About Power Factor Correction
The Power Factor of an electrical installation is the ratio between the power that is actually used (kW) and the power that is supplied (KVA). It is a measure of how efficiently an installation uses Electrical Energy.
Power factor equipment supplies the reactive current (eg. magnetising current required by electric motors to turn but does no real work) required by an installation that is normally supplied from the supply transformer and therefore passes through the electricity meters. Reducing this magnetising current through the electricity meters and the switchboard will reduce the cost if the tariff is based on KVA Demand (or apparent power). The power actually used is the ‘real ‘ Power (in watts). The power supplied is the “apparent” power (in Volt Amps) .
Power Factor = Real Power (kW)/Apparent Power(KVA)
Power Factor Correction Equipment is placed within, or near, the main electrical switchboard. The equipment is connected into this switchboard and connected to a convenient point below the electricity suppliers metering equipment (i.e. Current transformers). A new switch may be required in some cases.
Depending on the rating of the equipment (in”kVAr” or Kilo Volt Amps Reactive) the typical size is he same as a standard fridge.
This depends on the following:
• The Tariff Type. For PFC to reduce Energy Costs you must be on a “KVA” Demand Tariff
• Maximum demand (in KVA) as shown on your electricity Bill
• The initial power factor at this maximum demand.
• The target power factor (usually 0.98 for best economy)
• The “demand profile” eg. KVA demand over a, say, 12 month period and the power factor over this same period.
As an example: Average Maximum Demand = 200KVA @ 0.8pf improving PF to 0.98
o Cost per KVA/month (as shown on Bill) = $10:50
o Cost /mth without pf = $ 2,100
o New Avg KVA @ 0.98pf = 163KVA
o New Cost/Month = $1,712
o Savings/year(ave) = $ 4662
o Simple Payback (yrs) = 1.5 Years*
* based and an estimated installed cost of a 100kVAr PFC at approx. $7,000
Benefits – Electricity meters usually reset at midnight on the last day of each month. Because the electricity bill is based on a “Maximum Demand” for the month, benefits from reducing this demand will commence the month following the commissioning and setting to work of the equipment. Some Electricity suppliers require a form to be submitted so they can reduce the “contract demand” portion of the Bill.