Abstract: The electronic trip device includes a processing unit having inputs to receive electrical signals representative of electrical quantities and an output to supply a tripping signal to a tripping relay, and a man-machine interface connected to the processing unit to supply setting parameters and to display information and tripping curves on a screen. The man-machine interface includes display means displaying setting parameters which modify the visual aspect of at least one portion of curve representative of a parameter whose setting is being adjusted. The circuit breaker includes such a trip device connected to current sensors and to contacts to interrupt currents in electrical conductors.

Abstract: Selector switches placed on the front panel of the trip device enable first protection parameters to be set. The trip device comprises communication means enabling second protection parameters to be set by remote setting. The trip device compares each first parameter with the corresponding second parameter and determines third protection parameters representative of the lower of the first and second parameters. The third protection parameters are taken into account by the trip device for protection against overloads and short-circuits and are displayed on the front panel of the trip device when setting of the parameters takes place or on request.

Abstract: The communication device comprises a central unit and at least one station connected by a network. The station comprises a checking circuit and a storage circuit connected to the checking circuit. The storage circuit stores data representative of information which the station has to transmit to the central unit and transmission condition parameters associated to said information. In a parameter setting phase, the station receives the data and parameters to be stored. Then, in an operating phase, the checking circuit transmits information according to the stored transmission condition parameters.

Abstract: The communication device comprises a central unit and at least one station connected by a network. The station comprises a checking circuit and a storage circuit connected to the checking circuit. The storage circuit stores data representative of information which the station has to transmit to the central unit and transmission condition parameters associated to said information. In a parameter setting phase, the station receives the data and parameters to be stored. Then, in an operating phase, the checking circuit transmits information according to the stored transmission condition parameters.

Abstract: The electrical switchgear apparatus comprises a fixed part (1) and a removable part (2) designed to be connected to the fixed part to be connected to a power distribution system (4) and to a communication network (6). The removable part (2) comprises a communication circuit (23) and a first addressing device (24) connected to a first address input of the communication circuit (23). The fixed part (1) comprises a second addressing device (18) designed to be connected to a second addressing input of the communication circuit (23). To communicate, the communication circuit chooses in priority the address supplied by the second addressing device. If this address is not valid, it then chooses the address supplied by the first addressing device.

Abstract: The circuit breaker comprises a circuit breaker unit onto which there are fixed a communication module, a processing module and a calibration module. The communication module communicates with the processing module only via a connection with galvanic isolation, preferably an optical connection, whereas the calibration module is electrically connected to the processing module. The communication module is, in addition, connected by a mechanical connection to parts of the circuit breaker unit representative of the state of the circuit breaker, and by a bidirectional electrical connection to an external communication bus. An interface connected to the circuit breaker unit can act as support for the calibration module and for an additional module containing information representative of the breaking capacity of the circuit breaker and electrically connected to the processing module.

Abstract: A reference AC signal having a frequency of about 4-10 Hz is injected into a line of a DC electrical network for performing insulation measuring in a processing unit. The AC signal is measured in a mixed bridge having a first resistive dividing bridge connected in parallel with a second capacitive dividing bridge between the line and the ground. The intermediate output points of the first and second bridges are joined together and connected in an input of the processing unit. The impedance and the dividing ratio of the two bridges cause the DC voltage measured at said input to be low in relation to the value of the AC voltage measured at the output of said mixed bridge.

Abstract: An isolation monitor is electrically connected between the earth and an isolated neutral of a transformer which supplies AC electrical power to the main distribution network. In order to measure and to locate an isolation fault occurring somewhere on the feeders, each feeder is equipped with a toroid current measuring transformer, and comprises further a secondary winding connected to a processing locator performing synchronous demodulation. Two first and second transmission lines are provided between the isolation monitor and the locator. The first synchronous line transmits synchronization pluses from the monitor to the locator, and the second line transmits to the locator the demodulated values of the input voltage furnished by the monitor.

Abstract: In a system-powered solid-state trip device, the measurement voltage Vm, representative of the current flowing in the conductor to be protected and applied to the input of an electronic processing unit, can also be applied to the cathode of a thyristor connected in series with the trip coil and receiving on its gate, the tripping orders from the processing unit. A Zener diode is connected between the thyristor gate and the ground so as to set an instantaneous tripping pick-up of the trip device. In this way, a short-circuit in the conductor causes instantaneous tripping of the circuit breaker independently from the value of the supply voltage.

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.