Examine the name plate thoroughly. 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.
How do you calculate the resistance of a motor?
R in ohms = Rated voltage /(rated current x1. 732×3. 5). Example : 2000kw motor, rated voltage is 6600v, rated current is 175A, then R= 6600/(175*1.732*3.5) = 6.22.
What should be the motor winding resistance?
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 calculate resistance?
If you know the total current and the voltage across the whole circuit, you can find the total resistance using Ohm’s Law: R = V / I. For example, a parallel circuit has a voltage of 9 volts and total current of 3 amps. The total resistance RT = 9 volts / 3 amps = 3 Ω.
What is the resistance of the motor?
The unit of measure for resistance is an ohm. When testing electric motors, it is useful to know the insulation resistance between motor winding(s) and the frame ground. This value will normally be in the range of tens to millions of ohms.
How do you test winding resistance?
Current Voltage Method of Measurement of Winding Resistance
In this method of measurement of winding resistance, the test current is injected to the winding and corresponding voltage drop across the winding is measured. By applying simple Ohm’s law i.e. Rx = V ⁄ I, one can easily determine the value of resistance.
How do you check motor winding resistance with a multimeter?
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.
Why do we check motor winding resistance?
Winding resistance measurements detect various faults in motors, generators, and transformers: shorted & open turns, loose connections, and broken conductors & resistive connections problems. … Winding resistance measurements detect problems in motors that other tests may not find.
How do you calculate resistivity resistance?
The resistivity is a characteristic of the material used to fabricate a wire or other electrical component, whereas the resistance is a characteristic of the wire or component. To calculate the resistance, consider a section of conducting wire with cross-sectional area A, length L, and resistivity ρ.
How do you find resistance between two points?
The most general way to find the resistance between two points is to take a test voltage source and apply it between those two points. Then see how much current flows in the source as a result. Divide the voltage by the current and you have the effective resistance.
How do you find resistance with power and voltage?
For example if the power is 100 watts and the voltage is 50 volts, the current is 100 / 50, or 2 amps. Calculate the resistance, in Ohms, by dividing the voltage by the current. Ohms law states that voltage = current x resistance, so by rearranging the formula resistance = voltage / current.