SU1336150A1 - Temperature relay - Google Patents

Abstract

The invention relates to electrical engineering and is intended to disconnect a load, such as an electric heating element, when a given temperature is exceeded in the control zone. The aim of the invention is to improve the accuracy and reduce the level of radio interference. The goal is achieved by introducing into the device transistors 15 and 16 and a second voltage divider consisting of resistors 9 and 10. The frequency of the control pulses of the triac 1 is much higher than the frequency of the network. Due to this, the triac 1 is unlocked in the voltage of each half-period of the mains voltage, therefore almost all the power is released in the load 2, which leads to an increase in the accuracy of the temperature relay operation. The capacitor 20, which connects the emitter of the transistor 16 to its base, provides for the relay switching of the transistors and the noise immunity of the circuit. 1 il. (L

Description

The invention relates to electrical engineering and is intended to disconnect a load, such as an electric heating element, when a given temperature is exceeded in the control zone.

The purpose of the invention is to increase the accuracy and reduce radio interference in the network.

The drawing shows a diagram of a relay device.

. The circuit contains a triac 1, through which the load 2 is made, for example, in the form of an electric heating element with output pins 3 and 4 connected to the input terminals 5 and 6 of the AC mains, the first voltage divider formed in series with the TAR 7 and alternating a resistor 8, a second voltage divider formed by series-connected fourth 9 and fifth 10 resistors, a single junction transistor (OPT) 11, which forms with an RC circuit consisting of a third capacitor 12 and a second resistor 13 pulse puller, transistor 14, transistors 15 and 16, which form the threshold element, the first 17, third 18, fifth 19 resistors, fourth capacitor 2D, connecting the middle points of the voltage divider, the second diode 21 and the rectified voltage source from the first 22 and second 23 capacitors, the first diode 24 and the zener diode 25.

The relay device operates as follows.

When the relay is connected to the network under the influence of the electric heater 2. Due to the voltage at terminals 5 and 6, the alternating current flows through the capacitor 22 and the zener diode 25 to re-enable the electric to de-energize the device These voltages from transistors 15 and 16, and then reapply the mains voltage to terminals 5 and 6. Capacitor 20 connecting the emitter of transistor 16 to its base provides relay switching of transistors and noise protection circuit. Diode 21 eliminates the influence of the measuring part of the circuit on the operation of the pulse generator.

the voltage drop across the Zener diode 25. Prior to this voltage drop across the diode 24, the capacitor 23 is charged, from which two voltage dividers 7.8 and 9.10 are fed, the pulse generator made by OPT 11 and the RC circuit 13 and 12, and the transistor 14.

If the temperature in the installation zone of the thermistor is lower than the established temperature of the overheating of the electrical equipment being protected, the resistance of the thermistor 7 is large and, therefore, the voltage falling on the resistor 8 is less than the voltage unlocked by the threshold element on the transistors 15 and 16,

resistors 9 and 10. Therefore, through the diode 21, the capacitor 12 of the generator is not bridged by the transistors 15 and. sixteen,

and it is periodically charged through resistors 13 and 17 to the OPT unlocking threshold 11 and when this OPT is removed, it is discharged to resistors 17 and 18. As a result, voltage pulses are extracted from resistor 18. These

the pulses are amplified in power by the transistor 14, and under their action triac 1 is unlocked and the load is turned on - heating element 2.

The frequency of the control pulses with cusp 1 significantly (50 or more times) exceeds the frequency of the network. Due to this, the triac 1 is unlocked at the beginning of each half-period of the supply voltage,

and almost all of the mains voltage is in the load.

When the thermistor 7 is warmed to a temperature exceeding the alarm value, the voltage drop to

resistor 8 will exceed the voltage unlocked by the threshold element. Transistors 15 and 16 will open. The opening transistors 15 and 16 through the diode 21 shunt the capacitor 12 of the RC circuit,

OPT 11, transistor 14 and triac 1 are closed, and load 2 is disconnected. Due to the flow of direct current through the circuit made up by resistor 13, diode 21 and transistors 15 and

16, under the action of voltage on the capacitor 23, the transistors are held open, and after being removed. wives and temperatures in the area of thermistor 7 provide off co-J

electric heater 2. Therefore, to re-turn on the electric

the heater must be de-energized to de-energize the circuit in order to remove voltage from transistors 15 and 16, and then reapply mains voltage to terminals 5 and 6. Capacitor 20 connecting the emitter of transistor 16 to its base provides relay switching of transistors and circuit noise protection. Diode 21 eliminates the influence of the measuring part of the circuit on the operation of the pulse generator.

Thus, in the proposed device, the maximum power is released in the load, which leads to a decrease in the accuracy of the temperature relay, as well as reduction of radio interference in the network. All this will allow the proposed device to find application.

31336150

Claims (1)

to protect various electrical installations with a collector of the newly introduced power supply from emergency operation of both an N-P-N type transistor and from the industry first and. at home. terminal of the fourth capacitor, the claims of the invention s ° P ° the output of which is connected to the cathode of the second diode, the emitter of the temperature relay, containing a PNP type resistor and a connector to the point, the first electrode of which is a thermistor and alternating voltage directly, and the second through a resistor, the second NPN transistor is connected to the terminals Q type, the collector of which is through the alternating current, and the sixth resistor connected to the load terminal, connected to the terminal of the junction of the triac control electrode, alternating current, through the first condenser, while the base of the first transistor is connected An anode of a zener and an NPN type is connected to the collector of the cathode of the first diode, the anode of which is a PNP transistor, the first base is connected to the first output of the second single junction transistor of the capacitor and the first output of the first resistor, the second output is indicated - the resistor and the base of the second transistor resistor through the third condensation cable, the free transistor variable is connected to the emitter of a single junction resistor, the emitters of the first and second transistors and through the second transistor in the NPN type, the free zistor is connected to the cathode to the stabilizer of the fourth resistor. And the second plug, thermistor, alternating circuit of the third resistor are connected to the resistor, the third resistor, the second diode, the anode of the first diode, the second sign of the fourth capacitor, o l and h a- 25 second capacitor, free vyu e e so that, in order to raise the thermistor, the free output of precision and reduction of radio interference, the fifth resistor, the second base of the same one is additionally introduced the transistor and the cathode stabilize The four connected resistors are connected to the first one of the first and the fifth resistors, the common resistor, and the second diode anode. The point of which is connected to the base is again connected to the emitter of the single junction type P-N-P transistor.