Question

year
Difference between insulation and relation​

Answer 1

Answer:

Motor, alternator, and transformer windings are normally electrically insulated from the core (or ground)of the device. The resistance between a winding and the core/ground is called the insulation resistance. Its measured by applying a high voltage (typically 500 or 1,000 volts for lower-voltage equipment) between the winding and core /ground using a special insulation resistance (IR) measuring device called a “Megger” or high-voltage megohmmeter.

For example, the insulation resistance for new motors typically measures gigohms (10^9) or terohms (10^12) depending on the insulation class of the equipment. By periodically testing the equipment over its service life, any progressive or sudden decrease in insulation resistance can indicate insulation damage due to overheating, moisture absorption, accumulations of dirt/debris, etc. Once the insulation resistance becomes too low, the motor should be removed from service and repaired, cleaned, or rewound to avoid sudden catastrophic failure.

At the other end of the spectrum, winding resistance is the electrical resistance for the wire in a given winding. This is usually measured using a low-voltage ohmmeter and is typically ohms or tens of ohms.

Sometimes the effective AC reactance (a combination of DC resistance and AC impedance of a winding) is also sometimes measured at the operating frequency of the device using more sophisticated measurement equipment.