A factory has an electrical load of 1,800kW at a lagging power factor of 0.6. An

Question

A factory has an electrical load of 1,800kW at a lagging power factor of 0.6. An additional variable power factor load is to be added to the factory. The new loaf will add 600kW to the real power load of the factory. The power factor of the added load is to be adjusted so that the overall power factor of the factory is 0.96 lagging.
a) Specify the reactive power associated with the added load?

b) Does the added load absorb or deliver magnetizing vars?

c) What is the power factor of the additional load?

d) Assume that the rms voltage at the input of the factory is 480 V. What is the rms magnitude of the current into the factory before the variable power factor load is added?

e) What is the rms magnitude of the current into the factory after the variable power factor load has been added?

Explanation / Answer

The existing 1800 watts Kw load at 0.6 PF has a phase angle which has a cosine value of 0.6. This angle is about 53 degrees. The tangent of this angle (53 degrees) is 1.327.

This is the ratio of the KVAR divided by the Kw or 1.327 = KVAR / 1800 or KVAR = 1800 * 1.327 = 2388.6 KVAR.

a) When you add the additional 600 Kw to the 1800 Kw, the cosine of the phase angle for the power factor og 0.96 will be about 16 degrees. The tangent for 16 degrees is 0.287. This is the ratio of the KVAR divided by the Kw or 0.287 = KVAR / 2400 or KVAR = 2400 * 0.287 = 688.8 KVAR

b) This means there must be change in reactive power

= 688.8-2388.6 = -1699.8 KVAR

Thus load delivers reactive power

c)Power factor of load

Pf = Real Power/(Real Power^2 + Reactive Power^2)

Pf = 600k/ (600k^2 + (-1699.8k)^2) = 0.1107 leading

d) Before adding load

Pf = Real Power/ Total Power >>>>>>>Total Power = 1800k/0.6 = 3000 kVA

I(rms) = Toatl Power / V(rms) = 3000k / 480 = 6250 A

e) After adding load

Pf = Real Power/ Total Power >>>>>>>Total Power = 2400k/0.96 = 2500 kVA

I(rms) = Toatl Power / V(rms) = 2500k / 480 = 5208.33 A

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.