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What is the difference between 50N and 50G RELAYS?


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May 13, 2012 9:33AM

50N: Instantaneous Earth Fault Relay

50G: Instantaneous Ground Fault Relay

  1. 50N is main EF protection device but 50G is standby as backup of main device.
  2. 50N use for motor starters but 50G use for feeders.
  3. 50N see zero sequence of EF current but 50N see residual current due to sum of three CT.
  4. If you have a resistance grounded system, a 50N may not see enough ground current to trip properly. If you do not have a resistance grounded system, a 50G may create nuisance tripping.