(1) Select the rated pressure drop specification of the shunt according to the number of mV marked on the dial of the current meter (or current-voltage multimeter) (usually 75mV or 45mV is commonly used). If the current meter used does not have this value, use the following formula to calculate the voltage limit of the meter, and then select the rated pressure drop specification of the shunt.
The voltage limit of the meter (mV) = current at the full scale of the ammeter (A) × internal resistance of the ammeter (Ω) x 1000
(2) Select the rated current specification of the shunt according to the current range to be expanded.
(3) Connect the two current terminals of the selected shunt to the power supply and load respectively, and connect the current meter to the potential. Note that the polarity of the terminal of the ammeter should be connected, and the range of the ammeter is expanded to the current rated on the shunt. value.