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 much resistance should a motor winding have?
The windings (all three in a three-phase motor) should read low but not zero ohms. The smaller the motor, the higher this reading will be, but it should not be open. It will usually be low enough (under 30 Ω) for the audible continuity indicator to sound.
How do you calculate motor winding resistance?
Ohm’s law tells you that current through a wire – even a long wire wound around a motor solenoid – is equal to the voltage divided by the resistance. You can determine the resistance of a motor coil if you know the wire gauge, the radius of the solenoid and the number of windings.
What is the resistance of the winding?
Winding resistance is defined as the resistance of a length of copper wires from one end to the other. It is a measurement of DC voltage and current in regard to Ohm’s law, where R (resistance) is equal to V (voltage) divided by I (amps).
What is a good 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.
Which motor is never started on no load?
A series motor should never be started at no load. With no mechanical load on the series motor, the current is low, the counter-EMF produced by the field winding is weak, and so the armature must turn faster to produce sufficient counter-EMF to balance the supply voltage. The motor can be damaged by overspeed.
What does a reading of 0 ohms mean?
Secondly, what does a reading of 0 ohms mean? Resistance is measured in ohms with no current flowing through the circuit. It indicates zero ohms when there is no resistance between the test points. This shows continuity of current flow in a closed circuit.
How do I calculate resistance?
R = V ÷ I Question
What is the resistance of the lamp? To calculate the resistance of an electrical component, an ammeter is used to measure the current and a voltmeter to measure the potential difference. The resistance can then be calculated using Ohm’s Law.
What is the resistance value of 3 phase motor?
A good motor should result in a reading that is less than 0.5 ohms. If the value is greater than 0.5 ohms, however, this indicates that the motor’s insulation is failing and has the potential to cause an electric shock. Determining the causes of this failure may require further testing.
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.