Megger
Ohm meter
Wheatstone bridge
Earth tester
Potential dividing method
Fall of potential method
Fall of resistance method
Current dividing method
AC is easily available
Protect the coils in the meter
Reduce the value of current in the meter
Avoid the effect of electrolytic Emf interference
One primary winding
Two primary windings
Three primary windings
Four primary windings
Control the fault circuit current
Protect the residual current
Protect the equipment from over load
Protect the circuit from short circuit