Question

My pump is losing speed; does the drive have a problem?

Answer

Pumps are divided into three basic categories

• centrifugal
• rotary
• reciprocating.

Take any of the three types and break it down further into four parts

• the rotating element
• the casing
• the motor
• the drive

The rotating element has the shaft, sleeves, bearings and impeller. The casing has the pump shell, wear rings, and shaft seals. The motor and drive are intuitive.

Here is a basic remediation list:

1. Belts are slipping (if applicable);
2. Impeller worn
3. Impeller loose on shaft or shaft sheared
4. Casing worn
5. Original motor was replaced with a slower model or with greater amount of motor slip
6. Requirements have changed beyond the design specifications of the system.

Verify that you have a speed problem with a manual tachometer. If all of the above have been investigated, then a fix could be to increase the maximum frequency of the drive. Understand that anything beyond 60 Hz will result in a shift from a constant torque to a variable torque situation. There is a low probability that the drive will affect the intrinsic speed of the system detrimentally.

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FAQ Subcategory: None

This item was last updated on 2021-02-17
Document ID: 878

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