Testing times for generator maintenance

UPS Services Mark Trafford

UPS engineer Mark Trafford

It was another early start today – time waits for no UPS engineer!

With all the equipment and tools ready, we travelled up to Manchester where we were to test a 75kVA generator on load as part of a generator maintenance programme. During a generator test it is essential to check that the generator will be able to cope with the load it is designed to support, just in case of the ‘unlikely’ event of a power cut. When planning generator maintenance, we acknowledge the possibility of a power cut – even if our clients don’t!

We checked the status of the automatic mains fail (AMF) panel first, as, obviously when we are testing the generator, it means that it won’t work in the event of an outage – an ironic situation that we prefer to avoid! A typical generator maintenance test takes at least three hours so we do not want to leave a customer without energy for that amount of time while we complete the testing!

We carried out the following generator maintenance pre-test checks: coolant; oil; electrical/mechanical; and battery. We then simulated a ‘power cut’ to test the generator, incrementally increasing the energy ‘load’ (starting at around 10%) and recording the voltage thereafter at regular intervals. The oil pressure and coolant temperature was also recorded.

We eventually increased the load to 66kW (or 110%) for about 45 minutes, and then allowed the generator to cool down very gradually. After three hours of testing I was glad I had my ear defenders with me – the noise was deafening! The data we collected today as part of the generator maintenance programme will later be sent to the customer electronically to keep him up to date with the safety and efficiency of their UPS unit.

UPS repair requires replacement battery

In the afternoon we received a call-out request from a contract customer, who requested a visit for a UPS repair. We made sure that we had plenty of time to meet the standard four-hour response time. Their UPS power back-up unit, installed three and a half years ago, had failed its automatic weekly check and won’t start.

The customer looked pleased to see us and brought us both a mug of tea. We went to the outside housing where the unit was stored. When planning a UPS repair, we first carry out our preliminary checks, so we put the unit into manual mode. When we tried to start it from the controller, the starter motor hardly turned.

Upon testing the voltage we recorded a healthy 13.26V, but when we started it up the voltage dropped to about 6V. This immediately told us that a new battery was needed, so I fetched one from the van (we never set off in the morning without product parts and battery spares). We started up the generator again and it ran smoothly for 20 minutes, but we still made various other checks to ensure everything else was in full working order and ensure that the UPS repair is complete, inspecting the charger to make sure that there were no blown fuses or problems there. We switched the unit back to automatic then disposed of the old battery for the customer.

So there we have it – another eventful day including generator maintenance and a UPS repair, with two happy customers at the end of it.