Uninterruptible Power Supplies MINIpower PLUS User Manual

Also see for Minipower Plus Rack: User manual

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Uninterruptible Power Supplies MINIpower PLUS User Manual Manual pdf 43 page image

UPS453-01-00 MINIpowerPLUS User Manual Dated 08-03-12 7-17 Options7.1 Maintenance Bypass7.1.1 IntroductionFigure 7.1 Maintenance bypass circuitThe Maintenance Bypass option allows the load to be transferred to the raw input mains supply if it isnecessary to completely shut down or remove the UPS for maintenance or repair purposes.The maintenance bypass switch controls two relays, one of which is connected in the bypass circuit and theother in the UPS output line (see Figure 7.1). When the maintenance bypass switch is OPEN (0) the UPSoutput relay is closed, energised from the UPS output supply via a normally-closed switch contact, and thebypass relay is open. Conversely, when the maintenance bypass switch is CLOSED (1) the bypass relay isclosed, and the UPS output relay is opened. This interlocking action prevents the UPS output from beingback-fed from the raw mains supply.Key Point: When the load is connected via the maintenance bypass supply it is not protectedagainst mains failure or other power aberrations.UPSN/OFuseBypass RelayUPSOutputRelayPENLPENLMaintenanceBypassSwitchINPUTMAINSLOADSUPPLYN/C