Cable Insulation Test Using Megger

The megger insulation tester is essentially a high range resistance meter ohmmeter with a built in direct current generator.

Cable insulation test using megger.

The megger insulation tester is essentially a high range resistance meter. Insulation resistance testing is a non destructive test procedure. Never touch the test leads while the handle is being cranked. A megger sends voltage through a cable and measures any current leakage in megohms 1 000 ohms.

For cables 300 volt use 500 vdc megger. It s also known as an insulation tester. 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. For cables above and less than 1200 volt use 2500 volt megger.

Applied potential shall be 500 volts dc for 300 volt rated cable and 1000 volts dc. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. For good insulation the resistance usually reads in the megohm range. Insulation resistance testing purpose.

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. Testing electrical cable with a megohmmeter helps identify damage in the cable insulation. For good insulation the resistance usually reads in the megohm range. The cable s overall insulation system and will reveal localised problems such as poor joints and terminations.

Use megger on high resistance measurements only such as insulation measurements or to check two separate conductors on a cable. Cable testing and diagnostics. It will also reveal localised weak spots in the insulation. The insulation condition from values that are only relative.

Perform insulation resistance test on each conductor with respect to ground and adjacent conductors. A megger is an ohmmeter that measures resistance in the megohm scale. The test measures the insu lation resistance between the phases and or between phase and ground. 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.

De energize and discharge the circuit completely before connecting a megger. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. Cable testing and diagnostics provides information about the cable s global condition e g.