Generator protection

Components in electrical power systems, such as generators, are critical for the operation of a vessel and represent highly valuable assets. Their failure due to faults leads to an interruption in the power supply, potentially with far-reaching effects on downstream systems. Damage can lead to long downtime and costly repairs. 

Therefore, comprehensive generator protection is required by class societies and is defined internationally using ANSI codes.

Key generator protection functions include:

  • ANSI 24       overexcitation
  • ANSI 25/A   synchro check and automatic synchronization
  • ANSI 27       undervoltage protection
  • ANSI 32       directional power protection
  • ANSI 40Q    loss of excitation
  • ANSI 46       negative sequence
  • ANSI 47       voltage unbalance
  • ANSI 50       instantaneous overcurrent protection
  • ANSI 50G     ground overcurrent protection
  • ANSI 67G     directional ground overcurrent protection
  • ANSI 50BF   breaker failure
  • ANSI 51       delayed overcurrent protection
  • ANSI 59       overvoltage protection
  • ANSI 81       frequency protection (over- and underfrequency)
  • ANSI 87       differential protection 

SYMAP® devices can operate in special frequency ranges (for example from 5Hz for shaft generators, up to 300Hz for variable speed generators).

These and other protection functionalities are covered for generators by the following models: