Screw Compressor Resonance Case Study
Axial vibration exceeding 1.2 in/sec at 4X motor speed was observed after replacing a 260-ton refrigeration screw compressor. The vibration coincided with the compressor lobe pass frequency, and the vendor was unable to reduce this force.
High motor vibration on a screw compressor linked to natural frequency excitation
Problem Statement
260 Ton refrigeration screw compressor
- Compressor is mounted to the tank through the suction piping.
- Motor is flange mounted to the compressor through a bell that houses the flexible coupling.
- Additional support from the tank below, supports the rear feet of the motor
- After replacement of the screw compressor with a factory rebuilt unit, routine vibration data sampling showed axial vibration at the motor frame in excess of 1.2 in/sec at 4X motor speed.
- 4X frequency of vibration coincided with the compressor
lobe pass frequency, vendor was unable to reduce this force.
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