Siemens Aktiengesellschaft

Manfred Muller

Karl Klausecker

Franz Hauner

Gerhard Donig

Gunter Tiefel

Silver-based contact material for switchgear used in power engineering

A pulse-inverter, especially a transistor inverter, is required to generate a system of polyphase output voltages as symmetrical as possible, having, for instance, trapezoidal waveforms. For this purpose, several reference voltages having different waveforms are generated wherein each section of an output voltage coincides with a section of a reference voltage. These reference voltages are pulse-width-modulated with a high-frequency sampling frequency and an inverted sampling frequency to form pulse width modulated reference voltages and pulse width modulated inverted reference voltages, respectively. The pulse-width-modulated reference voltages and pulse width modulated inverted reference voltages are coupled to the control lines of the inverter switches so as to generate, section by section, the output voltages having the reference waveform. All reference voltages and components used for generating the driving signal for one inverter output are also used for generating the driving signals of the other outputs so that a symmetrical system of driving voltages is produced without costly adjustments.

Method and apparatus for driving a transistorized polyphase pulse

A power line control circuit receives audio-frequency signals from a pulsed inverter that is transformer-coupled to the power line. A filter circuit is connected between the inverter and the coupling transformer primary circuit to transmit the audio signals and prevent power line frequencies from reaching the inverter. A magnitude-measuring circuit determines when output current from the inverter exceeds a certain value and controls an intervening circuit to reverse, briefly, the state of conductivity of the inverter.

Audio-frequency powerline carrier control system with a current

An arc quenching arrangement is disclosed for a circuit breaker equipped with stationary contacts and a contact bridge having respective sides facing toward and away from the stationary contacts. The contact bridge is movable between closed and open positions to respectively contact and separate from the stationary contacts, whereby an arc is formed as the contact bridge moves away from the stationary contacts to the open position. The arc quenching arrangement quenches the arc and includes an arc guide having a longitudinal axis. The arc guide is located adjacent the side of the contact bridge facing away from the stationary contacts and is positioned such that the longitudinal axis thereof extends in a direction substantially parallel to the longitudinal dimension of the contact bridge. The arc guide has respective end portions bent in a direction away from the contact bridge; these end portions are located in the vicinity of the respective ends of the contact bridge. Each of the end portions is bent so as to form an acute angle .alpha. with the longitudinal axis in the range 15.degree.&lt;.alpha..ltoreq.75.degree.. This configuration prevents the arc from entering the region between the contact bridge and the arc guide.

Circuit breaker with arc quenching baffle arrangement

A protection arrangement for an inverter having fuses connected in series with its d-c inputs is disclosed. In particular, in one form of the arrangement, an electronic voltage monitoring device is provided for monitoring the input d-c voltage to the inverter at the connection points of the inverter inputs and the fuses. If the voltage monitored by the monitoring device falls below a predetermined level, the monitoring device delivers a protection signal to the control unit of the inverter directing the latter to release firing pulses for extinguishing the valves in the valves branches of the inverter. In another form of the arrangement, the voltage monitoring device monitors the voltage across each of the fuses at the d-c inputs of the inverter, and, if a monitored voltage exceeds a predetermined value, delivers a protection signal to the control unit of the inverter. Additionally, where the inverter being protected is included in a cycloconverter, provision is made for ensuring that a protection signal is not delivered before sufficient time has elapsed for the intermediate d-c link voltage of the converter to reach a predetermined value.

Growing community of inventors

Nuremberg, Germany

Manfred Muller