Three-phase current imbalance
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With a small oil pump, controlled by anABB motor protector and anABB contactor, measurements taken with a clamp meter showed an imbalance in the motor’s three-phase currents: A 0.036, B 0.036, C 0.044. However, when starting the motor directly, the three-phase currents were balanced, at A 0.035, B 0.035, C 0.036. Is the current in the contactor coil also being measured? Please advise, experts ?
It is suspected that direct activation is a reading action; previously, a clamp meter was used for measurement. It is recommended to measure the two different operating modes at the same location; you will find that the values obtained are similar. (When using a clamp meter, with the obvious side pressed against the cable, each item must be tested at the same position.) To ensure consistent magnetic field strength. ) It is recommended to take measurements at the output terminal of the contactor, as this provides the true value of the motor’s operation. Such a small current of yours can easily be misread.
I would like to ask what “obvious” means in the phrase “when using a clamp meter, press the obvious side against the cable”
When using a clamp meter, try to position the wire being measured at the geometric center of the measuring head in order to reduce measurement errors.
Dude, your current level is too low – will the accuracy of the ammeter be sufficient?