Acceptable Cable Insulation Resistance Test Values

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.

Acceptable cable insulation resistance test values.

A megger sends voltage through a cable and measures any current leakage in megohms 1 000 ohms. Hands down without a doubt one of the most universally searched topics on ec m s website from a historical perspective is insulation resistance testing as a result some of our most popular evergreen articles like understanding insulation resistance testing continue to top the charts when it comes to most popular content. Figure 4 typical record of insulation resistance of a mill motor. The results obtained from ir test are not intended to be useful in finding localized defects in the insulation as in a true hipot test but rather give information on the quality of the bulk material used as the insulation.

Temperature halves the insulation resistance while a 10 c reduction doubles the insulation resistance value. 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. Curve a shows test values as measured. Even when not required by the end customer many wire and cable manufacturers use the insulation resistance test to track their insulation manufacturing processes and.

3 shows a typical scale which reads increasing resistance values from left up to infinity or a resistance too high to be measured. 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. Values based on ieee std 43 2013. B kv is the rated machine terminal to terminal voltage.

Ansi neta mts 2015 table 100 11 insulation resistance test values rotating machinery for one minute at 40 c. 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. Since 80 of electrical maintenance and testing. Megohmmeters or meggers are testing meters used to measure the current leakage from an electrical cable by means of administering an insulation resistance test.

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. Care must always be taken not to measure the insulation resistance if the temperature is lower than. Insulation resistance tests are made to determine insulation resistance from individual windings to ground or between individual windings. 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.

Minimum acceptable insulation resistance for 600 v cable from 100 to 1000 feet.