Power Conditioning Equipment

[racobb]

For the Utility Guys Here:

I have an issue where a fairly large (480 volt, 1200 kW) customer feels they have voltage regulation issues. PF averages 75 to 80%. The customer is served from 2 miles of 336 Al. OH line at 25 kV and a 2500 kVA padmount tx. We have recorded the voltage on 2 separate occasions at 1 minute intervals and found the service voltage to vary +/- 4 to 5 percent which we believe is pretty good and the levels are well balanced.

Probably a 3000 amp plus service.

Facility is located in the Southeastern US.

The problem appears that the customer has purchased some equipment that has a +/- 2% tolerance, to which we have told them that we could not gaurantee that level of swing on the system and they would need to install additional equipment to maintain their required level of voltage. The customer is asking for +/- 1% swing!

Aside from ideas anyone might have, I am also interested in others that have seen this issue and any equipment/mfg that might have been used to solve the problem.

Thanks in advance!
Alan

Alan

 

[rbulsara]

I am wanting to see if anyone has experience with a manufacturer for 2000+ kVA voltage regulating equipment at 480 for an input of +/- 10% and output a +/- 1% or 2% level.

Yes, of course. Those systems are not cheap. Although, cost is all relative to the size of the problem. You are essentially looking at UPS systems without or with minimal batteries. The type of load would also dictate the selection. Also the factors such as if there are large motors to start etc. Reliability of service and behavior during a short circuit will also change dramatically. Essentially it will require a good engineering analysis. Correcting the power factor may also aid in the solution.

Liebert's "datawave" could be a magnetic solution. Bulky but reliable. Not too state of the art but very rugged.

Mitsubishi's static UPSs can work without batteries as power conditioners and can be stacked up to a few MVA. All other static UPSs in the USA need batteries, I believe.

You can also look at the M-G sets.

The question still remains, why would you want to do it when the customer should be doing it. But that is not your question at the moment. As stated before, installing a PC system just for the problem load will be much more economical.


Rafiq Bulsara

http://www.srengineersct.com

 

[racobb]

Thanks for all of the input. As it is with many muni's they do not enforce the PF penalty. Not necessarily saying that the utility will or should do the correction, but if they do, the customer will "hopefully" still pay for it!

Just exploring options at this point to see who has the equipment available. My first recommendation was certainly to correct for the specific equipment, but the customer says it is "plant wide".

First step is to get past the posturing and finger pointing so we can get down to a solution for the issue. I do believe that the customer is aware of what needs to be done to get the voltage regulation that are requesting, but would love for someone else to pay for it. Wouldn't we all.

Thanks

Alan

 

[racobb]

Update:

After several weeks of voltage recordings, we found that the mins and max were approx. -.5% to +5%. Pretty good for service one would think. Had to chuckle when the customer complained about a dip to 456 volts. Asked for how long...the answer was a whole 8 milliseconds!

We are looking at simply changing the tap on the service transformer 2.5% to see if the customer can live with it. Should take it to about -2 and 3 to +2 and 3% if circuit load variations don't hurt us to badly.

Otherwise the customer has a problem to fix!

Thanks

Alan