Why measure the current each time a motor is installed using a clamp ammeter?
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.
The first step is to 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. Keep the pointer on the right, and the method of use is the same as that of an ordinary multimeter. When the voltage level is unknown, it will gradually go from high to low;
The second step is to 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.
1. How to use the 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 for estimation.
3. When the minimum range is used for measurement and the reading is not obvious, you can wind the wire under test for several turns, 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 switch should be placed at the maximum range. diangongwugwu.com Electrical Engineering Learning Network Copyright.
5. When measuring, the wire under test should be in the center of the jaws, and the jaws should be closed tightly to reduce errors.
Second, 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 a high-voltage line, wear insulating gloves, wear insulating shoes, and stand on an 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 for 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 you also connect a power factor meter, but you must know that due to the load, the power factor is changing.
