Abstract: The invention relates to apparatus for supplying an electric consumer with a high DC voltage which includes provisions for minimizing the danger and hazard of electrical shocks associated therewith. The apparatus includes a power circuit and a measuring control circuit which are separated by high ohmic resistors and an optocoupler.

Abstract: The invention relates to an inverter circuit for operating a speed-controllable asynchronous motor. The inverter circuit is of the type wherein the voltage and frequency are substantially proportional until the nominal frequency has been reached at nominal voltage. The circuit includes and inverter, a desired value control, a D.C. voltage supply with a voltage regulator which sets the voltage depending on the desired value, and a voltage-operated frequency regulator. The circuit can be operated at frequencies above the nominal frequency to avoid damage to the inverter which would otherwise be caused by (1) high voltage due to the motor operating as a generator or by (2) the rapid reduction of the speed setting controls which is not accompanied by a corresponding drop in the voltage supplied to the inverter.

Abstract: The invention relates to an inverter circuit for operating an asynchronous motor having an adjustable speed. The inverter has its output frequency regulatable by a frequency regulator and the D.C. supply has its voltage regulatable by a voltage regulator. There is a desired value frequency regulator having a signal (f) and voltage and current measuring devices having output signals (E) and (I). A control circuit processes these signals (f, E, I) to form input values for the referred to voltage and frequency regulators. The control circuit includes a computer circuit which, from at least two output values and at least one constant, calculates a computed value of the third output value which, together with the first-mentioned output values, given by way of computation a substantially constant slip frequency for a given desired value, and this computed value is compared with a value substantially corresponding to the actual third output value.