SU1367005A1 - Device for protecting supply source against current overload - Google Patents

Abstract

The invention relates to electrical engineering and can be used in power supplies. The goal is to increase reliability. When overloaded, transistor 1 leaves a saturation short circuit, decreases the base current of transistor 2, which leads to an avalanche-like process of locking transistor 1. In this case, the generator is excited at unijunction transistor 4, which periodically opens transistor 1 for a short time, so the current is negligible. When the overload disappears, the device turns on, and the pulse generator stops generating pulses. 1 il. (C (L

Description

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The invention relates to electrical engineering and can be used to protect power sources.

The purpose of the invention is to increase reliability.

The drawing shows the principle of the electrical circuit device to protect the power source from overcurrent

The device contains a locking transistor 1 connected to the power supply power bus, a control transistor 2 connected to the collector and the base of the transistor 1 by the base and the collector, respectively, and the common power supply bus with the emitter circuit and the start pulse generator on the single junction transistor A, the resistor 5 and the capacitor 6 o The load 7 of the device is connected between the common bus and the collector terminal of the transistor 1. The first and second bases of the transistor 4 are connected respectively to the emitter and transistor collector. 2, the emitter of the transistor A is connected through a resistor 5 to the emitter of transistor 1, and through the encoder 6 to the first base of a single-junction transistor A o

The device works as follows.

When the supply voltage is applied, the transistor A is turned on, ensuring that the transistor 1 is turned on, a voltage appears on the load 7 that unlocks the transistor 2, as a result of which the transistor 1 turns on reliably, and the generator ceases to break the generation.

When increasing the output current above the set value, the transistor 1 goes out of sight, the output voltage decreases, the base current of the transistor decreases, and its avalanche-like blocking occurs.

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In this case, the start-up generator begins to generate, providing a periodic unlocking of the transistor 1 with a high duty cycle, so that the average current is small. When the overload disappears, the transistor 1 is turned on again, and the generation fails.

The presence of a pulse start generator allows for a reliable start, to ensure the device returns to a working state after the overload is removed, to provide a low average current through the blocking transistor in the protection mode. The indicated properties allow to increase the reliability of the device.

Formula of the invention

A device to protect the power source from overcurrent, containing a locking transistor connected to the power supply bus, the base of which is connected to the collector of the control transistor of the opposite conductivity type of the locking transistor, the emitter of the control transistor is connected to the common power source latch through the resistor, and the base is with the collector of the locking transistor, O T L and

In order to improve reliability, a pulse generator was introduced into it, made on a single junction transistor, resistor and capacitor, while the first and second bases of the single junction generator transistor are connected respectively to the emitter and collector of the control transistor, and its emitter through the specified resistor - with the emitter of the blocking transistor and through the specified capacitor - with the first base of the single-transition transistor.

Claims (1)

2Q Claims A device for protecting the power supply from overcurrent, containing a locking transistor included in the power bus 25 of the power supply, the base of which is connected to the collector of a control transistor of the opposite type of conductivity to a locking transistor, the emitter 30 of the control transistor is connected through a resistor to a common bus of the power source, and the base is with a collector of a locking transistor, characterized in that, in order to increase reliability, a pulse trigger generator made on a single-junction trans stories, resistor and capacitor, wherein the first and second base unijunction transistor oscillator are respectively connected to the emitter and collector of the control transistor, and its emitter through said resistor - to the emitter of the latch transistor and said capacitor through - with a first base unijunction transistor.