Compressor Starting
Compressor Starting
(OP)
We are trying to start a reciprocating compressor by Autotransformer. We can only achieve 5% flicker limit by using 40% tap. The load torque curve we received is as below,
Speed Torque
0% 12.5%
10% 6%
20% 10.4%
30% 17.5%
39% 26.9%
49% 38%
59% 50%
69% 63%
79% 76%
88.5% 88%
98% 100%
With this load torque, we will never start the compressor even with aross the line.
I am assuming something wrong is wrong with this curve. We may have to request a different curve, such as minimum flow start curve, no load startup curve. Any suggestions?
Any inputs would be apprecisted.
Speed Torque
0% 12.5%
10% 6%
20% 10.4%
30% 17.5%
39% 26.9%
49% 38%
59% 50%
69% 63%
79% 76%
88.5% 88%
98% 100%
With this load torque, we will never start the compressor even with aross the line.
I am assuming something wrong is wrong with this curve. We may have to request a different curve, such as minimum flow start curve, no load startup curve. Any suggestions?
Any inputs would be apprecisted.





RE: Compressor Starting
How long does it take to start a compressor by 40% Tap seeting?
RE: Compressor Starting
RE: Compressor Starting
"The more the universe seems comprehensible, the more it also seems pointless." -- Steven Weinberg
RE: Compressor Starting
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Compressor Starting
RE: Compressor Starting
Voltage dip on supply bus is 40% and the total innertia is 6375+4196=10571 (lb.ft2).
It seems to me it is too long such a compressor DOL.
RE: Compressor Starting
You may have to resort to alternate methods to start this compressor.
One approach may be to use a smaller pony motor on a VFD to spin the main motor and compressor up, unloaded and go DOL when it is up to speed. You may want to consider comparing the phase angle of the residual voltage at the motor terminals to the line voltage and go DOL when the residual is in phase with the line to minimize current surges when the main contactor puts the main motor DOL.
BUT: If the supply is as soft as I understand, youmay have problems with with voltage dips during normal running. (For instance when the unloader cycles.)
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Compressor Starting
RE: Compressor Starting
http://www.eng-tips.com/viewthread.cfm?qid=242000
Have you thought about fluid coupling ?