Calculation method of ammeter multiples after using shunt
For motor test measurement, often an ammeter needs to be equipped with multiple shunts to solve the problem of ensuring the required measurement accuracy in a large measurement range. At this time, it is required that the rated voltage drop of all the shunts used is consistent with that of the ammeter, for example, 75mV. In this way, after the shunt is selected, the full scale of the ammeter is the rated current value of the selected shunt, and the multiple of the ammeter (that is, the current per division of the dial scale) is the rated current of the shunt divided by the total number of divisions of the dial scale.
There are slotted and non-slotted shunts for DC current measurement. The shunt has manganese-nickel-copper alloy resistance rods and copper strips, and is plated with nickel. Its nominal voltage drop is 60mV, but it is also available as 75, 100, 120, 150 and 300 mV.
The rated current of the slot type shunt is as follows: 5A, 10A, 15A, 20A and 25A.
Non-slot shunts are available in standard intervals from 30 A to 15 kA.
