CC59.4 | Schneider Electric Thermal Unit, Type S, Type CC

The CC59.4 Thermal Unit, classified as Type S and Type CC with a melting alloy composition and rated at Class 20, serves the primary function of safeguarding motors, controllers, and branch circuit conductors from excessive heating caused by prolonged motor overcurrents, including locked rotor currents. These units do not protect against higher currents resulting from short circuits or grounds, as this falls within the domain of branch circuit fuses or circuit breakers. 

Operating according to specific trip curves, Class 20 thermal units are designed to respond swiftly to overload current conditions. They are engineered to trip in 20 seconds or less upon detecting an overload, ensuring prompt intervention to prevent damage to connected equipment. Constructed as a single unit, these thermal units feature a design where motor current flows through a small heater winding. In the event of an overload, the generated heat melts a specialized solder within the unit. This action allows a ratchet wheel to rotate freely, thereby initiating the opening of control circuit contacts and subsequently disconnecting the motor contacts. 

The CC59.4 thermal units are characterized by their robust one-piece construction, enhancing reliability and durability in demanding operational environments. Their functionality is critical in maintaining the operational integrity of electrical systems by preventing overheating that could lead to equipment failure or damage. By integrating melting alloy technology, these units offer a precise and effective means of overload protection, ensuring consistent performance across a wide range of industrial and commercial applications.