Motors and Pumps - Reducing Power Absorption

1. Check that the seals and bearings are not so tight as to cause excessive shaft friction.
2. Check that the impeller is not colliding with the volute and that power is not being lost due to mechanical attrition.
3. Check that the impeller is complete and well-balanced.
4. Check the volute does not contain any solid obstructions. Rags? Spanners? Dead animals or birds?
5. The power required of any fluid mover is the product of the pressure rise and the volumetric flowrate. Reduce either or both of these.
6. Check that the pump and its motor are correctly matched; the original equipment manufacturer can advise.

What type of pump is it and what are you pumping?

thank's for answering , the type of pumps are seweage pumps and centrifugal pumps and the fluid pumped is water

Crabtree gave good advice and I would add to that:

A re-circulation line may reduce load but that is dependent on other factors being resolved.

If you are pumping sewage, there is probably particulate in the water that would cause a greater load on the impeller and or jamming up in the casing.

If the pump/motor are a manufacturer's match and they are being used as intended, i.e., sewage, then I would check the integrity of the motor windings (megohm-meter). It could be that they are damp or there has been a deterioration of insulation.

There quite a few forum members who know a lot more about pumps than do I, with luck they will browse this post.

The testing is it done in the system or simulated on a bench?

If the testing is done on a bench and the delivery head is lower than the required head the pump will deliver more water and draw more power.

For water this can be corrected by closing a valve on the outlet until the pressure gauge on the pump indicates the correct pressure head.

more detail will enable better answers.

Can you describe your testing method and equipment.

How do you measure the head?

How do you measure the flow?

How do you measure the speed of the pump?

Have you got a pump curve?

What us the required duty point?

In principle power demanded by the pump may change as the performance of the pump is lost due to wear. However, consideration should be given to the following areas.

1) Has the system characteristic changed and the flow rate increased through the pumping system?

2) Sewage could result in an additional restriction which may cause the pump to demand more power?

3) Is there a possibility that the pump performance has degraded during operation

4) Please could you out line what type of tests were carried out and what data was obtained?

I am afraid that in reality unless there is more information relating to the pump type, application, situation etc., it is difficult to provide advise, but if there is a problem, a performance test on the unit to establish it's actual running condition and the system characteristic is required.

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