Insulation Resistance Test Standard For Cable

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.

Insulation resistance test standard for cable.

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. 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. The insulation resistance test is the second test required by the electrical safety testing standards.

The insulation resistance test consists in measuring the insulation resistance of a. Principle of insulation testing and influencing factors insulation resistance measurement is based on ohm s law. Minimum acceptable insulation resistance for 600 v cable from 100 to 1000 feet. Also acceptable values of insulation resistance depend upon the equipment you re testing.

Table 100 22 minimum radii for power cable. Insulation resistance testing purpose. Deviations from the baseline information permit evaluation of the insulation. 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.

Test results are dependent on the temperature of the insulating material and the humidity of the surrounding environment at the time of the test. Insulation resistance testing is a non destructive test procedure. 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. The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and.

The test measures the insu lation resistance between the phases and or between phase and ground. 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. If insulation resistance of the cable is found between 1000 and 100 kω km at buried temperature the subject cable should be replaced urgently within a year. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs.

Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv. Insulation resistance decreases in temperature or moisture. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms.