Cable Megger Test Insulation Resistance Values Table

A rated line to line voltage for three phase ac machines line to ground voltage for single phase machines and rated direct voltage for dc machines or field windings.

Cable megger test insulation resistance values table.

1k v 1 mω minimum 1kv 1 mω 1kv. At a pressure of 1000 v applied between each live conductor and earth for a period of one minute the insulation resistance of hv installations shall be at least 1 mega ohm or as specified by the bureau of indian standards. 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. To test a cable with a megger you connect one probe to the outside of the cable and with the power turned off you touch the probe to the conducting wire at the point of connection.

Curve b shows same values corrected to 20 c see page 22 giving a definite downward trend toward an unsafe condition. Figure 3 typical scale on the megger insulation tester. For good insulation the resistance usually reads in the megohm range. Based upon equipment rating.

Electric heat tracing systems are widely used inprocessindustriesand have applications in many other areas as well. 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 of heat trace cable. In general these systems are used to maintain a preferred temperature.

A megger is an ohmmeter that measures resistance in the megohm scale. Figure 4 typical record of insulation resistance of a mill motor. Curve a shows test values as measured. Comparing this result with the correct row of table 2 shows that our cable passes the insulation resistance test.

If the cable does not pass if a cable does not pass the test the cable still may be good but additional cable evaluation should be per formed. One meg ohm rule for ir value for equipment. Reverse side of card at right is used to record the test data. The first thing to check is the cable testing environment and cable preparation.

The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. As per ie rules 1956. 2621 van buren avenue. 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.

It s also known as an insulation tester. Values based on ieee std 43 2013. The megger insulation tester is essentially a high range resistance meter ohmmeter with a built in direct current generator. 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.