Is it necessary to use clamp Ammeter to install the motor?
Clamp Ammeter is used to measure the actual current of one phase line, because clamp Ammeter is equivalent to CT with open primary winding, and the current detected at one time will be reflected and displayed at the second time, independent of the connection of three-phase motor.
The first step is to measure the phase separately. You can directly measure the phase voltage at the secondary side of the Voltage transformer (the method is the same as above), or you can directly measure the phase voltage (the input end of the clamp meter). However, it is necessary to insert the probe and select the appropriate measurement range. Its "bayonet" can only be a specialized clamp type meter for measuring AC current. Keep the pointer on the right side and use the same method as a regular multimeter to gradually change from high to low gear when the voltage level is unknown;
The second step is to measure the voltage with probes in parallel. The clamp meter cannot directly "clamp" the voltage with its attached multimeter, and adjust the change-over switch to an appropriate range.
1、 The use of digital clamp watches
1. Mechanical zero adjustment is required before measurement.
2. Choose an appropriate range, first select a large range, then select a small range or estimate the nameplate value.
When using the minimum range measurement, when the reading is not obvious, the measured wire can be wound several times. The number of turns should be based on the number of turns in the center of the jaw, and the reading=the indicated value × Range/full deviation × Number of turns.
After measurement, place the transfer switch in the maximum range.
When measuring, the measured wire should be in the center of the clamp, and the clamp should be tightly closed to reduce errors.
2、 Precautions for digital pliers watches
The voltage of the tested circuit should be lower than the rated voltage of the clamp meter.
When measuring the current of high-voltage lines, wear insulated gloves, insulated shoes, and stand on an insulated pad.
3. The jaws should be tightly closed and the range cannot be changed by electricity.
Measuring the current of a single winding of a motor with a clamp Ammeter is phase current, but it will bring trouble to the actual measurement, or connect all three pairs of winding wires externally. The current on the power line is always the line current; Calculating the power of an electric motor is both difficult and impractical. Power factor is an uncertain factor, unless you connect a power factor meter, but you should be aware that power factor can vary depending on the load.
