The BU1AC110 is Woodward's AC voltage relay for over- and under-voltage protection on low-voltage circuits. Rated for 110 V AC across a 45-66 Hz window at about 3.5 VA, it uses a DOK-ZERT-M microcontroller to monitor the bus and trip on a programmable window.

Why adjustable setpoints beat a fixed relay

A fixed-threshold relay trips at one voltage and one time, which rarely matches the application. The BU1AC110 lets you set both the over- and under-voltage limits and the delay before each trips, so a brief sag on generator start does not nuisance-trip the contact while a sustained over-voltage still opens it in time to save the load.

What the DIN-rail package means for install

Mounted on a standard DIN rail, the relay drops into a generator or motor control enclosure next to the other protection devices, and its 45-66 Hz range covers both 50 and 60 Hz supplies. For LV power generation and motor protection it is the simple, configurable window guard that watches the bus the bigger controller assumes is healthy.