SU403059A1 - SWITCHING DEVICE - Google Patents

Description

one

This invention relates to switching equipment.

Switching devices are known that contain thyristors connected in series, shunted by a voltage divider, a source of starting pulses, and a C thyristor starting circuit.

In order to increase the reliability and noise immunity in the proposed device / C-circuit of thyristor startup, connected to their control electrodes through serial diode-resistor circuits, they form a divider with one of the extreme terminals, grounded through the source of starting pulses, and another terminal connected through additional circuit diode-resistor to the load.

The drawing is a schematic diagram of the described device.

The device contains power thyristors 1-4, zener diodes 5-9, diodes 10-13, pulse transformer 14, capacitors 15-18, resistors 19-26, load resistance 27, start terminals 28 and 29 and power supply terminal 30.

When the voltage on the anode of the thyristor 4 rises, the voltage on the plates of the capacitors 15-17 increases more slowly than on the cathodes of the corresponding thyristors, and the diodes 10-12 lock up. Anode voltage

thyristor 4 can grow at a speed not exceeding a certain value, opre, dU

case effect, so the voltage

dt

on the secondary winding of the pulse transformer 14 increases slightly. The magnitude of this voltage can be adjusted by a resistor 26. Zener diode 9 serves to protect thyristor 1 from interference arising

when switching. When a starting pulse arrives at terminals 28 and 29, the voltage on the positive plates of capacitors 15-17 instantaneously increases by the amplitude of the pulse on the secondary winding of the transformer 14. At the same time, the current of the thyristor cathodes starts to flow through the resistors reigns unchanged, i.e., close to the unlocking threshold of the zener diodes

5-8. Thyristors 1-4 are turned on almost simultaneously. After turning on the thyristors, the capacitors 15-17 are discharged. With forced switching of thyristors, the on-line processes are repeated.

Since the parameters of the resistive-capacitive divider can be selected so that diodes 11 and 12 are locked with a voltage higher than the voltage on a separate thyristor, the device has a high noise immunity and has a stable

operation even in case of accidental switch-ons from disturbances of one kz thyristors. The elimination of the capacitor 15 and the corresponding setting of the voltage divider could increase the device's nomekhostoykost. In this case, it is necessary to switch on the Zener diode in series with the diode 10, similar to the Zener diode 9.

The advantages of the described device are the simultaneous start-up of thyristors, high noise immunity, the possibility of using a pulse transformer with low isolation properties, the possibility of controlling low-voltage pulses from the ground and the use of relatively low-voltage parts, small dimensions of the starting circuit.

: 28th

Subject invention

A switching device containing sequentially connected thyristors shunted by a voltage divider, a source of starting pulses and; Thyristor starting circuits, characterized in that, in order to increase reliability and noise immunity, the thyristors C start circuit, connected to their control electrodes through serial diode-resistor circuits, form a voltage divider with one of the extreme terminals grounded through source of starting pulses, and another output connected via an additional diode-resistor circuit to the load.