Electrical Engineering ⇒ Topic : Multirange voltmeter

Multirange voltmeter. The single movement may be used with several multipliers to make a multirange voltmeter as shown in Fig. (a). The different ranges are determined by a selector switch connecting the proper multiplier into the circuit. With switch at position 1, only multiplier R, is in series with the meter. Similarly, with switch at position 2, only multiplier R₂ is in series with the meter. It may be noted that here short-circuiting type switch is not desirable and a non-shorting type switch must be used. The multipliers are constructed of high resistance wire, such as manganin wound on wooden spools. Where the resistance required is so high as to make the windings prohibitively large and costly, composition resistors are employed. Some of the less expensive types of voltmeters use composition resistors throughout. The usual ranges of such instruments are from 0-1000 V in two or more steps.

                                                                  figure (a)