Negative Power and Power Factor Readings
If users are metering a load that is consuming energy, seeing negative power (kW) and power factor
readings would cause errors when reading the total consumed energy on the meter. Negative readings
can be a result of the following:
- CT reversal: If users have Current transformer leads or the actual CT installed in the reverse direction, this will cause both power and power factor readings to read negative.
- CT alignment: CT alignment refers to the Current transformer being installed on the incorrect phase. For example, if the Phase A CT is installed on the Phase B reference voltage line this would cause misalignment with the voltage and current phase angles resulting in negative readings for power. The CTs must be installed on the correct phase in order to avoid this.
If users have a load that is generating energy, seeing negative power and power factor readings are
correct and expected. When the current flows in the reverse direction (generating as opposed to
consuming) this causes the power and power factor readings to become negative.