AC motorised insulation tester is a high voltage tester ... generally used for insulation testing of transformer oil / electrical equipment winding test, where AC high voltage is applied to check the inter turn insulation quality / & peak volt is 1.41 * V rms . This is not a portable equipment , & useful in the final quality check of the electrical equipment.
DC insulation tester is a portable instrument, available in the range of 500 V, 1000V, 2500V, 5000V.... operated by rotating a handle. This checks the over all insulation quality w.r.t. earth body / phase to phase. Very useful instrument for maintenance purpose in the field & work shops . General common name is MEGGER.
500V megger for electronics equipments & instruments / pcb testing.
1000V megger is for testing of Low voltage equipments - 415 V rated.- range is 0-200Mohms
2500 / 5000V megger for Medium & high voltage equipments - 22kv / 33kv / 66 kv.
Range is 0- 10K meg Ohms.
Range 0 - 50K meg Ohms are also available.
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Exploring the Science of Electricity