E-T-A Circuit Breakers Ltd

Thermal circuit breakers, are ideal for protecting loads against overcurrent. However, bimetals reach their limits in applications requiring a very fast thermal disconnection. There is a solution for these applications: E-T-A's 1410 circuit breaker with hot wire principle.

The trip time of thermal circuit breakers depends on the level and duration of the overcurrent and the ambient temperature. Therefore, they only provide a delayed disconnection compared to magnetic circuit breakers, i.e. in case of small overcurrents, it takes notably longer until the faulty circuit is disconnected. This makes thermal circuit breakers the ideal protection device for loads such as motors, transformers and supply lines, as they can handle short, non-hazardous overcurrents without being damaged. If the overcurrent continues for too long, the circuit breaker reliably trips. This helps prevent undesired early or nuisance tripping. The delay also ensures that high current peaks of motors, transformers or magnetic valves do not lead to a disconnection.

BIMETAL, FUSIBLE AND HOT WIRE PRINCIPLE

The bimetal is the conventional trip element in thermal circuit breakers. Complementing bimetals, also fusibles, hot band or hot wire tripping elements are used. Hot wire tripping elements are very effective as they help realize thermal circuit breakers with very fast trip curves. Additionally, they are temperature-insensitive due to their high operating temperature of about 300 °C.

THE 1410 WITH HOT WIRE PRINCIPLE

E-T-A's 1410 series are single pole, thermal circuit breakers with current ratings up to 10 A, for AC 240 V and DC 28 V rated voltages. The tripping element is a bistable hot wire element providing a fast and precise trip curve in the event of an overcurrent. All five 1410 versions are hardly bigger than a sugar cube. This means that they can be easily installed even in applications with small space requirements.