Abstract:
A static converter composed of a converter-transformer and a rectifier bridge connected thereto has a bypass member connected in parallel with the bridge. Two series-connected rectifiers in one phase of the bridge constitute a bypass path. A direct voltage source can be connected with said two bypass rectifiers, the source having such a polarity as to furnish a current in the conducting direction of the two rectifiers.
Abstract:
A chain of series-connected semiconductor rectifiers has a voltage divider connected in parallel therewith. A firing circuit is connected on the one hand to the control electrode and to one of the main electrodes of each rectifier and on the other hand to two different points on the voltage divider. The firing circuit derives a control voltage between such points, which is fed to the rectifier by a switching means, such as an optically controlled semiconductor.
Abstract:
A converter is formed of a group of rectifiers arranged in series with reactors. A protection device is provided which includes a short-circuiting arrangement for the rectifiers. The reactors are provided with iron cores which are saturated at approximately 1 percent-10 percent of the short-circuiting current of the converter.
Abstract:
A STATIC CONVERTER IS PROVIDED WITH SHORT-CIRCUITING MEANS ON BOTH THE DC AND AC SIDES, AND WITH MEANS TO OPERATE THE SHORTCIRCUITING MEANS AND TO DISCONNECT THE AC SIDE UPON AN INCREASE IN THE DC CURRENT ABOVE A PREDETERMINED VALUE; THE CURRENT SENSITIVE DEVICE OPERATES THE SHORT-CIRCUITING MEANS SUCCESSIVELY WITH LOW TIME DERIVATIVES OF THE DIRECT CURRENT AND SIMULTANEOUSLY WITH HIGHER TIME DERIVATIVES.
Abstract:
A thyristor has a control device connected between a base layer and an emitter layer. The base layer is provided with a plurality of connecting electrodes one at the center and several around the periphery. A control device is connected to the central electrode while a capacitor is connected between the emitter electrode and the peripheral electrodes.
Abstract:
In combination with two AC networks, there is at least one converter connected to one of the networks which is composed of diodes and at least one other converter composed of controlled rectifiers. A further converter composed of controlled rectifiers is connected to one of the networks. All the converters are connected in series in one or several DC circuits. The further rectifier is controlled by the current in the DC circuit in such a way as to compensate for variations in the direct current therein. It is possible to connect the converters alternatively to either of the AC circuits.
Abstract:
In a static converter with thyristor-rectifiers, a protection against auto-ignition includes an arrangement for sensing the polarity over the rectifier, and an And-gate. The sensing arrangement emits a first signal to the And-gate when a voltage after a commutation becomes negative and a second signal when a voltage after a commutation becomes positive. The And-gate is connected to the ignition system of the rectifiers to supply both signals thereto. The connecting means for the first signal includes a delay device which delays the signal by a time corresponding to the longest recovery time for the thyristors, so that, if the second signal is emitted during this time, an ignition signal is allowed to pass the And-gate.