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What are the three terminals of megohmmeter?
A Megger basically has three terminals: Line terminal, Earth terminal, and Guard terminal. 4). What is an electrical Megger test? An electric megger test is basically used in the verification of electrical insulation in the circuit.
How do you test a Megger?
Clamp the alligator clip on one of the megger probes to the wire or cable, touch the other probe to the exposed conductor and press the test button. The megger will generate a current between the probes, and the meter will record the resistance of the jacket to the flow of the current.
Why Guard terminal is used in Megger?
The guard terminal is a third connection that is made to the asset under test. This takes the surface leakage current out of play and allows the test instrument to measure just the true insulation leakage current. Measured current = insulation leakage current only. Surface leakage current is “guarded out”.
How many terminals are in a Megger?
How to use Megger. Meggers is equipped with three connection Line Terminal (L), Earth Terminal (E) and Guard Terminal (G). Resistance is measured between the Line and Earth terminals, where current will travel through coil 1.
Why 3 terminals insulation testers are used in HV insulation measurements?
By using the guard terminal to perform a ‘three-terminal test’, the surface leakage current can be ignored. This may be important when high values of resistance are expected, such as when testing high voltage components like insulators, bushings and cables.
What is guard wire?
[′gärd ‚wīr] (electricity) A grounded conductor placed beneath an overhead transmission line in order to ground the line, in case it breaks, before reaching the ground.
What are the two coils of Megger?
Working of Megger The Megger has three coils two pressure coils and one current coil. The pressure coil rotates the moving coil in the anticlockwise direction, whereas the current coil rotates it in the clockwise direction.