Reverse power Tripping

Can you run 1 and 3 together without tripping on reverse power? How about 2 and 3?

try to give us as much information as you can.

Orpheuse

Dear Orheuse,

Thanks for your reply

No we can't run 3 with any other generator. 3 only can be run indepenendtly( on dead bus only)

have you tried replacing gen. 3?

Orpheuse

Such large machine have a KW meter, please check what is the KW value at tripping time.

If KW> 100 recheck the reverse relay

If KW around 0 please check the woodward or equivalent for speed control

Dear Friends,

Thanks for replying, After sychronising GHT-3 it's not taking any active load but it's drawing reactive power from GTG-1 & or 2( which are running in paralell ) and resuted in black out. ( GTG-3 reactive power meter showing/ going up to maximum leading var before trips on reverse power)

That is strange, if you are drawing reactive that means that the voltage is too low.

But this shall not trip the reverse power which avoids that the turbine is driven by the generator operating as synchrone motor.

When synchronizing ,the speed ( Hz) on the slave machine shall be slighty above the master and you close the breaker within the limits of +/- 10º on the synchroscope, this avoid the reverse power. After closing the breaker the speed selector to be activated on the + side to take the load.

You shall do exactly the same on the voltage adjustment to share the reactive power

If you your machine is pumping reactive load to such an extend I suspect that there is a wrong connection on your CT's .

Please give more infos about the Speed control ( Woodward) the AVR and others sytems installed.

IF GTG-3 works well by itself, there is no inherent damage to the generator. It sounds like the instrument wiring for GTG-3 is incorrect. It's also possible that one or more of the GTG-3 CT's are installed backwards. Since GTG-1 & GTG-2 work together, those units must be wired the same way.

I would compare the following items of GTG-3 to the same circuits of GTG-1 & GTG-2:

• Polarity of all CT's.
• CT phasing through each element of all CT secondary circuits.
• Polarity of all PT's.
• PT phasing through each element of all PT secondary circuits, including the synchronizing circuit.

I do not suspect CT polarity and PT Polarity ,if it is so, the breaker will trip even on normal individual operation for forward Power

Controller/avr/connections to be checked,best way is to interchange the controller and check .

They have to furnish information and feedback should be fast.

It looks to me like you need to check your reverse power relay setting on the breaker or check out the governor on the GTG or whatever setup you have controlling the fuel to it.

Dear Friends,

I am facing the same problem. I have three Gas generators A(975 KW),B(975 KW), and C(1215 Kw). G 1 & 2 runnig parellel very well but G 3 is TRIPPING ON REVERSE POWER after synchronizing G 3 with G 1 & 2.

The different is that i keep watching the Power (KW) and Power Factor [on the generator meters] during the few seconds (≈2.8 sec) befor tripping and i found P(kw) increasing, with P.F‹1, which means that no actual reverse power occure.

Can anybody help me?

Falcon,

Please Check

• Polarity of all CT's.
• CT phasing through each element of all CT secondary circuits.
• Polarity of all PT's.
• PT phasing through each element of all PT secondary circuits, including the synchronizing circuit.

Thanks KKKp,

The reverse power installed is CEE Static relay PTG7100, it has 3-phase voltage signal and only one phase (C.T) signal. I checked the polarity (direction of current) of this current signal and found it OK, but the problem still existing.

The current signal is coming from C.Ts inside the generator, i checked its connection (star earthed) and then connect the C.T terminals according to it.

For this relay type, the current signal is for L3 phase, can we substitute with any other phase?

Hi Falcon,

Could you please provide history of hte gegerators, Did any major maintenance was carried out? Did you changed any major parts or relay for the generators?

Could you please provide history of the generators, Did any major maintenance was carried out? Did you changed any major parts or relay for the generators?

Dear Guest,

the 2 generators (A & B) have been working for 8 years, and already they passed through normal Preventive & Corrective maintenance, so if you can specify certain equipment to trace its history i will be grateful.

Another question, there is a Load Sharing signal between the 3 generators [connected through 2 points in the speed regulator & load sharing Device "WOODWARD" can this signal cause any problem?]