Best answer: How do you Megger a 3 phase motor?

How do you test a 3 phase motor insulation resistance?

Phase Resistance: Take the insulation tester and set it to 500V. Take each end and place it on different permutations of L1, L2 and L3 and record each reading. Phase to Earth Resistance: Take the insulation tester, using the same setting, and check each lead from phase to the frame of the motor.

What is the acceptable Megger reading for a motor?

If the motor is kept in a place with high humidity, a periodical inspection is necessary.

A general rule-of-thumb is 10 Megohm or more.

Insulation resistance value Insulation level
10-50 Megohm Good
50-100 Megohm Very good
100 Megohm or more Excellent

How do you use a multimeter to Megger a motor?

Inspect the Motor Windings With a Multimeter

To begin, set the multimeter to read ohms and then test the motor’s wires and terminal. You should test the windings for a “short to ground” in the circuit and open or shorts in the windings.

How many ohms should a 3 phase motor read?

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.

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How do you increase the insulation resistance of a motor?

Cleaning and drying the winding will usually improve the IR. If the winding temperature is at or below the dew point, moisture may accumulate on the surface, causing low IR values. When the winding is otherwise in good condition, drying will resolve this issue.

What does Megging a motor tell you?

Megger testing measures resistance between the phase windings of the motor under test and ground. If there is an insulation breakdown, the resistance is negatively impacted and there is a departure between phases or between one measurement and a previous one and a determination of motor health is made.

What is the resistance of a 3 phase motor?

Most are between 3 and 2.0 ohms. There are 8ohms. A short between phases exists if you read zero.

How do you Megger a single phase motor?

With a multimeter, measure the resistance between motor frame (body) and earth. A good motor should read less than 0.5 ohms. Any value greater 0.5 ohms indicate trouble with the motor. For single phase motors, the expected voltage is about 230V or 208V depending whether you are using the UK or America voltage system.