The method of measuring the running current of the motor with the clamp meter
The clamp meter measures the running current of the motor, which is generally smaller than the rated current. Only the current of the motor under rated load is the rated current.
By measuring the current of each phase of the motor in operation, it can be judged whether the motor is overloaded (the measured current exceeds the rated current value), whether there is a problem inside the motor or the power supply voltage, that is, whether the unbalance of the three-phase current exceeds the limit of 10%.
1. Correctly select the voltage level of the clamp ammeter, check whether its appearance insulation is good, whether it is damaged, whether the pointer swings flexibly, whether the jaws are rusted, etc. Estimate the rated current according to the motor power to select the range of the meter.
2. When measuring, it can be measured once for each phase, or once for three phases. Because the phasor sum of the three-phase current is zero, the number on the meter should be zero when the three-phase measurement is performed once.
3. When there are two phase wires in the jaw, the value displayed on the meter is the current value of the third phase.
