SU706930A1 - Switch for switching inductive loads - Google Patents

Description

(54) KEY FOR INDUCTIVE LOAD COMMUNICATION

 I

The invention relates to communication technology and is intended for switching inductive loads, in particular electromagnet telegraph devices.

Devices for switching circuits with inductive load are known, using a series connection of several transistors 1 and 2. In these devices, in order to reduce the voltage acting on the switching element, the latter is designed as a series connection of several transistors, but at the same time to ensure simultaneous closing and the opening of these transistors introduced additional elements that complicate and reduce the reliability of the device as a whole.

Also known are keys with inductive load, in which, in order to reduce losses, {3 |, 4J or 1 parallel to the load. In addition, the primary winding of the transformer, the secondary winding of which is connected to the power supply, is included. 8 of these devices, the transistors must be designed for a collector voltage that is much greater than the supply voltage, since they actually

not protected from EMF arising when switching on the load. Such keys can be used in telegraph circuits with a power supply voltage higher than 120 V.

Also known is a switch for switching inductive loads, containing a switching element, such as a transistor, a capacitor, a diode and resistors connected between the switching element 5. It has the disadvantage that during the switching period a voltage exceeding the source voltage appears on the collector nutrition

The purpose of the invention is to protect the switching element from the EMF of self-induction of an inductive load. The goal is achieved by introducing two zener diodes into the device containing the switching element, such as a transistor, a capacitor, a diode and resistors, between the first output terminal of the switching element a switching element, for example, a collector, and an inductive load. By connecting a capacitor and a diode connected between the common bus key n second terminal of the switching element, for example the emitter, and the point connecting the second output of the switching element n diode via a second resistor connected to a power source.

The drawing shows an electrical key diagram for switching inductive loads.

The key contains a transistor 1, a stabilitated zener diode 2, the stabilization voltage of which is less than the maximum allowable voltage U, transistor 1. In series with the transistor 1, the zener diode 3 n resistor 4 with a parallel-connected capacitor 5 is connected, as well as an inductive load 6 machine).

A resistor 4, a zener diode 3 and a capacitor 5 are provided to accelerate the operation of the electromagnet.

The total stabilization voltage of the zener diodes 2, 3 is greater than the voltage of the power source 7. The key is powered from source 7. Resistor 8 and power diode 9 are designed to securely lock transistor 1 with no signal at input 10.

The device works as follows.

In the initial state, the transistor 1 33 is covered by the bias created on the diode 9. The current through the inductive load b does not flow, since the zener diodes 2, 3 are closed. When a positive signal arrives at input 10, transistor 1 opens and closes the supply circuit of inductive load 6: + E of source 7, inductive load 6, capacitor 5, transistor 1, diode 9, -E

After charging the capacitor 5 to the voltage stabilizing the Zener diode 3, the latter opens and the power supply circuit of the inductive load is closed through the resistor 4 and the Zener diode 3. When the signal from input 10 is removed or the negative signal is received at input 10, transistor 1 closes. The EMF of self-induction of inductive load 6 and power supply 7 is added up, and the zener diodes 3, 2 are punctured. The extracurrent of an inductive load is closed in a circuit: + E, inductive load 6, resistor 4, zener diode 3, zener diode 2,

diode 9, E. Since the voltage drops across the Zener 2, the value of which is smaller than the maximum allowable voltage U of the transistor 1, the latter is protected from breakdown

The proposed device allows the use of transistors with a voltage U "for switching inductive fluxes,

lower voltage source.

The introduction of Zeners, which together with the resistor and capacitor form new circuits that protect the transistor from self-induced EMF, allows for switching an inductive load to use transistors with voltage ,, lower and voltage of the power source, i.e., increase the reliability of the main circuit element.

Claims (5)

Invention Formula 0 Key for switching inductive loads containing a switching element, for example a transistor, a capacitor, a diode and. resistors, characterized in that, in order to protect the switching element from the EMF of the self-induced Iuk and the load,  Two Zener diodes are inserted into it, the first of the second ones is connected in parallel to the switching element, between the first output of the switching element, for example a collector, and an inductive load is turned on 0 a circuit consisting of the first resistor and the second stabilizer connected in series, in parallel with which a capacitor is connected, and the diode is connected between the common key bus and the second output of the switching element, such as an emitter, the connection point of the second output of the switching element and the diode is connected to the source through the second resistor nutrition Sources of information taken into account in the examination o 1. Novikov, V.V., et al. Basics of telegraphy and telegraph stations. 1970, p. 153. 2. USSR author's certificate number 332573, cl. H 03 K 17/08, 1978. 3. USSR author's certificate j No. 307517, cl. H 03 K 17/60, 1971. 4. USSR author's certificate number 449448, cl. H 03 K 17/60, 1974. 5. USSR author's certificate No. 506943, cl. N. OZ K 17/08, 1975 (prototype). S D f ten s -Hz}