The Transformer protection tripping can grouped as follows
1. SET-1 Main Protection
The main protection can be divided in to two groups (CB TC-1 Tripping)
a. LOR 86-1 ( Neumarical relays protection)
1.Differential protection (86T)
2.REF protection (87 REF)
3.HV side Over Flux protection (24 - HV/T)
b. LOR 86-3 ( Mechanical protection)
1.Buchhloz Relay trip - Main tank (63 T)
2.WindingTemp High Trip - Serious Winding Main Tank (49 W-TS)
3.Winding Temp High Trip - Common Winding Main Tank ( 49W-TC)
4.Winding Temp High Trip - Tertiary Winding ( 49 W-TT)
5.Buchhloz Relay trip - OLTC (62-OLTC)
6.Buchhloz Relay Trip - Grounding Transformer (63- GT)
2. SET-2 Back up Protection
The back up protection can be divided in to two groups (CB TC-2 Tripping)
a. LOR 86-2 ( Numerical relays protection)
1.HV & MV side backup 3 phase & ground fault inverse time & inst O/C
relay unit and function (67HV & 67NHV and 67MV & 67NMV)
2.HV side Over Flux protection (24 - HV/T)
3. Neutral backup O/C relay ( 51 G-T)
4.Tertiary winding O/C relay ( 51TW/HS & 51 TW/LS)
b. LOR 86-4 ( Mechanical protection)
1.Pressure Relief - trip-main tank (63PR-T)
2.Oil Tem very high trip - main tank ( 26-T)
3.Oil Tem very high trip OLTC ( If any) (26- OLTC)
4.Pressure relief OLTC tank - (63-OLTC)
5.Oil pressure relay Main tank (63-T)
6.Pressure relief Trip grounding transformer ( 63 - PR-GT)
