Schematic diagrams slides

Learn about schematic diagrams in circuit wiring. Learn how to read a schematic diagram and build a circuit from the symbols and diagrams from ground zero. Visit skillcatapp.com to learn more from our free courses.

1. SkillCat

2. Schematic Diagram

Wiring Diagrams

Schematic Diagrams

LEGEND

3. Schematic Diagrams

In this module, we will introduce you to the schematic diagram.
We will cover:

+ The diagram,
The notes,

+ The legend, and
+ How to read a schematic diagram

4. HH what is a schematic Diagram? Schematic: Diagram)

A schematic diagram is a
blueprint of the electrical
components within a system.

Schematic diagrams include
a diagram, notes, and a
legend

See the picture to the right
for an example of schematic
diagram.

5. HH why Read a Schematic Diagram?

Schematic diagrams can be
used to:

«See components in a
circuit, and

«See how components are
wired

Aschematic diagram shows
the wiring of each
component in the circuit.

Schematic diagrams are very
useful when you are
troubleshooting or wiring a
circuit.

Schematic Diagram

"Door.
BLOWER
= MOTOR

6. HME reading the Legend

The best place to start
when reading a
schematic diagram is
with the legend.

The legend will explain
what some symbols on
the schematic diagram
mean.

LEGEND

FACTORY POWER WIRING
— FACTORY CONTROL WIRING
== FIELD CONTROL WIRING
+ FIELD POWER WIRING
© COMPONENT CONNECTION
A FIELD SPLICE
4 JUNCTION

"CH
*CHS
Ku)
“015
“HPS
‘US
"15
“
“SR
‘ST

CRANKCASE HEATER
CRANKCASE HEATER SWITCH
COMPRESSOR TIME DELAY
DISCHARGE TEMP SWITCH
HIGH PRESSURE SWITCH
LIQ LINE SOLENOID VALVE
LOW PRESSURE SWITCH
START CAPICATOR

START RELAY

START THERMISTOR

CONT CONTACTOR

CAP CAPACITOR (DUAL RUN)
COMP. COMPRESSOR

IFR INDOOR FAN RELAY

OFM OUTDOOR FAN MOTOR

*MAY BE FACTORY INSTALLED

7. HH reading the Legend schematic Diagram

For example, look at the
schematic diagram to the
right.

You can see that there are
abbreviations on the
diagram like CONT, CAP, and
cH.

Without reading the legend,
you cannot understand the
abbreviations and the
components of the circuit.

8. BEE reading the notes Section

After you read the legend, it
is important to read the
notes section of the
diagram.

The notes section can have
important information
about the circuit.

NOTES

. When start relay and start capacitor are installed, start thermistoris not used.

, CH not used on all units,

. Ifany of the original wire, as supplied must be replaced, use the same or
equivalent wire,

. Check all electrical connections inside control box for tightness,

. Donot attempt to operate unit until service valves have been opened.

. Donot rapid cycle compressor. Compressor must be off 3 minutes to allow
pressures to equalize between high and low side before starting,

Wire not present if HPS, LPS or CTD are used.

9. BEE reading the notes Section

—
For example, the notes section
may have a note about the
crankcase heater (CH) on a
schematic diagram.

The notes may say something
like “CH not used on all
diagrams”,

If you did not read the notes,
you may have an incorrect
understanding of the circuit. The
CH may not be present.

"4

NOTES

. When start relay and start capacitor are installed, start thermistor is not used,
CHnot used on all units,

.. Ifany of the original wire, as supplied must be replaced, use the same or
equivalent wire

|. Checkall electrical connections inside control box for tightness.
Donotattemptto operate unit until service valves have been opened.

. Donot rapid cycle compressor. Compressor must be off 3 minutes to allow
pressures to equalize between high and low side before starting,

_Wire not present if HPS, LPS or CTD are used,

10. HB the Diagram Schematic Diagram

The next step is to look at ee
the diagram on the

schematic.

Each symbol on the diagram
represents a component
within the circuit.

The lines running between
each component represent a [ wo
wire.

IK gg ALUIPNAG, >) wenn

11. Two Sides Of The Circuit

There are two sides of every
circuit:

sLine side

«Control side

Components on the line side
of the circuit will receive a
higher voltage. For example,
230V.

Components on the control
side of the circuit will
receive a lower voltage. For
example, 24V.

208/230
1D
POWER
SUPPLY

12. BEE Line voltage

Ll and L2 power the line side
of the circuit.

Ll and L2 represent the two
poles on an AC power supply. 208/230

The picture to the right shows 1 @
Ll and L2 on a schematic POWER

diagram. Note that the line

voltage is labeled above LI SUPPLY
and L2.

13. BEER the Line Side of the circuit

The line side of the circuit will
have bolder wiring
connections than the control
side,

The line side will also have L1
and L2 nearby.

The picture to the right shows
the line side of the circuit.
Note that the wiring lines are
bolder than the bottom half of
the diagram.

Schematic Diagram

14. BEER contro! voltage

The control side ofthe circuit
can be powered by an
external power supply.

The control voltage will
usually be a lower value than
the line voltage, for example,
24V.

The image to the right
highlights an external power
supply.

BRN / VEL

WO

*HPS *DIS ‘Les

ACTA
TT Oe

“Us
AN

INDOOR THERMOSTAT

I ax AA A aux Ir - -
TAO

I be /
|
I

à Pe
BLU/PNKA_—\ BLU
y Blk y! br EW,

\e/

lies

j 8
à UL.

“INDOOR
BLOWER
MOTOR

EXTERNAL POWER SUPPLY 24V

Schematic Diagram

15. BEER the control Side of the circuit

The control side of the
circuit will have thinner
wiring lines than the line
side of the circuit.

The picture to the right
shows the control side of a
circuit.

Note that the wiring lines
are thinner than the top part
of the diagram.

[e

208/230

INDOOR THERMOSTAT

| exrennaL power SUPPLY 26v

Schematic Diagram

16. Recall that the lines
between components on a
schematic diagram
represent wires.

There are two main types of
wiring on a circuit:

«Field wiring

«Factory wiring

LEGEND

777 FACTORY POWER WIRING

—— FACTORY CONTROL WIRING|

"= 7 - FIELD CONTROL WIRING
FIELD POWER WIRING

17. Recall that factory wiring is
done by the manufacturer.
Field wiring is done by the
technician.

Factory wiring is
represented by a solid line
on the diagram.

Field wiring is represented
by a dashed line on the
diagram.

LEGEND

777 FACTORY POWER WIRING

—— FACTORY CONTROL WIRING|

"= = FIELD CONTROL WIRING
FIELD POWER WIRING

18. HB Wire colors

Most schematic diagrams will
also tell you the color of
wires.

On each line in the diagram,
you will see a symbol. For
example, BLK or BLU.

BLK stands for black wiring
and BLU stands for blue
wiring. Some legends will
define the color symbols.

19. HEME reading symbols Schematic Diagram

Recall that a schematic
diagram represents
components with symbols.

Ona diagram, some
symbols will have a black
border around them.

You can see an example in
the picture to the right.

20. BEE reading symbols

A black border around a
group of symbols indicates
the internals of a single
component.

For example, the image to
the right shows a contactor
on a schematic diagram.

You can see that the
contactor is labeled CONT,
and it has a black box
around several internal
components.

21. Reading Symbols

The diagram shows the
internal components so that
you can determine the type
of contactor.

In the picture, you can see
that this is a single pole
contactor since there is only
one contactor switch.

There is one contactor switch
between 11 and 12, a wire
running beneath the switch,
and a coil underneath the
wire.

22. WE circuit connections

Aschematic diagram can also
be used to determine how
components are wired to each
other.

For example, view the image
to the right.

You can see that this image
shows a dual run capacitor,
start capacitor, start relay, and
a start thermistor.

23. WE circuit connections

Start by looking at the dual run
capacitor on the left hand side
of the image

You can see that a blue (BLU)
wire runs from the HERM
terminal on the compressor to
the start thermistor.

The wire is highlighted in blue
in the image.

24. WE circuit connections

Look at the dual run capacitor
again.

You can also see that a yellow
wire runs from the common
terminal on the dual run
capacitor to the start
capacitor.

The wire is highlighted in
yellow in the image.

25. Schematic Diagram

HE conclusion

In this module, you learned
how to read a schematic
diagram.

Always read the notes and
legend before looking at the
diagram.

Schematic diagrams display
the components and wiring
within a circuit.

LEGEND