role of the series resistance connected in PMMC movement.
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A PMMC Instrument can be used as voltmeter by just connecting a series resistance with the moving coil. This series resistance is called Voltmeter Multiplier. This combination of moving coil and multiplier is connected across the point whose voltage is to be measured. There are two main function of voltmeter multiplier are 1) It limits the current through the PMMC moving coil to a value less than full scale deflection current and thus prevents moving coil from being damaged. 2) It minimizes the flow of current through the voltmeter and thus do not alter the circuit current whose voltage is to be measured. Ideally the resistance of voltmeter should be infinite