Transformer Megger Test

The megger has three terminal posts: one for "L", one for "E" and one for "G" (shield). L is connected to the wires, E is connected to the cable, and the "G" is attached to the insulated paper of the cable. The following points should be noted when measuring:

  • The power must be cut off first.
  • The megger must be kept flat when used.
  • Before we use the megger, we need to rotate several times to see whether the pointer is at the largest location. Then we will short-circuit the two terminals of "L" and "E", then slowly turn the hand of mega ohmmeter to see whether the pointer is at zero.
  • The megger cable must be insulated well, and the two lines shall not be twisted together.
  • When measuring the megger, the reading should be based on the number after a minute of rotation.
  • During the measurement, the number of meters should be transferred to 120 revolutions per minute.
  • The megger has a range of several thousand megaohm, with a minimum scale of about 1 trillion euro, which is not suitable for measuring the resistance below 100 kiloohm.

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