Shunts for a.c. Instruments

Shunts for a.c. Instruments Points : Shunts for a.c. Instruments, Precautions of Shunts for a.c. Instruments A shunt, which is usually employed with d.c. ammeters, can also be used with a.c. instruments. When the shunt is to be used for a .c. measurements, which is now extremely rare, the inductances of both the instrument and the shunt must be taken into account as well as their resistances. In order to maintain the current division between shunt and instrument constant for all frequencies the ratio of impedance of the instrument and leads to that of shunt must remain constant. Precautions The resistance of the leads used with the instrument forms the part of the resistance of the instrument circuit and therefore must be considered while determining the required shunt resistance. A special pair of leads is usually supplied with the instrument by the manufacturer intended to be used. These leads should always be used in order to obtain the stated accuracy, as the instrument is calibrated with these leads in use.