The MBSW is a manual maintenance bypass switch designed to isolate AC input and output to allow for routine UPS maintenance without load interruption. The purpose of the MBSW is to ‘bypass’ the UPS and supply mains power to critical loads. Once the maintenance is complete, the loads are transferred back to the UPS and returned to normal operation. Only AC input and output are isolated in this switch. The DC supply from batteries is not isolated as the batteries have an independent circuit breaker.

The make-before-break design guarantees no interruption to the loads since the switch is fitted with an electro-mechanical mechanism between itself and the UPS to prevent incorrect or accidental operation. The shaft in the contact is locked by a solenoid which is electrically coupled with the UPS ‘load on bypass’ relay, meaning the switch cannot be operated unless the load is manually transferred to bypass mode on the UPS front panel first.

MBSW Technical Description