Typical Electrical Drawing Symbols and Conventions.
49 Machine or Transformer Thermal Relay 50 Instantaneous Overcurrent 51 AC Time Overcurrent Relay 52 AC Circuit Breaker 53 Exciter or DC Generator Relay 54 HighSpeed DC Circuit Breaker 55 Power Factor Relay 56 Field Appliion Relay 59 Overvoltage Relay 60 Voltage or Current Balance Relay