Abstract: A static converter equipment comprising at least two converters, each with a DC terminal; each converter having a load with a feeding point connected to the DC terminal of the converter, the converters being arranged to work in offset phase relation to each other. The feeding points are interconnected with impedance means with resistance of at least the same order of magnitude as the load resistance and an impedance at the most of the same order of magnitude as the load impedance.

Abstract: The speed of a cable being unwound and wound onto a cable drum disposed on a movable vehicle is controlled by developing a control signal from an error signal which is the difference of an actual value representing the drum speed and a reference value which contains two components, one proportional to the vehicle speed and another proportional to the position of a tensioning means associated with the cable drum.

Abstract: A convertor for supplying a load with direct voltage pulses of variable frequency includes input terminals for connection to a DC source and a main circuit, with a filter circuit connected between the input terminals and the main circuit. The filter circuit includes a capacitive parallel branch and a series inductor connected between one of the input terminals and the capacitive parallel branch. A resistor for reducing the Q-value of the filter circuit is connected in parallel with the series inductor. A second series inductor may be connected in series with the parallel connection of the first series inductor and the resistor. The first series inductor has an inductance which, at low current values, is larger than that of the second inductor.

Abstract: Drive equipment supplied with direct current, which includes a DC motor with a series field winding and with a semi-conductor rectifier arrangement in parallel with the field winding and working in pulse operation for variable shunting of the field winding. The controllable semi-conductor rectifier has a reactor connected in series with it. A load object is connected in parallel to the semi-conductor rectifier. The load object may be an accumulator battery series-connected with a second semi-conductor rectifier which blocks the battery voltage.

Abstract: For supplying a load, such as motor for rail vehicles, with direct voltage pulses with a variable frequency from a direct voltage source, a pulse generating member is connected between the source and the load and delivers direct voltage pulses with a variable frequency to the load. The pulsing member can be switched for the pulsing in groups or symmetrical pulsing. When pulsing in gropus, it delivers pulses in groups of two pulses with a constant time interval T.sub.1 between the two pulses of each group. A control arrangement is provided for switching the pulse generating member to symmetrical pulsing when, in the case of pulsing in groups, the group frequency exceeds a value of substantially (K/2T.sub.1), where 0.5 is < K < 1. Immediately after switching to symmetric pulsing, the working frequency is brought to (K/T.sub.1).