Common Terms used with meanings

Some Common Terms used with meanings

1) ONAN - Oil Natural, Air Natural (For Transformer Cooling) 

2) ONAF - Oil Natural, Air Forced (For Transformer Cooling) 

3) OFAF - Oil Forced, Air Forced (For Transformer Cooling) 

4) WTI - Winding Temperature Indicator 

5) OTI - Oil Temperature Indicator 

6) PRV - Pressure Relief Valve 

7) OSR - Oil Surge Relay 

8) OLTC - On Load Tap Changer 

9) RTCC - Remote Tap Change Control 

10) MOG - Magnetic Oil Level Gauge 

11) IDMT - Inverse Definite Minimum Time (For Relay) 

12) NO - Normally Open Contact 

13) NC - Normally Closed Contact 

14) LILO - Loop In Loop Out (Used for defining Substation) 

15) CRP - Control Relay Panel 

16) TTB - Test Terminal Block 

17) ACDB – A.C. Distribution Board 

18) DCDB – D.C. Distribution Board 

19) MB – Marshalling Box (For Breaker, Transformer control) 

20) AVR – Automatic Voltage Control (For Tap Changing on RTCC Pan