Insulation Resistance Test Results Table

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.

Insulation resistance test results table.

The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and. However let s talk now about three basic types of insulation resistance tests using megger tester. Helps to plan for the future with respect to funding for. The measurement of insulation resistance is a common routine test performed on all types of electrical wires and cables.

The insulation resistance test is an electrical test which uses a certain type and level of voltage 500v d c. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. The measured resistance indicates the condition of the insulation between two conductive parts. B kv is the rated machine terminal to terminal voltage.

For low voltage installations i e. The most common voltages are 500v and 1 000v. The results obtained from ir test are not intended. Do not allow the leads to touch during the test.

Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv. Also acceptable values of insulation resistance depend upon the equipment you re testing. For this reason care must be taken to properly prepare the cable to be tested. Why perform insulation resistance testing it s the law 33 cfr 208 10 f 1 megger tests of all insulation shall be made whenever wiring has been subjected to undue dampness and otherwise at intervals not to exceed one year.

For good insulation the resistance usually reads in the megohm range. Minimum acceptable insulation resistance for 600 v cable from 100 to 1000 feet. As a production test this test is often used as a customer acceptance test with minimum insulation resistance per unit length often specified by the customer. Insulation resistance decreases in temperature or moisture.

Ansi neta mts 2015 table 100 11 insulation resistance test values rotating machinery for one minute at 40 c. 230v to measure insulation resistance in ohm s. Higher voltages are used to stress an insulation to a greater degree and thus obtain more accurate results. Short time or spot reading test.

Insulation resistance test results are dependant on a number of factors such as temperature and humidity. A record shall be kept showing the results of such tests. Insulation resistance testing path can affect the test and reduce the insulation resistance reading. Suspend and isolate the test set leads in air as much as possible.

With a little record keeping and common sense however you can get a good picture of the insulation condition from values that are only relative. Values based on ieee std 43 2013.