Insulation Resistance Test Standard For Cable

Insulation resistance decreases in temperature or moisture.

Insulation resistance test standard for cable.

The test measures the insu lation resistance between the phases and or between phase and ground. Principle of insulation testing and influencing factors insulation resistance measurement is based on ohm s law. Insulation resistance test data may be used to establish a trending pattern. Table 100 22 minimum radii for power cable.

Cables for rated voltages of 1 kv um 1 2 kv and 3 kv um 3 6 kv reference number. The insulation resistance test is the second test required by the electrical safety testing standards. Insulation resistance testing purpose. The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and.

Minimum acceptable insulation resistance for 600 v cable from 100 to 1000 feet. Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv. After dc overpotential test is completed the insulation resistance test is done again to assure that the cable has not been damaged by the hi pot. Power cables with extruded insulation and their accessories for rated voltages from 1 kv um 1 2 kv up to 30 kv um 36 kv part 1.

With a little record keeping and common sense however you can get a good picture of the insulation condition from values that are only relative. Also acceptable values of insulation resistance depend upon the equipment you re testing. Deviations from the baseline information permit evaluation of the insulation. For cables rated 600 v the minimum acceptable insulation resistance values for cable lengths from 100 to 1000 feet would be as shown in the following table from ieee 525.

Developed early in the 20th century the insulation resistance ir test is the oldest and most widely used test for assessing the quality of insulation. When overpotential testing cable its common practice to conduct the insulation resistance measurement first and then proceed with the dc overpotential test if acceptable readings are achieved. Regular testing of the insulation on an installation or machine is therefore a useful way of monitoring this type of deterioration so you can act before total failure occurs. If during periodical testing insulation resistance of cable is found between 5 and 1 mω km at buried temperature the subject cable should be programmed for replacement.

Insulation resistance testing is a non destructive test procedure. Test results are dependent on the temperature of the insulating material and the humidity of the surrounding environment at the time of the test. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs.