TEST and RUN an Electric MOTOR

INSTRUCTORS INTRODUCTION

These videos show the proper methods and metering devises used for testing motors in both the power on and power off mode.  While there is a wide variety of different metering tools available the general methods and procedures shown here basically unchanged.

INSTRUCTOR INTRODUCTION:

                                  MEG- OHM TESTING A MOTOR;

WARNING: BEFORE CONDUCTING A MEG-OHM TEST INSURE THAT THE ELECTRICL POWER IS OFF AND THAT THE UNIT TO BE TESTED IS DISCONNECTED FROM THE POWER SUPPLY;

The Theory of the Test, The Intent Of An Insulation Test; is to apply a known voltage to a conductor and then test to see if that voltage is shorting out to ground or to any adjacent conductors. If there are a number of conductors then you must test between each conductor and then from each conductor to the motor housing to see if any of the windings are shorted or gone to ground. If you are testing a new piece of equipment or a 10 year old motor the testing times will vary. For new piece of equipment or installation a 30 second to 1 minute test is usually sufficient. This is also suitable if an ongoing PM (Preventative Maintenance) program is in effect and you have a series of test results on an older piece of equipment. On older equipment with no known test history and results to compare against, a 10 minute test is required to understand the true condition of the insulation. For new electrical equipment testing ensures that the insulation is adequate and it provides a baseline reading for future tests. Another type of test is called the Time Resistance Test it provides conclusive results with past test measurements, successive test readings are taken at fixed time intervals; it’s very effective when moisture and dirt are present. Resistance values may start low then increase over time this trend will continue for several minutes for healthy insulation – resistance that decreases over time indicates a problem. Testing induces a voltage which may be stored in the test motor be sure to allow time for this induced voltage to discharge at the end of the test. The One-Meg Ohm Rule is the lower limit used for ordinary industrial equipment rated up to 1000 volts, for equipment rated above 1000 volts, use one  meg-ohm per 1000 volts

INSTRUCTOR TO STUDENTS ; WE WILL NOW WATCH A SHORT VIDEO ON MEGGER TESTING;