Can anyone help with this thread? I am sure there was previous discussions on this subject. i am looking for the pro's and cons of load testing motors and gearboxes.
Thanks in advance
Jackman

Jackman:

Con: Additional cost, and availability of the dyno or other load equipment by the repair shop or manufacturer. That's it.

Pro: The detection of defects that do not show at no-load in both the motor and gearbox.

I would recommend that you determine when it is cost effective to add the load testing expense. For critical equipment, this would be an excellent approach (Safety/Environment, Production, or Expensive Equipment or Replacement Costs).

Howard

Jackman,

Load testing is beneficial to verify performance and for detecting machine condition issues that are dominant or detectible under load. A shop load test may have limitations in reaching rated speed (at rated load), full machine train setup (torional vibrations), full stable temperature, and structural mounting.

Assuming that the new or rebuilt machine train or component is worthy (acceptable) for shipping and installing, then I recommend full load testing at the plant for purposes of purchase specifications, owner accpetance, warranty, and performance and condition baselines.

Walt

As mentioned some faults show only under load. One example may be rotor bar fault. Another example may be twisting of a flimsy stator frame under torque loading which can cause 2*LF and other problems.

Another aspect is simply verifying the thermal design. It's possible that the motor winding may operate above it's specification temperature at full load, which does not bode well for the insulation life. Would rather know that before you accept the motor than after.

One other intersting aspect which actually may be missed by torque load test is the effect of thrust loading on performance of thrust bearing (for example Kingsbury thrust bearing on top of a vertical motor). If you're buying a large motor chances are it is a unique design and errors can be made in the design of that upper bearing, and the associated oil system and cooling system which cause the bearing to run hotter than tolerable at full load. You'd rather test that up front if you can although applying thrust load can be difficult.