Moeller Gmbh

Wilhelm Melchert

Wolfgang Meid

A control circuit for an electromagnetic drive includes first and second electronic switching elements, which in conjunction with a timing element subject the drive coil to a corresponding direct current in the starting phase or in the maintenance phase. A starting current and a maintenance current are provided by means of a current source that is controlled by the timing element and a direct current converter with downward control.

Control circuit for an electromagnetic drive

An electronic drive control apparatus for controlling a drive coil of a contactor includes a microcontroller configured for generating an inverted pulse width modulated signal, and at least one semiconductor switch. A pulse-shaping stage is connected downstream of the microcontroller for varying the pulse width modulated signal. The pulse-shaping stage includes a preselectable RC combination and an inverter connected downstream of the RC combination and having a Schmitt trigger input. A preselection of the RC combination is carried out via a plurality of outputs of the microcontroller to open collector transistor stages of discharge resistors of the RC combination. The pulse width of the driving signal of the semiconductor switch is determined from the inverted pulse width modulated signal and the preselected RC combination.

Electronic drive control apparatus

The invention relates to a method for effecting an electronic drive control of a drive coil of a protection system using an electronic device which comprises a microcontroller. The aim of the invention is to increase the serviceable life of a protection system. To this end, the invention uses a randomly selected and constantly changing delay time (t ) that occurs after a time (t , t ) at which the supply voltage is established on the electronic device.

Method for effecting an electronic drive control

A circuit arrangement for overvoltage protection of a power transistor for controlling an inductive load includes a first varistor which bridges-over the supply connections. A second varistor is arranged parallel in relation to the switching path of the power transistor and in series with a switching transistor. The switching transistor can be controlled by a voltage divider which is connected to the supply voltage via a Zener diode.

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Hennef, Germany

Wilhelm Melchert