One wattmeter method is used to measure power in a three-circuit when
One wattmeter method is used to measure power in a three-circuit when the load is balanced in all three phases.
In a balanced three-phase, three-wire system, the one-wattmeter method can be used to measure the total power.
This method involves connecting a single wattmeter to one of the phases and then multiplying the reading by three to obtain the total power.
To use the one-wattmeter method, the current coil (CC) of the wattmeter is connected in series with one of the phases, and the potential coil (PC) is connected between that phase and the neutral point (if present) or the center of the delta connection.
The connection of the potential coil in this manner allows the wattmeter to measure the voltage across the load, which is necessary to calculate the power.
It is important to note that the one-wattmeter method assumes a balanced load, meaning that the same amount of power is consumed in each phase.
If the load is unbalanced, the accuracy of the measurement may be affected.
Additionally, the one-wattmeter method assumes that the power factor is the same in all three phases, which may not be the case in some situations.