Schneider Electric B17.5

This Thermal Unit is engineered to provide protection for motors, controllers, and branch-circuit conductors against excessive heating caused by sustained over-currents, which may include locked rotor conditions. The functionality of this unit is critical in preventing damage from higher currents resulting from short circuits or grounds, which is managed by branch circuit fuses or circuit breakers.

Class 20 thermal units specifically respond to overload conditions based on defined trip curves, ensuring activation within 20 seconds during overload scenarios. The unit features a one-piece construction that enhances reliability. During operation, motor current flows through a heater winding embedded within the thermal unit. In the event of an overload, the heat generated melts a specialized solder, releasing a ratchet wheel that subsequently opens the control circuit contacts and interrupts the motor contacts.

According to UL512, this unit has an AIC rating of 10,000 Amp. The product is UL listed and CSA certified, aligning with industry standards for safety and performance. Notably, the product is classified under the range B, with a thermal overload type of melting alloy.