Have you tried to troubleshoot the meter's incorrect reading? This technical tip should make things clearer.
What is normal reading?
Most power systems have a hysteretic (inductive) power factor, such as current lagging behind voltage. This mainly occurs in systems with power factor correction capacitors, which increases the chance of having a leading power factor.
Normal readings will be those with the following values. The power factor is in the range of -0.70 to 1.00, the kW and kVA readings are positive, KVAR is negative, and the phase voltage and current are approximately equal to each other.
You can further check to confirm that the voltage and current displayed on the meter match the system value measured by the multimeter. If not, check whether the VT and CT ratios in the meter are set correctly.
Assuming all these checks have been completed, the meter reading is correct and no further checks are required.
What is an abnormal reading?
If the amperage kW, kVAR and KVA readings are zero, there are two possibilities, one is the CT secondary short circuit or the load on the circuit is less than 2% of the CT primary current. For example, if a circuit with a CT ratio of 100: 5 is installed, the current is less than 2 amps.
In another case, the negative KW reading is positive KVAR and the power factor is normal. In this case, there are many possible causes, as shown below ...
All three CT polarities are installed backwards. An example might be that the primary polarity mark is facing the load instead of the power source, or the CT auxiliary coil has been interchanged. In addition, if the PT has not been installed in reverse, it may be connected from the primary to the secondary, and vice versa.
Another possible abnormal reading is that the frequency reading is far from the power frequency. In this case, if you are using a PT, check that the common terminals of the primary and / or secondary neutral points are not grounded, or whether the system is grounded at the distribution transformer.
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