How do you test a Megger on a 3 phase motor?

How do you test a 3 phase motor for insulation?

TEST Procedure:

  1. Disconnect the motor from power supply using main breaker.
  2. Use do not operate tag to avoid injury.
  3. Open the motor terminal box.
  4. Check for current using the tester/Ground motor terminals / short motor terminals for safety purpose to avoid getting shock.

What is the acceptable Megger reading for a motor?

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 much resistance should a 3 phase 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 I know if my 3 phase motor is bad?

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.

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What is a bad reading on a Megger?

What is a bad Megger reading? If the megger reads a resistance under 1 (1,000 ohms) on your meter after the initial 60-second interval, the cable has failed and the cable should be removed. If the megger reads a resistance between 1-1.25 on your meter, then the cable passes.

What is considered a bad Megger reading?

Turn on and read the meter. 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.

What is a bad insulation resistance reading?

The purpose of the IR test is to check for damaged insulation, this can be mechanical damage or damage by heat, (overloaded cables), readings less than 2 Mohm indicate damaged insulation, readings of 2-50 Mohm are indicative of long circuit lengths, moisture and contamination and do not indicate the insulation quality, …

What should be the insulation resistance of motor?

It is recommended that the insulation resistance of the motor should at least be 1 MΩ1, and for the voltage to ground of 200 V, I0r should be 200 μA or below.

What causes motor windings to fail?

Looseness and bearing failures. … Another common fault stems from mechanical rubs, which can be the result of looseness of the motor shaft and/or the motor bearings. The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings.

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