Power factor, PF, in the electrical installation can tell us about how efficient the plant, factory, building, or installation load is operating at.
Low power factor cost money and in most cases is against the law. In Malaysia, TNB/SESB set a minimum power factor of 0.85 that every consumer must achieve and if yours falls below this value, you will be charged with power factor penalty in a staggered manner.
kVA2 = kW2 = kVAR2
From this equation, we derive the power factor:
In the case of SESB, a subsidiary of Tenaga Nasional Berhad, the power factor penalty is calculated as follows:-
If the Average Power Factor of any consumer in any month is found to be:
(a) Below 0.85 and up to 0.75 lagging, a supplementary charge of 1.5% of the bill for that month for each one-hundredth part (0.01) below 0.85 will be added to the bill for that month; and
(b) Below 0.75 lagging, in addition to the charge above, a supplementary charge of 3% of the bill for that month for each one-hundredth part (0.01) below 0.75 will be added to the bill for that month.
Example:
Say, a premise is categorised under Commercial Tariff Class 1, CM1, and billing meters show the followings during January 2013 monthly meter reading:
kWh meter : 2,660
kVARh meter : 2,190
The average power factor for that month, according to the formula is
PF = kWh / [SQRT(kWh2 + kVARh2)]
= 2,660 / [SQRT(2,6602 + 2,1902)]
= 0.77
which is below 0.85 but above 0.75, and hence a PF penalty of 1.5% supplementary charge for every 0.01 part applies.
The PF penalty is about 12% of the monthly bill and for a larger installation/premise, this could be a lot of money. Plus, if you continue to register PF of below 0.75, the utility company has a provision to stop supplying power to your premise until you rectify the situation.
Reason for posting this? I'm putting this formula up here for ease of future reference. I can refer to it from my mobile device, too. Also, this maybe useful for the accountants and administrators who receive the bills and in need of quick answer on how/why they were penalised.
Low power factor cost money and in most cases is against the law. In Malaysia, TNB/SESB set a minimum power factor of 0.85 that every consumer must achieve and if yours falls below this value, you will be charged with power factor penalty in a staggered manner.
Calculating power factor without taking your toolbox with you
kVA2 = kW2 = kVAR2
From this equation, we derive the power factor:
In the case of SESB, a subsidiary of Tenaga Nasional Berhad, the power factor penalty is calculated as follows:-
If the Average Power Factor of any consumer in any month is found to be:
(a) Below 0.85 and up to 0.75 lagging, a supplementary charge of 1.5% of the bill for that month for each one-hundredth part (0.01) below 0.85 will be added to the bill for that month; and
(b) Below 0.75 lagging, in addition to the charge above, a supplementary charge of 3% of the bill for that month for each one-hundredth part (0.01) below 0.75 will be added to the bill for that month.
Example:
Say, a premise is categorised under Commercial Tariff Class 1, CM1, and billing meters show the followings during January 2013 monthly meter reading:
kWh meter : 2,660
kVARh meter : 2,190
The average power factor for that month, according to the formula is
PF = kWh / [SQRT(kWh2 + kVARh2)]
= 2,660 / [SQRT(2,6602 + 2,1902)]
= 0.77
which is below 0.85 but above 0.75, and hence a PF penalty of 1.5% supplementary charge for every 0.01 part applies.
| Supplementary charge | = | 100*(0.85 - 0.77) x 1.5% x Monthly bill |
| = | 8 x 1.5% x RM890.10 | |
| = | RM106.81 |
| Calculate monthly bill | ||
| First 200 kWh | = | 200 x 33.0 cents = RM66.00 |
| Next 2,460 kW | = | 2,460 x 33.5 cents = RM824.10 |
| Hence, monthly bill | = | RM890.10 |
| Total bill | = | RM996.91 |
The PF penalty is about 12% of the monthly bill and for a larger installation/premise, this could be a lot of money. Plus, if you continue to register PF of below 0.75, the utility company has a provision to stop supplying power to your premise until you rectify the situation.
Reason for posting this? I'm putting this formula up here for ease of future reference. I can refer to it from my mobile device, too. Also, this maybe useful for the accountants and administrators who receive the bills and in need of quick answer on how/why they were penalised.
