SU650162A1 - Geared electric motor - Google Patents

Description

one

The invention relates to electrical engineering, to control devices for low-voltage non-contact electric devices, namely, automatic thyristor power switches, which perform the functions of power switching for responsible AC consumers.

A switch control device is known, which contains a trigger, two shaping circuits, two logic gates, And, two control signal amplifiers, a current transformer in the load circuit, a current level driver. This device is intended for switches using natural switching thyristors 1.

A disadvantage of the known device is that the switching time, determined by the moment when the current in the load is zero, significantly depends on the nature of the voltage reduction and the load itself. Thus, with an abrupt decrease in voltage (short circuit at the input terminals of the switch), the current in the inductive load is exponential, the switching time can significantly exceed the period of oscillations of the source voltages, which is unacceptable for a number of consumers.

It is also known a switch control device comprising a voltage source voltage sensor, two triggers, the outputs of which are connected to a control pulse driver, the other inputs of which are connected to the voltage of the respective network and to current sensors located in the consumer circuit 2.

A disadvantage of a lime device is that it is unsuitable for operation as part of a switch that uses forced switching of thyristors and, moreover, malfunction when the main source feeder breaks, or the capacitive nature of the load, since the operability of this device is based on the formation of thyristor control signals during switching the voltage of the source and the current of the consumer in the polarity corresponding to the circuit polarity of the thyristor. This device also does not provide reliable operation in switching on, switching, as this may reduce the voltage of the newly connected source under the influence of inrush currents, which will lead to a false switch to another source.

Thus, the known devices have rather low operational reliability and narrow functionality, intended only for switches with natural switching thyristors.

The aim of the invention is to increase reliability and enhance functionality.

The goal is achieved by the fact that the device for controlling the switch of the power supply sources of the load, contains two triggers with three inputs for setting zero and two inputs for installing the unit, the output of each of which is connected to the input for setting zero of another trigger and for the inputs of the control pulse former connected to the control pulse shaper and to the second inputs of the zero-trigger setup, as well as a voltage source voltage sensor connected via the primary switch-on unit to the first and the installation inputs of the trigger unit are additionally equipped with a mode setting unit, two And elements, two delay blocks and a blocking relay, with the inputs of one And element connected to the voltage sensor outputs of the power sources, the inputs of the other And element connected to the voltage sensor outputs of the power sources through the mode setting unit, to the additional inputs of the And elements are connected the outputs of the trigger, the load current sensor and the blocking relay; the output of each of the And elements is connected to the third input of the zero setting, respectively trigger trigger, with a lock relay input and, via a delay unit, with a second unit setup input of another trigger, and the auxiliary locking relay inputs are connected to the outputs of the primary switching unit.

The drawing shows a device for controlling the switch of the power supply sources of the load.

It contains a voltage sensor of the power sources of the main Uon and the backup UPU, triggers 2, 3, respectively, of the main and backup sources; primary turn-on unit 4; elements And 5, 6; delay blocks 7, 8; blocking relay 9; load current sensor 10; unit installation mode 11; control pulse shaper 12. The device can operate in two modes — the first: switching mode with priority to the main source, in this case connecting the load, when the voltage of the main and backup sources exceeds the switch setting, Umax, during the initial turn on source, and when the voltage decreases in the main source below the setpoint for switching the UMKH, the load is switched to the backup source if the voltage level of the backup source exceeds rate on inclusion. The reverse switching from the backup source to the main source is carried out after the end of the action of the blocking of the reverse switching to the transient time after the switch formed by the relay 9, when the voltage of the main source is restored to

 /Max.

In the second: an equivalent switching mode, the initial switching is carried out as in the previous mode, but the reverse switching, after the switching pulse has expired, is performed only when the backup source voltage decreases below, while the primary source voltage is higher

 -max

The operation mode of the device is determined by the block. And, the operation of the remaining units of the device is the same, therefore, the operation of the device as a whole is considered below only in the switching mode with priority.

If at the time of the initial switching on of Uoa and t / pn is greater than t / mako, THEN at THIS, as soon as the supply voltage of the circuit reaches the required level, this level is monitored by block 4, from the output of block 4 (the input of which receives output signals from the voltage relay block) a trigger will be sent to the input of the installation of the trigger unit 3, resulting in the output of the trigger 3, the logical unit will enter the block 12 to generate control signals for the power unit (thyristors) of the power switch, as well as to one of the setup inputs of the trigger 2, for key false inclusions. At the same time, a pulse from the output of unit 4 is fed to the input of relay 9, the output signal of which is fed to the input of elements And 5, 6 for blocking the switch due to a possible decrease in voltage caused by starting load currents. If at some point in time, after the expiration of the impulse of relay 9, the voltage of the main source decreases below 7 min and t / pn t / max, then the output of the AND 6 element shows a signal (provided that the unit levels of the relay 9 coincide in time ), which indicates the end of the blocking pulse, the output signals of block 1, which indicates in this switching mode that the f / on voltage decreases and the backup source f / pn is exceeded, besides, the logic unit signal from the trigger output 3, testifying that At present, the main source is loaded, and from the output of unit 10, which indicates the allowable amount of current in the load. The last condition is very important for switches with both natural and forced switching of power thyristors, and for switches with natural switching, working on

the principle of switching off thyristors of a previously loaded source using the voltage of the backup source, depending on the direction of the current in the load at the moment of switching, is the minimum allowable amount of current in the load, since it determines the operability and errors of the load current sensors 10, and for switches with forced switching is also the maximum allowable amount of current in the load, since it determines the breaking capacity of the forced (capacitive) switching circuit of the thyristor, gab Arrits and weight switch.

The output signal of the AND 6 element is received: at the input of the block 12, for generating control signals for switching off the thyristors of the main source, at the input of setting zero trigger 3 for resetting, and at the input of relay 9 for generating a reverse switching blocking signal caused by a possible decrease in the voltage t / pn under load and voltage recovery Uon to f / max level in idle mode. In addition, the signal from the element And 6 enters the input of the delay unit 8, from the output of which the pulse signal with a time delay relative to the input signal, determined by the turn-off time of the thyristors of the main source, enters the installation input of the trigger unit 2, at the inputs of the zero setting which The present signals are "logical zero," and sets it to the state "logical one."

At the same time, the output signal of the trigger 2 is fed to the input of the block 12 for generating the thyristor control signals of the backup source and to the input of setting the zero of the trigger 3 to prevent the thyristors of both sources from turning on, as well as to the input of the And 5 element to allow the formation of a reverse switching pulse after the recovery and the expiration of the impulse of the relay 9, if at the same time the load current corresponds to the permissible value. When switching from a backup source to the main unit 5, 7 work similarly to blocks 6, 8 as when switching from the main source to the backup one.

The hysteresis (t / maxmin) is required to turn on or switch to a source with a known normal voltage and is determined by the nature of the load and the power of the source. Dual control f / max

and t / MHH is due to the fact that

The power switch that uses this device has a very high switching speed of trigger 3 (about 1-2 ms with forced switching and 10 ms with natural, for a source frequency of 50 Hz), and the i / max relay may not be fast-acting.

This device is universal for any type of thyristor switching in a switch and increases the reliability of the switch and the power supply of consumers.

Claims (2)

1.A. S. Kartavykh, G. M. Rogozhin, “Control of thyristors of alternating current switches when switching sources,“ EP, ser. “Low Voltage Appliances, vol. 2 (42), 1975. 2. USSR author's certificate number 316154, cl. H 02J 9/06, 1971. Yara signal