Specifications

like the water pipes in your kitchen or bathroom. This can cause electrical shock in the shower

or sink. Leaking current also results in higher electric bills. In addition, it can cause the ground

faults in your home to trip repeatedly and eventually overheat.

Fig.7.3 - Open circuit test Fig.7.4 - Short circuit test

Causes of Insulating Material Deterioration include:

 Excessive heat  Excessive cold  Moisture

 Vibration  Dirt  Oil

Insulation Tester(Megger) : The tester applies DC voltage to the insulation system and

measures the current that results. The results of the test show if the insulation is working well,

or if it is allowing current to leak.

Fig.7.5 - Megger

Megger, the insulation tester is a combination of hand driven generator and a true ohmmeter

in same case as shown in Fig.7.5.The magneto generator produces 500 V dc (1000 V in other

design) and supplies to megohm meter section. The internal parts are shown in Fig.4.Two

permanent magnet bars with four iron pole shoes provide magnetic flux for both the generator

and ohmmeter setup. Pressure coil and current coil are placed at right angle to each other on