What is the typical reverse power relay setting to trip open the generator breaker?

Our GTs opens 52G at +3MW to avoid motoring the generator. The relays trip the gen breaker at -3MW.

We open the the generator breaker upon reverse power of -1.5MW

normally it is set at 5-7% of machine rating

You say "52G opens at +3mw to avoid motoring". Then you say "relays trip the gen breaker at -3mw"?

Your answer makes no sense.

Setting of Reverse Power Relays

Data for setting calculations
-Rated Capacity of Generator -------- 440,000 KVA
-No Load Loss of Generator --------- 1,785 KW
-No Load Loss of Turbine ---------- 1,350 KW
-No Load Loss of TG unit ---------- 3,135 KW
-Permissible Motoring Time ------- 60 Sec.
-Relay Constant ------------------- 1 P.U. = Generator KVA



Setting Of Reveres Power Relay 32G ( #1 )

1- Reverse Power Trip Level

Trip Level < No load loss of TG unit * 0.3
= 3,135 * 0.3
= 940.5 KW
Pick up = Trip level / relay constant
= 941 / 440,000
= 0.0021 P.U.
Setting = - 0.002 P.U. ( 880KW )

2- Reverse Power Trip Delay

Trip Delay < Perm. Motoring time (60 Sec.)
Setting = 50 Cycles (1 Sec.)






Setting Of Reveres Power Relay 32G ( #2 )

1- Reverse Power Trip Level

Trip Level < No load loss of TG unit * 0.5
= 3,135 * 0.5
= 1,568 KW
Pick up = Trip level / relay constant
= 1,568 / 440,000
= 0.004 P.U.
Setting = - 0.004 P.U. ( 1,760KW )

2- Reverse Power Trip Delay

Trip Delay < Perm. Motoring time (60 Sec.)
Setting = 750 Cycles (15 Sec.)

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Maybe Dynasty was saying that a soft open is +3mw and a rolling the lockout from the gen protection is at -3mw.

Our 126MW Frame 9E GE machine has
-2.5MW at 0.5 sec. delay.