Difference between 51G, 51Gs, 51N Relays - Electrician Talk - Professional Electrical Contractors Forum

Dug · 11-15-2011, 06:12 PM

I was wondering what the difference is between 51G, 51Gs, and 51N Relays? In addition, how do they relate to current transformers (How could you tell which is which based on a schematic of a power system or other ways)?

brian john · 11-15-2011, 06:33 PM

A little google

http://www.aeusp.com/fundamentals/dvprgo.asp

The three most commonly used connections for ground-overcurrent relays are the residual connection (51N), the ground-sensor (balanced-flux or zero sequence) connection (50GS or 51GS), and the neutral current transformer connection (51G).

It should be simple to identify the current transformers from the schematic (if the drawings are accurate).

sparky970 · 11-15-2011, 08:50 PM

Quote:

Originally Posted by Dug

I was wondering what the difference is between 51G, 51Gs, and 51N Relays? In addition, how do they relate to current transformers (How could you tell which is which based on a schematic of a power system or other ways)?

http://www.csanyigroup.com/ansi-stan...ection-devices