All electrical installations and equipment comply with insulation resistance specifications so they can operate safely. Whether it involves the connection cables. IR Testing for Low voltage. Circuit voltage, Test voltage, IR Value(Min). Extra Low Voltage, V DC, MΩ. Up to V except for above. These minimum IR testing voltages must always be adhered to in order to accurately measure the Insulation Resistance in all electrical equipment. Any test .

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Luckily after searching in the web your article showed up. The resistance between Phase-Phase-Neutral-Earth must never be less than 0. It was found that the reading was less with oil than without oil. For electric motorwe used a insulation tester to measure the resistance of motor winding with earthing E. The transformer Neutral bushing is to be disconnected from earth during the test.

Value at 60 seconds after application of the test voltage is referred to as the Insulation Resistance of the transformer at the test temperature. Avoid meggering when the transformer is under vacuum. Auto transformer two windings 1.

Solidly grounded winding must have the ground removed in order to measure the insulation resistance of the winding grounded. To test the other, both two-way switches should i.r.tedting operated and the system retested.

I need to know the HV and Megger test voltage value and routine tests to be performed for medium voltage 6.

Benefits of Permanently Installed Automatic Insulation Resistance (IR) Testing: Part 1 of 3

Voltage Rating Of Equipment. Arabinda Feb 08, Dear Sir Thanks for all this good work that you have done. IR Value for Transformer 3. The result must i.r.testing with that specified in the British Standard concerned, or be at least 0. Very useful articleI appreciate your efferots to collect all these indexes and values in one paper Thank you….


I wish to thank the author for making this information available to the general public who could be harmed as a consequence. Where any equipment is disconnected for testing purposes, it must be subjected to its own insulation test, using a voltage which is not likely to result in damage.

IR Value for Tap Changer 4. Vincenzo Dec 30, Capacitors and indicator or pilot lamps must be disconnected or an inaccurate test reading i.f.testing result.

At a pressure of 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.

Arunkumar Dec 12, For insulation testing, we need to disconnect from panel or equipment and keep i.f.testing isolated from power supply.

Measurement of insulation resistance (IR) – Part 2

Insulation resistance tests are made to determine insulation resistance from individual windings to ground or between individual windings. For most dc armature and ac windings built after about form wound coils. Sir, it has been observed that during oil replacement procedure of a power transformer in one of our Substations IR values were taken after draining of oil and after filling with oil. Where two-way switching is wired, only one of the two stripper wires will be tested. Virendra Nathe Tiwari Jun 12, Discharge the winding capacitance.


Three winding transformer 1. Fluke insulation resistance tester up to 10kV Continued from first part: Transformer windings are never left floating for insulation resistance measurements. Insulation resistance tests are commonly measured directly in megohms or may be calculated from measurements of applied voltage and leakage current.

Thank you for this very useful article.

Electronic equipment like electronic fluorescent starter switches, touch switches, dimmer switches, power controllers, delay timers could be damaged by the application of the high test voltage should be disconnected. Continued from first part: Treat it as part of the grounded section of the circuit. Krishnaiah I.r.testign 24, I just have doubt that one of the i.r.twsting of insulation temperature correction factors is given with a probable mistake from the point I looked to the insulator.

Benefits of Permanently Installed Automatic Insulation Resistance (IR) Testing: Part 3 of 3

Premium Membership Premium membership gives you an access to specialized technical articles and extra premium content electrical guides and software. He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India.

A Very Useful Article Request i.r.testijg mentioned the source of the information provided. Motor Name Plate V. The wiring and cables need to test for each other phase to phase with a ground E cable.