A recent catastrophic failure of a 200kVAr Power Factor Correction unit on the main incoming supply at Large Recycling Centre has raised concerns that the quality of the supply may in some way be compromised, resulting in this failure.
In order to determine the quality of the power on this site, including the levels of harmonics, general voltage levels and voltage stability, a week-long power analysis was commissioned on the main incoming supply, highlighting the fact that, due to the failure of the power factor correction on this supply, the load was operating power factor is slightly below the minimum target power factor of 0.95. In addition, it was found that the site loading is uncomfortably close to exceeding the limits of main supply.
Whilst the reinstatement of the power factor correction would restore the load operating power factor, the high level of load current harmonics means that even with harmonic detuning reactors fitted to the power factor correction, excessive 5th harmonic current absorption within the power factor correction capacitors could still result, possibly resulting in further failures in the future.
In addition to potentially reducing the longevity of the power factor correction capacitors, the high level of load current harmonics is producing elevated levels of voltage harmonics and is placing significant stress upon the supply transformer.
The results of the PQA also showed Voltage 5th, 33rd, 39th, 45th and 49th harmonic voltages and the voltage THD exceeded the G5/5 design limit. The 5th harmonic voltage dominates the voltage harmonic voltage distortion, which is to be expected given the proliferation of 6-pulse inverter drives within the load.
In order to prevent future power factor correction capacitor failures and to minimise the effects of the load harmonic currents, we have recommended that a 450Amp rated active harmonic filter be installed that can perform the combined harmonic filtration and power factor correction requirements in one device.
The APQF was designed and built in our workshop, fully tested, and then shipped to site where it was lifted up to the 1st floor of a container switchroom where we have already removed the failed PFC equipment ready for connection of the new Filter.
New C.T circuits were installed and the 630A MCCB previously used for the PFC was utilized for reconnection of the Active Filter. Once connected, a full commissioning was carried out and the unit showed a reduced Voltage distortion down from 3.9%VTHD to 1.5%VTHD and a reduced Current Distortion down from 9.2% iTHD to 5.2%iTHD
This 350kVAr Power Factor Correction unit installed in 1998 was found to have multiple capacitor failures following a long period of not being annually maintained.
It was decided that an end-of-life replacement for all the tray assemblies would be the best option. As such we swapped out the old-style SBA trays with its cascaded contactor steps with a more modern SBA tray with two 50kVAr soft switching contactors on each and 480V-rated capacitors.
We also included a smaller tray with two stages of 25kVAr for finer correction at different loads.
As well as this we also installed forced air ventilation into the front of the panel to help regulate the internal temperature of the unit.
We were asked to carry out a full maintenance of a panel built Power Factor Correction unit at a UK rubber fabrication plant.
The existing PFC on site had not had a full service before despite being installed in 1997. The unit has a multitude of component failures including the failure of capacitor banks, contactors that had welded closed, burnt-out inrush coils and operated fuses.
Due to the age of the equipment and the lack of annual servicing we recommended an end-of-life replacement to the panel and the installation of a new FSi200 fully detuned PFC unit.
The new unit would consist of 3 stages of 50kVar and 2 smaller stages of 25kVAr all controlled by an 8 stage Lovato DCRL 8 digital control relay. We would also include additional forced air ventilation and filtered louvres.
Due to the construction of the existing panel, we were able to remove the PFC section entirely and put the new unit in its place. New power cables were installed and connected to the existing MCCB that fed the old equipment.
All the works were carried out by 2 engineers during normal working hours without any disruption to the site supply.
After a callout to a significant capacitor failure inside one of the Power Factor correction units, it was noted that the background harmonics had increased since our last annual service visit.
A week-long Power Quality Analysis was carried out on both LV supplies on-site and from the results it was confirmed that there was a notable increase in the load current and harmonic current distortion on the supply during the period of higher occupancy, this was in part due to the recent installation of multiple EV chargers.
The level of voltage harmonic distortion on both supplies was such that the original standard power factor correction equipment on site was magnifying this distortion when in circuit and as such now requires the incorporation of harmonic detuning reactors to prevent harmonic overload of the PFC capacitors.
The solution was to remove the existing PFC units and replace them with two fully detuned FSi200 units incorporating 480V capacitors, soft switching contactors and 189Hz reactors; utilizing the existing cable and C.Ts.
All the works were carried out by 2 engineers over 2 days without any disruption to site.
We recently carried out the second phase of our Active harmonic filter installations at a large insulation manufacturer in Cardiff.
This supply now consists of 3 x 180amp P300-180/690V units connected in a Master/Slave/Slave configuration all controlled via the New Comsys HMI 4 display.
The harmonic distortion on this supply was around 8.5% THDV and 30% THDI. When the filters were connected and in operation, we saw a drop of over half to 3.5% THDV and 14% THDU.
Built by our workshop team into a custom enclosure with added forced air ventilation and remote monitoring, then installed and commissioned by two of our engineers over 3 days with no disruption to the site operation.
Find out more about our Active Harmonic Filters here or contact us today.
Above: Site loadings Before Active Filter is off
Above: Site loadings Before Active Filter is on
A recommendation for an end-of-life replacement for a 100 kVAr ABB PFC unit was made following site’s annual maintenance due to the age of the existing equipment as well as multiple capacitor failures.
We also recommended adjusting the capacitor step sizes to be more suited to the site’s current load conditions.
With this in mind, a replacement FS200 was to be installed consisting of 2 x 13.5kVar capacitor stages and 2 x 25kVar capacitor stages along with its own integral interlocking load break switch for local isolation and fully digital Lovato DCRL 5 control relay.
Utilizing the existing power cable and C.T. circuit our engineer removed the failed unit and installed the new FS200 in the same location at the end of the main panel. The works were carried out during normal operating hours and did not affect the operation of the site.
This old 100kVAr Power Factor Correction unit had reached the end of its life expectancy and multiple internal components had started to fail. It also had very little to no annual servicing carried out on it and due to its location inside an external GRP container, it had also started to rust.
Following an on-site load survey carried out during the maintenance visit, it was confirmed that the 100kVAr was sufficient to reach a healthy power factor of 0.99 inductive and the site background harmonics were below 2%VTHd.
The unit was replaced with one of our standard FS100 fully automatic PFC units including all new 480V rated capacitors, soft switching contactors and a fully digital Lovato DCRL 5 control relay.
As the unit was being fed from its own dedicated 250A MCCB all the works could be carried out during normal working hours with no disruption to the site.
We recently had the pleasure of attending this year’s Comsys Colab conference in Lund, Sweden. This event hosted by our Active Harmonic Filtration Partner Comsys we a great chance to not only catch-up face to face with the Comsys team but to also connect with other partners from around the world.
Over the 2 day event, we found out more about the new technology being developed by Comsys along with technical service training and examples of how their ADF equipment is used in multiple scenarios to help improve harmonic distortion.
We have already integrated many Comsys ADF systems and look forward to our continued partnership.
Click here to find out more about how reducing your harmonic distortion can help you save money and extend the lifespan of your site’s electrical system.
Following a maintenance request from a large aggregate manufacturing plant just outside London we carried out a service on what turned out to be one of our Power Factor Correction units, a FSi300 originally built by us in 2007 for a 3rd party installer.
The unit had never been serviced since installation and due to its dusty environment years of accumulated dirt had built up in and around the unit which eventually led to the site isolating the unit in 2020 where it had been left ever since.
During our service, we found multiple capacitor failures along with lots of rust on the detuning reactors. All the ventilation fans in the roof had also seized and the unit’s key had ben lost.
Due to the failures and lack of servicing the best option was to replace the internal trays with new ones, including all capacitors, contactors and fuses. Along with this we also replace all the fans in the roof and upgraded the control relay to the latest Lovato DCRL range.
Upon completion, the site had improved its Power Factor from .041 inductive to 0.99 with all works being carried out during normal working hours without any disruption to site operation.
During a recent trip to Ireland, we carried out the commissioning of 6 Active Harmonic filters and 3 new Power Factor Correction units at a large horticultural manufacturing site.
All the equipment had been shipped to the site and installed by the on-site engineering team ready for the energising of a production line. Our engineers spent 3 days on-site reviewing the installation and getting the active harmonic filter set up with the correct parameters and then tested under load conditions. Each Active Harmonic Filter was 300A and set up on two different supplies in a master/slave/slave configuration.
While on-site we also commissioned 3 new 360kVAr Power Factor Correction units, each with its own detuning reactor, customed to the site’s load requirements.
We were asked to investigate a possible fault with a Voltage Optimisation unit installed at a Gym south of London. The site reported that the load started to flicker and eventually the VO unit went into bypass mode increasing the voltage back to its original levels.
Upon further investigation, it was found that the L2 phase terminal on the voltage transformer had failed and caused damage to the L2 transformer winding. The unit had not been serviced since installation and we suspect a poor connection was the cause of the terminal overheating and ultimately failing.
Therefore, we recommended a new 400A VO unit connected to the existing 400A-rated bypass device along with the removal and disposal of the failed equipment.
The work was to be done out of hours to prevent any disruption to the Gyms customers and keep downtime to a minimum. upon completion the site voltage was reduced from 429V per phase to 398V per phase, helping them save money on their electrical bills.
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