Adec, as a clear leader in the electrical engineering industry, now provide, Consultation, Design, Installation and Maintenance of Power Factor Correction Facitities.

The service within this specialist field benefits the user by greatly reducing electricity charges and increasing availability on existing supplies. New installations often re-pay customer job capital in a very short time period.

The application of power factor improvement equipment in UK commercial and industrial premises arise for many reasons, but the most common objective is to reduce the current flowing in the site electrical distribution network.

In addition to the useful power (kW) requirement, all electrical systems having inductive requirements, e.g. motors, fluorescent lighting, welders, etc, require reactive power (kvar). The kW and kvar components create the total kVA taken from the supply.

Installing capacitors for reactive power compensation reduces the kvar requirements. This reduction in the kvar component reduces the total kVA taken.

By reducing the kVA, the current drawn from the system point of installation of the power factor correction capacitor is reduced. This will reduce losses for the customer, electricity distribution and transmission system.

The attached papers show the saving in k.W.h by the installation of 1kvar of P.F.C applied on the "L.V." system of a factory, is 357k.W.h. per annum based upon average UK grid electricity generation statistics. Each kvar of applied P.F.C. will save 157KG of CO2 per annum.

BASIS OF ANALYSIS

A typical medium sized system is considered having:

Maximum Demand 2500kVA
PF at Maximum Demand 0.80 lag

The company operates 2 shifts totalling 500 hours per month.

By installing 1000kvar of LVPFC equipment the operating power factor is improved to 0.97 lag. This reduces the kVA demand to 2062kVA.

The effective electrical currents taken are:

CURRENT (AMPS)
BEFORE
PFC AFTER
PFC
On 415V side of customer transformer
On 11000V side of customer transformer & distribution
On 33kV distribution system
On 132kV distribution system 3475
131.2
43.74
10.93 2866
108.2
36.06
9.01

These currents are used in the calculation of kW loss reduction.

SUMMARY OF CALCULATION OF "kW LOSSES" SAVING

By installing the power factor improvement capacitors on the LV side of the factory system (most typical for PFC) additional saving in losses will be on the LV distribution network and transformer copper losses.

Consumer System Savings 11.17kW

kWh savings would be created from the point of metering at 11kV to the Grid Supply point at 132kV for a 2500kVA consumer who would improve his power factor from 0.80 lag to 0.97 lag by installing 1000kvar of pfc equipment. These are savings for the Electricity Distribution System.

Distribution System kW losses savings are 45.4kW

" kW losses will be saved between the 132kV grid supply point and the generator. These are savings on the Electricity Grid System.

Grid System kW losses savings are 3.05kW

Total kW losses saved by 1000kvar of LV PFC capacitors = 59.62kW

ENVIRONMENTAL IMPACT

Calculation of kWh saved at the Generator

The 2500kVA consumer generally operates at a high load factor for 500 hours per month.

Hence kWh saving = 500hrs x 12month x 59.62jWh = 357720kWh saving

Each 1000kvar of LV PFC saves 357,000kWh per year

From DETR data* this represents 157 tonnes of CO2 per annum

Each kvar of LV PFC saves 157kg of CO2 per annum.

*Source DETR

Average grid electricity generation produces 0.44kg of CO2 for each kWh generated.

Typical Power Factor Diagram

Active Power (kW) - actually performs the work.
Reactive Power (kvar) - sustains the electro-magnetic field.

As an example with an unloaded AC motor, on might expect the non-load current to drop near zero. In truth, however, the non-load current will generally show a value between 25% & 30% of full load current. This is because of the continuous demand for magnetising current by any induction load.

Please contact ourselves if we can be of any further assistance.