Case Study: Frequency converters for BAE Systems Frimley

When building a new BAE Systems facility to replicate both onshore and offshore voltages and frequencies, there was a need to create three different voltage supplies in addition to standard UK supply.

Scope of Works
The design called for two modular 50Hz to 60Hz converters, one 1,000kva and one 500kVA. These systems needed to be at least N+2, which allows for two modules to fail without impacting the load. With our SCSFA modular series, we supplied their requirements with 30 x 50kVA modules, all of which were “hot swappable”. This means that a single module can be swapped out whilst all the other modules are still working, so any singular failure will not impact the end load.

Once converted, the modules fed two galvanic isolation transformers, one being 350kVA 400VAC in and 440VAC out, the other being 800kVA 400VAC in and 115VAC out.

Finally, we added two 40kVA 50Hz to 400Hz converters, in an N+N configuration to allow our client to use one unit or another. Should one unit fail they can simply switch to the other unit, therefore not impacting operations due to a failure in any one system.

Frequency and Voltage Conversion
Many clients need to convert the voltage and frequency to use different equipment form the local supply, which in this case replicates the conditions onboard a submarine, to allow full testing in the factory.

The modular frequency converter selected by the client gave them the option to maximise operational “up time” in a compact style. This is down to each 500kVA system only taking up 2 metres high by 1.3 metres wide x 1.1 metres deep, and a structure where the 500kva and 1,000 kVA systems are both consistent.

For the added benefit of greater flexibility, our end client can remotely monitor the unit.

FAT testing
With our client opting for Factory Acceptance Testing (FAT), they were able to come and see the units working, and ask questions of those who designed and built them. This is different to the more common approach of commissioning engineers. We found there were added benefits to operating this way; we uncovered an adjustment that we were able to rectify early in the project, and we had added confidence that when we came to commission the units, they would work as designed.
Despite delays in starting the project, we were able to complete on time, significantly making up for the delays. The project was delivered on budget and exactly to our client’s specification.