Abstract: The signals transmitted on communication lines in a disturbed environment can be affected by strays. A digital filtering device eliminates these strays by suitable detection of the logic states of the digital signals. The signals received are sampled at a frequency greater than the digital information transmission rate, then detection of a state is effective when a minimum number of samples from among a predetermined number of successive samples is reached. The filtering device restores the rising and descending fronts, and also the high and low states without impairing the information. Application to a highly disturbed electromagnetic environment, notably communication links with circuit breakers.

Abstract: The interface card fixedly secured to the circuit breaker supplies information representative of the circuit breaker type and rating to a standard removable trip device. It comprises for example resistances designed to be connected in parallel to a resistance of a divider bridge defining in the trip device the instantaneous tripping threshold, modifying this threshold automatically according to the circuit breaker type and rating. The interface card can also supply the trip device with information representative of the rated current flowing in the primary winding of the current transformers fixedly secured to the circuit breaker.

Abstract: A test connector for connection to two test inputs of a trip device. The test connector includes a fixed component made of electrically insulating material, wherein the fixed component includes a sleeve defining an inner space. A movable component is provided within the inner space and is axially movable therein. The movable component includes a protruding portion which extends from the fixed component. A spring is provided between the movable component and the fixed component to provide a biasing force to urge the movable component in an outward axial direction. Two testing needles are housed within two longitudinal passages within the movable component. Upon insertion of the test connector into a recessed portion of a face of an electronic trip device, the movable component is urged rearwardly to expose the two testing needles which pass through orifices int he recessed portion to contact the two test inputs of the trip device.

Abstract: A digital solid-state trip unit of an electrical circuit breaker is equipped with an electrical contact wear indicator enabling the degree of wear of these contacts to be known. Each time the circuit breaker performs a break, the microprocessor determines a contact wear value, in terms of the maximum value of the current broken. The correspondence between the wear value and the current broken is stored in a ROM memory and the successive wear values are added in a NOVRAM memory whose contents are representative of the degree of contact wear. These contents can be displayed to indicate to the user that the condition of the contacts has to be checked.

Abstract: The digital solid-state trip release is equipped with a watch-dog which monitors the periodic running of the information processing controlled by the microprocessor. When a disturbance or a delay occurs in the periodic cycle, the watch-dog first emits a reinitialization order applied to the microprocessor input to attempt to rerun the periodic cycle. If this attempt is unsuccessful, the watch-dog emits a circuit breaker tripping order.