Generator Overcurrent Protection

[Power2all]

IEEE C37.102-2006 (Guide for generator protection) says:
“Instantaneous unit is set to pick up at 115% of FLA and is used to torque control the time-overcurrent unit”
What does this mean when using an electronic relay (Multilin G30)?

 

[pwrengrds]

It means what it says they use a instantaneous over current element at 115% FLA, to torque control a second element that trips in 7 seconds at 226% of FLA and is set to pickup at 75-100% of FLA,

I have never seen that approach used in the US for generator protecton. Typically generator protection used is 51 Voltage Control, 51 Voltage Restraint, or 21 Distance.

It's should be able to be done with a modern relay such as the GE G30 using the flex logic or the SEL 300G, or a Basler 11g. It takes two settings (50 and 51) and uses an "and" gate to output the required protection.