This is an insulation test of motor windings, commonly referred to as megging, to megger, or to meg a motor. We are testing the motor’s insulation, more specifically between the motor windings and the motor casing. … Using a megohmmeter properly will test any motor insulation.
Can a megger damage a motor?
Any megger with a higher voltage output than 500 volts DC should be used by an experienced technician. A high voltage for too long of a time may further weaken or fail motor windings and the winding insulation could be damaged by the testing procedure.
How do you test a motor with a megger?
How to Test a Three-Phase Motor With a Megger
- Turn off the power supply to the motor, usually accomplished by switching the circuit breaker. …
- Place one megger probe to the any mounting bolt on the breaker box to test for grounding continuity, then touch the other probe to a motor terminal.
What should a motor Meg?
The rule may be stated: Insulation resistance should be approximately one megohm for each 1,000 volts of operating voltage, with a minimum value of one megohm. For example, a motor rated at 2,400 volts should have a minimum insulation resistance of 2.4 megohms.
How do I know how much my Megger is worth?
IR Value Measurement (Conductor to Earth Insulation)
- Connect conductor under test to the Line terminal of the megger.
- Connect earth terminal of the megger to the earth.
- Rotate the handle of megger or press push button of megger. The reading of meter will show the insulation resistance of the conductors.
What does a Megohmmeter measure?
A megohmmeter is an electric meter that measures very high resistance values by sending a high voltage signal into the object being tested.
How do you test to see if a motor is bad?
With a multimeter set to low ohms (usually 200), test between each winding terminal and the metal casing of the motor. If there is any reading on any of these then the motor is bad, do not use it. You may find that when it runs ungrounded that the casing becomes live at up to supply voltage.
Is a Megger test destructive?
Non-destructive testing evaluates the properties of the DUT without causing or having the potential to cause damage. Tests that fall into this cat- egory include Insulation Resistance-to-Ground (RTG) commonly called a Megger® test, Polarization Index, Insulation Resis- tance Profile, and Capacitance-to-Ground (CTG).
How do I know if my 3 phase motor is bad?
Check all three wires singly T1,T2,T3 (all three phases) to the ground wire. Readings should be infinite. If its zero or reads any continuity at all, then a problem exists with either the motor or cable . If it is go directly to the motor and disconnect from cable and check motor and the cable separately.
How do you check a 3 phase motor winding?
Using a multimeter, check the continuity of motor winding from phase to phase ( U to V, V to W , W to U ). Each phase to phase must have a continuity if winding is OK. If any particular phase fails the continuity test, your motor is probably burnt.
What is a 3 phase motor?
A three-phase motor is an electric machine that transforms electric power into mechanical energy by means of electromagnetic interactions.
What are good Megger readings?
Anything reading between 2 megohms and 1000 megohms is usually considered a good reading, unless other problems have been noted. Anything less than 2 megohms indicates an insulation problem.
How much winding resistance does a motor have?
The reading should be between 0.3 to 2 ohms. If it is 0, there is a short. If it is over 2 ohms or infinite, there is an open. You can also dry the connector and retest to possibly get more accurate results.
How do you Megger wires?
Clamp the alligator clip on one of the megger probes to the wire or cable, touch the other probe to the exposed conductor and press the test button. The megger will generate a current between the probes, and the meter will record the resistance of the jacket to the flow of the current.