SU675571A1 - Static change-over switch of loaded power transformer adjustment taps - Google Patents

Description

FIG. 1 shows a diagram of a switching device; in fig. Figure 2 shows the process of switching the transformer branches under load.

The switching device can be made for an arbitrary number of branches. Each branch is connected to control thyristors 1-14, forming the two arms of a bridge. The other two arms are formed by uncontrolled diodes about 15 and 16. An actor 17 is included in the bridge diagonal. In series with the reactor, an uncontrolled bridge rectifier can be connected to the diagonal of the bridge: on diodes 18-21, powered by auxiliary transformer 22. Specified

The auxiliary source of the postoshga voltage is not a fundamental element of the switch. The switching device can work with an additional source and without it. The adjusting zone of the winding in this case contains six sections 23-28.

The operation of the device is as follows.

{Switching on the circuit occurs after the supply of control pulses to any pair of thyristors 1-2, 3-4, etc. At the moment when a positive voltage appears on them, the angle of regulation e1 O. On the diagonal of the bridge, there is a straightened voltage, under Exposure of which increases the current in the reactor to

the amplitude value of the load current i t (Fig. 2). A rectified current flows through the reactor, which is formed from the bridge arm currents, 1 V. At the high quality factor of the reactor, all four bridge valves are in the 5th state — the switching angle of the rectifier f 180, the valve currents have a constant component equal to half of the maximum; the maximum value of the load current is -C and. sinusoidal component with amplitude, - ....

The 1k circuit proceeds in the circuit as follows: a positive current wave from clamp A, then, for example, through sections 23, 24, 25, 26, thyristor 9, reactor 17, diodes 18-21, if they are used in the circuit, diode 16, k clamp B. Return the half-wave of the working i ifc & ftpOTeKaet from clamp B through diode 15, reactor 17, diode 18-21, thyristor Yu, winding section: and 6- F to Clamp A. similar .;

The soldering valve and reactor in a real circuit have a finite resistance, the current in the reactor in the switching interval fades (Fig. 2) and inter-switching intervals of operation of the switching device appear when the circuit between the thyristors, for example 13, 16 and 15, 14 , turn on the reactor.

This bridge interval may

several electrical degrees, unipolar voltage spikes occur in the reactor.

The influence of these explorations on the operating modes is small, since their mean value is small. The magnitude of the average value of the voltage drop across the switching device is determined by the sum of the voltage drops across the reactor and valve actuation resistance.

The device allows, if necessary, to completely eliminate the indicated voltage drop. For this, the reactor in series 6 is included in the circuit of a source of constant voltage, made in the form of an auxiliary transformer 22 and rectifier on diodes 18-21.

The process of switching from one branch to another can be carried out at an arbitrary point in time, for which control pulses are removed from the working thyristor group and fed to any adjacent group. So, when the thyristors are turned on 13 and 14, i.e., the entire control zone of the windings of the power transformer is wrapped around the operating current to switch to the adjacent branch at an arbitrary time O (Fig. 2), the control impulses from the thyristors 13 and 14 are transferred on thyristors 11 and 12. At the moment of transfer, as shown above, all four thyristors 13, 14, 15, 16 are circled by the operating current. When the thyristors 11 and 12 are turned on, a short circuit of section 28 is formed. This short circuit is formed through the thyristor 13, diode 15, reactor 17, thyristor 12. Short Closing current ya | $ reaches the amplitude value of the reactor current for the interval f, then one from the thyristors 13 and 14, in this case 14, the reactor is switched off and the reactor is introduced into the short-circuit, which limits the current to the desired value. The switching process is pumped through the time, at the moment of, the natural switching of the thyristor 13.

Claims (2)

1. The static switch of the adjusting branches of the power transformer under load, containing thyristors connected to the adjusting; branches, characterized in that, in order to ensure the reliability of the switch, each of the adjustment branches is connected to the load by means of a four-arm bridge, the two arms of which are indicated thyristors, two other arms are uncontrollable diodes, and a reactor is inserted into the diagonal of the bridge . 2. A switch according to claim 1, characterized in that a DC source is connected in series with said bridge diagonal in series with the reactor. 21 m Fy