Square D B28.0 Thermal Unit - Melting Alloy - Class 20

Product Description

Square D B28.0 thermal unit is designed to protect motors, controllers, and branch circuit conductors from excessive heating caused by prolonged motor over-currents, including locked rotor currents. These thermal units operate based on trip curves and will trip in twenty seconds or less under overload conditions. The one-piece construction allows motor current to pass through a small heater winding, triggering a melting solder mechanism. When an overload occurs, the solder melts, spinning a ratchet wheel that opens the control contacts, disconnecting the motor. The AIC Rating in accordance with UL512 is two hundred thousand Amps, ensuring high reliability in various applications.

• Cannot be reset until cooled.
• Available in designs: standard trip (Class 20), slow trip (Class 30), quick trip (Class 10).
• Calibration set for a range of motor full load currents.

Product Highlights

This thermal unit provides essential overload protection for most motors and maintains its original calibration even after repeated tripping.

Product Information

Standard Information

• Catalog Number: B28.0
• Brand: Square D