FEEDER AND BUS BAR PROTECTION

Plug Setting Multiplier and Time Multiplier Setting

1. LENDI INSTITUTE OF ENGINEERING AND TECHNOLOGY Jonnada , Andhra Pradesh- 535005 Department of Electrical and Electronics Engineering UNIT -IV FEEDER AND BUS BAR PROTECTION Presented by, Dr. Rohit Babu, Associate Professor

2. Syllabus Department of Electrical and Electronics Engineering Protection of lines Over current Protection schemes PSM, TMS Numerical examples Carrier current and three zone distance relay using impedance relays Protection of bus bars by using Differential protection

3. PSM & TMS Department of Electrical and Electronics Engineering Plug Setting Multiplier (PSM) and Time Setting Multiplier (TMS) are used only for Electromechanical Relays. PSM  and  TMS  settings are the settings of a relay used to specify its tripping limits.    Plug setting multiplier (PSM) Indicates the severity of the fault.

4. PSM & TMS Department of Electrical and Electronics Engineering Plug Setting Multiplier  actually refers how dangerous the fault is and in what time it should be cleared. Changing the position of plug changes the number of turns of the pickup coil. Time Multiplier Setting  used to change the value of operation of the relay. If it is more the relay will take more time to operate and vice versa. Changing the position of TMS setting, changes the distance between the contact of the rotating disk and the coil.

5. PSM & TMS Department of Electrical and Electronics Engineering

6. PSM & TMS Department of Electrical and Electronics Engineering PSM is nothing but a ratio between the actual  fault current  in the  relay  operating coil to  pick up current  (the relay current setting). In other words, the ratio between the CT secondary current to relay operating  current  is called PSM.

7. PSM & TMS Department of Electrical and Electronics Engineering The plus setting multiplier is used only in electromagnetic relays, not in numerical relays. Therefore, the numerical relay does not require plugs.

8. Example Department of Electrical and Electronics Engineering If the plug position 5 means the relay operates when the fault current is 5 times of the CT ratio. i.e The supply CT is rated 400:5A and the  fault  current will be 3200A means, the plug position is 5 then the relay operates, because of the relay gets the current value of 25 Amps. Sol. The operating Times is depending upon the PSM. The high value of PSM indicates low operating time. In our case PSM is 8, hence the relay trip the circuit in 2 seconds wheres the TMS is 100%.

9. PSM & TMS Department of Electrical and Electronics Engineering Time Setting Multiplier (TSM):

10. PSM & TMS Department of Electrical and Electronics Engineering What is TMS or Time setting multiplier: TMS is nothing but an adjusting or speeds up the tripping mechanism of the relay (it is called as the dial). The dial is nothing but a rotating disc, which rotates when the fault current in the relay coil reaches the pickup current. It means, one end connects with the tripping mechanism and another end connect with the relay operation mechanism. By changing the dial or disc position we can increase or decrease the tripping time of the relay.

11. PSM & TMS Department of Electrical and Electronics Engineering Here the position zero indicate the tripping position and green colour shade indicate the operating position. In the first disc, position indicates the TMS is 10%. It means the relay operating time is 10% of the Plug setting multiplier time. Time setting value will be 10%, 25 %, 30 % …100% like that.

12. PSM & TMS Department of Electrical and Electronics Engineering The total relay operating time= Plug setting Multiplier time (Which is available in the relay) * Time Multiplier Setting Take an example of the above mentioned, in this, consider relay TMS is 10% and PSM=8.. Hence the timing for PSM 8, Time =2 sec…then the relay operating time is 2 * 10% = 0.02sec.