Testing Overview

Our motor testing capabilities include multiple electrical and mechanical tests. Whether upon inspection or client request, motor testing can be completed for a variety of reasons including detecting shorts between lamination, testing for defective rotor bars, testing motor windings and more. Test results will be included in a motor repair report, sent out on applicable motors 100 HP and up, or per Customer requirements.

Electrical Testing

Megohmmeter Test - All motor windings will be given a megohmmeter test to ground before disassembly and upon completion of repairs, with results recorded on Bradleys' Insulation Test Data form. The minimum acceptable value of insulation resistance in megohms upon completion of rewinding is 100 megohms.

Polarization Index Test - All motor windings rated at 2300 volts and above will be given a one minute versus ten minute polarization index test after completion of repairs, with results recorded on the back of Bradleys' Insulation Test Data form.

Surge Comparison Test - Windings will be tested by surge comparison with results recorded on Bradleys' Insulation Test Data form.

DC High Potential Test> - Will be performed on all motors according to NEMA MG-1-2 0.47 and Safety and test procedures will be carried out in accordance with NEMA MG-1-3.01.

Wet Test - When specified by the Customer, a wet test on the stator will be performed on 2300 and 4160 volt form wound coil motors by water spray method as outlined in NEMA MG-1 - 20.49.2.

DC Winding Resistance Test - When specified by the customer or otherwise required, the test will be given all like coils, i.e., individual stator, phase grouped stator - A to B, A to C, and B to C. The DC resistance difference between like coils should not vary more than + or - 0.5%.

Core Loop Test - The acceptable method for detecting shorts between lamination will be to induce magnetic flux in the stator core by transformer action. This is accomplished by winding several turns of cable around one side of the stator core, then energizing cable from a low voltage source. Core testing on small motors below approximately 1250 HP will be performed using a 25 KVA core loss tester. Larger motors will be checked using the EASA Stator Core Test Form.