Insulation Resistance Test Results Table

Also acceptable values of insulation resistance depend upon the equipment you re testing.

Insulation resistance test results table.

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. 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. The results obtained from ir test are not intended. The measured resistance indicates the condition of the insulation between two conductive parts.

The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. For this reason care must be taken to properly prepare the cable to be tested. The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and. 230v to measure insulation resistance in ohm s.

However let s talk now about three basic types of insulation resistance tests using megger tester. Higher voltages are used to stress an insulation to a greater degree and thus obtain more accurate results. 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. B kv is the rated machine terminal to terminal voltage.

The measurement of insulation resistance is a common routine test performed on all types of electrical wires and cables. Suspend and isolate the test set leads in air as much as possible. Short time or spot reading test. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms.

For low voltage installations i e. Do not touch or move conductor during testing as results will be affected. A record shall be kept showing the results of such tests. Ansi neta mts 2015 table 100 11 insulation resistance test values rotating machinery for one minute at 40 c.

Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv. 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. The most common voltages are 500v and 1 000v. Recommended test voltages for routine maintenance insulation resistance tests of equipment rated to 4 160v and above.

Helps to plan for the future with respect to funding for. Insulation resistance decreases in temperature or moisture. Insulation resistance test results are dependant on a number of factors such as temperature and humidity. Insulation resistance testing path can affect the test and reduce the insulation resistance reading.

For good insulation the resistance usually reads in the megohm range. Do not allow the leads to touch during the test.