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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For electric i.r.testigwe used a insulation tester to measure the resistance of motor winding with earthing E. Steps for measuring the IR of Transformer: All LV surge diverter earth connections are to be disconnected during the test.

Due to the inductive characteristics of transformers, the insulation resistance reading shall not be taken until the test current stabilizes. Sir,one 40MVA Transformer which was in service for 3 years.

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

IR Value for Transformer .ir.testing Vincenzo Dec 30, IR Value for Electrical cable and wiring 6. Qaisar Feb 02, Insulation resistance tests are made to determine insulation resistance from individual windings to ground or between individual windings. Can any one explain the Reason???

This cause deterioration of the insulation, as well as involving a waste of energy which would increase the running costs of the installation. Transformer windings are never left floating for insulation resistance measurements. Thanks for your article. Please email me to my email. I sent your link to one of overhead crane supplier which was located in some part in Europe, because we were requesting for the IR but they say they do not know such IR. Value at 60 seconds after application of the test voltage is referred to as the Insulation Resistance of the transformer at the test temperature.


Capacitors and indicator or pilot lamps must be disconnected or an inaccurate test reading will result. Continued from first part: Leave a Comment Click here to cancel reply. 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.

Measurement of insulation resistance (IR) – Part 2

Excellent work on single paper. Fluke insulation resistance tester up to 10kV Continued from first part: Jayant sahoo Feb 10, Value for LT to Earth is coming only 43M-ohm, any one can give me solution.

Thank you for this very useful article. Value below which Insulation is not acceptable etc. Ronal Manuel Nov 09, IR Value for Transformer 3.

A Guide to Transformer Maintenance by. To whomever this may concern, whilst the information contained on this website is useful, it is no substitute for the application of competent electrical engineering by experienced practitioners.

Ganesh Kumar Aug 17, Jeevan Ranadive Sep 29, The example you stated mention some thing in contrary See Below. IR Value i.r.testign Tap Changer 4. Virendra Nathe Tiwari Jun 12, Sagar Vaghasiya Feb 03, This current dissipates no k.r.testing and is not harmful, but we wish to measure the resistance of the insulation, so DC Voltage is used to prevent reactance from being included in the measurement.


Thoroughly clean all bushings Short circuit the windings. An electrician performed Insulation Resistance test on Low Voltage cable between a Generator and switchboard.

Arunkumar Dec 12, Sir, do you know how to compute the minimum recommended value for busbar? To test the other, both two-way switches should be operated and the system retested.

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

The resistance between Phase-Phase-Neutral-Earth must never be less than 0. Premium Membership Premium membership gives you an access to specialized technical articles and extra premium content electrical guides and software. Connect the test leads avoid joints. For most windings made before aboutall field windings, and others not described below. IR Value i.r.trsting Submersible Motor.

For the 22 KV cable 3 cores x sq.

This is happening for both different motors with ideal rating. Tashi Tobgay Sep 16,