Electrical Cable Insulation Test

The measurement of insulation resistance is a common routine test performed on all types of electrical wires and cables.

Electrical cable insulation test. What makes insulation go bad. The top terminal might be the center conductor of a power cable and the bottom terminal its shield. We verify the electrical insulation level of any device such as motor cable generator winding or general electrical installation. The dielectric withstand test is a basic electrical stress test conducted to ensure an insulation system will provide adequate service life.

Furthermore manufacturers of wire cable motors and so on have continually improved their insulations for services in industry. Either turn off the breaker or if you re testing the wiring in a piece of equipment unplug it. The current flowing through the cable s insulation would be that current noted as total current in the diagram. Cable faults cost money and create disruption so there is an enormous demand for cable test techniques to ensure cables and joints are in good condition and to allow cable faults to be located rapidly.

This is a very poplar test being carried out since very long back. A cable insulation test is basically a continuity test so the power to the circuit must be off. Insulation resistance test. The minimum values of insulation resistance have changed over the years.

For the withstand test the insulation under test must withstand a specified applied voltage that is higher than the service voltage across the insulation for a specified period without breakdown of the. Because electrical insulation will exhibit dynamic behavior during the course of your test. When your plant electrical system and equipment are new the electrical insulation should be in top notch shape. Nevertheless even today insulation is subject to many.

The insulation resistance test consists in measuring the insulation resistance of a device under test while phase and neutral are short circuited together. Locate the connection point of the wire or cable you want to test so you have access to the exposed conductors. We look for corrosion on the copper cracks in the insulation moisture on the cables and many other indicators of damage to the cables. As a production test this test is often used as a customer acceptance test with minimum insulation resistance per unit length often specified by the customer.

There is no documented justification for the 1 megohm minimum value of insulation resistance but it has survived the test of time and in practice has proved to be a useful starting point when determining the condition of the insulation of cables and electrical equipment. An equivalent circuit for electrical insulation is shown in fig. The insulation resistance test is the second test required by the electrical safety testing standards.