reverse power protection

The GTG3 is motoring when ever it is synchronized with GTG1 or GTG2.This means the the GTG3 is running at a lesser speed than the other two.

There should be governor controller for each machine and this controller will have communication between each other and this controller will control the speed of the machine.In your case the controller attached to GTG3 should increase the speed of GTG3 to match with other GTGs.

It looks like the Controller may not effective.It might be the control signal is not going to the governor.Please check the cable,termination and the controller.

May be intercommunication between the controllers missing.

To find out whether Speed raise/Speed lower signal reaches the governor,run the machine GTG3 individually and increase the speed manually by increasing the speed from controller ( there should be provision in the controller) if it is responding then the signal reaches the governor.If this is OK,then check inter communication between the controller and the voltage and frequency input to the controller.

Please check and give us more information like engine model,controller type etc I could throw more light on this matter based on the feedback

Please also let us know whether this problem cropped up suddenly or at the time of commissioning ?

Dear Friend,

Thanks for reply, Above problem starts after replacing GTG relays in all generators. but GTG-1 & 2 runnig without problem. All relays and wirings are identical and relay wiring checked twice.

Details furnished by you not adequate.You have to give history for us to trouble shoot.It looks like that you have replaced the GTG relays for all the three and the problem cropped up recently.if this is true may be relay fixed to the GTG3 defective,since you have confirmed the connections are in order.Try and inter change the relays 2 and 3 and watch the performance and let us know.

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)

Dear Sir,

Whenever you are paralleling there will be an option in electronic governor where in you can set minimum load. this ensures the machine will go to minimum load the moment it is synchronised, or else it will trip on Low Forward Power Realy / Reverse Power trip. Please check these setting and revert back.

rangacharya

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)

As I said earlier one of the following not working:

1) Controller

2) Communication from from controller to Engine /Alternator

3) AVR

Since you have said connections are in order,you have to check the devices viz Controller and the AVR.

What has happened ? Is the problem solved ? If so what was the problem ? Interested to know to update ourselves.

Since your generator 3 is working fine as a standalone..then i would suggest

a) Check again the wiring of reverse power relay.

b) If convinced that the wiring is perfect, change the relay.

c) Check AVR (see whether the voltage of GTG3 is increasing ..after you synchronise, i suspect the voltage is shooting up..) ..and the load sharing signal wires of Gen-3

d) In case you have a stepup transformer at the output of the generators check that they are all at the same tapsetting..usually at Tap 3.

More importantly give feedback...

cheers...

their is no defiancy of power in network their is excess of power flowing in the network then only gtg-3 is running as motor