An external maintenance bypass switch enables a UPS system to be electrically isolated – taken out of the critical power circuit – for safe UPS maintenance, service work, or unit replacement without any disruption to the load.
Without an external bypass switch, such as UPS’s Multi Pass, to allow for preventive maintenance opportunities, the only safe alternative is to power down the entire critical load, not just the UPS system.
The external maintenance bypass will use a manual switching method to transfer the load between UPS output and the mains power supply. This can comprise of a single transfer switch (three or four pole) or an array of isolators. External maintenance bypass shouldn’t be confused with the internal maintenance bypass built into some UPS, which only allows for safe maintenance work in isolated parts of the UPS – there may still be other “live” parts such as the busbar connections.
Helios UPS’s external maintenance bypass switches are available for both single phase and three phase applications and can be fully customized to suit your particular specifications(terminals, protection, interlocks..). If you need help selecting the right bypass switch for your application, please do not hesitate to contact our sales engineers on firstname.lastname@example.org