KR102260843B1 - Electric switch for protection of an over current using critical-temperature device - Google Patents

Abstract

The present invention discloses an electromagnetic switch that controls the electromagnet using an electromagnet, a critical temperature element, and an electromagnet controller without using a bimetal and mechanical contact, which is a problem of the conventional electronic switch. The electromagnet switches the power applied through the power line to the power device connected to the load in response to the flow of the control current. In the critical temperature element, the output current value changes when the heating temperature caused by the supply current flowing from the power line to the power device exceeds the critical temperature. The electromagnet control unit that can be implemented as SCR generates or blocks the flow of the control current of the electromagnet in response to the output current value of the critical temperature element.

Description

Electronic switch for protection of an over current using critical-temperature device

The present invention relates to an electromagnetic switch, and more particularly, to an electromagnetic switch using a critical temperature metal-insulator transition switch element.

In general, an electric switchgear for preventing overcurrent is a combination of a magnetic contactor (MC) including an electromagnet and a thermal overload relay, as shown in 10a3 of FIG. 1 .

The electromagnet has a very simple structure and has the function of an electromagnet according to Lenz's law like a coil-type solenoid made by winding a conductor on a metal. An electromagnet becomes a magnet when current flows through the coil, and loses its function when current flows through the coil.

The magnetic contactor 10a1 is switched on or off based on the force generated by such an electromagnet so that the electric power is supplied or cut off.

On the other hand, the thermal overload relay (Thermal overload relay) (10a2) is a nichrome wire and a bimetal in series to the power supply (Operation power) line (2-1) extended through the magnetic contactor (10a1) as shown in FIG. have a connected structure. In this case, the nichrome wire 20-2 has a structure in which the heat of the nichrome wire 20-2 can be well transferred to the bimetal 20-3 by winding the bimetal 20-3.

When an overcurrent flows in the power line, the bimetal is bent due to the heat of the nichrome wire. When the mechanical relay contact is turned off as in FIG. 3 due to the bending phenomenon of the bimetal, the power supplied from the power line 20-1 to the terminal block 20-4 is cut off. However, when the relay contacts are turned on or off, sparks of sparks fly between the relay contacts. If a thermal overload relay is used for a long time, the flame may malfunction the mechanical contact and damage the power equipment connected to the power line. Also, since bimetal has a wide bending temperature range, it is difficult to cut off power quickly, and there are also disadvantages that change over time occurs.

A circuit breaker using a mechanical contact blocks the current when 8 to 12 times the rated current flows, so it actually performs the breaking operation after the power device is damaged.

The earth leakage breaker has the same principle as the circuit breaker and is also shut off afterwards. Therefore, more precise current management and fast interruption have been required. In fact, in order to solve the problems of mechanical contact and bimetal, an electronic circuit that protects the wire using the method of measuring the current with a coil (CT: Current Transformer) is presented as an alternative. This is a good improvement, but the disadvantage is that the circuit is complex. Therefore, more improved electromagnetic switchgear is desired.

The technical problem to be solved by the present invention is to provide an electromagnetic switch capable of removing a mechanical contact and a bimetal that cause a malfunction of an overload relay.

The technical problem to be solved by the present invention is to provide a simple yet highly reliable electronic switchgear.

According to an aspect of the concept of the present invention for achieving the above technical problem, the electronic switchgear,

An electromagnet for switching power to a power device connected as a load by turning the power line on and off in response to the flow of the electromagnet control current;

a critical temperature element in which the output current value changes when the heating temperature of the heating conductor connected to the power line by the supply current flowing from the power line to the power device exceeds the threshold temperature;

and an electromagnet control unit for generating or blocking the flow of the electromagnet control current in response to the output current value of the threshold temperature element.

In the present invention, in order to generate heat in the power line for supplying power equipment, a heating resistance wire having a larger resistance is connected to flow a current to generate heat in the wire. This heat is a device (critical temperature device) whose resistance or current suddenly changes at a specific critical temperature, and the temperature is sensed, and the SCR and transistor (or triac) are controlled by the difference in current generated at the critical temperature.

The SCR and transistor (or triac) cut off the electromagnet control power used to make the electromagnet in the electromagnetic contactor, and short-circuit the main power line that allows the current to flow in the electromagnetic contactor. If such a circuit is built inside the magnetic contactor (MC), the electromagnetic switch can be made small without a separate thermal overload relay.

The electronic switchgear according to the present invention does not use a mechanical relay that causes bimetal and spike discharge, which are problems of the existing switchgear, but also has a simple circuit and a part for controlling overcurrent built into the electromagnetic contactor. there is

1 is a view exemplarily showing the form of a conventional mechanical electronic switchgear.
Figure 2 is a component configuration diagram of the thermal overload relay of Figure 1.
3 is a diagram of a mechanical contact of the thermal overload relay in FIG. 1 .
FIG. 4 is a view presented to explain the post-blocking operation of the thermal overload relay in FIG. 1 .
5 is a diagram presented to explain the characteristics of a critical temperature metal-insulator transition switch (MIT-CTS).
6A to 6E are diagrams presented to explain gate control of the SCR.
7 is a circuit configuration diagram in which MIT-CTS is applied in parallel in the case of three-phase current draw.
8 is a view showing a structure in which a resistance element is coupled to the front end of the MIT-CTS.
9A and 9B are diagrams presented to explain an increase in resistance according to a wire width.
10A to 10D are diagrams presented to explain heat generation according to a connection type of MIT-CTS.
11 is a connection configuration diagram of an adiabatic resistance distribution switch arranged with constant resistance values for MIT-CTS control.
12 is a connection configuration diagram of adiabatic resistance distribution switches arranged with different resistance values for MIT-CTS control.
13A to 13D are diagrams illustrating various examples of a constant voltage supply circuit.
14 is a circuit diagram of an electromagnetic switch according to an embodiment of the present invention.
FIG. 15 is a diagram provided to explain the operation according to FIG. 14 .
16 is a circuit diagram of an electronic switch according to another embodiment of the present invention.
17 is a protection circuit diagram for preventing SCR destruction applied to an embodiment of the present invention.
18A and 18B are diagrams illustrating an application example of an electromagnetic switch according to an embodiment of the present invention.
19 is a view showing an application example of another electronic switch according to an embodiment of the present invention.
20 is a diagram provided to explain heat generated according to a size or material of a conducting wire in an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention are described, and descriptions of other parts will be omitted so as not to obscure the gist of the present invention.

A portion where two metals having different temperature coefficients are connected has a relatively high resistance. When such a large resistance is used, heat generation is relatively high.

In an embodiment of the present invention, the critical temperature device is a device having a characteristic in which a large current suddenly flows due to a change in resistance at a specific temperature. The critical temperature device is also called a Metal-Insulator-Transition Critical-Temperature-Switch (MIT-CTS) or a Metal-Insulator-Transition Device (MIT Device).

5 is a diagram presented to explain the characteristics of a critical temperature metal-insulator transition switch (MIT-CTS).

50a1 shows the shape of MIT-CTS, which is a type of critical temperature device, and 50a2 shows the constituent terminals of the MIT-CTS.

The first terminal 1 is connected to the control input terminal and functions as an electrically positive (+) or negative (-) terminal. The third terminal 3 is connected to the control output terminal and functions as an electrically negative (-) or positive (+) terminal. The second terminal 2 is electrically insulated from the first and third terminals 1 and 3 and functions as a thermal terminal connected to a heat source.

50a3 shows MIT-CTS as a type of critical temperature device that can measure the temperature of the power line in a non-contact manner. As shown in the front view and device photo of MIT-CTS, the terminals of the critical temperature device are the same as those described through 50a2. In this case, the heat generated from the conductor is transferred to the critical temperature element in the form of infrared rays. A place where infrared rays are transmitted in a non-contact manner corresponds to the second terminal of 50a2.

50a4 shows a graph GR1 of resistance versus temperature of a critical temperature metal-insulator-transition switch (Metal-Insulator-Transition Critical-Temperature-Switch: MIT-CTS). In the graph, the horizontal axis indicates temperature and the vertical axis indicates resistance. From the graph, it can be seen that the critical temperature is about 340 K (67 ^{o C).} As a general metal-insulator transition material, vanadium oxide is representative, but a material having a higher critical temperature is being developed.

The MIT-CTS device may require a constant voltage circuit as shown in FIGS. 13A to 13D to increase device reliability.

In addition, the characteristics of the MIT-CTS can be implemented using a thermistor (TM), a comparator, and a transistor whose resistance decreases exponentially with an increase in temperature.

6A to 6E are diagrams presented to explain gate control of the SCR.

The circuit of FIG. 6A includes a temperature sensing unit 60 and a control transistor 62 .

The temperature sensing unit 60 includes a thermistor TM having the critical characteristics as shown in FIG. 5 , a comparator AMP1 , and voltage setting units R1 and R2 for implementing the function of the MIT-CTS. A reference voltage is connected to one end of the resistor R3.

When the control transistor 62 is the NPN transistor TR1, the output of the comparator AMP1 is connected to the gate of the NPN transistor TR1. The emitter of the NPN transistor TR1 may be connected to the gate of the SCR through a resistor R5.

Referring to FIG. 6B , a characteristic graph of temperature versus resistance of the thermistor TM is shown. In the graph, the horizontal axis indicates temperature and the vertical axis indicates resistance. As can be seen from the graph, the resistance decreases exponentially as the temperature increases.

The thermistor may be manufactured using a PN junction diode and ceramic. In addition, the circuit of FIG. 6A including the thermistor, comparator, and transistor TR1 may be implemented as a one-chip commercial critical temperature IC device to provide the MIT-CTS function. The PN junction diode can be used as a critical temperature device because it has an MIT characteristic in which a large current flows when the PN junction semiconductor gap disappears.

6C shows a characteristic graph of resistance versus temperature of a PTC (Positive Temperature Coefficient) device. In the graph, the horizontal axis indicates temperature and the vertical axis indicates resistance. As can be seen from the graph, the resistance increases rapidly with increasing temperature from 100°C. Practically above a temperature of 130 °C and a resistance of 1 K) the current can be interrupted. PTC devices have very low resistance at room temperature and a sudden increase in resistance at about 100°C or higher. However, the actual current blocking effect appears from 130℃ or higher, which is the temperature at which the resistance increases significantly.

6D shows a simplified circuit for controlling an SCR gate using a PTC device. A resistor R1 and a PTC device may be sequentially connected between the power supply voltage and the ground voltage, and a gate control voltage may be provided through the other end of the resistor R1.

6e shows another simplified circuit for controlling an SCR gate using a PTC device.

The PTC element and the resistor R1 are sequentially connected between the power supply voltage and the ground voltage, and the gate control voltage may be provided through the collector of the transistor TR10 connected between the resistors R2 and R3.

6d or 6e, the characteristics of the PTC device are opposite to those of the MIT-CTS. However, even if the critical temperature of the PTC device is high, if the PTC device is used, the circuit can be configured to exhibit the characteristics of MIT-CTS.

As described above, the circuit (temperature sensing unit + transistor) that produces the MIT-CTS function using the MIT-CTS or thermistor will be collectively referred to as a threshold temperature switch element or a threshold temperature element.

The critical temperature element has three terminals functionally and has an electrically insulated thermal terminal 2 as described above.

Even if the critical temperature element has two terminals, it can be said that the body part of the element functions as a thermal terminal when it reacts by applying heat.

When three-phase current is applied or when there are a plurality of power lines, the critical temperature element may be connected in parallel for each heat source.

7 is a circuit configuration diagram in which MIT-CTS is applied in parallel in the case of three-phase current draw.

Referring to FIG. 7 , heat sources 70b, 71b, and 72b are present in three-phase power lines such as R, S, and T, and MIT devices 70a and 71a in each of the heat sources 70b, 71b, and 72b. , 72a) is connected. When the heat generated by the heat source is sensed by the MIT device, which is a critical temperature device, and reaches the critical temperature, a control voltage is generated at the gate of the SCR and the SCR is turned on. Accordingly, the electromagnet is changed from an active state to an inactive state or from an inactive state to an active state, so that the switches S1, S2, and S3 are switched to an open state. Accordingly, the power supply to the power device is cut off. The activated state means having the function of an electromagnet, and the inactive state means that a current does not flow in the coil and thus the function of the electromagnet is lost.

Since the critical temperature element has a critical characteristic as described above, the current value at the critical temperature becomes the cut-off current. In addition, the critical temperature element is made in the shape of a chip of a semiconductor element, but the frame of the element may be made of copper, copper alloy, or iron alloy, and the frame itself may function as a heating conductor.

8 is a view showing a structure in which a resistance element is coupled to the front end of the MIT-CTS.

Referring to FIG. 8 , a resistance element RL functioning as an adiabatic resistor is connected to a conductive wire HPL between a heat source such as a nichrome wire L10 and a heat terminal 2 . When heat generation is relatively large, the resistance element RL serves to protect the critical temperature element by partially blocking the heat transferred to the thermal terminal 2 .

9A and 9B are diagrams presented to explain an increase in resistance according to a wire width.

Although the plate on which the chip of the critical temperature element is placed is made of iron or copper, the outside of the plate is plated, so the resistivity is relatively small and the hardness of the plate is relatively hard. Therefore, a large current can flow through the thermal terminal of the critical temperature element. However, the resistivity of the critical temperature element is greater than that of copper used as a conductor. So, when current flows, greater heat is generated in the critical temperature element than in the power line.

In FIG. 9A , when a current flows from region A to region B along the direction arrow, the wire width gradually decreases from WA to WB, so that heat generation in region B is greater than that in region A.

In Fig. 9b, when the current flows from region A to region B along the direction arrow, the wire width is sharply reduced from WA to WB, so that heat generation in region B is similarly larger than that in region A.

As a result, when the width of the conductive wire is reduced, resistance increases in the portion of the reduced wire, so that heat in the portion of the reduced width is greater than that in the portion in which the width is not reduced.

10A to 10D are diagrams presented to explain heat generation according to a connection type of MIT-CTS.

FIG. 10A shows a heating wire appearing based on the same principle as in FIGS. 9A and 9B when the critical temperature element 100 is connected to a branch wire separated from the main power line MPL. In the part where the width of the wire is reduced from WA to WB, a relatively large amount of heat is generated and it functions as a heating wire. The thermal terminal 2 of the critical temperature element 100 is connected between branch conductors.

FIG. 10b also shows a structure in which the critical temperature element 100 is installed on the main power line MPL based on the same principle as in FIGS. 9a and b. In this case, in order to increase the effect of heat generation, the thermal terminal 2 of the critical temperature element 100 is connected on the reduced width power line.

10c shows a structure in which the critical temperature element 100 is connected between the main power lines MPL. In this case, the critical temperature element 100 also serves as a power line. In this case, in order to increase the effect of heat generation, the thermal terminal 2 of the critical temperature element 100 may be connected between power lines having a reduced width.

10D shows the form of a critical temperature switch 400 in which a frame is made of a material of the main power line and a critical temperature switch (CTS) in which a conductor of a material different from that of the main power line is connected in series. Here, the threshold temperature switch 400 and the threshold temperature switch CTS function as the threshold temperature element 100 .

At 10da, HPL indicates the heating conductor, and at 10db, HPL indicates the heating conductor.

A portion where the main power line MPL2 and the critical temperature switch 400 are connected is a portion where two metals having different temperature coefficients are connected. Therefore, the resistance of this part is relatively large, so it generates more heat than the main power line and the temperature is high. As a result, it is possible to effectively design the heating conductor (HPL) by using this phenomenon.

Note that the main power line in this embodiment means a power line that is a line for supplying power, and is used only for distinguishing it from a heating conductor.

Referring to FIG. 20, which will be described later, various examples using a copper wire, a copper alloy wire, and an iron alloy wire are shown as the heating conductor.

11 is a connection configuration diagram of an adiabatic resistance distribution switch arranged with constant resistance values for current control. 12 is a connection configuration diagram of adiabatic resistance distribution switches arranged with different resistance values for current control. 13A to 13D are diagrams illustrating various examples of a constant voltage supply circuit.

14 is a circuit diagram of an electronic switch according to an embodiment of the present invention.

FIG. 14 will be described earlier than FIGS. 11 to 13 .

Referring to FIG. 14 , a circuit configuration including an electromagnet 200 , a critical temperature element 100 , and an electromagnet controller is shown.

The electromagnet 200 switches the power applied through the power line (R, S, T) to the power device connected to the load in response to the flow of the control current through the coil L10.

In the critical temperature element 100 , the output current value changes when the heating temperature caused by the supply current flowing from the power line to the power device exceeds the threshold temperature.

The electromagnet control unit 150 includes an electromagnet drive switch (TR20, electromagnet current supply switch) and an electromagnet current cutoff switch (SCR). The electromagnet control unit 150 generates or blocks the flow of the control current of the electromagnet 200 in response to the output current value of the critical temperature element 100 .

The electromagnet driving switch TR20 may be included in the electromagnet 200 or may be configured separately. The electromagnet driving switch TR20 serves to allow the control current to flow or block the electromagnet 200 in response to the control voltage applied to the base. The electromagnet driving switch TR20 is configured as a bipolar transistor, but is not limited thereto and may be implemented as a triac, an SCR, or a relay. In addition, the resistance R1 connected to the electromagnet current cut-off switch (SCR) used 30 and R3 used 50.

In order for the switches S1, S2, and S3 of the electromagnetic contactor 400 to be switched by the deactivation or activation operation of the electromagnet 200, the base of the electromagnet drive switch TR20 is connected to the anode of the SCR through a resistor R3. Connected. Here, the electromagnet current cut-off switch (SCR) was used to maintain the cut-off state.

When the heating temperature reaches the threshold temperature by the heating sensing operation of the threshold temperature element 100 , a voltage higher than the voltage applied below the threshold temperature is provided to the gate of the SCR. Accordingly, the SCR is turned on, and the current flowing in the base of the electromagnet driving switch TR20 flows from the anode to the cathode of the SCR. Accordingly, since the current path is formed toward the ground, the base voltage of the electromagnet driving switch TR20 is lowered and finally the electromagnet driving switch TR20 is turned off. Accordingly, the current flowing through the coil L10 of the electromagnet 200 disappears and the function of the electromagnet is lost. Accordingly, the switches S1 , S2 , and S3 that were closed in the previous state are opened to cut off the power supply.

In FIG. 14 , the resistor R2 is a device for smoothing the turn-on operation of the electromagnet current cutoff switch SCR. If the resistance value of the resistor R2 is too low, the current flowing from the critical temperature element 100 when it is on may flow to the ground through the resistor R2 a lot, and the SCR may not operate. Therefore, the resistance value of the resistor R2 needs to be set to an appropriate value. In this embodiment, the resistance value of the resistor R2 is set to 5K. The resistor R2 may be implemented as a PN junction diode for environmental temperature compensation. The capacitor C1 may be installed to prevent a malfunction due to a noise signal that suddenly pops up when power is input. That is, a 220 pF ceramic capacitor may be used for filtering or signal delay.

A transistor may be used instead of the SCR in FIG. 14 for delay of the setting time. And even without the SCR, the electromagnet driving switch TR20 may be controlled by a programmable logic controller (PLC).

On the other hand, it may not be easy to arbitrarily adjust the critical temperature of the critical temperature element 100 . When the temperature of the heat source HS is too high, the temperature may be controlled by placing a resistor for insulation (heat blocking) in front of the thermal terminal of the critical temperature element 100 .

In this case, as shown in FIG. 11, a plurality of insulation resistors may be used in series. It can also be arranged as a channel with one insulation resistance, a channel with two, a channel with three, a channel with four, etc. In addition, the amount of current may be adjusted according to the selected resistance value by selecting one of the channels using the rotary switch. The connection configuration of the adiabatic resistance distribution switch arranged with constant resistance values for current control is shown in FIG. 11 .

For example, it is assumed that the resistance values of the insulation resistors R10-R19 are the same (eg, 1M ohm), and when the switch SW1 of the rotary switch CS is selected for the first channel R10, the insulation resistance is It is set to the smallest value. On the other hand, when the switch SW1 of the rotary switch CS is selected for the fourth channels R16-R19, the insulation resistance is set to the highest value.

Meanwhile, as shown in FIG. 12 , adiabatic resistors having different resistance values may be connected to each other and the threshold current may be adjusted by selecting a channel of the rotary switch CS. The connection configuration of the adiabatic resistance distribution switch arranged with different resistance values for current control is shown in FIG. 12 .

The circuit of FIG. 14 may include a constant voltage circuit 300 for applying a constant voltage to the first terminal 1 of the threshold temperature element 100 .

The constant voltage circuit 300 may include a voltage follower structure using resistors R4-R6 , an NPN transistor TR10 , and a Zener diode ZD.

Also, the constant voltage circuit 300 may be similarly configured as shown in FIG. 13A .

And, the constant voltage circuit 300 may be similarly implemented as a voltage follower structure using resistors R1-R3 and a PN P transistor TR40 as shown in FIG. 13b,

As shown in FIG. 13C , a voltage follower structure using resistors R1-R3 and an FET transistor FE10 may be included.

In addition, the constant voltage circuit 300 may include a voltage follower structure using a resistor R1 , an NPN transistor TR50 , a capacitor C10 , and a Zener diode ZD.

Although it is shown in FIG. 14 that the electromagnet is controlled by direct current, an embodiment of the present invention may be applied regardless of whether the electromagnet is controlled by alternating current or direct current. That is, when the current for controlling the electromagnet is AC 110V or 220V, the only difference is that the resistance of the electromagnet is larger than that of the DC type electromagnet. As a result, if the DC control is changed to the AC control, an extension circuit as shown in FIG. 16 can be made based on the circuit of FIG. 14 .

FIG. 15 is a diagram provided to explain the operation according to FIG. 14 .

In the experiment shown in FIG. 15 , a magnetic contactor (MC) having a standard of DC 24V 0.1A was used for power (operation power for supplying power equipment) and electromagnet control power of AC 10A voltage of 220V. A nichrome wire with a thickness of 1 mm was connected to an operation power line for power equipment. And for the test, a radiator of 2500W was used as a power device. The MIT-CTS of FIG. 6A, which shows the graph characteristics as shown in FIG. 5, was connected to a nichrome wire, a heat source, as shown in FIG. 15, and then the entire circuit was connected to match the circuit of FIG.

In the experiment, the power of the radiator power 220V 10A and the electromagnet power (8.1V 0.09A) were put. As a result, the electromagnet was operated and the radiator was turned on, the temperature of the nichrome wire increased, and the MIT device was operated at a critical temperature (a state that fell from high resistance to low resistance, Fig. 15). The system was disconnected by shorting the magnetic contactor. The current flowing to the SCR in the SCR On state was about 150 ~ 200 mA. No abnormalities were found in this system even in repeated experiments. 15a1 shows a state in which the switches in the magnetic contactor are closed and power is supplied to the load, and 15a2 shows a state in which the switches in the magnetic contactor are opened after the critical operation is performed and the power supplied to the load is cut off.

Also, an AC 100V 0.1A for electromagnet control (voltage current for electromagnet magnetization, resistance 1K) electromagnetic contactor was used as an experiment. When DC 50V 0.5A was applied to this contactor, it was confirmed that the coil part in the electromagnetic contactor was magnetized with an electromagnet, so that the contact operation of the AC contactor was performed. Therefore, it was confirmed that the circuit of FIG. 14 can be used as an electromagnetic switch circuit because it operates on either a DC or AC contactor.

16 is a circuit diagram of an electronic switch according to another embodiment of the present invention.

Referring to FIG. 16 , it is shown that the triac TRA1 is used as an electromagnet driving switch to control the electromagnet with an alternating current. Accordingly, the electromagnet of the electromagnetic contactor for AC control is controlled in an activated state or an inactive state.

The electronic switchgear of FIG. 16 may also be applied to an Earth Leakage Breaker and a circuit breaker including a function for preventing overcurrent. In this case, it is possible to force the power line to be connected by force using a passive seesaw switch that connects the power line. In such a state, when the electromagnet is activated, the AC power can be cut off by pulling the manipulating part of the passive switch by manpower to open the power line.

On the other hand, on the other hand, the power supply may be connected by the attraction of the electromagnet, and the power supply may be cut off by the deactivation control of the electromagnet.

The magnetic contactor in the electromagnetic switch may correspond to the manual switch and the electromagnet in the circuit breaker. The corresponding application circuit is shown in FIG. 19 .

16 shows an electromagnetic switch that directly controls an electromagnetic contactor (electromagnet) with AC 220V using a triac (TRA1).

When AC 220V flows between the T2 terminal and the T1 terminal of the triac (TRA1), the electromagnet is activated. The deactivation state of the electromagnet, that is, the blocking operation (Off) is realized by blocking the gate current of the triac TRA1. A DC power supply is used as a control power supply to control the gate current of the triac (TRA1) and the SCR1.

First, when the power is On, the AC magnetic contactor, that is, the electromagnet is On. After that, when a large current flows in the power line and the temperature of the critical temperature element 100 reaches the critical temperature, the SCR is turned on, and the current flowing to the gate of the triac TRA1 flows from the anode of SCR1 to the cathode. Accordingly, the T2 terminal and the T1 terminal of the triac TRA1 are electrically disconnected. The monitoring system (MS) is operated by the current flowing from the anode to the cathode of the SCR1, and the LED connected to the monitoring system (MS) may emit light.

The monitoring system (MS) may generate a buzzer sound notifying the electromagnetic switch blocking signal when the SCR is on and the triac is off, or may output a communication signal for warning.

In FIG. 16, two SCR1,2 are installed based on the circuit principle of FIG. That is, two SCRs are connected in series to prevent the SCR from being destroyed by applying a high voltage to the SCR.

Meanwhile, one of the constant voltage circuits as shown in FIG. 13 may be applied so that an excessive voltage is not applied to the MIT-CTS 100 as well. The resistors used in FIG. 16 are R1=20K, R2=450, R3=10K, R4=20K, R5=820, R6=15K, R7=1K, R8=1K. Capacitor C1 is 10nF. A power LED was used in the monitoring system (MS). Transistor TR10 used 2N3904, and SCR used P0115DA 5AL3. R6 can use a PN junction diode for environmental temperature compensation. Capacitor C1 is used for signal delay in order to prevent malfunction due to a sudden noise signal when power is input. The triac (TRA1) was used for AC in the TO-200 package. The MIT-CTS 100 is 1M at room temperature and has hundreds of ohms above the critical temperature. Here, to turn on the triac (TRA1) gate, the DC voltage is set to 220V or higher. Since this DC voltage corresponds to a very high value when the SCR is turned on, it is necessary to reduce the voltage without reducing the current. In general, if one SCR is applied to a high voltage, the SCR may be burned by the high voltage when the SCR is operating.

Meanwhile, a diode D2 is connected between the critical temperature element 100 and the gate of the SCR in order to prevent the high voltage from burning into the gate of the SCR and destroying the threshold temperature element 100 . In addition, a diode D1 is connected between the gate of the triac and the resistor R5 in order to block the high voltage alternating current from entering the gate of the triac.

The circuit of FIG. 16 may include a constant voltage circuit 300 for applying a low and stable voltage to the first terminal 1 of the threshold temperature element 100 .

The constant voltage circuit 310 may include a voltage follower structure using resistors R1-R4 and an NPN transistor TR10. Also, the constant voltage circuit 310 may be similarly configured as shown in FIGS. 13A to 13D .

17 is a protection circuit diagram for preventing SCR destruction applied to an embodiment of the present invention.

Referring to FIG. 17, a circuit structure in which two or more SCRs are connected in series is shown. A control voltage is applied to the gate of the first SCR1, and the gate of the second SCR2 is connected to the anode through a resistor R20. This structure is essential when applying a high voltage to the SCR.

18A and 18B are diagrams illustrating an application example of an electromagnetic switch according to an embodiment of the present invention.

Referring to FIG. 18A , it is shown that the phototriac PTRA1 is used as the electromagnet driving switch 152 to control the electromagnet with alternating current. Accordingly, the electromagnet of the electromagnetic contactor for AC control is controlled in an activated state or an inactive state.

18A shows an electromagnetic switch that directly controls an electromagnetic contactor (electromagnet) by AC 220V using a phototriac (PTRA1).

When AC 220V flows between the MT2 terminal (anode) and the MT1 terminal (cathode) of the phototriac (PTRA1), the electromagnet is activated. The deactivation state of the electromagnet, that is, the blocking operation (Off) is realized by blocking the current between the anode and the cathode of the phototriac PTRA1. As the gate of the phototriac (PTRA1), a DC power is used as a control power to control the current and SCR of the photodiode (Photo LED).

In FIG. 18A , power is taken from the power lines R, S, and T, but from the front end of the AC magnetic contactor 400 to make a phototriac control signal. When power is turned on (On) in the power lines R, S, T, current flows to the AC magnetic contactor 400, that is, the electromagnet, and the R, S, T power is connected to the power device. After that, when a large current flows in the power line and the temperature of the critical temperature element 100 reaches the critical temperature, the SCR is turned on, and the voltage applied to the LED of the phototriac PTRA1 becomes small. Accordingly, the current flowing in the photo LED of the photo triac (PTRA1) is reduced, the MT2 terminal and the MT1 terminal of the photo triac (PTRA1) are electrically cut off, the current in the magnetic contactor 400 is cut off (Off) and the power is cut off .

The monitoring system (MS) is operated by the current flowing from the anode to the cathode of the SCR, and the LED connected to the monitoring system (MS) may be emitted.

The monitoring system (MS) may generate a buzzer sound notifying an electronic switchgear blocking signal when the SCR is turned on and the phototriac is blocked, or may output a communication signal for warning.

Meanwhile, one of the constant voltage circuits as shown in FIG. 13 may be applied so that an excessive voltage is not applied to the MIT-CTS 100 as well. In the monitoring system (MS), a buzzer, LED, Ethernet, Bluetooth communication, etc. may be used to implement a monitoring function. R4 can use a PN junction diode for environmental temperature compensation. Capacitor C1 is used for signal delay in order to prevent malfunction due to a sudden noise signal when power is input. The MIT-CTS 100 is 1M at room temperature and has hundreds of ohms above the critical temperature. Here, to turn on the gate of the phototriac (PTRA1), the DC voltage is set to 5V or more.

The circuit of FIG. 18A may include a constant voltage circuit 330 for applying a low and stable voltage to the first terminal 1 of the threshold temperature element 100 .

The constant voltage circuit 330 may include a voltage follower structure using resistors R1-R5 and an NPN transistor TR10. Also, the constant voltage circuit 330 may be similarly configured as shown in FIGS. 13A to 13D .

On the other hand, in the case of FIG. 18B, a phototriac (PTRA1) is used as the electromagnet drive switch 153, and the power supply is a manual switch 400 brought from power lines R, S, and T to make a phototriac control signal. ) from the rear end (this part is different from Fig. 18a). In this case, the magnetic contactor is changed to a manual switch. When comparing FIGS. 18B and 18A , SCR and R5 in FIG. 18A are eliminated, and the other parts are maintained as they are. The R, S, T power lines are connected to the power device by a manual switch, and even when the power for controlling the photo triac is turned on, the photo triac and the electromagnet do not operate (this part is also different from FIG. 18A). When a large current flows in the power line, when the temperature of the critical temperature element reaches the critical temperature, the photodiode inside the phototriac is turned on and the phototriac is operated, and the electromagnet (L10) is operated and the ball in the manual switch is manually operated. The power line is cut off by turning off the manual switch by pulling the operation part of the switch. The circuit configuration of FIG. 18B may be used to block overcurrent in a wiring breaker and an earth leakage breaker. 19 is a view showing an application example of an electromagnetic switch according to an embodiment of the present invention.

19 is an application circuit that the switchgear of the present invention can be applied to overcurrent detection and control of a circuit breaker and an earth leakage breaker. That is, the circuit of FIG. 19 is a modified circuit of FIG. 14 .

First, during normal operation, the manual on-off seesaw switch 400 for blocking is turned on and an alternating current flows to the power lines (R, S, T), and the electromagnet does not operate at this time. However, when an overcurrent flows through the power line, the critical temperature element (MIT-CTS) operates and controls the SCR. At that time, the electromagnet is operated and a mechanical ball (such as a gun's trigger, which is attached to the front of the electromagnet) pulls the switch control unit. That is, the pulling force, that is, the attractive force, is turned off by pulling the operation part of the manual seesaw switch 400 for blocking. At this time, since the AC power line is completely cut off, the current supplied to the electromagnet is also cut off. In this way, the current flowing through the power line is completely cut off. In the electromagnetic switchgear, the attraction of the electromagnet (the force generated when current flows through the electromagnet) plays a role in connecting the power line through the magnetic contactor, but in the breaker, the manually connected power line is cut through the power line flowing to the manual switch through the attraction of the electromagnet These are opposite to each other.

In FIG. 19 , the electromagnet driving switch is implemented by the SCR and the SCR is controlled by the threshold temperature element 100 . That is, the gate of the SCR is controlled by the threshold temperature element 100 so that a current flows from the anode to the cathode of the SCR. Accordingly, the electromagnet becomes active and power is cut off.

At the gate of the SCR, a current control resistor R4 for allowing a rated current to flow through the SCR is connected in parallel to the electromagnet, and a capacitor may be connected in parallel with the current control resistor. The current control resistor R4 may be implemented as a PN junction diode.

A reverse flow prevention diode for protecting the critical temperature element is further connected to the gate of the SCR.

In addition to the SCR, the electromagnet drive switch may be implemented as a transistor, a triac, or a relay.

19 can be applied to a wiring breaker having an overcurrent blocking function and an earth leakage breaker having an earth leakage blocking function.

20 is a diagram provided to explain heat generated according to a size or material of a conducting wire in an embodiment of the present invention.

FIG. 20 shows exothermic experiments of various types of conductive wires (nichrome wires, copper and copper (copper) alloy wires, and steel wires). To apply a load, radiator (2500W) and copper wire 0.1Ω or less, nichrome wire 1 (130 x 1 mm) 0.8Ω, copper (copper) alloy (in thermal overload relay) 0.2Ω·, stainless steel 1 (150 x 4 mm) ) 0.5Ω, stainless 2 (30 x 4 mm) 2Ω was used. The resulting table is shown below. For the PCB copper plate, 1 oz (copper plate thickness 35 m) was used.

<Experimental data> division Dimensions Current 4A (℃) Current 6A (℃) Current 10A (℃) copper wire 1 30 x 0.5 mm 35 54 burnt copper wire 2 30 x 1 mm 32 42.7 82 copper wire 3 30 x 1.5 mm 30 35.6 54 copper wire 4 30 x 2 mm 30 33 45.6 copper wire 5 30 x 3 mm 28.5 30.5 39.9 copper wire 6 5 x 1 mm 31.4 35.4 46.4 copper wire 7 10 x 1 mm 30.2 35.5 53 copper wire 8 20 x 1 mm 32 39 68.5 copper wire 9 40 x 1 mm 33 44.4 80.2 copper wire 10 60 x 1 mm 34 46.8 95 stainless 1 150 x 4 mm 36.2 53.9 102.5 stainless 2 30 x 4 mm 53 85 163 nichrome wire 1 130 x 1 mm 79 168 240 or more Copper alloy (Brass) (yellow) 36.1 45.2 79

The above experimental data show that the heating of the conductor can be adjusted to the critical temperature of the critical temperature element according to the different degree of heating according to the material of the conductor and the width and length of the conductor and the design of the conductor.

Meanwhile, in the detailed description of the present invention, although specific embodiments have been described, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be defined by the claims and equivalents of the claims as well as the claims to be described later.

100: critical temperature element 200: electromagnet
300: constant voltage circuit
400: magnetic contactor or manual switch

Claims (57)

an electromagnet that turns on/off the power line in response to the flow of the electromagnet control current so that power is supplied to or cut off from the power device as a load;
a threshold temperature element in which an output current value changes when the temperature of the heating conductor connected to the power line by the supply current flowing to the power device exceeds a threshold temperature; and
An electromagnet control unit for generating or blocking the flow of the electromagnet control current of the electromagnet in response to the output current value of the critical temperature element,
The critical temperature element includes an input terminal, an output terminal, and a temperature-sensing terminal, wherein the temperature-sensing terminal senses a temperature varying according to a level of heat generated by the heating conductor, and the critical temperature element includes: and a metal-insulator transition element comprising vanadium oxide connected between the input terminal and the output terminal. The electromagnetic switchgear according to claim 1, wherein the electric power device is at least one of a motor, a heater, an LED, and a lamp. The electromagnetic switchgear according to claim 1, wherein the electromagnet control current is operated by receiving direct current or alternating current. The electronic switch according to claim 1, wherein the critical temperature element measures the temperature of the heating conductor in a contact or non-contact manner. According to claim 1, wherein the critical temperature element,
a first terminal connected to the control input;
a third terminal connected to the control output; and
and a second terminal insulated from the first and third terminals and connected to a heat source. The electronic switchgear according to claim 5, further comprising at least one insulating element connected between the heat source of the critical temperature element and the second terminal to insulate the heat source. 7. The electronic switchgear according to claim 6, wherein the heat insulating element is arranged to form a plurality of channels, and the channels are selected by a rotary switch or an adjustable switch for adjusting the level of heat insulation. delete The electronic switchgear according to claim 1, further comprising a constant voltage circuit for applying a constant voltage to the threshold temperature element. The electronic switchgear according to claim 9, wherein the constant voltage circuit includes a voltage follower structure using a resistor and an NPN transistor. The electronic switchgear according to claim 9, wherein the constant voltage circuit includes a voltage follower structure using a resistor and a PNP transistor. The electronic switchgear according to claim 9, wherein the constant voltage circuit includes a voltage follower structure using a resistor and an FET transistor. The electronic switchgear according to claim 9, wherein the constant voltage circuit includes a voltage follower structure using a resistor, an NPN transistor, and a Zener diode. delete delete delete delete The electronic switchgear according to claim 1, wherein the threshold temperature element is connected to each of the power lines when a plurality of the power lines are installed. The electronic switchgear according to claim 1, wherein the heating conductor includes at least one of a copper (copper) wire, a copper (copper) alloy wire, a nichrome wire, a nichrome alloy wire, and an iron alloy wire. The electronic switchgear according to claim 19, wherein the heating conductor is formed of a conductor having a higher temperature coefficient than that of the power line. The electronic switchgear of claim 19, wherein the heating conductor is formed by reducing a width of the power line. The electronic switchgear according to claim 19, wherein the heating conductor is branched from the power line and connected to a thermal terminal of the critical temperature element. 20. The method of claim 19, wherein the heating conductor is formed of a material different from that of the power line on the upper portion of the power line (electrically connecting the heating conductor and the power line in parallel) and is connected to the thermal terminal of the critical temperature element to generate the heat. An electromagnetic switch configured such that the heat generation of the conducting wire is higher than the heat generation of the power line. The method of claim 19, wherein the heating conductor is connected to the front end of the thermal terminal of the critical temperature element (electrically connecting the heating conductor and the power line in series) and is formed of a material having a temperature coefficient different from that of the power line, An electromagnetic switch configured to generate higher heat of the thermal terminal. The electromagnetic switchgear according to claim 1, wherein the electromagnet control unit comprises at least one of a transistor, a TRIAC, and a relay as an electromagnet driving switch element (electromagnet current supply element). The electromagnetic switchgear of claim 1, wherein the electromagnet control unit comprises at least one of an electromagnet transistor, a Silicon Controlled Rectifier (SCR), and a TRIAC, and a relay as an electromagnet current cutoff switch element. 27. The method of claim 26,
The electromagnet control unit includes an electromagnet driving switch and a driving switch control unit,
When the electromagnet driving switch is composed of an NPN transistor and the driving switch control unit is composed of an SCR, the gate of the SCR is connected to the output of the threshold temperature element, and the anode of the SCR is connected to the base of the NPN transistor. , when the SCR is turned on, the electromagnet driving switch is turned off and the electromagnet control current does not flow in the electromagnet, so that the function of the electromagnet is lost. 28. The electronic switchgear according to claim 27, further comprising a resistive element formed of a PN junction diode between the gate and the cathode of the SCR. 29. The electronic switchgear of claim 28, further comprising a capacitor connected in parallel with the resistive element between the gate and the cathode of the SCR. 28. The electronic switchgear of claim 27, further comprising a constant voltage circuit for receiving the first DC voltage, generating a second DC voltage lower than the first DC voltage, and applying the second DC voltage to the threshold temperature element. The electronic switchgear of claim 27 , further comprising a monitoring device that generates a sound, an alarm, or a communication signal in response to a current flowing through the SCR when the SCR is turned on. an electromagnet for supplying or blocking power to a power device as a load by switching the power line on/off in response to the flow of the AC control current;
a threshold temperature element in which an output current value changes when the temperature of the heating conductor connected to the power line by the supply current flowing to the power device exceeds a threshold temperature; and
An electromagnet control unit for generating or blocking the flow of the electromagnet control current of the electromagnet in response to the output current value of the critical temperature element,
The critical temperature element includes an input terminal, an output terminal, and a temperature-sensing terminal, wherein the temperature-sensing terminal senses a temperature varying according to a level of heat generated by the heating conductor, and the critical temperature element includes: and a metal-insulator transition element comprising vanadium oxide connected between the input terminal and the output terminal. 33. The method of claim 32, wherein when the electromagnet driving switch is configured as a triac and the driving switch control unit is configured as an SCR, a gate of the SCR is connected to an output of the threshold temperature element, and an anode of the SCR is configured with the triac An electromagnetic switch connected to the gate of evil, the triac is turned off when the SCR is turned on, and the AC control current does not flow in the electromagnet, so that the function of the electromagnet is lost. 34. The electronic switchgear according to claim 33, further comprising a resistive element comprised of a PN junction diode between the gate and the cathode of the SCR. 35. The electronic switchgear of claim 34, further comprising a capacitor connected in parallel with the resistive element between the gate and the cathode of the SCR. 34. The electronic switchgear according to claim 33, wherein a gate resistor and a high voltage inflow prevention diode are further connected between the gate of the SCR and the gate of the triac. The electronic switch according to claim 33, wherein a reverse flow prevention diode is further connected between the gate of the SCR and the output terminal of the threshold temperature element. 34. The electronic switchgear of claim 33, further comprising a monitoring device that generates a sound, alarm, or communication signal in response to a current flowing through a cathode of the SCR when the SCR is turned on and the triac is turned off. 33. The electronic device of claim 32, further comprising a constant voltage circuit that receives a first DC voltage to prevent damage to the threshold temperature element, generates a second DC voltage lower than the first DC voltage, and applies the second DC voltage to the threshold temperature element. switch. The electromagnetic switchgear according to claim 33, wherein the electromagnet, the triac, the critical temperature element, and the SCR are installed inside an electromagnetic contactor. 33. The method of claim 32, wherein when the electromagnet drive switch is configured as a triac and the drive switch control section is comprised of first and second SCRs connected in series to prevent breakdown, the gate of the first SCR is the threshold An electromagnetic switch connected to the output of the temperature element, and the anode of the first SCR is connected to the gate side of the triac. The method of claim 32, wherein when the electromagnet driving switch is configured as a phototriac and the driving switch control unit is configured as an SCR, the SCR and the phototriac are connected in parallel and the SCR is turned on. When the triac is turned off, the AC control current does not flow in the electromagnet, so that the function of the electromagnet is lost. 43. The electronic switchgear according to claim 42, further comprising a resistive element comprised of a PN junction diode between the gate and the cathode of the SCR. 44. The electronic switchgear of claim 43, further comprising a capacitor connected in parallel with the resistive element between the gate and the cathode of the SCR. 43. The electronic switchgear of claim 42, further comprising a monitoring device that generates a sound, alarm, or communication signal in response to a current flowing through a cathode of the SCR when the SCR is turned on and the triac is turned off. 43. The electronic device of claim 42, further comprising: a constant voltage circuit that receives a first DC voltage to prevent damage to the threshold temperature element, generates a second DC voltage lower than the first DC voltage, and applies the second DC voltage to the threshold temperature element switch. 43. The electromagnetic switchgear of claim 42, wherein the electromagnet, the triac, the critical temperature element, and the SCR are installed inside an electromagnetic contactor. 33. The method of claim 32, wherein a manual switch for connecting a power line to the power device is provided, and when the electromagnet driving switch is composed of a phototriac, the manual switch is turned on to turn on the power when the power is turned on. The triac is configured to be turned off, and the electromagnet is not operated because the AC control current does not flow in the electromagnet. When a large current flows through the power line and the temperature of the critical temperature element reaches the critical temperature, the An electromagnetic switch configured to turn off the manual switch by operating the electromagnet when the photodiode inside the phototriac is operated. 49. The electromagnetic switch according to claim 48, wherein the electromagnetic switch can be used for the purpose of preventing overcurrent in the circuit breaker and the earth leakage breaker. a manual switch for supplying power applied through the power line to the power device in response to a manual operation;
an electromagnet for cutting off the power supplied to the power device by pulling the operating part of the manual switch with a physical force to turn off the manual switch;
an electromagnet driving switch for allowing a control current to flow to or blocking the electromagnet in response to a control voltage;
a threshold temperature element that functions as a driving switch control unit of the electromagnet driving switch and changes an output current value when a temperature of a heating conductor connected to the power line by a supply current flowing from the power line to the power device exceeds a threshold temperature; and
a driving switch control unit for generating the control voltage for controlling the electromagnet driving switch in response to the output of the threshold temperature element,
The critical temperature element includes an input terminal, an output terminal, and a temperature-sensing terminal, wherein the temperature-sensing terminal senses a temperature varying according to a level of heat generated by the heating conductor, and the critical temperature element includes: and a metal-insulator transition element comprising vanadium oxide connected between the input terminal and the output terminal. 51. The electromagnetic switchgear of claim 50, wherein, when the electromagnet driving switch is the SCR, the gate of the SCR is controlled by the threshold temperature element to cut off the power supply so that the electromagnet is driven in an active state. The electromagnetic switchgear according to claim 51, wherein a current control resistor for flowing a rated current to the SCR is connected in parallel to the electromagnet at the gate of the SCR. 52. The electronic switchgear according to claim 51, wherein the gate of the SCR includes a capacitor connected in parallel with a current control resistor. 54. The electronic switchgear of claim 53 comprising a PN junction diode for the current control resistor. The electronic switch according to claim 51, wherein a reverse flow prevention diode for protecting a critical temperature element is further connected to the gate of the SCR. 51. The electromagnetic switchgear of claim 50, wherein the electromagnet drive switch comprises at least one of a transistor, an SCR, a triac, and a relay. 51. The electronic switchgear according to claim 50, further comprising a wiring breaker having an overcurrent blocking function and an earth leakage breaker having an earth leakage blocking function.

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