Name Plate Issue

[Sargardani]

We have a recent generator rewind and upgrade. Runner was also refurbished. We asked the contractor/supplier to provide a name plate that would show exactly the power the generator would generate when coupled to the existing generator which is less than what the generator is actually designed for. But the contractor is insisting that they would only provide the name plate showing the rating specified in the contract and what the generator is capable of irrespective of the fact that this rating cannot be practically reached due to the limiting factor of undersized turbine.

Is our demand logical? Need the forums comments.

Thanks

Sarg

 

[Skogsgurra]

The name-plate of the generator shall give data for the generator as such. Not for something that is coupled to it. You are, of course, free to add an extra plate telling about the capacity of the turbine and what maximum power the combination can output.

Gunnar Englund

http://www.gke.org

 

[byrdj]

Its been a while since I looked that closely at a "name plate". But I recall one side gave the turbine serial #, its specifications and its rated output in KWmechinacal. the other side gave generoator specifics and its output in KVA.

 

[Sargardani]

skogsgurra: whom should this second plate come from? The contractor or us?



Sarg

 

[Skogsgurra]

That, you have to think about. The turbine manufacturer. Or you. The generator people have not much to do there.

Gunnar Englund

http://www.gke.org

 

[rmw]

The contractor is not 'on the hook' if his refurbished equipment exceeds the original name plate, but if he re name plates it, and the performance subsequently falls off (especially during the warranty period,) he has to make it good, or so he might reason.

I have dealt with rebuilders and refurbishers who, althought they certainly had the capability to do so, wouldn't guarantee their repair past what the original name plate said. They didn't want the liability.

rmw

 

[Sargardani]

rmw.
In our case the contractor wants to provide a name plate with a higher rating 30MVA where as we are asking for 24 MVA. because this is what the generator can generate with the max available head and the present turbine. The thing is that we go with a higher rating we'll have to get into getting permits from the hydro authorities etc...

Just trying to get the forums advice on the eithical and logical solutions.

Appreciate your help.

Sarg

 

[edison123]

I have personally seen in my recent trip to Saudi Arabia, 100 MW name plated Generators (atleast 12 of them)connected to 50 MW name plated Gas Turbines. I don't know their logic of using generators with prime movers of half the rating, but there it is.

 

[rcw retired EE]

Many Combustion Turbines(CT's) have generators that seem to be rated much higher than the turbine maximum output. Turbine output can vary 20-30% with ambient temperature changes, with higher output at lower temperatures. The CT nameplate may indicate the reduced turbine output at the specified high ambient conditions, while the generator nameplate lsits its capability at standrd temperatures.

Gas turbines are usually designed as package units with a standard size generator to match the standard turbine package. It is not economical to have a seperate generator design for every application of a standard product, especially when all of the type testing and other Quality Control issues are considered. One design covers the complete range of output for the turbine package, so it will seem to be oversized in some cases.

The generator nameplate is specifed at some ambient temperature and cooling water or cooling air temperature, or H2 pressure and temperature. Most of the time, this does not match the ISO temperatures used in the turbine rating. When you adjust the turbine output and generator capability curves to the same amvient conditiosn, teh discrepancy is not as large.

Adding inlet air cooling equipment or using water injection can boost gas turbine output significantly. In some cases the generator is sized to allow future turbine output enhancements.

Remember that turbines are rated in MW, generators in MVA. Soem bids for Saudi Arabia required lower than normal power factor (0.80 lagging)capabililty with a margin. This led to oversize generator requirements.