft power of the motor with an
ambient temperature not exceeding 45°C/50°C and an
altitude not exceeding 1000m above mean sea level.
6.Rated speed, slip
Rated speed corresponds to the operating speed of the
motor at the rated power when it is being fed at rated
voltage and frequency.
The synchronous speed of an induction motor depends on
the supply frequency and the number of poles of the stator
winding. Thus,
±10%, frequency variations of
±5% and a combined voltage and frequency variation of
10%, over rated values. The temperature rise may increase
by 10K at extreme voltage and frequency.
If the motors are required to operate continuously at
voltage approaching the limits of voltage tolerances without
exceeding the temperature rise limit, this must be specified
at the time of enquiry.
h= x 60(rpm)
s
where h= synchronous speed (rpm)
s
f = frequency (Hz)
p = number of pair of poles
note 2p = number of poles
The rated speed given in the list is for motors operating at
rated power under normal voltage and frequency.
The difference between synchronous speed, hand rotor
s
speed, n; referred to the synchronous speed, is called slip.
This slip, s, is expressed as a percentage;
s = x 100 (%)
When the motor is partly loaded the slip varies almost
linearly with the load.
7.Rated current
It is the value of the current taken by the motor when
delivering rated power at rated voltage and frequency. The
value of rated currents are at specified voltage, for other
voltages, Ux, the current Ix may be calculated as:
Ix =
Where Ux= new voltage
Ix = new current
I = current at 415V
The current consumption varies also with the loading of the
motor, but it should be noted that the relationship is not
linear.
8.Starting current
Usually, given as a percentage or as a multiple of rated
current, it is the value of the current drawn by the motor
during starting. The value of the starting current is generally
between 500-700% (5-7 per unit) of the rated current.
9.Torque characteristics
10.Moment of inertia
2
The moment of inertia J is given in Kgm. The moment of
2
inertia is numerically equal to 1/4 GD. The moment of
inertia J
11.Overloads
In accordance with IS:325 motors are rated to withstand an
overload, an excess torque of 60% of their rated torque at
rated voltage and frequency for 15 seconds.
Typical torque/speed characteristics of the motor is shown
in figures on page no. 15 along with different relevant
parameters.
The nominal torque of the motor T is the torque developed
N'
by the motor at rated speed, n while delivering rated power
P. The relationship between the torque T the power P, and
N'
the speed n is
T= 9550 x [Nm]
N
Where P=power (kW)
n=motor speed (rpm)
alternatively, torque T, in kgm can be given as
T= 974 x [kgm]
N
Starting torque of the motor T is the torque developed by
S'
the motor at zero speed when it is directly switched on.
Value of starting torque is usually given as a percentage or
as a multiple of nominal motor torque T.
N
Pull out torque of the motor T is the maximum torque that
max'
the motor can develop when it is operated directly on line.
Value of pull out torque is usually given as a percentage or
as a multiple of nominal motor torque T.
N
of the driven machine at nrpm when referred to
L L
motor speed n rpm is given by
2
J = J [n/n]
LL
Electrical features
f
415.I
415.I
P
p
Ux
Ux
n
h - h
s
h
s
13

Direct-on-line (DOL) start:
Direct on line starting is suitable for stable supplies and mechanically stiff and well dimensioned
systems. It is the simplest, cheapest and most common starting method. Starting equipment for
small motors that do not start and stop frequently is simple, often consisting of a hand operated
motor protection circuit breaker. Larger motors and motors that start and stop frequently, or have
some kind of control system, normally use a direct-on-line starter which can consist of a contactor
plus overload protection, such as a thermal relay.
Star-Delta (Y/D) starting:
Most low voltage motors can be connected to run at either 400V with delta connection or at 690V
with star connection. This flexibility can also be used to start the motor with a lower voltage.
Star/delta connection gives a low starting current of only about one third of that during direct-on-
line starting, although this also reduces the starting torque to about 25%. The motor is started with
Y-connection and accelerated as far as possible, then switched to D-connection. This method can
only be used with induction motors delta connected for the supply voltage.
Soft starters
Soft starters are based on semiconductors, which, via a power circuit and a control circuit, initially
reduce the motor voltage, resulting in lower motor torque. During the starting process, the soft
starter progressively increases the motor voltage so that the motor becomes strong enough to
accelerate the load to rated speed without causing torque or current peaks. Soft starters can also
be used to control the stopping of a process. Soft starters are less costly than frequency converters
but like frequency converters, they may inject harmonic currents into the grid, disrupting other
processes.
Frequency converter start
Although a frequency converter is designed for continuous feeding of motors, can also be used
exclusively for start-up only. The frequency converter enables low starting current because the
motor can produce rated torque at rated current from zero to full speed. As the price of frequency
converters continues to drop, they are increasingly replacing soft starters. However in most cases
they are still more expensive than soft starters, and like these, they inject harmonic currents into
the network.
Reducing electrical and mechanical stress at start-up
The starting current of an AC motor can vary from 3 to 7 times the nominal current. This is because a large amount of energy is required to
magnetise the motor enough to overcome the inertia the system has at standstill. The high current drawn from the network can cause
problems such as voltage drop, high transients and in some cases, uncontrolled shutdown. High starting current also causes great
mechanical stress on the motor’s rotor bars and windings and can affect the driven equipment and the foundations. Several starting
methods exist, all aiming to reduce these stresses. The load, the motor and the supply network determine the most appropriate starting
method. When selecting and dimensioning the starting equipment and any protective devices, the following factors must be taken into
account:
• The voltage drop in the supply network when starting the motor
• The required load torque during start
• The required starting time
UN
Ist
UN =Rated net
voltage
st I=Start current
at full voltage
UN
stI
UN =Rated net
voltage
st I=Start current
at full voltage
Starting methods for AC motors
UN
IstR
UN =Rated net
voltage
stR I=Start current
at red. voltageMU
MU=Motor voltage
NU
IstR
UN =Rated net
voltage
stRI=Start current
at red. voltage
UM
UM =Motor voltage
14

Typical motor current and torque curves
Comparison between starting methods
T =Motor torque
M
T =Motor torque with direct-on-line starting
MD
T =Motor torque with start-delta starting
MY
T =Load torque
L
T =Load breakaway torque
L0
T =Rated motor torque
N
T =Breakaway torque or locked rotor torque
S
T =Pull-up torque
min
T =Breakdown torque or pull-out torque
max
T =Acceleration torque
acc
I =Current
I =Rated current
N
I =Current in D-connection
D
I =Current in Y-connection
Y
n =Speed
n =Synchronous speed
S
Current Torque
1 =Direct-On-Line starter
2= Y/D-starter
3 =Start with soft starter
15

Starting time
Theory
The starting current of an induction motor is much higher than
the rated current, and excessively long starting period causes
harmful temperature rise in the motor. The high current also
leads to electro-mechanical stresses. It is, therefore, of
importance to know the time taken by the motor to accelerate
the load to rated speed. This time is called starting time or
acceleration time.
Starting time depends upon:
-Total inertia of the system
-Torque speed curve of the motor
-Torque speed curve of load
If the torque curves for the motor and the load are known, the
starting time can be calculated by integrating the equation:
T - T=(J + J)
LM L
whereT=Motor torque, Nm
T=Load torque, Nm
L
2
J=Moment of inertia of motor, kgm
M
2
J=Moment of inertia of load, kgm
L
W=Motor angular velocity
If only the starting torque and maximum torque of the motor and
the nature of the load are known, the starting time can be
approximately calculated with the equation:
T= (J + J)
st M L
whereT=starting time
st
T=acceleration torque as per diagrams, Nm
acc
K=as per table below
1
Speed Poles Frequency
Constant2 4 6 8 10 Hz
n 300015001000750600
M
K 34515710478 62
1
n 360018001200900720
M
K 41518812594 75
1
This method of calculation may be used for direct-on-line
starting and for motors up to about 250kW. In other cases more
points on the motor torque curves are required. In any case up
to the point of maximum torque.
If there is speed transformation between the motor and the
driven machine, the load torque must be recalculated for the
motor speed, by using the following formula:
T'=
L
whereT'=Recalculated load torque, Nm
L
n=Motor speed, rpm
M
n=Load speed, rpm
L
The moment of inertia must also be recalculated.
2
J'=J' (n/n)
LL LM
2
where J'= Recalculated moment of inertia, kgm
L
¶w
¶t
K
1
Tn
L L
n
M
T
acc
50
50
x
x
x
x
16

Example of starting performance with different load torques
4-pole motor, 160 kW, 1475krpm
Torque of motor:
T =1040 Nm,
N
T =1,7 x 1040 = 1768 Nm
S
T =2,8 x 1040 - 2912 Nm
max
2
Moment of inertia of motor: J = 2,5 kgm
M
The load is geared down in a ration of 1:2
Torque of load:
T =1600 Nm at n = rpm
LL
Example 1:
Lift motion
Speed
T =1600 Nm T' = 800 Nm
LL
Constant during acceleration
T =0,45 x (T + T) - T'
acc S max L
T =0,45 x (1768 + 2912) - 800 = 1306 Nm
acc
t =(J + J') x
st M L
t =22,5 x = 2,7 s
st
Example 2:
Piston pump
Speed
T =1600 Nm T' = 800 Nm
LL
Linear increase during acceleration
T =0,45 x (T + T) - T'
acc S max L
T =0,45 x (1768 + 2912) - €800 = 1706 Nm
acc
t =(J + J') x
st M L
t =22,5 x = 2,1 s
st
T =1600 x = 800 Nm at n rpm
LM
Moment of inertia of load:
2
J =80 kgm at n = rpm
LL
22
J =80 x ( ) = 20 kgm at n rpm
LM
Total moment of inertia:
J + J at n r/min
ML M
2
2,5 + 20 = 22,5 kgm
Example 3:
Fan
Speed
T =1600 Nm T' = 800 Nm
LL
Square-law increase during acceleration
T =0,45 x (T + T) - x T'
acc S max L
T =0,45 x (1768 + 2912) - x 800 = 1839 Nm
acc
t =(J + J') x
st M L
t =22,5 x = 1,9 s
st
Example 4:
Fly wheel
Speed
T= 0
L
T =0,45 x (T + T)
acc S max
T =0,45 x (1768 + 2912) = 2106 Nm
acc
t =(J + J') x
st M L
t =22,5 x = 1,7 s
st
n
M
n
M
K
1 K
1
1
1
K
1
K
1
1
1
157 157
157
157
2
2
T
acc T
acc
3
3
T
acc
T
acc
2
2
1360 1839
1706
2106
Torque Torque
Torque Torque
T
LT
L
T
L T
L
1
2
1
2
17

Countercurrent braking (Plugging)
With countercurrent braking, an ordinary standard motor is
switched at full speed for the opposite direction of rotation. This
can be done with a reversing switch. After braking to a
standstill, the motor starts in the opposite direction of rotation,
unless the current is switched off at the right moment. A low
speed detector is therefore used to cut off the supply to the
motor when the speed approaches zero.
Countercurrent braking gives a very high braking torque. The
current during braking is about the same as during starting, so
that there is a considerable temperature rise in the motor.
Consequently the permitted frequency of braking with the
countercurrent technique is only about one-quarter of the
number of permitted braking can easily be exceeded with
countercurrent braking, temperature sensors should always be
used to protect the motor windings from overheating.
The permitted number of counter current braking can be
calculated approximately with the formula:
3600x
X =

Tx
b
wherex=Permitted number of brakings per hour
P=Output taken from motor, kW
2
P=Rated output of motor in continuous duty, kW
1
t=Braking time, s
b
I/I=Starting current / full load current
st
For squirrel cage motors the braking time can be calculated
approximately with the formula:
t=
b
wheret=Braking time, s
b
K=Constant depending on number of poles, see
1
table
2
J=Moment of inertia of motor, kgm
m
J=Moment of inertia of load, referred to speed of
b
2
motor, kgm
M=Maximum torque of motor, Nm
max
M=Starting torque of motor, Nm
start
Frequency Constant K for different number of poles
1
Hz 2 4681 0
50 345 157 104 78 62
60 415 188 125 94 75
Although the load torque contributes to the braking torque,
making allowance for it complicates the calculation unduly if the
braking time must be accurately known. It can therefore be said
that the braking torque is approximately equal to the
acceleration torque, when the load current is approximately
zero.
For slip-ring motors the starting and braking times are both
determined by the dimensioning of the rheostatic starter.
Figure 1
(In this case the load torque contributes to the braking torque.
To be on the safe side, however, calculations are based on the
braking torque being the same as the acceleration torque.)
Figure 2
(It is a complicated matter to calculate theoretically the braking
torque curve for countercurrent braking. In most cases it can be
assumed that the braking torque is approximately equal to the
acceleration torque, when the load current is approximately
zero.)
With countercurrent braking there is no braking action in the
event of power failure. The technique is therefore unsuitable for
use in plant where loss of braking could cause danger.
Speed detector with countercurrent braking
A low speed detector designed to cut off the supply to the motor
when the speed approaches zero can be used to terminate
countercurrent braking at the right instant. The speed detector
is usually mounted on the N-end of the motor and is driven from
the motor shaft via a coupling.
Electrical braking
Kx (J + J)
1m b
0.45 x (M + M)
max start
Torque
Torque
Torque
Torque
Braking torque
Braking torque
Acceleration torque
Acceleration torque
M
b
Speed
Speed
Countercurrent braking
Countercurrent braking
Starting
Starting
P
2
2
I
st
P
2
22
I P
1
P
1
4 x -
18

Direct-current braking
When braking with this technique, the a.c. supply to the motor is
disconnected and the stator is excited with direct current; this
causes the motor to produce a braking torque.
An ordinary standard motor and suitable equipment for d.c.
excitation may be used. The a.c. voltage follows a decay curve,
and the d.c. voltage must not be connected until the a.c. voltage
has fallen to a value at which it will not harm the d.c. equipment.
The excitation current is determined by the braking time
chosen, but is usually 1 to 2 times the rated current of the
motor. However, saturation of the magnetic circuit imposes a
limit on the braking torque.
Direct-current braking gives a far longer braking time than
countercurrent braking, however high the excitation current, but
thermal losses are lower, so more frequent braking is
permissible.
If the d.c. voltage fails there will be no braking action. The
technique is therefore unsuitable for use in plants where loss of
braking could cause danger.
Figure 3
(The lower curve shows the output voltage from the stator
winding of a small induction motor after disconnection from the
supply. Only half the curve is shown. The upper curve is a 50
Hz scale. With countercurrent braking, the d.c. voltage must not
be connected until the a.c. voltage has fallen to a value at which
it will not harm the d.c. equipment.)
Figure 4
(Example of braking torque with d.c. braking and different
excitation currents.
I = rated current of motor.)
n
Regenerative braking
This is the method of braking multi-speed motors when
changing down to lower speeds. The thermal stresses are
approximately equal to those occuring when motors with dual
speed connections are started at lower rated speed. With the
motor at the lower speed working as a generator, it develops
very high braking torque in the interval between operating
speeds of motor corresponding to the two poles. The maximum
braking torque is slightly higher than the starting torque of the
motor at the lower speed. Regenerative braking is also used
with variable speed drives.
Based on the thermal stesses developed during different
braking methods, with reference to those developed during
direct-on-line starting, following thermal equivalence is drawn.
Four jogs (or inching) = One start
One DC injection braking = Two start
One plug stop = Three start
One regenerative braking = One start
Torque
Torque
Time
Braking torque
Acceleration torque M
b
Torque
Direct-current braking Starting
19

The duty types are indicated by the symbols S1 ... S9 according to IS:12824-1989. The outputs given in the tables are based on
continuous running duty. S1 with rated output.
S1
Continuous running duty
Operation at constant load of sufficient duration for thermal
equilibrium to be reached. In the absence of any indication of
the rated duty type, continuous running duty will be assumed.
Designation: S1
S2
Short-time duty
Operation at constant load during a given time, less than
required to reach thermal equilibrium, followed by a rest and de-
energised period of sufficient duration to re-establish motor
temperatures equal to the ambient or the coolant temperature.
The values 10, 30, 60 and 90 minutes are recommended for the
rated duration of the duty cycle.
Designation e.g. S2 60 min.
S3
Intermittent duty
A sequence of identical cycles, each including a period of
operation at constant load and a rest and de-energised period.
The period is too short for thermal equilibrium to be obtained.
The starting current does not significantly affect the temperature
rise.
Recommended values for the cyclic duration factor are 15, 25,
40 and 60%. The duration of the duty cycle is 10 min.
Designation e.g. S3 25%
S4
Intermittent duty with starting
A sequence of identical duty cycles, each cycle including a
significant period of starting, a period of operation at constant
load and rest and de-energised period. The period is too short
for thermal equilibrium to be obtained. In this duty type the
motor is brought to rest by the load or by mechanical braking,
where the motor is not thermally loaded. After the duty type the
following factors must be indicated; the cyclic duration factor;
the number of duty cycles per hour (c/h); the factor of inertia FI;
the moment of inertia, J, of the motor rotor; and the permissible
M
average moment of resistance, T, during the change of the
V
speed given with the rated load torque. The factor inertia FI is
the ratio of the total moment of inertia, to the moment of inertia
of the motor rotor.
2
Designation e.g. S4 - 25% - 129 c/h - FI.2 - J= 0,1 kgm - T =
M V
0,5 T.
V
Duty types
N R
P
N
P
Time
N
P
Time
Time
Period of one cycle
P
D N R
Time
Period of one cycle
P = Output power
D = Starting
N = Operation under rated condition
F = Electrical braking
V = Operation of no load
R = At rest and de-energised
20

S5
Intermittent duty with starting and electrical
braking
A sequence of identical duty cycles, each cycle consisting of a
significant period of starting, a period of operation at constant
load, a period of rapid electric braking and a rest and de-
energised period. The period is too short for thermal equilibrium
to be obtained.
After the duty type the following factors must be indicated: the
cyclic duration factor; the number of duty types per hour (c/h); the
factor of inertia FI; the moment of inertia J, of the motor, and the
M
permissible moment of resistance T (see duty type S4.)
V
2
Designation e.g. S5-40% -120 c/h- FI.3 - J= 1,3 kgm - T = 0,3 T.
M V N
S6
Continuous-operation periodic duty

A sequence of identical duty cycles, each cycle consisting of a
period at constant load and period of operation at no load. The
period is too short for thermal equilibrium to be obtained.
Recommended values for the cyclic duration factor are 15, 25, 40
and 60%. The duration of the duty cycles is 10 min.
Designation e.g. S6 40%
P
N
V
Time
P
D
N R
F
Time
Period of one cycle
Period of one cycle
S7
Continuous-operation periodic duty with
electrical braking

A sequence of identical duty cycles, each cycle consisting of a
period of starting, a period of operation at constant load and a
period of braking. Braking method is electrical braking e.g.
countercurrent braking. The period is too short for thermal
equilibrium to be obtained.
After the duty type the following factors must be indicated: the
number of duty cycles per hour c/h, the factor of inertia FI: the
moment of inertia J of the motor, and the permissible moment of
M
resistance T ( See duty type S4)
V
2
Designation e.g. S7 40% - 500 c/h - FI.2 - J= 0.08 kgm - T =
M V
0,5 T.
N
S8
Continuous-operation periodic duty with related
load speed changes
A sequence of identical duty cycles, each cycle consisting of a
period of starting, a period of operation at constant load
corresponding to a predetermined speed of rotation, followed by
one of more periods of operation at other constant loads
corresponding to different speeds of rotation. The period is too
short for thermal equilibrium to be obtained. This duty type is
used for example by pole changing motors.
After the duty type the following factors must be indicated; the
number of duty cycles per hour c/h; the factor of inertia FI; the
permissible average moment of resistance T (see duty type S4);
V
the cyclic duration factor for each speed of rotation and the
moment of inertia J of the motor.
M
Designation e.g.
S8 - 30 c/h - FI.30 - T = 24 kW - 740 rpm - 30%
V
30 c/h - FI.30 - T = 0.5 T = 60 kW - 1460 rpm - 30%
VN
30 c/h - FI.30 - T = 0.5 T = 45 kW - 980 rpm - 40%
VN
2
J= 2,2 kgm
M

The combinations of the load and speed of rotation are designed
in the order they occur in use.
S9
Duty with non-periodic load and speed variations

A duty in which, generally, load and speed are varying non-
periodically within the permissible operating range. This duty
includes frequently applied overloads that may greatly exceed the
full loads. For this duty type, suitable full load values should be
taken as the basis of the overload concept.
21
P = Output power
D = Starting
N = Operation under rated condition
F = Electrical braking
V = Operation of no load
R = At rest and de-energised

Space heaters
Motors subjected to atmospheric condensation, either through
standing idle on a damp environment or because of the wide
variation in the temperature of the surroundings, may be fitted
with a heater for extra precaution. The heater ensures that the
temperature of the air inside the motor, is maintained a few
degrees above that of the ambient to avoid any condensation.
Such heaters shall not be kept ON when the motor is operating.
These space heaters are generally rated for 240 V ac/dc.
For motors not having the provision of space heaters, 24 V dc
supply can be applied between any two terminals.
The leads of space heaters for frame 160 to 400 are terminated
in a separate auxiliary terminal box
Guide for fuse protection
In addition to the starters being used to protect motors from
overload and under voltage, the motors are protected with fuse
as per the following table
Protection accessories
0.37
0.55
0.75
1.1
1.5
2.2
3.7
4.0
5.5
7.5
9.3
11
15
18.5
22
30
37
45
55
75
90
110
132
160
200
250
1.2
1.6
2.1
2.9
4.0
5.7
8.3
9.5
12.2
15.5
19.4
22
29.5
37
42
52
66
80
98
128
155
188
223
270
332
415
6
6
6
6
10
16
16
25
25
25
32
32
50
63
63
80
100
125
160
200
225
250
315
355
400
500
10
16
16
16
25
25
25
50
50
63
63
80
100
125
160
200
200
250
300
350
500
kW Full load
current, A
Fuse rating, A
DOL start Y/D start
Characteristic of a thermistor
ohms
4000
1330
550
100
Typical value _
Shaded area = tolerance limits
Thermistors
PTC thermistor is the most common type of temperature
detector. It is the characteristics of the thermistors that its
resistance hardly varies with increasing temperature until the
threshold temperature is reached, thereafter the resistance
increases sharply as shown in figure below. Thermistors must
be connected to a separate control unit which trips power circuit
when the resistance in the thermistor circuit increases abruptly.
Thermistors generally provided are rated for 130°C (PTC 130)
for class B rise and 155°C (PTC 155) for class F rise.
Normally three thermistors are provided in series - one
thermistor in each phase. Six nos. (three nos. for tripping and
three nos. for alarm.) can be provided if intimated at the time of
enquiry.
Like space heaters, the leads of thermistors for frame 160 to
400 are terminated in a separate auxiliary terminal box.
22

Voltage drop along the cable
Determination of withstand capability
Since the negative sequence currents result in overloading, the
amount of negative sequence current carried by the winding as
a percentage of rated current can be used as a measure of
overloading due to unbalance. The thermal withstand
characteristics of the machine available for different overload
conditions can be used to represent the capacity of the machine
to withstand negative sequence voltage and current. The
negative sequence withstand characteristics are design specific
and will vary from motor to motor. A sample method for obtaining
negative sequence withstand characteristics of the motor is
given hereunder.
Sample calculation:
Let nominal voltage be 415 V and rated current be 60A.
Under unbalance condition let the voltages be
V = 385 L0° V
V =410 L120° V
V = 425 L 240° V
Average voltage = = 407V
Unbalance voltage = x 100 = 4.42%
Negative sequence voltage
V = =11.66Ð158° V
N
% negative sequence voltage = 11.66 / 407 = 2.86% (appx. 3%)
Now if the parameters of the machine are as given below:
R1 = 0.052
R2 = 0.071
X1 = 0.51
X2 = 0.53
s = 0.0123
thens1 = 2. 0.0123 = 1.9877
From the equivalent circuit diagram
V
N
(R1+ R2 1s1)+ j(X1 + X2)
11.66L158°
(0.052 + 0.071/1.9877) + j (0.51+ 0.53)
= 11.17 L -243.4°
This corresponds to 18.6% (approx. 20%) of the rated current
for the case considered here. This condition can be equated to
an overload of 20%. Now the thermal withstand characteristics
of the motor can be used to obtain the thermal withstand time
for this particular motor. Similarly, thermal withstand time for
different negative sequence voltage of voltage unbalance can
be calculated.
The following table gives the thermal withstand time of this
sample motor for different negative sequence voltage.
% negative % negative withstand time, sec
sequence sequence
voltage current Cold Hot
1 6 continuous continuous
2 10 continuous continuous
3 20 3500 1800
6 40 1600 600
9 60 1100 400
385 + 410 + 425
3
425 - 407
407
2
385Ð0° + a410Ð120° + a425Ð240°
3
Induction motors draw heavy currents during starting, resulting
in considerable voltage drop along the cable, If other loads are
connected in parallel to the motors, the voltage drop along the
common feeder causes operational problems to these
associated loads. Larger the starting current and longer the
common feeder, larger will be the voltage drop. In view of this
while specifying motors or cables, it is required to estimate the
right combination of starting current and cable size, alternatively, it
is important to know voltage drop for an installation when
starting / locking of motors occurs such that the maximum
voltage drop is less than 3%. The relative voltage drop, D u is
estimated as
where, U is the rated voltage of the motor
u is the voltage drop given as
u = b I
s
where u = Voltage drop
b = Factor equal to 1 for three-phase circuits and
equal to 2 for single phase circuits
r = Resistivity of conductors in normal duty
taken as being equal to the resistivity at the
normal duty temperature, i.e. 1.25 times the
resistivity at 20°C, giving 0.02250 mm2/m for
copper and 0.0360mm2/m for aluminium
L = Length of cabling in meters
S = Cross section of conductors in mm2
cosf =Power factor, if exact figure is not available it
is equal to 0.8 and sin~ = 0.6
l = Linear reactance of conductors, taken as
being equal to 0.08mQ/m if the exact figure
is not available
l = Current in use
S
Negative sequence withstand characteristics
Negative sequence withstand characteristics are used to obtain
capability of the motor to withstand the overloading caused by
negative sequence currents that occur due to unbalance in
supply voltage.
While % unbalance in voltage is given by the ratio
Max. deviation (phase value) from average value x 100
Average value
The negative sequence voltage, V for any degree of unbalance
N
can be calculated by
2
V = 1/3 (V + (aV + a V)
Na b c
2
where a = 1 L120° and a = 1 L240º
Estimation of negative sequence current
Once negative sequence voltage is known amount of negative
sequence current that is ultimately responsible for overloading
can be estimated from the following equivalent circuit of the
motor. The value of circuit parameters can be obtained from
design or from test results.
rx cosf + lLsinf
L
S(
Du = - *100
u
U
R
1
X
1 X
2R/S
21
23

The power factorcompensatingcapacitorsarespecifiedintermsofkVAR.TheinputkWofthemotorismultipliedbythereading
toobtainthenecessaryimprovementinthepowerfactor.
Example-Iftheinitialpowerfactor=COSf
1 =0.76
Inputactivepower =100kW
Correctedpowerfactor=COSf
2 =0.90
Fromthechart:capacitorkVARrequiredperkWload=0.37
hence
TotalcapacitorkVARrequired=0.37x100=37kVAR
Present Desiredpowerfactor,COSf
2
power
factor
COSf
1
0.7 0.75 0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96
0.30 2.16 2.30 2.42 2.48 2.53 2.59 2.65 2.70 2.76 2.82 2.89
0.35 1.66 1.80 1.93 1.98 2.03 2.08 2.14 2.19 2.25 2.31 2.38
0.40 1.27 1.41 1.54 1.60 1.65 1.70 1.76 1.81 1.87 1.93 2.00
0.45 0.97 1.11 1.24 1.29 1.34 1.40 1.45 1.50 1.56 1.62 1.69
0.50 0.71 0.85 0.98 1.04 1.09 1.14 1.20 1.25 1.31 1.37 1.44
0.52 0.62 0.76 0.89 0.95 1.00 1.05 1.11 1.16 1.22 1.28 1.35
0.54 0.54 0.68 0.81 0.86 0.92 0.97 1.02 1.08 1.14 1.20 1.27
0.56 0.46 0.60 0.73 0.78 0.84 0.89 0.94 1.00 1.05 1.12 1.19
0.58 0.39 0.52 0.66 0.71 0.76 0.81 0.87 0.92 0.98 1.04 1.11
0.60 0.31 0.45 0.58 0.64 0.69 0.74 0.80 0.85 0.91 0.97 1.04
0.62 0.25 0.39 0.52 0.57 0.62 0.67 0.73 0.78 0.84 0.90 0.97
0.64 0.18 0.32 0.45 0.51 0.56 0.61 0.67 0.72 0.78 0.84 0.91
0.66 0.12 0.26 0.39 0.45 0.49 0.55 0.60 0.66 0.71 0.78 0.85
0.68 0.06 0.20 0.33 0.38 0.43 0.49 0.54 0.60 0.65 0.72 0.79
0.70 0.14 0.27 0.33 0.38 0.43 0.49 0.54 0.60 0.66 0.73
0.72 0.08 0.22 0.27 0.32 0.37 0.43 0.48 0.54 0.60 0.67
0.74 0.03 0.16 0.21 0.26 0.32 0.37 0.43 0.48 0.55 0.62
0.76 0.11 0.16 0.21 0.26 0.32 0.37 0.43 0.50 0.56
0.78 0.05 0.11 0.16 0.21 0.27 0.32 0.38 0.44 0.51
0.80 0.05 0.10 0.16 0.21 0.27 0.33 0.39 0.46
0.82 0.05 0.10 0.16 0.22 0.27 0.33 0.40
0.84 0.05 0.11 0.16 0.22 0.28 0.35
0.86
0.06 0.11 0.17 0.23 0.30
0.88
0.06 0.11 0.17 0.25
0.90
0.06 0.12 0.19
0.92
0.06 0.13
0.94 0.07
Power factor improvement chart
24

Enclosure
Motors in frame 71 to 315 have cast iron enclosures and larger
ones have fabricated enclosures. Foot mounted motors have
integrated feet. The housing and the end shields are machined
to class tolerances to obtain perfect alignment and fits.
Core
The stator and rotor cores of the motor are made of high quality
cold rolled non-grain oriented magnetic steel having low iron
loss.
Protection against corrosion
Special attention has been paid to the finish. Polyurethane paint
is applied to motors. This provides an excellent finish and
protection against corrosion. The color of the paint is Munsell
Blue.
All the hardware are zinc passivated to give reliable anti-
corrosion protection under most server environmental
conditions.
Winding and insulation
The insulation of the motors meet class F requirements
(temperature limit 155°C) the normal temperature however
does not exceed the values permitted by class B (temperature
limit 130°C). The motors therefore have large overload margin
and long winding lifetime. If the temperature rise to class F is
allowed, the outputs given in the table can generally be
increased by approximately 12%.
Motor stators are wound with enamel wire and the winding is
then impregnated with solventless resin. The impregnation
effectively fills the gaps between conductors and makes the
winding mechanically strong, moisture and tropic proof.
The rotor cages of the motors upto 315 frames have die cast
construction whereas those of larger motors have fabricated
construction.
Earthing
Provision is given for earthing of motor. One earthing terminal
on terminal box and two earthing terminals on motor body are
provided.
Shaft and shaft extension
The shaft is made of EN8/C40 steel. On special request shaft
with EN24 steel can be offered. Standard motors have
cylindrical shaft extension in accordance with IS:1231.
Non standard shaft extensions on drive end are also available
on request. Orders should be accompanied by a sketch of the
shaft extension and if need be, a clear text description. A
second shaft extension has to be ordered as a special design.
All shaft extension of frame sizes have a drilled and tapped
shaft according to IS:1231. All standard flange motors comply
with tolerances N (normal) according to IS:2223 with respect to
shaft extension runout, concentricity and perpendicularity of the
extension in relation to the flange face.
Terminal box
As standard practice, the terminal box is located on the top of
the motor. Extended side terminal box can be offered for frame
90 to 280. The terminal boxes for frames 71 to 280 are
0
rotatable in the steps of 90 and are made of die cast aluminum
alloy. For frames 225 and 400 the terminal boxes are rotatable
0
in steps of 90 and are made from cast iron. For all the terminal
boxes protection of enclosure of IP 55.
Motor upto 1.5 kW (2 hp) are provided with 3 terminal and
others are provided with 6 terminals as standard practice. The
terminal plates and lead ferrules are marked U1, V1 and W1, of
U1, V1, W1 and U2, V2, W2. Terminal boxes have provision for
fixing cable glands to support copper or aluminum cables.
Drain holes
Motors for operation in very humid or wet environments, and
especially under intermittent duty, should be provided with drain
holes.
HX Motors from frame HX 180 onwards are provided with drain
holes and closeable plastic drain plugs in the drain holes. The
plugs will be opened, on delivery. When mounting the motors, it
should be ensured that the drain holes face downwards. In the
case of vertical mountings, the upper plug must be hammered
home completely. In very dusty environments, both plugs
should be hammered home.
Mechanical
Open
Closed
25

A RVM CDA RVM CD
1
2
3
4
6
8
14
31
51
16
17
91
5
12
18
7
11
01
9
20
21
22
23
1 Bearing Cover DS Outer
2 Endshield DS
3 Bearing DS
4 Bearing cover DS inner
5 Shaft extension key
6 Rotor assembly
7 Fan key
8 Wound stator
9 Terminal box
10 Terminal plate
11 Terminal box cover
12 Eye bolt
17 Fan
18 Circlip
19 Fan Cowling
13 Bearing NDS
14 Bearing Cover NDS Inner
15 Endshield NDS.
16 Bearing Cover NDS Outer
20
21
22
23
Grease Outlet Plug
Regreasing Hole
Drain Hole Plug
Earthing Bolt
Exploded view of HX motors
26

Pulley diameter
When the desired bearing life has been determined, the minimum
permissible pulley diameter can be calculated using Fas follows:
R'
D=
where:
D = Diameter of pulley, mm
P = Power requirement, kW
n = Motor speed, r/min
K = Belt tension factor, dependent on belt type
and type of duty. A common value for
V-belts is 2.5.
F= Permissible radial force
R
Permissible loadings on shaft
The tables below give the permissible radial force in newtons,
assuming zero axial force. The values are based on normal
conditions at 50Hz and calculated bearing lives for motor sizes 71
to 132 of 20000 hours and for motor sizes 160 to 400 of 20,000 and
40,000 hours.
Motors are foot-mounted 1MB3 version with force directed
sideways. In some cases the strength of the shaft affects the
permissible forces.
At 60Hz the values must be reduced by 10%. For two - speed
motors, the values must be based on the higher speed.
Permissible loads of simultaneous radial and axial forces will be
supplied on request.
If the radial force is applied between points Xand Xthe
0 max'
permissible force Fcan be calculated from the following formula :
R

F=F- (F - F)
R X0 X0 Xmax
E = length of shaft extension in basic version
7
1.9 x 10x K x P
n x F
R
F
R
X
X
0X
max
Permissible radial forces
Motor sizes 71 to 132
Length of Ball bearings
shaft
Motor extension 20,000 hours
size Poles E (mm) X(N) X(N)
0 max
71 2 30 415 335
4 30 415 335
6 30 415 340
80 M 2 40 670 545
4 40 890 725
6 40 970 830
90 SL 2 50 795 625
4 50 995 780
6 50 1135 880
100 2 60 1090 875
4 60 1360 1095
6 60 1560 1250
112 2 60 1410 1120
4 60 1735 1400
6 60 2000 1620
132 SM 2 80 1700 1330
4 80 2130 1660
6 80 2495 1935
27

Permissible radial forces
Motor sizes 160 to 400
Length of Ball bearings Roller bearings
shaft
Motor extension 20,000 hours 40,000 hours 20,000 hours 40,000 hours
size Poles E (mm) X(N) X(N) X(N) X(N) X(N) X(N) X(N) X(N)
0 max 0 max 0 max 0 max
160 2 110 2980 2310 2350 1810 5530 4260 4370 3360
4 110 3760 2900 2970 2290 6980 5380 5520 4250
6 110 4290 3300 3390 2750 7980 6150 6310 4860
8 110 4730 3660 3740 2880 8800 6780 6960 5360
180 2 110 3540 2880 2790 2260 6260 5080 4940 4010
4 110 4390 3560 3440 2790 7830 6350 6160 5000
6 1 10 5060 4110 3970 3220 9000 7300 7100 5750
8 110 5590 4540 4390 3560 9940 8060 7830 6350
200 ML 2 110 4510 3700 3530 2900 8520 7000 6710 5510
4 110 5660 4650 4430 3640 10710 8800 8440 6930
6 110 6470 5310 5050 4150 12250 10060 9640 7920
8 110 7160 5880 5600 5880 13520 11100 10650 8750
225 SM 2 110 4750 4010 3710 3130 9720 8200 7650 6450
4 140 6310 5040 4920 3840 12900 10310 10150 8120
6 140 7200 5760 5620 4500 14740 11800 11600 9280
8 140 7970 6375 6230 4980 16270 13010 12820 10250
250 SM 2 140 6100 4910 4750 3830 13600 10960 10710 8640
4 140 7650 6170 5960 5450 17100 13800 13470 10870
6 140 8700 7010 6760 5450 19520 15740 15360 12400
8 140 9630 7760 7505 6050 21550 17380 16970 13690
280 SM 2 140 7300 6200 5800 4900 20200 6600 16500 6600
4 140 9200 7800 7300 6200 25000 12000 20300 12000
6 140 10600 8900 8400 7100 28000 12000 23000 12000
8 140 11600 9800 9200 7800 30700 12000 25000 12000
315 SML 2 140 7300 6000 5800 4950 20200 6350 16500 6350
4 170 11300 9400 9000 7500 32500 10700 26500 10700
6 170 13000 10600 10300 8500 37000 10600 30000 10600
8 170 14300 10400 11300 9400 40000 10400 32700 10400
355 SM 2 140 9000 7900 6100 5300 26700 8900 21800 8900
4 210 15200 12500 12000 9850 45000 21400 36700 21300
6 210 17300 14300 13700 11300 51000 21100 41500 21100
8 210 19000 15700 15200 12400 55500 21700 45200 21700
355 ML 2 140 9100 7100 6100 5400 26900 7100 21800 7100
4 210 15200 12800 12000 10100 45500 19500 36700 19500
6 210 17300 14600 13700 11500 51000 19000 41500 19000
8 210 19300 16200 15200 12700 55500 19500 45200 19500
400 L 2 140 8900 3000 5700 3000 27000 3000 22000 3000
4 210 15000 13000 1 1700 10100 46000 15000 37000 15000
6 210 17200 13700 13600 11700 52000 13700 42000 13700
8 210 19200 15000 15000 12900 55500 15000 46000 15000
28

Permissible axial forces
The following tables give the permissible axial forces in newton,
assuming zero radial force. The values are based on normal
conditions at 50Hz with standard bearings and calculated
bearing lives of 20,000 and 40,000 hours.
At 60 Hz the values are to be reduced by 10%.
For two-speed motors, the values are to be based on the higher
speed. The permissible loads of simultaneous radial and axial
forces will be supplied on request.
Given axial forces Fassumes D-bearing locked by means of
AD'
locking ring.
Mounting arrangement 1M83
20,000 hours 40,000 hours
2-pole 4-pole 6-pole 8-pole 2-pole 4-pole 6-pole 8-pole
MotorF F F F F F F F F F F F F F F F
AD AZ AD AZ AD AZ AD AZ AD AZ AD AZ AD AZ AD AZ
size N N N N N N N N N N N N N N N N
71 270 270 350350 440440 - - 1) 1) 1) 1) 1) 1) - -
80 400 400 510 510 590 590 - - 1) 1) 1) 1) 1) 1) - -
90 450 450 560 560 640640 - - 1) 1) 1) 1) 1) 1) - -
100 620 620 780780 890 890 - - 1) 1) 1) 1) 1) 1) - -
112 810 810 1020 1020 1170 1170 - - 1) 1) 1) 1) 1) 1) - -
132 980 980 1220 1220 1400 1400 - - 1) 1) 1) I) I) 1) - -
160 2120 2120 2660 2660 3040 3040 3360 3360 1670 1670 21002100 2400 2400 2640 2640
180 2480 2480 3070 3070 3540 35403910 3910 1950 1950 2430243027802780 3070 3070
200 3050 3050 3850 3850 4400 4400 4850 4850 2430 2430 3050 3050 3500 3500 3850 3850
225 3440 3440 4340 4340 4960 496054605460 2730 2730 3440 3440 3940 3940 4340 4340
250 4180 4180 5260 5260 6020 60206630 6630 3320 3320 4180 4180 4780 4780 5260 5260
280 7300 5300 8000 6000 9000 7000 10000 8000 5750 3750 6200 4200 6900 4900 7700 5700
315 7000 5000 9000 7000 106008600 11600 9600 5600 3600 6900 4900 7900 5900 8900 6900
355 105003500 135006500 153008300 16800 9800 8750 1750 108003800 120005000 133006300
400L101003200130006000150008000165009500 83501350102003250118004800130006000
Mounting arrangement 1MV1
20,000 hours 40,000 hours
2-pole 4-pole 6-pole 8-pole 2-pole 4-pole 6-pole 8-pole
MotorF F F F F F F F F F F F F F F F
AD AZ AD AZ AD AZ AD AZ AD AZ AD AZ AD AZ AD AZ
size N N N N N N N N N N N N N N N N
71 290 260 380 330 460 420 - - 1) 1) 1) 1) 1) 1) - -
80 430 390 540 490 620 560 - - 1) 1) 1) 1) 1) 1) - -
90 480 420 610 520 700 600 - - 1) 1) 1) 1) 1) 1) - -
100 680 580 880 740 990 840 - - 1) 1) 1) 1) 1) 1) - -
112 890 760 1140 950 12801100 - - 1) 1) 1) 1) 1) 1) - -
132 1100 919 1390 1120 1580 1300 - - 1) 1) 1) 1) 1) 1) - -
160 2420 1820 3040 2280 3480 2600 3810 2920 1970 1370 2480 1720 2840 1960 30902200
180 2860 2100 3690 2450 4160 2920 4530 3290 2300 1570 3050 1810 3400 2160 36902450
200 3600 2500 4580 3120 5280 3530 5720 3980 2970 1870 3780 2320 4370 2620 47202980
225 4140 2740 5230 3440 6030 3900 6530 4400 3430 2030 4330 2550 5010 2870 54003270
250 50203330 6380 4150 7440 4610 8050 5210 4160 2470 5290 3060 6200 3360 66803840
280 8500 4300 9500 4600 11000 5500 12200 6600 6950 2700 7700 2800 8900 3350 97504200
315 SML 90003700 11600 5400 13500 6200 14500 7500 7450 2100 9450 3200 10900 3650 119004650
355 SM 14900800 19200 3100 22200 4100 24000 5800 13000 1) 16400 1) 18900 850 203002100
355 ML15000 1) 19800 1700 23100 2500 25000 4300 13100 1) 17000 1) 19800 1) 21300 1)
400 L 17300 1) 21800 1) 24300 1000 26200 2500 15400 1) 18900 1) 21100 1) 22500 1)
1) On request
F
AD F
AZ
F
AD
F
AZ
29

The standard test programmes are dividing into four parts:
routine tests, type tests, optional tests and special tests. The
routine test program is done to every machine. Type test is
performed in addition to routine tests normally to one of the
machines of a series of similar machines or by a request of the
customer. Optional tests are additional type tests subject to
mutual agreement between purchases and the manufacturer.
Special tests are needed if the machine has to run in special
conditions e.g. roller table, hazardous areas, cranes
applications. The special test program is specified by the
customer/consultant/standards bureaus.
If the motor will be fed by a frequency converter it is most often
tested together with the frequency converter.
Unless otherwise specified all the tests are performed
according to standard IS:325-1996.
Contents of test programmes:
Routine tests
1.Insulation resistance test
2.Measurement of resistance of the stator
3.Locked rotor test
4.No load test
5.Reduced voltage running test
6.High voltage test
Type test
1.Dimensions
2.Measurement of resistance of stator
3.Locked rotor test
4.Temperature rise test
5.Full load test
6.No load test at rated voltage
7.Reduced voltage running test
8.Momentary overload test
9.Insulation resistance test
10.High voltage test
Optional tests
1.Vibration severity test
2.Sound level measurement
3.Degree of protection test
4.Temperature rise test at limiting values of voltage and
frequency variation
5.Over speed test
6.Test on insulation system
Special tests
1.Acceleration constant test (B value test, for roller table
motors)
2.t time test (for increased safety motors)
E
3.Suitability to PWM supply
Testing
30

Squirrel cage induction motors offer excellent availability,
reliability and efficiency. In addition to that, a motor with a
frequency converter - variable speed drive (VSD) - has even more
excellent properties. A variable speed drive motor can be started
softly with low starting current, and the speed can be controlled
and adjusted to suit the application demand without steps over a
wide range. Also the use of a frequency converter together with a
squirrel cage motor usually leads to remarkable energy savings.
Most of the squirrel cage motors manufactured by ABB are
suitable for variable speed use, but in addition to the general
selection criteria, the following points must be taken into account:
1. Dimensioning
The voltage (or current) fed by the frequency converter is not
purely sinusoidal. This may increase the losses, vibration, and
noise of the motor. Furthermore, a change in the distribution of the
losses may affect the motor temperature balance and lead to an
increase in the temperature of the bearings. In every case, the
motor must be correctly sized according to the instructions
supplied with the selected frequency converter.
When using ABB converters use the Drive Size dimensioning
program or "ISOTHERM GUIDE-LINES" of the corresponding
converter type for sizing the motors. The loadability curve of a
standard motor used with a ACS 600-frequency converter can be
found from figure 3.
2. Speed range
In a frequency converter drive, the actual operating speed of the
motor may deviate considerably from its nominal speed (i.e. the
speed stamped on the rating plate).
For higher speeds, ensure that the highest permissible rotational
speed of the motor or the critical speed of the entire equipment is
not exceeded. When high speed operation exceeds the nominal
speed of the motor, the following points should be checked:
• Maximum torque of the motor
• Bearing construction
• Lubrication
• Balancing
• Critical speeds
• Shaft seals
• Ventilation
• Fan noise
Permissible maximum speeds for standard motors are described
in figure 1.
Figure 1.
Maximum permissible speeds for basic motors
Frame size Speed r/min
2-pole 4 -pole
71 - 200 4000 3600
225 - 280 3600 2600
315 3600 2300
355 3600 2200
400 3600 1800
At low speed operation the motor's ventilation fan loses its cooling
capacity, which causes a higher temperature rise in the motor
and bearings. A separate constant speed fan can be used to
increase cooling capacity and loadability at low speed. It also
important to check the performance of the grease at low speeds.
3. Lubrication
The effectiveness of the motor lubrication should be checked by
measuring the bearing temperature under normal operating
conditions. If the measured temperature is higher than + 80°C, the
relubrication intervals specified in ABB' s standard instruction
manuals must be shortened; i.e. the relubrication interval should
be halved for every 15K increase in bearing temperature. If this is
not possible ABB recommends the use of lubricants suitable for
high operating temperature conditions. These lubricants allow
normal relubrication interval and a 15K increase in bearing
temperature conditions.
4. Insulation protection
If the frequency converter has IGBT power components with very
rapid switching, practically all cables between the converter and
the motor will be long. In that case, steep voltage pulses and
reflections at the cables increase voltage stresses at the winding
of the motor and therefore, the precautions described in figure 2
below must betaken to avoid risks of insulation damage.
For GTO converters, consideration must be given to the
information about cable length, pulse rise time and the voltage
overshoot using the voltage/ cable length guideline.
5. Bearing currents
Bearing voltages and currents must be avoided in all motors.
When using an IGBT frequency converter insulated bearings
and/or a properly dimensioned filter at the converter output must
be used according to instructions in figure 2 below. (For other
alternatives and converter types, please contact ABB.) When
ordering clearly state which alternative will be used.
For more information about bearing currents and voltages, please
contact ABB.
6. Cabling, grounding and EMC
The use of a frequency converter causes some extra
requirements on the cabling and grounding of the drive system.
The motor must be cabled by using shielded symmetrical cables
and cable glands providing a 360º bonding (also called EMC-
glands). For motors up to 30 kW unsymmetrical cables can be
used, but shielded cables are always recommended.
For motor frame size 280 and upward, additional potential
equalisation between the motor frame and the machinery is
needed, unless they are installed on a common steel fundament.
When a steel fundament is used for the potential equalisation, the
high frequency conductivity of this connection should be checked.
More information about grounding and cabling of a variable speed
drive can be found from the manual "Grounding and cabling of the
drive system" (Code: 3AFY 61201998RO125REVA)
Motors for frequency converter drive
31

For fulfilling the EMC requirements, special EMC cable(s) must be used in addition to the correct cable gland mounting, with special,
extra earthing pieces. Please refer to the manuals of the frequency converter.
Figure 2. Selection rule for insulation and filtering in variable speed drives
dU/dt filter
Series reactor. dU/dt filters decrease the changing rate of the
phase and main voltages and thus reduce voltage stresses in
the windings. dU/dt filters also decrease so called common
mode currents and bearing currents.
Common mode and light common mode filters
Common mode filters are made of toroidal cores installed
around motor cables. These filters reduce so called common
mode currents in VSD applications and thus decrease the risk
of bearing currents. Common mode filters do not significantly
affect the phase or main voltages on the motor terminals. For
the exact type of the core, please contact ABB.
Common Mode Filter = 3 toroidal cores per each 3-phase motor
cable
Light Common Mode Filter = 1 toroidal core per each 3-phase
motor cable
Figure 3. Motor loadability with ACS 600, Field weakening point 50Hz.
U
N
<500 V
U
N
<690 V
U
N
<600 V Standard motor
+ dU/dt-filter
OR
Reinforced insulation
Reinforced insulation
+ dU/dt-filter
Standard motor Standard motor
+ Insulated N-bearing
Standard motor
+ dU/dt-filter
OR
Reinforced insulation
+ Insulated N-bearing
Reinforced insulation
+ dU/dt-filter
Standard motor
+ Insulated N-bearing
+ Common mode filter
Standard motor
+ Insulated N-bearing
+ dU/dt-filter
OR
Reinforced insulation
+ Insulated N-bearing
+ Common mode filter
Reinforced insulation
+ Insulated N-bearing
+ dU/dt-filter
+ Light Common mode filter
Motor nominal power P or frame size
N
NP < 100 kW
NP 100 kW or IEC 315
3
<
NP 350kW<
Motor loadability with ACS 600
The loadability curve in figure 3 below is a guide line curve, for exact
values please contact ABB.
These guidelines present the maximum continuous load torque of a
motor as a function of frequency (speed) to give the same temperature
rise as with rated sinusoidal supply at nominal frequency and full rated
load.
The temperature rise of squirrel cage motors manufactured by ABB is
normally class B. If the ABB catalogue indicates that class F
temperature rise is utilised on a sinusoidal supply, the dimensioning of
the motor at frequency converter supply should be done according to
the temperature rise class B loadability curve
For further information, please contact ABB. .
32

Guide and check points for motor selection
(mechanical aspects)
1000m or less Altitude
Above 1000m Environment Corrosion
45°/50°C or less Ambient Dust, carbon, Etc
Low Temperature Humidity
Housing Protection Drip proof, IP23
Totally enclosed, IP55
Special, IP56
Totally enclosed
fan cooled Ventilation
Separately cooled
Natural cooled
Standard
Double shaft Shaft end Power Transmission Direct
Tapered Belt
Special Gear box
Mounting Foot
Horizontal Installation Flange
Vertical Face
Dimension IS/IEC
User specific
Epoxy Terminal Plate Terminal Box Position TOP/LHS/RHS
Bakelite Material Cast iron
Aluminum
Single armour Type
Double armour Cable Entry Bottom
Without armour Top
One or two Numbers side
size
Noise Standard
Low
Standard Vibration
Precision
Bearings Ball
Roller
Special paint shade Thermistor
Special name plate Others Space heater
Direction of rotation Brake
Tacho
33

Drive torque Characteristics Torque
Operating speed of the load characteristics
Transfer efficiency
2
Load GD Operating Continuous operation
Load torque characteristics Intermittent duty & CDF
Equivalent starts
per hour
Rated output Single speed
and speed Dual speed
VVVF application
Single voltage with variations voltage
110V - 660V
Dual voltage - l / D
D / DD
Frequency 50 Hz
Any other frequency
Type of starting DOL start
Star-Delta start
Auto-transformer start % tapping
Soft start
Mechanical Braking
Plugging
DC injection
Regenerative
Torque
Characteristics Normal starting
High torque
Soft starting (Low pull out torque)
B/F Temperature
F/F rise / insulation
F/H
Determination
of motor
specification
Guide and check points for motor selection
(electrical aspects)
34

Customer Name_____________________________________
Date______________________________________________
Application_________________________________________
01Output_______________kW (___________________hp)
02Frame size____________________________________
03Volatge______________________________________V
04Voltage variation_______________________________%
05Frequency Hz 50 60, Other___________________Hz
06Frequency variation____________________________%
07Number of poles
08Ambient temperature
45°C
50°C
0
Special (Specify)_____________________________C
09Temperature rise by resistance method
70°C
75°C
100°C
0
Special (Specify)_____________________________C
10Altitude
Standard (Sea level upto 1,000m)
Special (Specify)
11Insulation B F H
12Duty Continuous (S1)
Other(Specify)______________________
13Environment
High humidity Dusty Tropical
Corrosive gas, vapour
Area classification class
Temp. Class______________ Division__________
14Enclosure
Open drip proof (IP23)
TEFC(IP44)
TEFC(IP55)
Type 'n' (Non sparking)
Type 'e' (Increased safety)
Type 'd' (Flame proof)
Special (Specify)
15 Construction
Horizontal Vertical Special
16Mounting
B3 V1 Other(Specify)
17Applicable codes and standards
IS 325
IS 6381 (Increased safety motors)
IS 9628 (Non sparking motors)
IS 3682 (Flame proof motors)
IPSS:1-03-007-85 (A.C. roller table motors)
IS 2972 (Textile application)
IS7538 (Agriculture application)
Other_______________________________________
18Starting current
600% subject to IS tolerance
600%maximum
Other_________________% full load current
19Starting method
Direct-on-line (full voltage)
Star-Delta
Auto-Transfer___________%taping____________secs
Frequency converter
• Frequency range____________Hz to____________Hz
• Fieldweakning point____________________________
• Load torque speed curve________________________
20Braking details
No braking
Electromechanical braking
Countercurrent(Plugging)_________________no./hour
D.C. injection___________________________no./hour
Reversal by plugging_____________________no./hour
Other (specify)________________________________
21Winding connection
Star Delta Special________________________
22Starting duty
1 Hot, 2 Cold, 3 Equally spread
Special (Specify)
23Load inertia with respect to motor shaft
22
Actual GD___________kgm at ___________rev./min
24Load torque curve
Enclosed
Not enclosed
25Method of coupling
Flexible Belt Gear box
Fluid Other ____________________________
26 Belting data
Motor pulley dia. and wt.____________mm________kg
Load pulley dia. and wt._____________mm________kg
Centre distance between pulleys_______________mm
Type of belt___________________________________
No. of belts___________________________________
27Direction of rotation
Bi-directional
Clockwise from driving end
Anti-clockwise from driving end
Ordering Information
35

28Terminal Box
Without
With
Location
Top on driving end
Right side from driving end
Left side from driving end
Special (specify)______________________
29Terminal box construction
Stud type 3 terminals
Stud type 6 terminals
Other_______________________________________
External power cable
Type________________________________________
No. of cable____________No. of core______________
2
Conductor sectional area_____________________mm
Diameter : Overall ___________________________mm
Inner sheath_______________________mm
Conduit size____________________________________
Special (specify)_______________________________
30Anti-condensation heater
Not required
________________Volt
Special (specify)_______________________________
31PTC Thermistors
Class B 130°C
Class F 155°C
Special (specify)_______________________________
32Paint
Standard Munsel Blue
Epoxy shade 631 of IS 5
Any other__________________________shade of IS 5
33Balancing
Half key (ABB standard)
full key
33Special features
Export packing
Tropical protection
Foundation bolts
Jacking facility
Jacking bolts
Grounding lug
Cable gland
Cable lugs
Special (specify)_______________________________ 35Mounting base
Not required
Slide rails
Special(specify)_______________________________
36Thrust for vertical motor
Design thrust Up__________kg Down _______kg
Momentary thrust
Up__________kg Down _______kg
37Rotor end float
ABB standard as per IS
Special(specify)____________________________mm
38Test
ABB standard (Non-witnessed)
Routine test as per IS 325
Witness routine test as per IS 325
Witness type test as per IS 325
Special (specify)_______________________________
39Any special requirement __________________________
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
Prepared by ___________
Dated ___________
36

Q. What are the general performance concerns of
motor?
Rated current, speed, starting current, starting torque, efficiency,
power factor, noise and vibration. Above all is the temperature rise
of the motor in accordance with operating environment and class
of insulation.
Q. Why is the consideration for efficiency growing ?
Higher efficiency means lower kW power drawn from electric
supply and hence, lower electricity bills. Further, energy efficient
operation has been a top social obligation from an environmental
and global viewpoint.
Q. How are efficiency and power factor
correlated?
Due to continuous innovations made in the designs of motors,
over the years, values of efficiency and power factor in standard
motors have reached an optimum level. Thus here onwards,
unless an entirely new series of motors are made, improvement in
one adversely affects other. That is, in standard motors, an
attempt to improve efficiency normally results in lower power
factor and vice-versa.
Q. What is efficiency based design (EBD) and
what is power factor based design (PFBD) ?
Around the world, in standard series motors, there are two design
philosophies. One is called "Efficiency Based Design (EBD)" and
the other is called "Power Factor Based Design (PFBD)". In the
former case, the basic design including stamping designs are
optimised for maximising efficiency, while retaining power factor
to reasonably acceptable level. Where as in the latter case, it is
otherwise.
Q. What is the difference in electromagnetic
parameters in case of the above two designs?
EBDs are based on lower losses and hence lower resistances.
Lower resistance in the circuit could lead to lower power factor.
Where as PFBDs have higher rotor resistances.
Q. How EBDs and PFBDs compare on other
performance parameters?
Since EBDs have lower rotor resistances, the starting torque
could be lower. To compensate this, flux level might go up leading
to higher magnetic current.
Q. How about starting current?
Starting current is dependent on stator and rotor leakage
reactances and resistances. Since leakage reactances and
resistances are lower for EBDs, the starting current is likely to be
higher as compared to the case of PFBDs.
Q. What is no-load current and why is one
concerned about it?
No-load current is a quality control parameter used to check
health of motor as per design and manufacturing practice. It is a
normal practice to provide this data to the customer for each
motor, so that the motor could be subjected to routine test, as and
when required.
Q. What is the normal value of no-load current?
There is no standard value of no-load current. It depends on the
design philosophies and manufacturing practices. This parameter
is in-fact manufacturer specific and its value varies widely from
manufacturer to manufacturer. Further, pole number and size of
motor greatly influence values of no-load current. Value of no-load
current can vary from 20% of full load current for 4 pole motors to
80% for 8 pole motor. Similarly, in smaller motors the value of no-
load current as a percentage of full load current is much higher as
compared to larger motors. In smaller motors of higher pole
numbers, there are cases where no-load current is higher than full
load current.
Q. How is no-load current related to the design
philosophy?
Since EBDs use magnetic circuit more optimally than electric
circuit, the magnetising current could be higher as compared to
PFBDs. This could lead to higher no-load current in EBD designs.
Q. Is there any adverse effect of higher no-load
current on the motor?
No, if the motor is designed for higher no-load current, it would
have no effect on its declared performance and life.
Q. Does higher no-load current design affect
other performance parameters?
Only in a few cases, the rated current of EBD motors could be
slightly higher than that of PFBD motors. Since the motor is
designed for the rated current, declared performance is
guaranteed. But in terms of input kW, EBD motors would result in
lower electricity bills. After all it must be understood that no-
load current is a quality control parameter and not a
performance parameter.
Q. Why EBDs are more popular than PFBDs ?
Both efficiency and power factor can be built into the motor. But
once the motor is built, efficiency can not be improved by external
measures, though, power factor can be improved by using
capacitors. Hence, the usual practice is to maximise the motor
efficiency at design stage and improve power factor at operational
stage i.e. by capacitors. A case study of benefits in energy saving
by employing EBD motor is illustrated below for 3 number 30kW
/4pole motors in a pump application.
Parameter PFBD EBD
motor motor
Efficiency, % 90 92.5
Power factor 0,89 0.83
Ampere= Rated kw/(sqrt(3)xVxEffxPower factor) 52 54
Input power=Rated Power*100/Eff, kW 33,333 32.432
Pdiff=Difference in Input Power, kW 0.901
Energy saved/year, kWh=Pdiff x No. of hours/yr
when each pump runs 8 hr/day 7081
kWh = Pdiff x 7860
Saving in Rs., @ Rs.3.50/- per kWh 24784
Frequency asked questions
37

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Technical guide for selection of LT motor

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