- 21/21N = Distance Relay Phase & Ground
- 21BU = Backup Distance Relay
- 25 = Synchronizing Check Relay
- 27 = Under Voltage
- 32 = Reverse Power
- 33Q = Transformer Oil Level
- 40 = Loss of Excitation.
- 46 = Negative Phase Sequence Protection
- 48 = Locked Rotor
- 49 = Overload
- 49W = Transformer Winding Temp
- 49Q = Transformer Oil Temp
- 50ARC = Instantaneous Overcurrent relay for Arc Protection System
- 51G = Ground Fault Relay
- 50/50N = Instantaneous Overcurrent Phase & Ground
- 51/51N = IDMT. Overcurrent Phase & Ground
- 59 = Over Voltage
- 59N = Zero Sequence Overvoltage
- 63D = Transformer Pressure Relief Device
- 63TC = Transformer OLTC Protection Relay
- 67/67N = Directional Overcurrent Relay / Directional Ground Overcurrent
- 68 = Voltage Relay Block Closing Circuit While De-Energize
- 79 = Auto Reclose Relay
- 80T = Transformer Buchholz
- 81 = Under Frequency Relay
- 86 = Lockout Function
- 87B = Bus Differential Relay
- 87L = Line Current Differential Relay
- 87T = Transformer Differential Protection Relay
- 87REF = Differential Restricted Earth Fault Relay
- 90 = Voltage Regulating Relay
- 95B = CT Supervision Relay for 87B
- BF = Circuit Breaker Failure Relay
- Q = Power Factor Controller
- DPM = Digital Power Meter
- DIM = Distributed I/O Module (for CSCS Control)
- ODF = Optical Distribution frames.
- SCADA = Supervisory Control and Data acquisition.
- SA = Substation Automation
- SAS = Substation Automation System
- SCMS = Substation Control and Monitoring System
- SCPS = Substation Control and Protection System
- PLC = Programmable Logic Control (Device Part) or Power Line Carrier (Telecom Part)
- RMU = Ring Main Unit.
- RCC = Remote Control Cubicle / Regional Control Center (SCADA)
- LCC = Local Control Cubicle
- NCC = National Control Center
- BNCC = Backup National Control Center
- AISC = American Institute of Steel Construction
- ASCE = American Society of Civil Engineers
- ANSI = American National Standards Institute
- ASME = American Society of Mechanical Engineers
- ASTM = American Society for Testing and Materials
- AWS = American Welding Society
- IEEE = Institute of Electrical and Electronics Engineers
- NEMA = National Electrical Manufacturers Association
- NFPA = National Fire Protection Association
- TIS = Thai Industrial Standards
- EIT = Engineering Institute of Thailand