Plant Oxford is the birthplace and heart of MINI production. Hundreds of MINIs leave the plant's assembly lines each day destined for new owners in more than 110 countries around the world.
In common with many modern production facilities, Plant Oxford utilizes a wide variety of equipment such as electric motors and variable speed drives (VSDs) that present a non-linear load on the network. This can result in the introduction of potentially harmful harmonics that cause voltage distortion leading to overheating of cables, motors and transformers, damage to sensitive equipment, tripping of circuit breakers and blowing of fuses as well as premature ageing of the installation. That is why APDS, the ABB Drives Alliance partner that has supplied a large number of VSDs for the site, called in ABB’s Power Quality team to carry out a survey to identify and eliminate harmonics before they can cause any issues.
ABB’s survey identified significant levels of harmonics, mainly at the 5th and 7th levels, across the plant, but especially at the paint shop. To return the site supply to the level of harmonics specified in the G5/4 standard ABB then proposed a solution based on the state-of- the- art PQFM active filter technology. These filters continuously monitor the current in real time to determine what harmonics are present and then inject harmonic currents into the network with exactly the opposite phase. The two harmonics effectively cancel each other out so that the feeding transformer sees a clean sine wave.
To meet the specific needs of Plant Oxford, ABB’s UK-based Power Quality team developed a bespoke 300 A rated PQFM system housed in a Rittal cubicle. The filter is operated by the PQF-Manager, a simple, user-friendly front panel module that offers direct control, programming, monitoring and network analysis capability.
The first eight PQFM units were installed during the Summer 2016 shutdown and a further four will be installed later in the year.