SU1283890A1 - Device for short circuit and overload protection of power source - Google Patents

Abstract

The invention relates to electrical engineering and can be used in devices for power supplies of electronic equipment. The aim of the invention is to increase the speed of protection of electronic equipment against short circuits and overloads. When the supply voltage is turned on, the transistors of the regulating element 1 are opened and current begins to flow through the load. When the load current exceeds the allowable value, transistor 9 opens and current flows through resistor 8, diode 6 and base-emitter junction of transistor 7. Transistor 7 opens and the current flowing through resistor 10 increases, which will lead to further opening of transistor 9, and therefore , and transistor 7. Due to the fact that the current sensor and the control node are covered with deep positive feedback, transistors 9 and 7 will open to saturation, almost all of the supply voltage will drop at resistor 10. The transistors of the regulating element 1 are closed and the load will be de-energized. In the event that an emergency increase in the supply voltage occurs, transistors 4 and .7 will open, and then transistor 9. Then, an electronic latch will occur and load will be controlled by the regulating element 1. 1 sludge. with e GO 00 & d

Description

The invention relates to electrical engineering and can be used in devices for the protection and control of secondary power sources.

The purpose of the invention is to increase the speed of the device.

The drawing shows a diagram of the proposed device.

The device contains a regulating element 1 connected between the power supply and the load, an active voltage splitter 2 connected to the negative terminal of the power supply terminal by the bottom input, and the first transistor 4 connected by the collector through the first resistor through the closing button 3 to the positive terminal of the power supply 3. 5 to another input of the active divider 2 voltage, the lower arm of which is made adjustable, connected to the base of the first transistor A, the emitter of which is connected to the anode of diode 6, the base of the third ranzistora 7 and through a third resistor 8 - to the collector of the second transistor 9 which together with the second resistor 10 connected between the emitter and base of the second transistor 9 form a current sensor.

The control input of the regulating element 1 is connected to the collector of the third transistor 7, the emitter of which is combined with the cathode of diode 6 to a common point and connected to the negative pole of the power supply. The emitter of the second transistor 9 is connected to another input of the active voltage divider 2 and through the second resistor 1.0 - to the collector of the third transistor 7.. I The device works as follows.

In the nominal mode, the regulating element 1 is in the open state. The nominal load current does not create a voltage drop on the regulating element 1, sufficient to unlock the second transistor 9 of the current sensor and the third transistor 7, which acts as a control element. If the current exceeds the allowable value on the regulating element 1, a voltage drop is sufficient in magnitude to turn on the second transistor 9 of the current sensor. The second transistor 9 opens, which leads to the opening

five

0

and the third transistor 7, an increase in the current through the second resistor 10 of the current sensor, as a result of which the second 9 and third 7 transistors are fully opened (due to the positive feedback between them). In this case, the regulating element is completely closed and the load is de-energized. To return to the initial state, it is necessary to disconnect the current through the open second 9 and third 7 transistors with the release button 3.

In the case of overvoltage, the first transistor 4 is switched, which also leads to almost instantaneous switching of the second and third transistors and the locking of the regulating element 1.

Claims (1)

Invention Formula Device to protect against short 25 short circuits and overloads of the power source, containing a regulating element designed to be connected between the power source and the load, an active divider of voltage 30, one input intended to be connected to the negative terminal of the load, and an output connected to the base of the first transistor, whose collector is connected to one end of WATER of the first resistor, and the emitter - to the anode of the semiconductor element, a current sensor consisting of the second transistor and the second resistor connected between the base and the emitter 40 of the second transistor, characterized in that, in order to increase speed, it is equipped with a third transistor, a disconnecting button and a third resistor, the lower 45, the active voltage divider arm and the second resistor are adjustable, and a diode is used as a semiconductor element, with another output of the first resistor connected to another input of the active voltage divider, the emitter of the second transistor of the current sensor and one output of the disconnecting button, the other output of which is intended for connecting to the positive pole of the power supply source, the collector of the second transistor of the current sensor is connected through the third resistor to the base of the third transistor and the anode of the diode, the cathode 312838904 which is connected to the collector of the third transistor to the common point, the pre-transistor and through the second resistor of the current sensor, to the negative pole of the power source, the emitter of the second transistor, the control input regulating Elec tric current.