Want To Know About Earth Fault And Over Current Relay Setting

Still plugging for a fast buck EE

Yes! But how does that matter to you? If you are not interested, please keep quiet.

ensure overcurrent settings do not interfere with any normal operating currents. i.e The TCC of overcurrent relays should be above the normal operating currents

for earth fault relays the PMS and TMS must be initially set to close to minimum

Perform short circuit study calculations and identify the faults through the relays [both for phase and earth fault relays]

compute the relay operating time for fault current [for all primary and backup pairs]

If Backup is not having adequate discrimination, update its tms, pms or both to achieve the required discrimination in operating time.

IN THE BEGINNING YOU HAVE TO READ THE CHAPTER: NETWORK ANALYSIS AND FAULT CALCULATIONS_INTRODUCTIONS TO FAULT CALCULATIONS_SYMMETRICAL COMPONENTS_FAULTS ON POWER SYSTEMS.

THEN FROM BASIC THEORY U WILL BE ABLE TO CALCULATE FAULT CALCULATIONS.

APART FROM THAT U CAN USE SOFTWARES-ETAP/PSS SINCAL/CYME ETC .

BUT EVEN U USE SOFTWARE U HAVE TO PROVIDE CORRECT INPUT FOR THE BASIC DATA THAT KNOWLEDGE U GET FROM READING ANY STANDARD ENGG BOOK EG FAULT CALCULATION CHAPTER ONLY.

THERE IS NO SHORT CUT.

SOME GOOD BOOKS IN INDIA_SWITCHGEAR PROTECTION_S RAO./POWER SL UPPAL

TRANSMISSION &DISTRIBUTION_ A.T.STAR

The definite time [50,50N] settings for backup relays must be restricted to primary zone protection of backup relays only.

These can be used for load end relays where relays are not backup to other relays and have only primary protection function.

Can I set T.M.S through Time Dial of relay?????

Where I live the protection settings are calculated by the power network monitoring people. One substation cannot be take out of the network to calculate its protection settings. There must be a coordination between other protections in the network and those guys know all of this. talk to them.