Siemens Aktiengesellschaft

Andreas Fischer

Stefan Widmann

Adelheid Gonschorek

An embodiment of the invention relates to a method for ground fault detection for low-voltage three-phase AC circuits having a neutral conductor, in which first to fourth analog current signals of the first to third phase conductors and of the neutral conductor of the three-phase AC circuit are ascertained that each contain the level or an equivalent of the level of the current. The analog current signals are time-division multiplexed, subjected to a/d conversion, and a sequence of time-division-multiplexed first to fourth digital current values present in first to fourth successive time frames form first to fourth current signals. Three of the four digital current signals are interpolated to ascertain interpolated current values. The current value of the time frame of the uninterpolated current signal and the interpolated current values for the time frame of the uninterpolated current signal are used for discovering the ground fault.

Low-voltage circuit breaker and method

A method is disclosed for testing a latching solenoid of a switch and a testing device for carrying out the method is disclosed. The switch includes a switching contact, formed by contact elements mechanically separated from one another when the switching contact is open; an electronic trip unit, to respectively monitor the current passing via the contact elements and test whether a current-dependent tripping condition is satisfied; and an actuator, to separate contact elements after actuation, the trip unit actuating the actuator via the latching solenoid when the tripping condition is satisfied; and an electrical energy store, to charge to a voltage before the tripping and to be discharged via the latching solenoid. After a period of time after the tripping, the voltage of the energy store is compared with a reference value and a fault signal is output if the voltage of the energy store is above the reference.

Method for testing a latching solenoid of a switch and testing device for carrying out the method

A method and a test device are disclosed for testing a latching magnet of a switch. The switch includes a switching contact; an electronic trip unit to monitor the current flowing and to test whether a current-dependent trip condition is met; an electrical energy store, forming a circuit with the winding of the latching magnet, the circuit being closed by the trip unit when the trip condition is met; an actuator, actuated for a first closing time by closing of the circuit and configured to separate the contact elements; and a first diode, connected in parallel with the winding and via which stored energy of the latching magnet is dissipated. The test device is configured to close the circuit for a second closing time, which is so short that no actuation of the actuator takes place. After the reopening, a test is performed to ascertain whether stored energy is dissipating.

Method for testing a latching magnet of a switch and test device for the latching magnet

A method is disclosed for testing a latching magnet of a switch including a switching contact, formed from contact elements mechanically separated from one another for opening the switching contact; an electronic trip unit, to monitor current flowing via the contact elements and to perform a test for a current-dependent trip condition; an electrical energy store, forming a circuit with the winding of the latching magnet, the circuit being closed for a first closing time when the trip condition of the trip unit is met; and an actuator, actuable by closing off the circuit and configured to separate the contact elements. For test purposes, the circuit is closed for a second closing time, which is so short that separation of the contact elements by the actuator does not take place. A test is then performed to ascertain whether there is a current flowing via the winding of the latching magnet.

In order to provide a high impedance between two sensor terminals, for instance for connecting a Rogowski transducer to a circuit breaker, but to prevent the coupling-in of interference signals in the case of a non-connection to the terminals, two auxiliary terminals are connected. In at least one embodiment, they are connected in such a manner that in the basic state, the sensor terminals are short circuited but in the case of a connection, for example of a plug to the sensor terminals and simultaneously to the auxiliary terminals, the short circuit is canceled with external short circuiting of the auxiliary terminals.

Method for operating an electrical apparatus and circuit breaker

A circuit breaker is disclosed. A Rogowski converter is checked for wire breakage by applying a voltage to the Rogowski converter which is output by a digital/analog converter in response to a digital signal. The digital signal is dependent on the switch rated current of the circuit breaker.

Circuit breaker and method for checking a Rogowski converter in a circuit breaker

A circuit is disclosed for a power supply unit for generating a DC voltage, the power supply unit having a current transformer, a rectifier, a series circuit including a first blocking diode and a charging capacitor, an electronic switch which is in parallel with the current transformer, a comparator, a voltage reference circuit for the comparator. In at least one embodiment, the circuit includes a circuit for monitoring the voltage across the charging capacitor. The comparator is used to control the electronic switch on the basis of the voltage across the charging capacitor in relation to the voltage which is generated by the voltage reference circuit and is applied to the comparator. In at least one embodiment, provision is made of a tap which is located between the rectifier and the first blocking diode and at which the circuit for monitoring the voltage across the charging capacitor is located. The circuit is in the form of an RC combination having a second blocking diode connected in series.

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Amberg, Germany

Andreas Fischer