Generator Syncing but trips on 32 relay when GV are opening and steam is plentiful

One of our Generators, in this case a 30 MW unit, was rebuilt this outage season. It is coupled to a steam turbine. We are able to sync unit but trip 7 seconds later from 32 relay. The GV’s open and there is plenty steam, as its sister unit is running like never before. We have had the Shermco guys tell is we have incorrect rotation of PT secondaries. Would really like anyone’s input as to what might be the cause. 32 relay has been tested and verified good twice. AVR, Basler Decs 400, also shows negative MW after sync and power quality metering with wrap CTs place on generator buss also show negative MW. Any ideas ?
 
Shermco, MD&A and Woodward onsite. Their consensus is something is up inside Turbine. My question really being would the PTs having opposite rotation be causing that problem? Generator was verified correct rotation at 15KV stabs.
 
Perhaps, someone should find the drawings for generator protection and get up and go find the terminal strips for the 120 VAC secondary voltage that feeds the devices and ensure the wiring is correct.
 
Done. I just don’t see how opposite rotation on PT secondary would cause inaccurate 32 trip. Thanks for your input and time.
 
One of our Generators, in this case a 30 MW unit, was rebuilt this outage season. It is coupled to a steam turbine. We are able to sync unit but trip 7 seconds later from 32 relay. The GV’s open and there is plenty steam, as its sister unit is running like never before. We have had the Shermco guys tell is we have incorrect rotation of PT secondaries. Would really like anyone’s input as to what might be the cause. 32 relay has been tested and verified good twice. AVR, Basler Decs 400, also shows negative MW after sync and power quality metering with wrap CTs place on generator buss also show negative MW. Any ideas ?
Can you tell us :

Governor model
Turbine type ( extraction, condensing..)
What you mean by GV's....
Protection relay IED or analog ...type model..software settings.. ..
Grid configuration....
Load sharing mode ....


I can then try to support ...

james
 
IK43, I am not an electrical engineer so I am also confused. My teaching is that a "32" relay element is for directional power. Power is calculated based on current and voltage potential. I could understand if something was wired incorrect for the CT circuit such that the relays are sensing current in the wrong direction, and tripping based on reverse power.
I like you don't understand if someone is trying to say the PT circuits are incorrect. PT's sense the voltage potential and must also be correct for phasing so that your generator sync's in phase with the system. PT's are not directional as I have been taught, just specific to phase A, B, C specifically.
If you have several different devices measuring current, using different PT and CT devices, and they all agree that power is going the wrong way then more focus is needed on the prime mover. I always look to what devices were last worked on first, then work out from there.
 
I have a funny story. After the restart of a small industrial steam turbine after an ST maintenance outage the unit could be synchronized but every time the operator started to load the machine it would trip on reverse power. Everyone was CERTAIN the excitation system was to blame. I asked to observe the synch’ing and loading (manual) and I immediately noticed that the operator was having to move the speed/load switch the opposite direction to get the synchro scope to move in the proper direction and not to move very quickly. He was struggling to get it synch’ed but he finally did—and when he did he then twisted the speed/load switch in the RAISE direction and the unit immediately tripped on reverse power. So I asked to synchronize and load the unit again (to everyone’s dismay!) and, again, it required opposite SPEED/LOAD switch movements to get the synch scope moving correctly—and when the operator closed the breaker I asked him to move the SPEED/LOAD switch in the LOWER direction and the unit started loading as it should.

I pronounced that the speed/load changer motor (a DC motor) was wired incorrectly, to which the mill electrician replied, “Like hell!” (a US colloquialism meaning, “You’re crazy!”) but the mill maintenance manager told him to go check it anyway. He returned in pretty quick time and said it had been improperly connected and was fixed now. So I asked the operator to load the unit by twisting the SPEED/LOAD switch in the RAISE direction—and the load increased as it should. I then asked him to unload the unit (to which he responded, “How?”) and I said to twist the SPEED/LOAD switch in the LOWER direction. To everyone’s surprise, the load decreased. We loaded and unloaded the unit several times and I pronounced it fixed. The maintenance manager immediately said, “What about the exciter???!!?!!?” I’ll end my story here as it got not so funny after this point.

Anyway, is there any chance that some how the steam flow is actually being reduced when it should be increasing???

I’m in agreement with MARKVI—reversed CT leads/wires would also cause this because the 32 relay would think the current was flowing into the generator when it was actually flowing out if the steam flow was actually increasing during loading. I have seen this problem, also, when CT leads were incorrectly reterminated after switchgear maintenance.

But, if the relay tests all indicate the CTs and PTs are wired correctly AND the 32 relay is working correctly, then as has been said: Something else is wrong. If the unit has extractions and something is amiss with the way the valves are operating that might explain the problem. But, other than that (a check valve (non-return valve) in an extraction line might not be installed or working correctly) it’s not likely the problem is internal to the steam turbine—unless it’s a spatial steam turbine.

Also, what is GV, please?

Please write back to let us know how you resolve the problem.!
 
I have a funny story. After the restart of a small industrial steam turbine after ST maintenance outage the unit could be synchronized but every time the operator started to load the machine it would trip on reverse power. Everyone was CERTAIN the excitation system was to blame. I asked to observe the synch’ing and loading (manual) and I immediately noticed that the operator was having to move the speed/load switch the opposite direction to get the synchronized scope to move in the proper direction and not to move very quickly. He was struggling to get it synch’ed but he finally did—and when he did he then twisted the speed/load switch in the RAISE direction and the unit immediately tripped on reverse power. So I asked to synchronize and load the unit again (to everyone’s dismay!) and, again, it required opposite SPEED/LOAD switch movements to get the synch scope moving correctly—and when the operator closed the breaker I asked him to move the SPEED/LOAD switch in the LOWER direction and the unit started loading as it should.

I pronounced that the speed/load changer motor (a DC motor) was wired incorrectly, to which the mill electrician replied, “Like hell!” (a US colloquialism meaning, “You’re crazy!”) but the mill maintenance manager told him to go check it anyway. He returned in pretty quick time and said it had been improperly connected and was fixed now. So I asked the operator to load the unit by twisting theSPEED/LOAD switch in the RAISE direction—and the load increased as it should. I then asked him to unload the unit (to which he responded, “How?”) and I said to twist the SPEED/LOAD switch in the LOWER direction. To everyone’s surprise, the load decreased. We loaded and unloaded the unit several times and I pronounced it fixed. The maintenance manager immediately said, “What about the exciter???!!?!!?” I’ll end my story here as it got not so funny after this point.

Anyway, is there any chance that some how the steam flow is actually being reduced when it should be increasing???

I’m in agreement with MARKVI—reversed CT leads/wires would also cause this because the 32 relay would think the current was flowing into the generator when it was actually flowing out if the steam flow was actually increasing during loading. I have seen this problem, also, when CT leads were incorrectly reterminated after switchgear maintenance.

But, if the relay tests all indicate the CTs and PTs are wired correctly AND the 32 relay is working correctly, then as has been said: Something else is wrong. If the unit has extractions and something is amiss with the way the valves are operating that might explain the problem. But, other than that (a check valve (non-return valve) in an extraction line might not be installed or working correctly) it’s not likely the problem is internal to the steam turbine—unless it’s a spatial steam turbine.

Also, what is GV, please?

Please write back to let us know how you resolve the problem.!
GV= Governor Valves

I understand the CT in reverse connection. We did find the PT secondary connections in reverse. That has been corrected. I just don’t see how Phasing on PTs would affect a 32 GE electromechanical Relay.
 
CSA...
I like your "true" stories!

IKE43...
The "32 GE electromechanical relay" calculates Watts, and can differentiate if its "flow" is away from or towards the generator! If either the PT's or CT's connections are reversed or their relative connections at the relay are reversed, then the relay will operate improperly. It has nothing to do with steam flow!
Regards, Phil Corso
 
Can you tell us :

Governor model
Turbine type ( extraction, condensing..)
What you mean by GV's....
Protection relay IED or analog ...type model..software settings.. ..
Grid configuration....
Load sharing mode ....


I can then try to support ...

james
When one post some questions. One can atte'd a reply.. You did not reply... To my questions...
Good luck with your problem!
I leave this.... Thread... Adios...

What is in your mind.... Do not treat people like that.. Otherwise.. You will regret it...
 
When one post some questions. One can atte'd a reply.. You did not reply... To my questions...
Good luck with your problem!
I leave this.... Thread... Adios...

What is in your mind.... Do not treat people like that.. Otherwise.. You will regret it...
Apologies sir, I’ve been answering as I see the emails. I’m at work currently and just got through racking that generator breaker 4 times. It’s 10 am here.
 
Can you tell us :

Governor model
Turbine type ( extraction, condensing..)
What you mean by GV's....
Protection relay IED or analog ...type model..software settings.. ..
Grid configuration....
Load sharing mode ....


I can then try to support ...

james
Steam turbine
Woodward governor
GV= Governor Valve
GE electromechanical 32 relay
 
Allright ya’ll. Correcting PT secondary phasing fixed problem. Unit is online at full rates. Relay Test guy says the phasing on PT sets the direction on 32 relay reading direction of power. Thanks to all.
 
CSA...
I like your "true" stories!

IKE43...
The "32 GE electromechanical relay" calculates Watts, and can differentiate if its "flow" is away from or towards the generator! If either the PT's or CT's connections are reversed or their relative connections at the relay are reversed, then the relay will operate improperly. It has nothing to do with steam flow!
Regards, Phil Corso
That was in effect the problem.
 
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