Power Factor Correction

jorpaul; what kind of power quality meter do you have? 3 phase 3 wire 2 single phase meters, 3 phase 4 wire, 3 single phase meters required, perry

dEAR,

All being scalar parameters,

Average pf pf = (pf1 + pf2 + pf3 )/3

Total KW load = (kw1 + kw2 + kw3 )

Total KVAR = ( KVAR1 + KVAR2 + KVAR3 )

Total KWH = kwh1 + kwh2 + kwh3

Thinking about it, assuming V_i and I_i being phase to neutral voltage(assuming Y connection) and line currents,

KW₁ =V₁I₁CosΦ₁

KW₂ = V₂I₂CosΦ₂

KW₃ = V₃I₃CosΦ₃

KW = KW₁+KW₂+KW₃ =V₁I₁CosΦ₁+V₂I₂CosΦ₂+V₃I₃CosΦ₃

In case of balanced then

KW = 3KW_ph = 3V_phI_phCosΦ

but it isn't is it ?

Ah! CR4's favourite topic: power factor.

Now a days multi function meters are available in the market.you can connect to your supply .You will get result.

Dear all,

3phase power measurement by single phase power meter.

1 Connect volt probe to phase A and B

Connect amp probe to phase A.

Recored KW and KVar

2 Do not remove the volt probe at phase B, but move the volt probe at phase A to phase C.

Move the amp probe from phase A to phase C. Do not change the direction of Amp probe.

Recored KW and KVar

3 Total of both kW above is 3phase kW

Total of both KVar above is 3 phase kVar

3phase KVA is sqrt(sq(3phase kW)+sq(3phase kVar))

3phase PF is (3phase KW) / (3phase kVA)

Regards

Thank you, very profound.

Power Factor (PF) is equal to the cosine of theta. Draw a right triangle with True Power (watts) on the base (side Adjacent) Reactive Power (VARS) on the vertical (side Opposite) and Apparent Power(KVA) on the hypotenuse. Use Trig to solve. The cosine of angle then should be expressed as Percentage and this is PF. A good PF for AC power is 95% (lagging- inductive) never go over 100% for utility supplied power, this would be leading (capacitive). So if reactive power goes up in relation to resistive power, then phase angle increase and PF decreases. So if angle theta is 25 degrees the Cosine is .9063 so the PF is 90.63%.