What is a UPS Make-Before-Break Bypass Switch?

A UPS Make-Before-Break (MBB) Bypass is a bypass that makes contact between the primary (UPS output) and secondary (bypass supply) power sources before transferring the load. The bypass switch may be built-into an uninterruptible power supply or installed as a separate and external wrap-around bypass switch. The device helps isolate the UPS for maintenance without interruption to the connected critical loads.