Why clamp Ammeter is used to measure current when installing motor
The clamp Ammeter is used to measure the actual current of one phase phase line, because the clamp Ammeter is equivalent to a CT with a primary winding opening. The current measured at one time and the current measured at two times will reflect and display, which has nothing to do with the connection of three-phase motor.
Step 1: measure the phase difference separately, and directly measure the phase voltage at the secondary side of the Voltage transformer (the method is the same as above), The phase voltage can be directly measured at the input end of a clamp meter. However, it requires the insertion of a probe and the selection of a suitable range. Its "bayonet" can only measure AC current with a specialized clamp meter. Keep the pointer on the right and use it in the same way as a regular multimeter, gradually shifting from high to low gear under unknown voltage levels;
Step 2: Measure the voltage through the parallel connection of the probes. The clamp meter is used to measure the voltage through the attached multimeter. The clamp meter cannot directly "clamp" the voltage. Adjust the change-over switch to an appropriate range.
Usage of digital clamp watch
1. Mechanical zero adjustment is required before measurement
2. Select the appropriate range, first select the large range, then select the small range, or estimate the nameplate value
3. When using the minimum range measurement and the reading is not yet obvious, the measured wire can be wound several turns, and the number of turns should be based on the number of turns in the center of the clamp, then the reading=the 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 measured wire should be placed in the center of the clamp and the clamp should be tightly closed to reduce errors
Precautions for digital clamp watches
1. The voltage of the tested circuit should be lower than the rated voltage of the clamp meter
2. When measuring the current of high-voltage lines, it is necessary to wear insulating gloves, shoes, and stand on an insulating mat
3. The jaws must be tightly closed and cannot be changed with power
The clamp Ammeter is used to measure the current of a single winding of the motor, which is the phase current, but it will bring trouble to the actual measurement. Either connect the three pairs of winding wires to the outside; The current on the power line is always the line current; It is difficult and impractical to calculate the power of a certain motor. The power factor is an uncertain factor, unless a power factor meter is also connected, but it should be noted that due to load reasons, the power factor is changing.
