# What is the acceptable Megger reading for a motor?

Contents

## What is a good megger reading for a 480v motor?

20 to 50 is good. 50 megs and above is excellent.

## What is a passing megger test?

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 the minimum megger value?

(1) IR Values For Electrical Apparatus & Systems:

Max.Voltage Rating Of Equipment Megger Size Min.IR Value
600 Volts 1,000 Volts 100 MΩ
5 KV 2,500 Volts 1,000 MΩ
8 KV 2,500 Volts 2,000 MΩ
15 KV 2,500 Volts 5,000 MΩ

## What is the resistance of a good motor?

Earth Continuity and Resistance Test

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.

## 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.

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## What is the minimum insulation resistance of a motor?

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.

## What should a motor Meg to ground?

IEEE recommends that for motor starting that the operational voltage, expressed as a meg-ohm value doubled plus 1000 is the minimum meg value for starting. For a 480V motor that would mean . 480Meg x 2= . 960 Meg + 1000, so a minimum ground resistance for starting a 480V is 1.960 Meg or round up to 2 meg-ohms.

What is a bad reading on a Megger test? 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.

## How do you find the insulation resistance of a 3 phase motor?

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 resistance value of 3 phase motor?

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

## What is the resistance of HP motor?

Motor Winding Resistance, Circuit Breakers

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Tuhorse Motor Winding Static Resistance (at 25°C)
1HP 0.75 7.8
1.5HP 1.1 5.8
2HP – 2015 and before 1.5 4.1
2HP – 2016 and after 1.5 4.1