# Computing power of 3 phase system without knowing the load configuration

I am trying to find out the power consumption for a 3 phase balanced system below: I only have access to the L1, L2, L3 and N connection points at the main connection box and I only know that it is connected to a mixture of 3 phase and single phase loads.

The RMS voltage measurements between each line and natural is as below:

V(L1 to N) = 241.7V

V(L2 to N) = 242.1V

V(L3 to N) = 244.0V

The voltage measurements between each line is as below:

V(L1 to L3) = 420.9V

V(L1 to L2) = 418.7V

V(L2 to L3) = 421.7V

The current measurements were taken using clamp meter and values are as below:

I(L1) = 9.99A

I(L2) = 10.34A

I(L3) = 10.05A

I(N) = 0.45A

Without knowing if the load is Y or Delta, how can I compute the power consumption in this setup?

• For three-phase/total active power measurement of a four-wire network, you can use the three-wattmeter method. It's very general (whether the load is in wye or delta, balanced or unbalanced impedances, passive or active, with balanced or unbalanced voltages, sinusoidal or non-sinusoidal currents). Is that an option? Aug 12, 2021 at 2:34
• @AlejandroNava Is it possible to estimate without using the wattmeter? Aug 12, 2021 at 2:45
• I've seen the three-ammeter method (and the three-voltmeter method) used to compute active power and power factor of a single-phase load. Perhaps there's an analogous method for three-phase loads. // BTW, given that your load is four-wire, it is most probably connected in wye (since deltas don't have neutral). Aug 12, 2021 at 3:14

You measured this: I(N) = 0.45A and that means that the load isn't balanced. It's not bad but, it ain't perfectly balanced. Given the small variations in your line and phase voltages, you cannot say that the supply is balanced either.