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


Replacement of a failed power factor correction unit at a plastic sheet manufacturer in Hertfordshire.

The existing unit on site was in need a of replacement following a full maintenance inspection carried out by one of our engineers. Multiple capacitors and fuses had failed and the unit seemed to lack any form of annual servicing. The method of installation was also poor with the main power cable feeding the unit being run across the floor and up over a water pipe into the unit.


As such a new fully detuned FSi100 PFC unit was supplied along with its own built in isolator. The original power cable was removed and replace with 70mm singles run inside the existing trunking that run around the wall.

This FSi100 was made up of 4 stages of 25kVAr each with its own detuning reactor. The unit is then controlled by a Lovato DCRL 5 digital control relay providing instantaneous power factor readings along with other site load details such as KW, KVA, THD and weekly PF average.


All the old equipment was removed and disposed of by PFC Engineering and the new equipment was installed and operational in 1 day without any disruption to the site.


Power Factor replacement at a roof tile manufacturer in Gloucestershire.

After carrying out what was possible the first maintenance of the Power Factor correction equipment in the last 40 years it was found that all the capacitor banks had failed. Each capacitor stage is 100kVAr and controlled via a old volt free control relay. It was also noted that each capacitor cubicle had no solid base and the current capacitors installed were sitting on a metal grate.

After checking the contactors were still operating satisfactorily all the original capacitor assemblies were removed and replace with 100kVAa CM capacitor tray assemblies. A new solid plate was installed in the bottom of each cubicle and secured down.

The control relay was also upgraded to a new Lovato DCRL8 and was wired in a volt free arrangement as per the original install. This volt free wiring prevents any foreign voltage’s at contactors when the capacitor bank is isolated locally at the main fuse carrier.



After the completion of a full maintenance service, it was found that the Power Factor Correction equipment on site had multiple failures across all the capacitor banks and contactors. A load survey also carried out during the maintenance service showed that site no longer required the full 400kVAr that was originally installed.

As such the unit was to be stripped out and replaced with 200kVAr of standard PFC equipment on our newly designed BW50 tray assemblies.

The new trays would include 480V rated capacitors, IMO MC32 soft switching contactors with sub fusing and 100A fuses for protection.

All failed components were removed, and the internal framework was adjusted to accommodate the new BW50 trays along with reconfiguration of the control circuit and power leads.

The power factor control relay was also upgraded to a more modern Lovato DCRL8 which provides details of not only the sites power factor but also instantaneous kVAr, KW, KVA readings along with voltage, amps and THD monitoring.

All the works were completed in 1 day by 1 engineer with no disruption to site.


Following a site inspection, it was found that site required a full rebuild of their 300kVAr panel-built Power Factor Correction.

We recommended replacing the existing failed capacitor tray assemblies with our own SBA 100 trays which included all new 480V rated capacitors, soft switching IMO MC62 contactors and sub fusing for all stages. This unit would be made up of 6 stages of 50kVAr and would be controlled by a Lovato DCRL8 digital control relay.


Our engineer completed the full rebuild in 1 day without any disruption to site and the unit was fully commissioned and left operating upon completion.





A medium sized coatings factory in Hertfordshire required some help reducing the reactive charges there were receiving on there electricity bills, so following a desktop review of their monthly charges it was determined that a 4 stage 50kVAr Power Factor Correction unit would be needed.

Installed on the Main LV Switchboard via a 100A MCCB the wall mounted T-Type unit consists of 4 stages of 13.5kVAr capacitors each switched by a IMO MC18 soft switching contactors all controlled by a Lovato DCRL 5 digital control relay.

A 4” 230V filter fan was also installed to help vent excess heat from inside the unit.



Recently a customer running a large waste recycling centre wished to move a Power Factor Correction installed in 2021 from its old site in Hartlepool to new plant in Derby, so one of our engineers attended site to remove, relocate and re-install the unit in its new location.


The site in Darby had a very poor power factor of 0.41 inductive and once the Power Factor Correction unit had been installed the sites PF readings were increased to a much healthier 0.99 indictive. This will now help remove the reactive charges they were receiving on their monthly electricity bills.


Our workshop team have been busy adapting our PN100 reactor tray assemblies to incorporate theses Lovato DCTLA4000500 thyristor switching contactors for faster switching times for the capacitor banks.

The unit is controlled by a Lovato DCRG8F digital control relay specifically designed to operate the rapid switching thyristors contactors.

Here are some images of the new units from the workshop. These units will be tested in-house and then wrapped and delivered to a site in Swindon ready for our engineering team to install in the next few weeks.



High harmonic distortion at Recycling plant.

Due to the proliferation of inverter loading at this site, concerns have been raised as to the amount of harmonic distortion being produced at this site and its potential effect on the other connected load as well as the wider effect on the MV supply to this site.

In order to determine the level of harmonic distortion present at this site as well as monitoring other power quality indices, a two week long power quality analysis was commissioned.

In addition to power quality indices, general power consumption data is presented in the form of active power (kW), reactive power (kVAr), apparent power (kVA) and operating power factor.


From the preceding results for this analysis it was clear that the load at this Recycling Centre operates with very high levels of harmonic distortion, high enough to distort the voltage to the point where the levels of voltage harmonic distortion exceed the G5/5 design recommendations


Despite the very high levels of harmonics on this supply, it will be possible to operate power factor correction at this site as it incorporates harmonic detuning reactors to prevent overload damage to power factor correction capacitors operating under such conditions.

Due to the very little additional space within the switchroom a stand alone AHF would not be possible, however the space within the distribution board allocated to power factor correction is generous and can be utilised to install harmonic filter modules that could be configured to remove the load harmonic currents and also correct the load operating power factor simultaneously.


With all these factors considered, a 300amp, 480volt P300-300/480 type Power Quality Filter System was installed inside of the existing LV panel along with 200kVAr of fully detuned Power Factor Correction.

All works and commissioning was carried out by 2 PFC Engineers over the course of 2 days with no interruption to sites load, with the majority of the equipment being pre-built and tested in our workshop prior to the install.


Another 500kVAr power factor correction unit built and ready to be sent out to customer. Two FSi Deep units connected in a Master/Slave arrangement each made up of 2 x 25kVAr detuned capacitor stages and 4 x 50kVAr capacitor stages all controlled via a DCRL 12 Stage digital control relay.


Both units come with its own local isolator and forced air ventilation consisting of 2 12” filter fans and filtered louver plates.


Master Unit




Slave Unit








This repair for a large supermarket distribution change involved a rebuild of the existing Power Factor inside of the LV panel.

The original block contactors were removed and replaced with soft switching IMO MC62 contactors as well as replacing the original detuning reactors for new.

Each capacitor bank was also replaced with new higher rated 480V self-healing capacitor banks mounted on a custom AM tray.

All waste was removed from site and all works were carried out during normal working hours without any disruption to site.