Detuned PFC install at Major Chemical Distributor

After being approached by a customer to review their site’s Power Factor following high reactive charges a desktop review of the site’s electricity bills and an on-site load survey it was found that significant savings could be made from installing some detuned PFC equipment.


Based on the half-hourly data provided, the following maximum demand load was recorded:


 1764 kVA                   1493.9 kW                      0.847  PF                      937.6 kVAr


We calculate that in order to improve the above PF to a satisfactory level of 0.966, approximately 540kVAr of detuned PFC would be required.

With the above 540kVAr of PFC in circuit, the following improved maximum demand conditions would result:


  1545.9 kVA          1493.9 kW            0.96 PF             397.6 kVAr



Total Reduction in Maximum Demand:  218.1kVA (303Amps)



Based on the above, Sites Network Operators “Use of System” charges for supplies metered at high voltage and current site unit charges, we estimated that the above improved conditions would provide the following potential annual savings:


Reactive Power Charge Reduction:             £1,100.00 + VAT

Supply Capacity Reduction (200kVA):     £2,088.00 + VAT

Transformer loss reduction:                        £1,473.90 + VAT (£0.155 x 9,509kWh pa)


Total Potential Annual Savings:                 £4,661.90 + VAT


Considering the above, we proposed the following:

The 540kVAr would be arranged in 2 x 270kVAr detuned PFC systems arranged in “Master-Slave configuration and connected via an existing 630Amp MCCB’s.

Since this supply has 2 transformer feeds (typically one on duty with a closed bus-coupler), a current signal will be taken from each of the transformer’s LV supply and connected via a summation CT within the Master PFC unit. This ensures that the PFC control will operate correctly, irrespective of transformer connection and bus-coupler status.