Power Factor?

Power factor is the ratio of true power (or active power KW) consumed by a load to the apparent power (KVA - which is the product of voltage and current) drawn by the load.

Before and after Power Factor Correction (PFC)

S1 = apparent power before PFC
S2 = apparent power after PFC
P = active power
Q1 = reactive power before PFC
Q2 = reactive power after PFC
Qc = Q1-Q2 compensation power of capacitor
j1 = phase angle before PFC
j2 = phase angle after PFC
Load type Approximate power factor
(half ...full load)
Electric heater. 1.0
Incandescent lamp (glow) 1.0
Induction motor 250 kW 0.8...0.9
<100kw 0.6...0.8
Thyristor drives 0.7
Arc furnace 0.6...0.8
AC arc or resistance welder 0.5...0.6
Fluorescent lamp (hot cathode) 0.5...0.6
Mercury arc lamp 0.5
Neon tube lamp 0.4...0.5
Induction furnace -.2...0.6

From the view point of both LT as well as HT industrial consumers, to reduce losses, optimise ratings of equipment and cables, reduce voltage drop, minimise expenditure on regulatory equipment and also to minimise monthly electricity bills, power factor of the order of 0.9 or higher is necessary.

Capacitors are connected in a circuit across the load (shunt) to reduce the demand of reactive power and thereby increase power factor of the whole electrical system.
Lastly, TNB levies a penalty for low power factor, the following is an excerpt from the TNB Tariff Book.
For all Tariffs, except Tariffs A and G, the consumer shall use his best endeavours to obtain the highest Power Factor possible in the operation of any of his electrical installations. If the Average Power Factor in any month is found to be:
  1. Below 0.85 and up to 0.75 lagging, a supplementary charge of one and one-half per cent (1½%) of the bill for that month for each one-hundredth part (0.01) below 0.85 and up to 0.75 lagging Power Factor will be added to the bill for that month, and
  2. Below 0.75 lagging, in addition to the charge payable under subparagraph (A) above, a supplementary charge of three per cent (3%) of the bill for that month for each one-hundredth (0.01) part below 0.75 lagging Power Factor will be added to the bill for that month.
Example: A Consumer has a Power Factor at 0.60 and his consumption is RM4,800.00
(a) 0.85 - 0.75 = 1½% x 10 units lagging = 15%
(b) 0.75 - 0.60 = 3% x 15 unit lagging = 45%
Total extra levied = 60%
Therefore, his penalty charge would be 60% of RM 4,800.00 which is RM 2,880.00

The total payable will hence be RM 7,680.00