Why measure the current using a clamp ammeter when mounting the motor?
What the clamp ammeter measures is the actual current of the phase line of one phase, because the clamp ammeter is equivalent to a CT with the opening of the primary winding. Law doesn't matter.
Step 1: Measure the phases separately. You can directly measure the phase voltage on the secondary side of the voltage transformer (the method is the same as above), and you can directly measure the phase voltage (the input end of the clamp meter. But you need to insert the test leads and select the appropriate range. Yes, its "bayonet" can only measure AC current, a special clamp card meter. Make the pointer stay on the right, use the same method as an ordinary multimeter, and gradually lower the gear from high to low when the voltage is unknown;
Step 2: Measure the voltage through the parallel connection of the test leads. The clamp meter measures the voltage through its attached multimeter. The clamp meter cannot directly "clamp" the voltage measurement, and adjust the switch to an appropriate range.
How to use digital clamp meter
1. Mechanical zero adjustment is required before measurement
2. Select the appropriate range, first select the large range, then select the small range or see the nameplate value estimation
3. When the minimum measurement range is used to measure and the reading is not obvious, the measured wire can be wound several times, and the number of turns should be based on the number of turns in the center of the jaw, then the reading = indicated value × range / full deviation × number of turns
4. After the measurement is completed, the transfer switch should be placed at the maximum range
5. When measuring, the wire to be tested should be in the center of the jaws, and the jaws should be closed tightly to reduce errors
Digital Clamp Meter Precautions
1. The voltage of the line under test should be lower than the rated voltage of the clamp meter
2. When measuring the current of the high-voltage line, wear insulating gloves, wear insulating shoes, and stand on the insulating mat
3. The jaws should be closed tightly and the range cannot be changed with power on.
Measuring the current of a single winding of a motor with a clamp ammeter is the phase current, but it will cause trouble to the actual measurement, or connect all three pairs of winding wires to the outside; the current on the power line is always the line current; to calculate the current of a certain motor It is very difficult and impractical. The power factor is an uncertain factor, unless a power factor meter is connected, but you must know that due to the load, the power factor is changing.
