SU1576966A1 - Device for overvoltage protection of load connected to power supply source - Google Patents

Abstract

The invention relates to electrical engineering and is intended to protect radio devices from an increase in the voltage of a power source. The purpose of the invention is to increase the speed and reliability of protection. Under normal voltage of the power supply 3, the protective transistors 14, which are connected in parallel with the collector-emitter transitions to the power supply circuit of the load 2 from the source 3, are in a deep saturation mode due to the base current flowing through the collector-emitter of the matching transistor 13 from an additional source 22. The threshold element 9, connected in series to a voltage divider across resistors 10, 11, is in the initial state, in which the voltage on resistor 11 is insufficient to open the control junction 12. When the voltage of power supply 3 increases, threshold element 9 opens, voltage increases at resistor 11, which leads to unlocking of transistor 12 and switching on optocouplers 23, 24. Phototransistor of optocoupler 23 shunts the input circuit of transistor 13, closes it and disconnects the additional source 22 from the bases of the transistors. 14. After the source is disconnected, the 22 transistors 14 conduct current due to the charge of minority carriers accumulated in the bases. Turning on the phototransistor of the optocoupler 24 translates into a saturated state an additional transistor 25, which connects the capacitor 27 to the base-emitter junctions of the transistors 14 in polarity, providing accelerated absorption of the charge of minority carriers in the bases of the transistors 14 and the fast closing of the transistors. A zener diode 26 connected in parallel to the capacitor 27 provides the required blocking voltage on the capacitor 27. 1 sludge.

Description

of the optocoupler torus 24 translates an additional transistor 25 into a saturated state, which connects the capacitor 27 to the base-to-emitter transitions of the transistors 14 in polarity, providing accelerated resorption

charge of minority carriers in the bases of transistors 14 and fast closing of the transistors. A zener diode 26 connected in parallel to the capacitor 27 provides the required blocking voltage on the capacitor 27. 1 sludge.

The invention relates to electrical engineering and is intended to protect radio devices from an increase in the voltage of a power source. 1 The purpose of the invention is to increase the speed and reliability of protection.

The drawing shows a diagram of the device.

The device 1 for protection against overvoltage of load 2 connected to the power source 3 contains the first 4 and second 5 input terminals for connecting the power supply 3 of the power source 3, the first 6 and the second 7 output terminals for connecting the positive and negative terminals respectively. power supply 2, an overvoltage sensor 8, made on the threshold element 9, the first 10 and second 11 resistors, controlling 12 and matching 13 transistors, at least two parallel-connected protective transistor 14 whose combined respectively collector and emitter, the third 15, fourth 16, fifth 17, sixth 18, seventh 19 and an eighth resistor 20, the diode 21 and the additional power source 22. The first input terminal 4 is connected through a chain of series-connected threshold element 9, the first 10 and second 11 resistors of the overvoltage sensor 8 to the second input terminal 5. The base of the control transistor 12 is connected to the midpoint of the voltage divider formed by the first 10 and second 11 resistors and the collector of the control transistor 12 through the third resistor 15 is connected to the collector of the matching transistor 13 connected to the positive terminal of the additional power source 22, the negative terminal of which is connected with the first output terminal 6, the first terminal of the fourth resistor 16, the cathode of the diode 21 and the combined emitters of the protective transistors 14,

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the combined collectors of which are connected to the first input terminal 4. The first terminals of the fifth 17 and sixth 18 resistors and the anode of the diode 21 are connected to the second input 5 and output 7 terminals.

The device has phototransistor first 23 and second 24 optocouplers, additional transistor 25, zener diode 26, and capacitor 27. The LEDs of the first 23 and second 24 optocouplers are connected in parallel between the emitter of the control transistor 12 and the second input terminal 5 according to the emitter of the control transistor 12. The base of the matching transistor 13 through the collector-emitter of the phototransistor of the first optocoupler 23 is connected to the first output of the fourth resistor 16, the second output of which is connected to the base of the phototransistor of the first optocoupler 23. The emitter cons The transistor 13 is connected to the bases of all protective transistors 14, to the second output of the fifth resistor 17, and through the collector-emitter of the phototransistor of the second optocoupler 24 to the base of the additional transistor 25, the collector of which is connected to the bases of the protective transistors 14, and the emitter to the second the output of the sixth resistor 18, the anode of the Zener diode 26 and the first output of the capacitor 27, the second output of which is connected to the cathode of the Zener diode 26 and the negative output of the additional power source 22. The seventh resistor 19 is connected between the collector and the base of the matching transistor 13, and the eighth resistor 20 is connected between the base and the emitter of the phototransistor of the second optocoupler 24.

The device works as follows oO.

Under normal supply voltage 3, the protection transistors 14 are in deep saturation mode due to the base current flowing through the collector-emitter junction of the matching transistor 13 from the additional source 22. The threshold element 9 is in the initial state at which the voltage across the resistor 11 is not enough to open the control transistor 12.

As the voltage of the power source 3 increases to a value exceeding the breakdown voltage of the threshold element 9, the latter opens, the voltage drop across the resistor 11 increases, which leads to the opening of the control transistor 12 and the inclusion of the optocouplers 23 and 24. The phototransistor of the optocoupler 23 shunts the input circuit of the matching transistor 13, the latter closes and disconnects the additional source 22 from the bases of the protective transistors 14, which up to this point were in deep saturation mode. After the additional source 22 is disconnected, transistors 14 conduct current due to charge of minority carriers accumulated in the bases. Turning on the phototransistor of the optocoupler 24 translates into a saturated state an additional transistor 25 that connects the capacitor 27 to the base-to-emitter transitions of the protective transistors 14 in polarity, ensuring the accelerated absorption of the charge of minority carriers in the bases of the protective transistors 14 and their fast closure. Zener diode 26 provides the required blocking voltage on the capacitor 27. Through the diode 21, the current of the additional power supply 22 is closed during overvoltage of the power supply 3.

The present invention improves the speed and reliability of overvoltage protection of a load and can be used to protect both capacitive and active loads.

Claims (1)

Invention Formula Device for protection against overvoltage of the load connected to the power source, containing the first and second input terminals for connecting respectively to the positive and negative terminals of the power source, first and second output terminals for connecting the positive and negative terminals of the load, respectively, overvoltage sensor performed on the threshold 69666 element, the first and second resistors, the control and the matching transistors, at least two parallel-connected protective transistors, in which the collectors and emitters are combined, the third, fourth, fifth, sixth, seventh and eighth resistors, a diode and an additional source power supply, with the first input terminal through a chain of series-connected threshold element, the first and second resistors of the overvoltage sensor connected to the second input terminal, the base of the control transistor connected to midpoint voltage divider formed by first and second rezisto10 15 and the control transistor collector is connected via a third resistor to a matching transistor collector connected to the positive output of an additional power source, the negative output of which is connected to the first output output, the first output of the fourth resistor, the cathode of the diode and the combined emitters of protective transistors, combined collectors which are connected to the first input pin, and the first pins of the fifth and sixth resistors and the anode of the diode are connected to the second input and output pins, I distinguish This is because, in order to increase the speed and reliability of protection, phototransistor first and second optocouplers, an additional transistor, a zener diode and a capacitor are inserted into the device, with the first and second optocouple LEDs connected in parallel between the emitter of the control transistor and the second input terminal according to the emitter of the control transistor , the base of the matching transistor through the collector-emitter of the phototransistor of the first optocoupler is connected to the first terminal of the fourth resistor, the second terminal of which is connected to The phototransistor base of the first optocoupler, the emitter of the matching transistor is connected to the bases of all protective transistors, to the second output of the fifth resistor, and through the collector-emitter of the phototransistor of the second optocoupler to the base of the additional transistor, and the collector is connected to the bases of the protective transistors, and the emitter to the second view of the sixth resistor, the anode of the zener diode and the first terminal 715769668 a sensor whose second pulse is connected between a collector and a dinene with a Zener cathode and a negative base of a matching transistor, and the additional output of an external resistor is between the base and the power supply emitter, while the seventh relay of the phototransistor of the second optocoupler,