UPS the basics

Relationship and partnership with generators.

UPS are designed to keep critical infrastructure running when there is a mains power anomaly. For most power anomalies, 20-30 minutes of protection are sufficient to cover the disruption before mains is regulated again. However, when the lights go out for longer, there are other options available.

Diesel/gas powered generators can be utilised to power buildings or homes for extended periods of time, beyond what is considered a normal power anomaly time period. Whilst UPS systems can be used for longer runtimes, generators may be preferred for many reasons, including: price, longevity, reliability, footprint, etc.

When utilising generators, premises owners often install these emergency power devices to provide energy to all areas of the building, not just areas considered critical. Things such as air conditioning units, lighting (emergency and/or general), etc which are sometimes omitted by UPS power, can be covered by a generator solution.

The biggest problem with generators is that they do not provide uninterrupted power by themselves. For hyper critical applications, UPS solutions are still required to bridge the gap between mains failure and generator start up. This amount of time is usually well under 5 minutes, so often when pairing generators with UPS, the latter is only sized to cover the critical infrastructure for a short period of time (5-10 mins commonly).

Additional delays are caused by AMF (Automatic Mains Failure) or ATS (Automatic Transfer Switch), which need signalling to transfer power pathways from the primary source (commonly mains power) to the secondary power source (in this example gas/diesel generators). Time delays may also be implemented, to avoid the genset starting and stopping for short power disturbances.

Whilst the delays are happening, with a suitably sized UPS and battery system in situ, critical infrastructure will remain operational, whilst non-critical devices shutdown. When generator power becomes available, these devices will start up once more.

Additional factors when pairing UPS and generators must be considered. Things such as the voltage acceptance window of the UPS must be significantly wide enough to handle generator fluctuations. Widening of the window is possible utilising the manufacturer service software, which is another reason why UPS commissioning services are so important. Without this widening, the UPS may transfer to battery power, destroying the battery set over a shorter period of time than expected, leaving the site vulnerable to downtime. Other considerations include correct sizing, parallel redundancy, fuel tank locations, etc, etc.

We are not generator experts, however, when it comes to UPS systems, paired with generators or not, you only need TheUPSTeam Ltd.