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from the Maintenance department...
Load Sharing
Continuous process industries, DCS questions. topic
Posted by DAMENE Amar on 11 December, 2007 - 2:18 am
Hi, I need help.

At the end of gas pipeline, a compression of gas got 4 machines. 3 GTs equipped with Speedtronic Mark V have 50% of base load. Compressor is Nuovo Pignone PCL 602.

1 GT (a new one installed) equipped with Speedtronic Mark VI has 60% of base load. Compressor is Nuovo Pignone PCL 802.

To set all machines on REMOTE (DCS CONTROL) I think that problem appears to share the entire load.

Can I accept the different setpoint or require from the contractor to unify the setpoint for all machines?

Thanks for your help.


Posted by DAMENE Amar on 11 December, 2007 - 11:05 pm
Hi,

Sorry. All compressors are Nuovo Pignone PCL 602.

Thanks.


Posted by CSA on 11 December, 2007 - 11:32 pm
Load sharing does *NOT* mean that all machines will have the same amount of load.

It means that all machines will contribute torque to the process in a stable manner, some may contribute more than others, some less than others. But, they are all "sharing" the load without any fighting of controllers.

"Load sharing" is such a misleading term, but we're stuck with it.

As for how you want to operate your plant, well, that's up to you and your supervision or management. We don't have all the information to understand the lay-out of the plant, the capabilities of the compressors, and any operating limitations of the equipment given the physical lay-out of the plant. I have been on sites where because of the location of one compressor with respect to others and differences in the compressors it was not possible to run one of the compressors at less than 60% of rated load without adversely affecting the other compressors. Perhaps, this is the case here?

But, please do try to understand that load sharing does not mean each machine will drive an equal amount of load or produce an equal amount of torque.

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