screw compressor loading

[drdanshore]

My transformer is underrated by about 15%.

Can i reduce the electric motor loading by limiting the inlet throttle valve of a wet screw air compressor? I see that a closed throttle results in about a 60% current draw compared to the full load so perhaps i can adjust the linkage to manage the full load amps.

I have installed a thermometer on the transformer and am considering adding a cooling fan to it. This compressor will be used intermittently.

Thanks

 

[BigInch]

Lesser flow almost always translates to lesser power.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[zdas04]

Does that screw have an unloader valve (slide valve in process machines, turn valve in air-derivative machines)? If so that is the least inefficient way to limit your power requirement. The only way that is worse than a suction controller is a recirc line.

David

 

[drdanshore]

No, This old pump has no unloader or slider so I will now experiment with the throttle linkage adjustment.

Thank you for your comments.

 

[waross]

Transformer capacity is based on self heating at the maximum rated ambient conditions. If you have an ambient significantly lower than the design ambient, (and many installations do), the actual overload based on temperature rise may be less than 15%. When a step increase in load is applied to a transformer it takes about 15 minutes for the transformer to respond thermally (reach a new, higher temperature). Transformers will often accept an overload with only a reduction in service life, but the reduced life may be many years.
Many transformers may be re-rated with the addition of external cooling.
The best approach may be to contact the transformer manufacturer and ask for recommendations for increasing the rating with increased cooling. This will avoid code violations.
An alternate is to compare the actual ambient to the rated ambient to see if the transformer is in fact overloaded. I would take this question to the electric power forum. Have accurate figures fr the rated ambient of the transformer and the actual ambient. Note, this approach may result in a code violation even if the transformer is safe.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[drdanshore]

Bill,

thank you for this response. this is my own hydro plant so i write the code here which requires that I look at the drag pointer on the thermometer all day determined not to cause a fire.

the manufacturer is a rebuilder that has no advice worth listening to so I am watching the instruments carefully. I have fans and capacitors ready to install.

I know you are a quasi moderator so with your invitation i will move the question to theelectric power forum without fear of violating any cross posting policy here.

thanks so much for the help.