Cable Insulation Test Using Megger

Never touch the test leads while the handle is being cranked.

Cable insulation test using megger.

Applied potential shall be 500 volts dc for 300 volt rated cable and 1000 volts dc. For good insulation the resistance usually reads in the megohm range. Routine megger tests of aged electrical cable is a prudent way to ensure your circuits are safe from arc faults that can cause circuits to be blown and safe. Use megger on high resistance measurements only such as insulation measurements or to check two separate conductors on a cable.

The first dc portable insulation tester was developed in 1889 by our founders sydney evershed and ernest vignoles and by 1903 was being sold as a megger insulation tester. A megger sends voltage through a cable and measures any current leakage in megohms 1 000 ohms. Testing electrical cable with a megohmmeter helps identify damage in the cable insulation. For good insulation the resistance usually reads in the megohm range.

Insulation resistance testing purpose. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. The megger insulation tester is essentially a high range resistance meter ohmmeter with a built in direct current generator. It will also reveal localised weak spots in the insulation.

It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. Cable testing and diagnostics. A megger is an ohmmeter that measures resistance in the megohm scale. The insulation resistance test a k a the megger test is as relevant as ever and in many applications is preferred to other insulation test methods.

For cables 300 volt use 500 vdc megger. Cable testing and diagnostics provides information about the cable s global condition e g. It s also known as an insulation tester. The cable s overall insulation system and will reveal localised problems such as poor joints and terminations.

The megger insulation tester is essentially a high range resistance meter. For cables above 300 volt to 600 volt use 1000 volt megger. The test measures the insu lation resistance between the phases and or between phase and ground. Perform insulation resistance test on each conductor with respect to ground and adjacent conductors.

De energize and discharge the circuit completely before connecting a megger. Insulation resistance testing is a non destructive test procedure. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms.