SU137576A1 - Sensor to protect mechanical rectifiers from direct current - Google Patents

Description

To provide sparkless switching in mechanical rectifiers, commutating chokes and circuits that shunt the contacts in circuits using silicon or germanium diodes are commonly used. However, in order to avoid the destruction of contacts and diodes, this requires high-speed protection using short circuits.

In the described sensor, to protect mechanical rectifiers from direct current in the diode circuit, bypassing the contacts of the rectifier, saturation throttles with steel cores of an alloy with a rectangular hysteresis loop are included.

Such an embodiment of protection drastically reduces the number of cases of contact damage and the duration of the re-entry of the rectifier into operation after an emergency shutdown.

To eliminate reverse current, a diode may be included in the auxiliary windings of the saturation chokes, containing short circuit coils.

FIG. 1 shows a diagram of the described sensor; in fig. 2 - the characteristic of his work.

The described direct current protection sensor consists of two throttles DR and DR2 with steel cores with a hysteresis rectangular loop. One choke is connected to the common circuit W of the diodes BI and 2 and bz of the positive half-wave, and the other is connected to the common circuit W of the diodes B, B and .Sg of the negative half-wave.

In known devices, sparkless operation of the rectifier takes place only when the contact K o is opened in the region 1-3 (Fig. 2). If the moment of opening of the contact / Co takes place behind the point / in the direction of lagging, reverse ignition occurs, and at the moment of opening of the contact

№ 137576-2 -:.

point 3 in the direction of advance contact falls on the direct current. Both modes of operation of the rectifier are emergency and lead to the burning of contacts and the destruction of the shunt diodes B (,.

The proposed protection works as follows (with reference to the work of one Drossel Dro.

On the windings IF ,, and W ,, a current flows / „, which creates ampere turns

alF ,, .--, directed inversely with amperages shunt

1T7G RllI 1 about

chain 11 / w - where / is the length of the power line in the magnetic circuit.

t ,. ,

Ampervits AJ eliminates false triggering of the protection at start-up and provides the necessary magnetic condition of the core of the throttles Dr after the triggering. During operation / contact; / Co in the region of / - (Fig. 2), the induction in the core does not change (with ideal steel) and there is no impulse in the winding Wn. When moving a point of opening time / Co beyond point 3 (for example, point 4) aW is greater than aWn, which leads to a change in induction from B to B. The resulting pulse on the winding affects the short circuit breakers KB-I protecting the contacts and diodes. A diode Bn is inserted in the circuit W, which excludes the effect of reverse current protection circuits. ,

The subject matter of the invention is g; ,

1. Sensor for protection of mechanical rectifiers from direct current, excluding the fact that, in order to prevent: damage to the contacts and shorten the time for re-introduction of the rectifier into operation after an emergency shutdown, in the circuit of diodes, bypassing the contact circuit straightener, saturation throttles with steel

alloy cores with rectangular hysteresis loop ,. ,

.. 2. V.datchik.po p. 1, in order to eliminate the reverse current, the inclusion of a diode in the auxiliary windings of the circuit of the inductor saturation, containing coils short circuits ... .