what are the protection relays for LT panel.

For power distribution/MCC/Genesets you need OC,EF,Phase failure,undervoltage, overvoltage, phase sequence,reversepower,phase unbalance etc

What is the type of connected load ? To Which you need protection, source or load ? What is the source ?

It is a commerial office building of 4000 KW load, where chiller, AHU, office lighting, etc. are used. The source is the 3* 1010 KVA generator and 2*2000 Kva transformer . The state incoming supply is 11KV/433v.


Basically this question is asked by me in an interview, So i want the idea that, there are protection available for transformers and diesel generator set but for PCC Panel except the surge protect what other protection relays are used?

As per Sekhar comments it depends on type of LV Panel,
For MCC Mr.Sinnadurai comments are applicable.

For LV Switchgear there are many types.
LV Switchgear that is intended to be used for public distributions ( to feed feeder Pillars/ ST or Load centres) where all the out going feeders are protected by HRC fuses and the incomers are Isolator (whether motorized or not), the protection can be achieved from the primary side while the Standby Earth Fault relay to be provided where its CT to be located in the Transformer LV Termination Box.

LV Switchgear that is intended to be used for industrial purposes where all the out goings feeder may be protected by MCCB /ACB ,,etc and the incomers are mainly ACB (MCCB. ICCB) , the protection scheme may be as per Mr.Sinnadurai comments