Following an annual maintenance check at a large grain storage and drying facility found that there are high harmonic distortion levels on the sites load and as such the standard FS200 Power Factor equipment installed was now elevating the harmonics even more. As such a replacement fully detuned FSi200 Power Factor Unit was now required.

As the units output rating stayed the same all the original power cables were able to be re-used from the standard PFC unit along with the MCCB feeding the unit. This also meant all the work could be completed during normal working hours without the need for a shutdown.

Ventilation for the unit was also installed due to the heat produced from the reactors. An over temperature safety circuit was also installed as standard to cut the power to the relay should the heat in the unit reach an unsafe level.


Above – Original Standard FS200 PFC Unit


Below – New Fully detuned FSi200 PFC Unit


After a full site load and power quality analysis, recommendations were made to this fencing manufacturer for the installation of a fully detuned Power Factor Correction unit.

This unit would be one of our new style FSi 400 Deep units and would include 8 stages of 50kVAr, each detuned by a 7% 189hZ reactor to help with harmonic distortion.

The new unit was close coupled to the main LV panel and connected directly to the bus bars due to the LV Panel having no spare ways. An 800MCCB was built into the PFC unit for isolating and fault protection.

The unit was positioned and fitted during normal working hours and then a shutdown of around 30 minutes was carried out at the end of the day for final connections keeping both install costs and disruption to the site down to a minimum.




Working with one of our facility providers we were asked to carry out Power Factor services at several Courts around the UK. At one of the sites, it was found that the PFC capacitor banks had failed and the main MCCB had failed internally and required replacement.

A load survey was carried out as standard while carrying out the service and it was found that the site no longer required the full 300kVAr worth of correction and that smaller, more refined capacitor banks would benefit the site.

As such, it was decided that the original 630A MCCB would be replaced and reduced in size, along with a new 100kVAr SBA tray assembly, including all new 480V rated capacitors, soft switching contactors and sub fusing.


Due to the need to replace the Power Factors main MCCB, a full shutdown was required to remove and install the new main switch. This was done after hours to minimise any disruption to site staff.

The original capacitor banks and control relay were all removed during normal working hours and the new SBA tray was installed ready for the final connections during the scheduled shutdown period.


All the old equipment was removed by us and disposed of by PFC Engineering.





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.



Here are some examples of recent capacitor installations for drive motors.

Firstly, we have 2 22.3kVar ‘fixed’ C-Type PFC Units each connected to a 75kW 6-pole start/delta drive. These fixed style capacitor units work in line with the motor switching contactor so come into circuit whenever the motor comes online and then shuts off when the motor is stopped.

Above: PFC C-Type Fixed capacitor banks mounted on side of Motor control panel



Another example of a 22.3kVAr PFC unit connected to a 75kW 6-pole soft start drive, this time mounted in its own enclosure incorporating a rapid discharge circuit and timer all controlled by the soft start 24V run signal few via a relay circuit.


Above: T-Type style PFC unit conneted to Motor Control Panel 

Following the annual maintenance at a grain mill it was found that additional capacitors were required to help the site reach a healthy Power Factor above 0.95 inductive.

The existing equipment on site was fully operational however space was very limited with the LV panel being built against the wall of the operating control room. An external door gives access to the rear of the PFC section, and it was via this that a custom framework was built to mount one of our fully shrouded 100kVAr SBA capacitor tray assemblies.

The new assembly was then wired as additional stages to the existing unit. Site are now back to a good power factor even when running at full load, helping to reduce and eliminate the reactive charges on their monthly bills.


Above: Front of PFC Section.   


Above: Rear of PFC Section with additional SBA tray mounted at the top

Following the installation of main meters and remote access network gateways, we have recently returned to a site in Sheerness to continue to add even more sub metering.


Using the Rayleigh Ri-F100 series Three Phase Multimeter we have now connected another 22 metering cubes to outgoing ways in the LV panels. All connected to and fully monitored by our partner Go Monitor.


Find out more about Go Monitor and the monitoring solutions we can provide here.







A recent installation of 2 x 200kVAr Power Factor Correction Master – Slave units at a city centre cement works.

Following a maintenance and a full power quality survey on site, two new detuned Power Factor Correction units were quoted to replace the existing failed equipment on site. With the units being located on the 2nd floor plantroom of the cement silo both the new units were designed with extra reenforced roofing and lifting eyes so that the units could be winched up to the top via the sites service hatch.

Once the units were in position the old PFC units were removed and the new ones were connected using the same power cables are before to help keep costs down for the customer.

With the new Power Factor installed the sites PF went from 0.85 inductive to 1.

All works were carried out during normal working hours with no disruption to site.



With the high harmonic distortion levels on this site in central London the standard Power Factor equipment installed in the original LV Panel was starting to fail. As such a new detuned capacitor stage was required.

Following a survey carried out by our engineer during the original site maintenance it was determined that the amount of kVAr was sufficient however the unit required a reactor to help prevent the capacitors from increasing the THD and causing the capacitor bank to fail.


As such we installed one for our detuned PN54 50kVAr reactor assemblies which we install into our own FSi Power Factor Units. With some additional framework and some new power cables we were able to fit this tray into the existing LV Panel without the need for a shutdown or any disruption to sites supply.


Along with the new PN54 Tray we also upgraded the control relay to a new digital Lovato DCRL 5 with the capacitor stages split into 2 x 25kVAr steps



Above: Original standard capacitor assembly




Above: New Detuned PN54 Tray and Lovato DCRL 5 digital control relay.

A recent ‘End of Life’ replacement for 200kVArs worth of standard Power Factor Correction at a large car part manufacturer in Portsmouth.


During the annual site maintenance, multiple capacitor failure along with general age, wear are location of the PFC equipment, it was decided that it was time to replace the existing equipment with a new, free standing, Power Factor unit.

All the original capacitor assemblies were removed along with the panel-built relay and control circuit. The 400A MCCB in the LV panel that fed the old equipment was re-used to connect the new one. This meant that the works could be carried out safely without the need to shut the LV down.

Mounted close coupled to the end of the LV panel, the new PFC unit was wired with new 150mm tri-rated singles and the C.T circuit was re-run from the old relay to the new relay.


All the waste was removed from site and the works completed by 2 engineers within 5hrs

After carrying out power quality review at a large electrical component manufacture, the rapid fluctuation in load means that standard Power Factor Correction equipment cannot switch fast enough to correct the PF. As such thyristor switching contactor modules were required along side de-tuning reactor to help reduce harmonics.


Theses newly designed FSi Fast Switching units are split into 6 stages of 50kVAr each with its own 189hZ de-tuning reactor all controlled via an 8 stage Lovato DCRG8F digital control relay specifically designed for thyristor switching.


As most of these new Thyristor units were replacing existing PFC equipment, we were able to reuse the existing power cables and c.t circuits. This work was carried out by 3 engineers over 3 days during normal working hours


Above: Removal of standard FS400 Power Factor Unit and replaced with new FSi Fast swithing Thyristor unit



Above: Removal of a Standard Master/Slave PFC configuration and replaced with new FSi Fast switching Thyristor unit


Above: Removal of 3 Standard Master/Slave/Slave PFC configuration and replaced with new Master/Slave FSi Fast switching Thyristor units


Above: Removal of a Standard Master/Slave PFC configuration and replaced with new FSi Fast switching Thyristor unit