Three Phases Four Wires and Three Phases
Three Wires Measurement Method

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Model UT231: OPERATING MANUAL

The Model UT231 digital power clamp meter can
measure single phase power and power factor.  The
power of three phases four wires system can use single
phase power measurement method to measure, see
figure 7.

If it is a balance load, the total watts is three times of
single phase.  If it is not a balance load, test each
phase power separately, then sum up the three phases
power value to obtain the total watt.  The apparent
power, reactive power, active energy and active power
measurement methods are the same.

Power factor value can be obtained directly from each
phase power factor testing.  Thee phases total power
factor is equal to three phases total active power value
divided by three phases total apparent power value.

Under three phases three wires balance load situation,

its total watt can be directly by measuring its voltage of
the line and current of the line.  Connect the loaded two
phases to the V and COM input terminal of the power
meter, clamp the transformer jaw to the third phase, its
total watt is equal to the reading obtained times 1.732.

Three phases total watt also can be obtained by using
the specified clamp type three phases digital power
meter.