SU1236449A2 - D.c.voltage stabilizer with overload protection - Google Patents

Abstract

This invention relates to constant voltage stabilizers with overload protection, and is further to the invention in accordance with the author. St. No. 1023304. The aim of the invention is to increase the reliability in operation. The goal is achieved by introducing into the circuit of transistors 4 and 5 and resistors 8.9, 10,12,14,15 and 16. When overcurrent is applied, the voltage from the current sensor 2 opens the protective transistor 3, which bypasses the control circuit of the regulating element 1. At this, due to the charge of the capacitor 7 through the resistor 13, the voltage at the base of the transistor 3 is shunted by the resistor 13, which leads to a short-term increase in the current limit threshold. As the capacitor 7 is charged, the current limit threshold is reduced to a nominal value. In the event of a short circuit, transistor 4 opens and shunts a voltage divider formed by resistors 8.12 and 14, which leads to locking of transistor 5. This eliminates the bypass of resistors 13 of capacitor 7 and triggers protection at the rated current of the limiting. 1 il. (L with go with Oi 4a X KZ

Description

The invention relates to electrical equipment, can be used in the power supply devices of automatic, computer and communication devices, and is an improvement of the invention according to the author. 1023304,

The goal is to increase reliability in work.

The drawing shows a block diagram of the proposed device.

The proposed device comprises a series-connected regulating element 1 and a current sensor 2, a protection transistor 3, transistors 4 and 5, a measuring and amplifying element 6 connected by an output to the control input of the regulating element 1, a capacitor 7 and resistors 8-17.

The proposed device works as follows.

In the initial state, the load current is less than the protection operation threshold. The voltage drop on the sensor 2 is 1 current insufficient to unlock the protective

transistor 3. The transistor 4 is closed because the parameters of the voltage divider formed by resistors 15 and 17 and the voltage divider formed by resistors 9 and 16 are chosen so that the emitter voltage of the transistor 4 is greater than the voltage at its base, and its peak circuit shunts the voltage supplied to the base of transistor 5 through a voltage divider formed by resistors 8, 12 and 14 and transistor 5 is open, and capacitor 7 is connected through it through a small resistance of open transistor 5 to the output power output m.

At the time of overcurrent, the voltage on the current sensor 2

through resistors 10 and 11, opens for 45 and the eighth resistors with a zero-width shishitch transistor 3, which, by shunting the control circuit of the regulating element 1, limits the load current, and due to the charge of the capacitor 7 through the resistor 13 The 50 voltage supplied to the base of the protective transistor 3 is bridged by the resistor 13, which leads to a short-term increase in the limited threshold, which is connected to the output power output through the series-connected ninth and tenth resistors, the base of the first transistor is connected to chkoy compound of the fifth and sixth resistors, the point of the compound of the fourth and fifth resistors connected to the collector of the second tran ican ,, which is connected to the base

ki current. Then, as the Conden-55 charge point is the junction point of the seventh and eighth

The threshold 7 of the current limit is reduced to the nominal value. According to the choice of the ratio

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Resistors 10, 11, and 13 determine the ratio of the thresholds for limiting the load current during short-term and long-term overloads, and the choice of capacitor 7 determines the duration of the permissible short-term overload.

In the event of a short circuit, transistor 4 opens, because the voltage across the emitter through the resistor 17 becomes zero, and with its collector circuit it shunts the voltage divider formed by resistors 8, 12 and 14,

15 which leads to the closing of the transistor 5, its resistance to the collector-emitter increases dramatically and thus the shunting effect of the resistor 13 and the capacitor 7 on the voltage is eliminated.

The current coming from the current sensor 2 through the resistors 10 and 11 to the base of the protective transistor, which immediately triggers the protection at the nominal current limit.

Claims (1)

Invention Formula DC voltage stabilizer with overload protection by bus. St. No. 1023304, characterized by the fact that, in order to increase reliability in operation, two transistors and seven resistors are inserted in it, the connection point of the first and second resistors through a series-connected third resistor and a capacitor connected to the collector of the first transistor whose emitter is connected with the output power output, the input power output is connected through series-connected quarter, fifth and sixth resistors with the output power output, and through series-connected seventh The base of the first transistor is connected to the connection point of the fifth and sixth resistors, the connection point of the fourth and fifth resistors is connected to the collector of the second transistor, the base of which is connected to resistors, and the emitter - with the point of connection of the ninth and tenth resistors.