SU1363166A1 - Device for automatic control of temperature - Google Patents

Abstract

The invention relates to devices for automatic temperature control and can be used in various sectors of the national economy for automatic temperature control using electric heaters. He. ib of the invention - improving the quality of regulation and extending the service life of electric heaters. The essence of the invention is that the three-position information about the temperature of the control object is converted into a change in the constant time of the RC circuit, which provides a corresponding change in the unlocking phase of the power thyristors that discharges the power into the electric heater, and during the process of setting up the device the power level corresponding to each position of the temperature sensor is selected from the conditions of real disturbances on the o6.j object in order to minimize temperature drops on the surface the electric heater. 2 Il. SB at) ch at) Ot)

Description

The invention relates to control technology and can be used to control the temperature in objects with electric heaters.

FIG. Figure 1 shows a part of the basic circuit of the device that converts the positional signals of the reference “little and” much into the resultant control signal; in fig. 2 is a part of the device that converts the resulting control signal into an analog voltage signal of a predetermined value supplied to the electric heater.

The part of the device that converts the positional signals, the “little and many” tasks to the resulting control signal, includes switch I, minimum temperature indicator 2 and maximum temperature indicator 3, a measuring or regulating device, single-winding relays 4-6, double-winding relays and one winding relay 11, containing the closing contacts 12-29.

In addition, this part of the device contains capacitors 30-32 and resistors 33--38.

The part of the device that converts the resulting control signal into an analog voltage signal of a given magnitude contains power thyristors 39 and 40, diodes 41-49, capacitors 50 and 51, resistors 52-59, variable resistors 60-63, Zener diode 64, threshold element 65 , low-power thyristor 66, automatic switch 67, fuse 68 and electric heater 69.

Circuit breaker 67 serves to supply alternating voltage of the omnithrected frequency to the power part of the device, as well as to the circuits that form control signals and consist of power thyristors 39 and 40, diodes 41-44, resistors 52 and 53. This is also the case The supply is also supplied to a part of the circuit, with the help of which a permanently stabilized 40 or electric heaters are obtained.

As the temperature increases and as it approaches the set point, the opening of the interlock closure of the disconnecting terminal 2 of the minimum temperature tends to occur, as a result of which the relay 4 is turned off and one is turned on 5, the one-winding disconnects its closure 1 to this turn off.

Voltage is a source of constant voltage, and contains diodes 46-49, resistor 59, zener diode 64.

A constant stabilized voltage is used to power the phase-shifting node of the circuit containing variable resistors 61-63 and capacitor 50. The same voltage is applied to a divider consisting of resistors 57 and 58.

The device works as follows.

Switch 1 is set to the on state and when the temperature in the object is below the set point, the closing contact of the minimum temperature detector 2 occurs, and the closing contacts of the detector maximum 45

50

As the temperature rises in the object and approaches its predetermined value, the closing of the closing and closing of the disconnecting contacts of the indicator 2 of the minimum temperature temperature occurs, resulting in the one-winding relay 4 being turned off and the one-winding relay 5 turning on, the one-winding relay 11 turning off, opening its own Close 1 pin 29, while the power thyristors 39 and 40 are closed.

Due to the presence of resistors 33, 35 and capacitors 30 and 31 in the tripping winding circuits of the double-winding relays 7 and 8, the time required to prepare the initial conditions for the formation temperature 3 is open, and the next (middle) stage is closed and the contacts are closed . Turns on on the electric heater 69.

Disabling single-winding relay 4 and the inclusion of single-winding relay 5 results

Single winding relay 4, and its closing contacts 12 and 13 close.

0

Power is supplied to the tripping winding of the two-winding relay 7, but it does not immediately form the required magnetic flux, but it happens with a delay, the time of which is determined by the resistor 33 and the capacitor 30, after charging which the magnetic flux generated by the switching winding is charged for the supply voltage same relay. The closing contacts 18-20 of the double-winding relay 7. are disconnected. The power is disconnected from the disconnecting winding of the two-winding relay 10 and its closing contact 28 closes, after which the one-winding relay 11 is turned on, which closes its closing contact 29. A charge of the capacitor 50 across occurs. RC circuits using variable resistor 61, while variable resistors 62 and 63 are bypassed with closing contacts 24 and 27, respectively, of two-winding relays 8 and 9. The charging time of the capacitor 50 along the specified string is minimal, which will ensure such an angle from digging the power thyristors 39 and 40, at which the first preset voltage value and, respectively, the power removed from the electric heater 69 will be formed. The voltage of the charged capacitor 50 is compared with the voltage of the threshold element 65 with the preset value from the divider formed by resistors 57 and 58. When they are equal, the threshold element 65 forms at its output a control signal that opens the low-capacitor 66 when the capacitor 50 is discharged, as a result of which a periodic in each half occurs the period of the polarization-dependent alternating voltage, the formation of control signals on one resistor 52, then on another resistor 53. The signals received from these resistors 52, 53 open one power thyristor 39, then another power thyristor 40, by applying the first (largest) specified value is 0

five

0

five

neither on electric heaters.

As the temperature rises in the object and approaches its predetermined value, the closing of the closing and closing of the disconnecting contacts of the indicator 2 of the minimum temperature temperature occurs, resulting in the one-winding relay 4 being turned off and the one-winding relay 5 turning on, the one-winding relay 11 turning off, opening its own short circuit 1 pin 29, with the power thyristors 39 and 40 being closed.

Due to the presence of resistors 33, 35 and capacitors 30 and 31 in the tripping winding circuits of double-winding relays 7 and 8, the time required to prepare the initial conditions for forming the next (middle) voltage level on the electric heater 69 is provided.

to the fact that the disconnecting winding of the dual-winding relay 7 loses power and the disconnecting winding of the dual-winding relay 8 receives power.

With a further increase in temperature, the object opens the opening and closure of the closing contact of the maximum temperature detector 3, as a result of which the single-winding relay 5 turns off and the single-winding relay 6 turns on, the single-winding relay 11 turns off, opens its closing contact 29. The power thyristors 39 and 40 close . Turning off the mono winding relay 5 and turning on the mono winding relay 6 causes the disconnecting winding of the dual-winding relay 8 to lose power and the disconnecting winding of the two winding (1-time relay 9) receives power.

As a result, the variable resistors 61 and 62 are shunted by the contacts, respectively.

shut-off contacts of the minimum temperature alarm device, closing and disconnecting contacts of the maximum temperature alarm device, characterized in that, in order to improve the quality of operation of the device and increase the service life of the electric heater, a constant voltage source is added, four one winding relays with closing Contacts, four two-winding relays with switching and breaking windings and closing contacts, second power thyristor, seven diodes, zener diode, three variable resistors, thresholds th element, four capacitors, resistors and nine .s- single pole switch, the first winding odnoobmotochnogo relay is connected to a source of constant voltage in series via make contacts signaling the minimum temperature and a single-pole switch, the second winding

20 and 24 and the charge of the capacitor 50 is realized; the 20 one-winding relay is connected to the unit via a variable resistor 63, which provides the shortest charge time of the capacitor 50 and, therefore, the smallest opening angle of the thyristors. Thus, at the heater, the minimum specified power level is ensured.

Thereafter, the temperature rise in the object is suspended. A decrease in temperature will result in the need to increase the voltage on the electric heater.

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to a constant voltage source sequentially through the opening contacts of the minimum temperature detector, a single-pole switch and closing contacts of the maximum temperature detector, the winding of the third single-winding relay is connected to the constant voltage source sequentially through a single-pole switch and the closing contacts of the maximum temperature detector, which is ensured by the device, Q paths, to the source of a constant voltage reverse sequence.

In order to turn on low-power thyristor 66, diodes 46 and 48 do not exert a shunt effect on the control currents of the first 39 and second 40 power thyristors, the circuit contains a fifth diode 45, a second capacitor 51 and a fourth resistor 55, thanks to the second capacitor 51 low-power thyristor 66 at the time of inclusion is not reduced despite the presence of the fourth resistor 55

When using electric heaters of different power, it becomes necessary to change the voltage levels on them, which is ensured by adjusting the opening angle of the first 39 and second 40 power thyristors, which is performed using the second 61, third 62 and fourth 63 variable resistors.

Claims (1)

Invention Formula An automatic temperature control device containing an alternating voltage source to which a circuit of a series-connected electric heater, the first power thyristor and a fuse, two diodes, a variable resistor, a capacitor, a low-power thyristor, five resistors, a short circuit and a difference are connected via a bipolar switch of the disconnecting windings of the first two-winding relay, the first resistor and the closing contacts of the first one-winding relay in series, I turn on winding double-winding relay and second resistor, disconnecting windings of the second double-winding relay, third resistor and make contacts of the second one-winding relay, including windings of the second two-winding relay and fourth resistor, disconnecting windings of the third two-winding relay, fifth resistor and closing contacts of the third single-winding relay, the turn-on winding of the third two-winding relay and the junction resistor, breaking the windings of the fourth two-winding relay, closing contacts of the first , the second and third double-winding relays, including the winding of the fourth double-winding relay connected directly to a constant voltage source, the winding of the fourth single-winding relay connected to a constant voltage source sequentially through the closing contacts of the fourth double-winding relay and a circuit of sequentially connected second contacts of the second single winding , the first and third double-winding relays, which are bridged by a circuit from series-connected make contacts of the first one oobmotochnogo and second dvuh45 50 55 shut-off contacts of the minimum temperature alarm device, closing and disconnecting contacts of the maximum temperature alarm device, characterized in that, in order to improve the quality of operation of the device and increase the service life of the electric heater, a constant voltage source is added, four one winding relays with closing Contacts, four two-winding relays with on and off windings and make contacts, second power thyristor, seven diodes, zener diode, three variable resistors, thresholds element, four capacitors, nine resistors and a single-pole switch, the winding of the first single-winding relay connected to a constant voltage source sequentially through the closing contacts of the minimum temperature detector and a single-pole switch, winding the second 0 single-winding relay connected to the single-winding relay connected to the to a constant voltage source sequentially through the opening contacts of the minimum temperature detector, a single-pole switch and closing contacts of the maximum temperature detector, the winding of the third single-winding relay is connected to the constant voltage source sequentially through a single-pole switch and the maximum temperature detector contacts, to a constant voltage source circuits are connected from the series-connected disconnecting winding of the first two-winding relay, the first resistor and the closing contacts of the first one-winding relay, including the windings of the personal two-winding relay and the second resistor, disconnecting the windings of the second two-winding relay, the third resistor and the closing contacts of the second one-winding relay, including the windings of the second two-winding relay and the fourth resistor, disconnecting the windings of the third two-winding relay, the fifth resistor and the closing contacts of the third single-winding relay, including the windings of the third double-winding relay and the junction resistor disconnecting windings of the fourth two-winding relay, closing contacts of the first, second and third double-winding relays, including the winding of the fourth two-winding relay connected directly to a constant voltage source, the winding of the fourth single-winding relay connected to a source of constant voltage sequentially through the closing contacts of the fourth dual winding a relay and a circuit of series-connected make contacts of the second single-winding, first and third double-winding relays, which bridged chain of series-connected switching contacts of the first and second odnoobmotochnogo dvuh5 0 five winding relay and a circuit from the series-connected closing contacts of the third single-winding and second two-winding relays, disconnecting the windings of the first, second and third two-winding relays are bridged by corresponding capacitors, the second power thyristor is connected in parallel to the first power thyristor, through the seventh resistor to the first power thyristor the control relay is connected to the output of the threshold element, the anode of the sixth diode is connected to the anodes of the eighth diode and the zener diode, the cathode of the eighth diode and connected to the anode of the second power thyristor and the anode of the ninth diode connected by its cathode to the cathode of the sixth diode, and through the eleventh resistor to the cathode of the zener diode, the cathode of the third diode through the twelfth resistor shunted by the fourth terminating electrode of the first power thyristor 10 by the sensor, connected to the anode The stabilizer and the cathode of the first diode, connected by its own, which through a serial connection with the anode of the second diode, the cathode of a low-power thyristor and the anode of the third diode, the cathode of the second diode is connected to control electrode of the second power thyristor and through the eighth resistor - to the cathode of the second power thyristor, to the anode of the fourth diode, to the cathode of the fifth diode and to the anode of the sixth diode, the cathode of the fourth diode and through the ninth resistor is connected to the anode 2o of which is connected to the first input of a low-power thyristor, controlling the electrical threshold element, the second input of which is connected to the common connection point through the tenth resistor dinene with the anode of the third diode and through the th capacitor and the first switching contacts of the fourth single-pole resistor. The first fifth capacitor, the first, second, third, and fourth variable resistors are connected to the cathode of the Zener diode, the first to the third variable resistors are shunted by the closing contacts from the third to the first two-winding relays, and the Zener diode is connected in series by the thirteenth and fourteenth resistors, the common point of the connecting relay is connected to the output of the threshold element, the anode of the sixth diode is connected to the anodes of the eighth diode and the zener diode, the cathode of the eighth diode is connected to the anode of the second force thyristor and anode of the ninth diode connected by its cathode to the cathode of the sixth diode, and through the eleventh resistor to the cathode of the Zener diode, the cathode of the third diode through the twelfth resistor, shunted by the fourth horse of which is connected to the first input of the threshold element, the second input is connected to the fifth capacitor , the first, second, third and fourth variable resistors are connected to the cathode of the Zener diode, the first to the third variable resistors are shunted by the closing contacts from the third to the first two-winding relays, respectively tally, the zener diode is shunted by series-connected thirteenth and fourteenth resistors, the common point of (+) t fig IG