C3Controls 320B4U63 Industrial Overload Relay

320-B4U63 is a Series 320 bimetallic overload relay from C3 Controls, designed to pair with 300-series contactors to provide thermal motor protection in control panels. It is a three-pole unit with a Class 10 thermal trip and a current adjustment range of 50–63 A, allowing protection to be matched to the motor’s full-load current within that band. The B4U63 suffix identifies the 63 A maximum setting within the 50–63 A range, keeping protection coordinated with compatible starters. This overload relay is intended for use with Series 320 devices and works with contactor styles 300-S50, 300-S65, and 300-S80 to form an integrated motor control solution. Designed for industrial motor protection, it helps safeguard motors from overload conditions while enabling reliable operation in standard 3-phase applications.