My company uses Mark IV to control Gas Turbine Generator (GTG). It's often got trip caused by Unit Auxiliary Transformer (UAT) when the unit goes online.

The power plant was built by two different vendors, General Electric and Bailey. Both of them have their own wiring diagram. I found some difficulties on matching these two diagrams. Also I would like you to give me some advice about the causes of this trip problem and possible things I can do to solve this problem. Thanks.

nanang
(Instrument Engineer)

 

When you say the unit trips because of the UAT, how does the UAT trip the unit? Is it through a lock-out relay which trips the turbine when actuated? If so, then what protective relay of the UAT is actuating to actuate the lock-out relay? What alarm is annunciated when the unit trips?

What does this have to with the Mark IV, other than it gets a signal to trip the unit, and it does? Seems pretty straightforward; trip input gets actuated, unit is tripped. Doesn't seem like a Mark IV problem, unless you don't want it to trip the unit when it gets a signal to trip the unit. Oh, you thought you had the "fuzzy logic" version of the Mark IV! All of those have been since been taken out of service and scrapped. Not a single one escaped the crusher.

You haven't provided enough information for us to make an educated guess.

 

And try to identify which signal trips the turbine. Is it from Bailey DCS trip signal? If so, try to check digital output signal. If there is a customer trip from Mark IV, it's complicated. You must check one by one signal customer trip.

Hopefully you can do this and solve this problem.

 

Hello CSA, frankly, I'm not so sure, but I predict it's tripped by lockout relay 52. and then it should change over to 86LU. we have set the time delay on 0.2 sec. but on actual, the time delay is higher.therefore, it will shutdown many essential pump in the power plant, and the unit got tripped.

the difficulties is founding a things that make the UAT tripped.we have read the diagram but we couldn't see any information about it. is it possible the UAT tripped by temperature switch controlling winding temperature?

note: the type of the gas turbine generator is MS 9001E,capacity 100 MW, using MARK IV as a control system.

or maybe you have the diagram you can share with.

Thanks

 

You need to find help from someone who can read the drawings and understand what causes the UAT to be tripped. I've seen this happen before; once it was because of mismatched transformer impedances (*not* easily resolved). Another time it was a protective relay problem; another time it was a current transformer problem.

It is not recommended to change protective relay settings without understanding the knock-on effects.

We likely can't help you with this problem from afar; you need someone to come to your site and assist you with understanding and resolving the problem.