AC Voltage Protector

250 Series DIN-rail and Wall Mounted Relays, AC Voltage protector, 120 volts ac, 60 hz, flange size 4-1/2"

Features
Single-phase or three-phase,
three or four-wire
Live and dead bus versions
Adjustable set point
LED trip indication
Volt free relay contacts

Applications
Marine panels
Switchgear
Distribution systems
Generator sets
Co-generation
Control panels

http://cromptoncanada.com/wp-content/uploads/2014/11/Protector-256-PLDU..pdf