Eaton Powerware 9395 275 kVA MBM Installation And Operation Manual

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Eaton Powerware 9395 275 kVA MBM Installation And Operation Manual Manual pdf 61 page image

Eaton 9395 Maintenance Bypass Module Installation and Operation Manual 164201719 Rev 3 www.eaton.com/powerquality 5-1Chapter 5 Understanding MBM OperationThe Maintenance Bypass Module (MBM) enables power to completely bypass andisolate the UPS so that the UPS can be safely serviced or replaced withoutinterrupting power to critical systems.The MBM consists of a maintenance bypass breaker (MBP), a maintenance isolationbreaker (MIS), an optional bypass input breaker (BIB), and an optional rectifier inputbreaker (RIB). The MBP transfers the load from the UPS output to the bypass inputfeeder and the MIS isolates the UPS from the bypass feed and the load. The BIB andRIB provide a single point of rectifier and bypass input power control to the UPS andeasily removes power from the UPS for servicing.The MBP and MIS use either electrical or mechanical (Kirk key) interlocks to preventparalleling the UPS inverter output and the bypass source.5.1 MBM with Electrical InterlocksThe K1, K2, and K3 relay network in conjunction with the MBP and MIS shunt tripcircuits prevent the bypass source and the UPS inverter from being connected inparallel.When the UPS inverter is off (the UPS is in Bypass mode), K1 is energized. This isaccomplished by the closing of the UPS output contactor aux contacts when theoutput contactor opens.The MBP shunt trip is active when K2 is energized. This occurs when the UPSinverter is online (K1 is not energized) and the MIS is closed.The MIS breaker shunt trip is active when K3 is energized. This occurs when the UPSinverter is online (K1 is not energized) and the MBP is closed.If the UPS is online and the MIS breaker is closed and an attempt is made to close theMBP breaker, the MBP breaker shunt trip will activate, preventing the bypass sourceand the UPS inverter from being connected in parallel.If the UPS is online and the MBP breaker is closed and an attempt is made to closethe MIS breaker, the MIS breaker shunt trip will activate, preventing the bypasssource and the UPS inverter from being connected in parallel.5.2 MBM with Mechanical (Kirk Key) InterlocksThe Kirk key interlock system uses key-controlled mechanical locks on the MBP andMIS breakers to prevent the bypass source and the UPS inverter from beingconnected in parallel.Two A keys and one B key are used with the MBM. A and B keys are both required toclose the MBP and the MIS.Initially, one A key is in the solenoid lock, one B key is in the MBP, and the second Akey is in the MIS. All the keys are locked in place.After the UPS is transferred to Bypass mode, the red light on the front of the MBM isilluminated indicating the UPS inverter is off and Key A is removable from the solenoidlock.Figure