Selection of Bimetal + Moving iron meter

Maximum demand meters are intended for testing momentary thermal load of

transformers,cables,electrical machines etc.The bimetallic movement responds and

indicates the mean RMS current loading over a specified period of time.A black pointer

which is attached to the bimetal spiral moves in response to the current-(heating) in the

bimetal sprial.A red pointer(slave or memory pointer) is driven by the black pointer.The red

pointer remains at its maximum position to which the black pointer has reached during any

period of time.Further,when the loading is reduced,the red pointer remains at the maximum

value.This enables the operator to know the maximum loading of the system without

continuously watching the meter.A zero corrector is provided on the front of the meter to

bring back the red pointer to the position of the black pointer.A sealing/locking facility is

also provided on the zero corrector to prevent tampering of the reading at the red pointer.