What are acceptable 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 do you read Megger results?

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. Any reading above 1.25 is considered excellent.

What is Megger range?

For this purpose, megohmmeters, which can provide high DC voltages (typically in ranges from 500 V to 5 kV, some are up to 15 kV) at specified current capacity, are used. Acceptable insulator resistance values are typically 1 to 10 megohms, depending on the standards referenced.

What causes low Megger readings?

Two conductors have consistently lower values: Because the conductors adjacent to the ground conductor only have one layer of insulation, those conductors will have lower insulation resistance and the Megger values will be lower.

How do you Megger a 3 phase motor?

  1. Turn off the power supply to the motor, usually accomplished by switching the circuit breaker.
  2. 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.
  3. Crank the handle for about a minute, and notice the resistance reading.

What is IR value?

IR Value for Transformer. Insulation resistance tests are made to determine insulation resistance from individual windings to ground or between individual windings. Insulation resistance tests are commonly measured directly in megohms or may be calculated from measurements of applied voltage and leakage current.

What causes low megger readings?

What is the minimum acceptable reading for insulation resistance on a 230v circuit?

Test voltage 500v for 230v or 400v installations or circuits with a minimum insulation resistance of 1 M ohm (1000,000 ohms).

What is OL in megger?

If your megohmmeter is reading “OL” (over load) or “I” (infinity), these are commonly used readings on megohmmeters when the measurement exceeds the maximum indicated value of the tester.