Relay anti-adhesion protection system and electric heating equipment

Abstract

The utility model relates to a relay anti-adhesion protection system and electric heating equipment. The relay anti-adhesion protection system comprises a main relay circuit, an adhesion detection circuit and an alarm circuit, the main relay circuit comprises a main relay RL1 configured with a live wire ACL, and further comprises a protection relay circuit and a cut-off control protection circuit, and the protection relay circuit comprises a protection relay RL2 configured with the live wire ACL. A contact of the protection relay RL2 adopts a normally closed type, and the adhesion detection circuit detects the on-off state of the contact of the main relay RL1 in real time and controls the protection relay circuit to disconnect the contact of the protection relay RL2 and triggers the alarm circuit to give an alarm through the cut-off control protection circuit when adhesion occurs. The technical scheme of the utility model has the advantages that adhesion detection and cut-off protection are simultaneously realized completely through a hardware circuit, the response is sensitive and rapid, the reliability and the safety are higher, the abnormity can be timely reminded to a user, the number of components is small, and the cost is low.

Description

Technical Field

[0001] The utility model relates to the field of relay contact adhesion detection and circuit protection, in particular to a relay anti-adhesion protection system and electric heating equipment. Background Art

[0002] As an important control element in electric heating equipment, relays are mainly used to connect or disconnect the power supply of the heating load to achieve temperature control. However, during the long-term, high-power heating process of electric heating equipment, the relay contacts are prone to adhesion failure, causing the heating load to lose control and continue to be powered on for heating. In serious cases, it may cause safety accidents such as fire and explosion of the electric heating equipment. For example, the inner tank of an electric water heater exploded due to the adhesion of the relay contacts, which seriously endangered the safety of people and property. Therefore, relay adhesion detection and circuit protection work are particularly important in electric heating equipment.

[0003] However, currently on the market, the completion of relay adhesion detection and circuit protection of electric heating equipment (such as electric water heaters) is either highly dependent on the main control system and software program, that is, the AC voltage signal is processed by hardware and then the output signal is detected by the software program. In this way, once the main control system or the software program fails, the protection function will disappear completely; or the solution using only hardware circuits cannot achieve the functions of adhesion detection and cut-off protection at the same time.

[0004] For example, the Chinese utility model patent with authorization announcement number CN215328903U and titled "A clothes dryer" discloses: a control circuit for outputting a high-level or low-level signal; a drive circuit, which includes a first transistor and a relay, the base of the first transistor is connected to the control circuit, the collector of the first transistor is connected to the positive electrode of the first power supply, the emitter of the first transistor is connected to the negative electrode of the first power supply via the coil of the relay, the contacts of the relay are connected in series with the heater and then connected to the AC power line, the contacts of the relay are normally open contacts, when the contacts of the relay are closed, the heater works, and when the contacts of the relay are open, the heater stops working; an alarm circuit, which is connected to the control circuit, and the alarm circuit is connected to the series circuit of the contacts of the relay and the heater, and is used to alarm when it is detected that the contacts of the relay are sticky. The alarm circuit includes: a detection unit connected to the control circuit, and the detection unit is connected to the negative electrode of the second power supply; a first protection unit connected in parallel with the contact of the relay, the first protection unit is also connected to the detection unit, and the connection line between the first protection unit and the detection unit is connected to the ground; an alarm unit connected to the detection unit, and the alarm unit is connected to the positive electrode of the second power supply. The alarm circuit also includes: a second protection unit, one end of which is connected to the connection line between the first protection unit and the detection unit, and the other end of the second protection unit is connected to the ground. A second triode, whose base is connected to the control circuit, and the emitter of the second triode is connected to the positive electrode of the second power supply through the alarm unit; a third triode, the collector of the second triode is connected to the emitter of the third triode, the collector of the third triode is connected to the negative electrode of the second power supply, and the base of the third triode is connected to the first protection unit. The first protection unit includes: a first resistor, one end of which is connected to one end of the contact of the relay; a second resistor, one end of which is connected to the other end of the contact of the relay, and the other end of the second resistor and the other end of the first resistor are both connected to the base of the third transistor. The technical solution of the utility model cannot realize adhesion detection and cut-off protection at the same time, and requires the user to operate the cut-off circuit, which is prone to the problem of heating load out of control and continuous power-on heating, and has low safety.

[0005] For another example, a Chinese invention application with application publication number CN1903551A and titled "Injection molding machine manipulator mold closing signal contact adhesion detection and alarm device" discloses: an injection molding machine manipulator mold closing signal contact adhesion detection and alarm device, comprising a detection circuit and an alarm circuit, wherein the detection circuit: the positive electrode of the input end of the photoelectric isolator (6) is pulled up to +5V through a resistor (1), and the negative electrode of the input end of the photoelectric isolator (6) is connected to an interface (21); the output end of the photoelectric isolator (6) is connected in series with a resistor (2), a coil of a relay (4), and a transistor (3) in sequence to form a circuit. The transistor (3) is connected in series into the loop through a base connected to the output end of the photoelectric isolator (6) and a collector connected to the relay (4); the emitter of the transistor (3) is grounded, and a resistor (7) is connected in series between the base and the emitter; the resistor (2) and the wiring terminal of the relay (4) are pulled up to +24V; the output normally open contacts (41) and (42) of the relay (4) are connected to the wiring terminal (5); the output normally open contacts (41) and the interface (24) of the electrical appliance (4) are connected to the power supply terminal and the power supply ground terminal respectively; the input terminals of the photoelectric isolators (9) and (8) are connected through After reverse parallel connection, the same group of normally closed contacts (41) and (43) of the relay (4) are connected in series; the input ends of the photoelectric isolators (9) and (8) are connected to the interface (24) through the current limiting resistor (14) after reverse parallel connection; the output ends of the photoelectric isolators (9) and (8) are connected to the interface (22) after forward parallel connection, and the resistor (10) is pulled up to +5V; the alarm circuit: the positive pole of the input end of the photoelectric isolator (12) is pulled up to +5V through the resistor (11), and the negative pole of the input end of the photoelectric isolator (12) is connected to the interface (23); the output ends of the photoelectric isolator (12) are connected to the interface (24) through the current limiting resistor (14); the output ends of the photoelectric isolators (9) and (8) are connected to the interface (22) after forward parallel connection, and the resistor (10) is pulled up to +5V; the alarm circuit: the positive pole of the input end of the photoelectric isolator (12) is pulled up to +5V through the resistor (11), and the negative pole of the input end of the photoelectric isolator (12) is connected to the interface (23); The output end is connected in series with a resistor (13), a relay (17), and a triode (16) to form a loop. The triode (16) is connected in series with the output end of the photoelectric isolator (12) and the collector connected to the relay (17). The emitter of the triode (16) is grounded, and a resistor (15) is connected in series between the base and the emitter. The connection terminals of the resistor (13) and the relay (17) are pulled up to +24V. The output normally open contacts (31) and (32) of the relay (17) are connected in series with the emergency stop signal terminal (18) of the injection molding machine controller. The interface (21) is the signal output control point of the injection molding machine robot controller, the interface (22) is the signal input control point of the injection molding machine robot controller, and the interface (23) is the output control point of the injection molding machine robot output alarm.The "detection circuit" in the technical solution described in the invention application needs to be input to the input point of the robot controller through the interface 22 to detect the actual contact signal state of the relay 4. The injection molding machine robot saves the output control state of the relay 4 and compares the state of the interface 22 with the state; the "alarm circuit" is also compared with the state of the interface 22 and the actual contact signal state of the relay 4, and then the controller closes the robot arm descending output solenoid valve and outputs a signal to the interface 23 as an alarm output. Therefore, it is necessary to interact with the controller multiple times through each interface, and the dependence on the main control system and software program is too high. Utility Model Content

[0006] In view of the deficiencies in the prior art, the utility model provides a relay anti-adhesion protection system and electric heating equipment that can simultaneously realize adhesion detection and cut-off protection completely through hardware circuits, has a sensitive and rapid response, higher reliability and safety, can promptly remind users of abnormalities, has a small number of components and a low cost.

[0007] The utility model mainly adopts the following technical solutions:

[0008] A relay anti-adhesion protection system comprises a main relay circuit, an adhesion detection circuit and an alarm circuit, wherein the main relay circuit comprises a main relay RL1 configured with a live line ACL, and further comprises a protection relay circuit and a cut-off control protection circuit, wherein the protection relay circuit comprises a protection relay RL2 configured with the live line ACL, and the contacts of the protection relay RL2 are of a normally closed type, and the adhesion detection circuit detects the on-off state of the contacts of the main relay RL1 in real time, and when adhesion occurs, controls the protection relay circuit through the cut-off control protection circuit to disconnect the contacts of the protection relay RL2 and triggers the alarm circuit to sound an alarm.

[0009] Among them, the main relay circuit, the adhesion detection circuit and the cut-off control protection circuit are connected in parallel on the main relay control signal interface RL1 CTL, the adhesion detection circuit is connected to the cut-off control protection circuit, and the cut-off control protection circuit is connected to the protection relay circuit and the alarm circuit connected in series.

[0010] Wherein, the main relay circuit also includes resistors R1-R2, a diode D1 and a transistor Q1, the main relay control signal interface RL1 CTL is connected to the base of the transistor Q1 through the resistor R1, the diode D1 is connected in parallel with the main relay RL1, the anode of the diode D1 and the control end of the main relay RL1 are connected to the collector of the transistor Q1, the cathode of the diode D1 and the connection terminal of the main relay RL1 are connected to the positive electrode of the first DC power supply, the emitter of the transistor Q1 is connected to the DC ground, and the resistor R2 is connected in series between the base of the transistor Q1 and the emitter of the transistor Q1.

[0011] Among them, the adhesion detection circuit includes resistors R3-R6, a diode D3, a transistor Q2 and a photocoupler U1, the main relay control signal interface RL1 CTL is connected to the base of the transistor Q2 through the resistor R5, the emitter of the transistor Q2 is connected to the positive electrode of the second DC power supply, the input pin 1 of the photocoupler U1 is connected in series between the loop formed by the live wire ACL and the neutral line ACN through the resistors R3 and R4 connected in series and the load power supply output interface OUT1, the input pin 2 of the photocoupler U1 is connected to the anode of the diode D3, the cathode of the diode D3 is connected to the neutral line ACN, the output pin 3 of the photocoupler U1 is connected to the DC ground through the resistor R6, and the output pin 4 of the photocoupler U1 is connected to the collector of the transistor Q2.

[0012] Wherein, the cut-off control protection circuit includes resistors R7-R9, capacitors C1-C2, transistor Q3 and unidirectional thyristor Q5, the main relay control signal interface RL1 CTL is connected to the base of the transistor Q3 through the resistor R7, the emitter of the transistor Q3 is connected to the output pin 3 of the photocoupler U1, the collector of the transistor Q3 is connected to the gate of the unidirectional thyristor Q5 through the resistor R8, the cathode of the unidirectional thyristor Q5 is connected to the DC ground, the resistor R9 and the capacitor C1 are connected in parallel between the gate of the unidirectional thyristor Q5 and the DC ground, and the base of the transistor Q3 is connected to the DC ground through the capacitor C2.

[0013] The protection relay circuit further includes a diode D2, the diode D2 is connected in parallel with the protection relay RL2, and the anode of the diode D2 and the control end of the protection relay RL2 are connected to the anode of the unidirectional thyristor Q5.

[0014] Among them, the alarm circuit includes resistors R10-R12, a transistor Q4 and a buzzer BUZ1, the base of the transistor Q4 is connected to the control end of the protection relay RL2 or the anode of the unidirectional thyristor Q5 through the resistor R10, the emitter of the transistor Q4 is connected to the third DC power supply, and the collector of the transistor Q4 is connected in series with the resistor R12 and the buzzer BUZ1 in parallel through the resistor R11 and then connected to the DC ground.

[0015] An electric heating device uses the relay anti-adhesion protection system.

[0016] According to the technical scheme described in the utility model, the following beneficial effects are achieved: by using a pure hardware circuit through a specific circuit connection method, the relay adhesion detection and cut-off protection functions can be realized simultaneously without relying on software programs. When a relay adhesion failure occurs in the electric heating equipment, the cut-off protection can be performed in time and an alarm reminder can be given, thereby improving the safety, reliability and sensitivity of the electric heating equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a circuit functional block diagram of an embodiment of a relay anti-sticking protection system.

[0018] Figure 2 The present invention is a circuit functional block diagram of another embodiment of a relay anti-adhesion protection system.

[0019] Figure 3 This is the circuit schematic diagram of the relay anti-adhesion protection system.

[0020] 1 main relay circuit, 2 adhesion detection circuit, 3 alarm circuit, 4 protection relay circuit, 5 cut-off control protection circuit, ACL live wire, ACN neutral wire, RL1 main relay, RL2 protection relay, RL1 CTL main relay control signal interface, R1-R12 resistors, C1-C2 capacitors, D1-D3 diodes, Q1-Q3 transistors, U1 photocoupler, Q5 unidirectional thyristor, BUZ1 buzzer, OUT1 load power output interface. DETAILED DESCRIPTION

[0021] The technical solution of the utility model is further described below in conjunction with the accompanying drawings:

[0022] See also Figure 1 , 2As shown in Figure 3, a relay anti-adhesion protection system includes a main relay circuit 1, an adhesion detection circuit 2 and an alarm circuit 3. The main relay circuit 1 includes a main relay RL1 configured with the live line ACL, and also includes a protection relay circuit 4 and a cut-off control protection circuit 5. The protection relay circuit 4 includes a protection relay RL2 configured with the live line ACL, and the contact of the protection relay RL2 is a normally closed type. The adhesion detection circuit 2 detects the on-off state of the contact of the main relay RL1 in real time and controls the protection relay circuit 4 to disconnect the contact of the protection relay RL2 through the cut-off control protection circuit 5 when adhesion occurs, and triggers the alarm circuit 3 to sound an alarm. In this application, a pure hardware circuit is used through a specific circuit connection method to simultaneously realize the relay adhesion detection and cut-off protection functions, without being highly dependent on software programs. When the relay of the electric heating equipment has an adhesion failure, the cut-off protection can be performed in time and an alarm reminder can be given, thereby improving the safety, reliability and sensitivity of the electric heating equipment.

[0023] See also Figure 1 , 2 , 3, the main relay circuit 1, the adhesion detection circuit 2 and the cut-off control protection circuit 5 are connected in parallel to the main relay control signal interface RL1 CTL, the adhesion detection circuit 2 is connected to the cut-off control protection circuit 5, and the cut-off control protection circuit 5 is connected to the series-connected protection relay circuit 4 and the alarm circuit 3. In this application, the order in which the protection relay circuit and the alarm circuit are connected to the cut-off control protection circuit is not limited.

[0024] See also Figure 3 As shown, the main relay circuit 1 also includes resistors R1-R2, a diode D1 and a transistor Q1, the main relay control signal interface RL1 CTL is connected to the base of the transistor Q1 through the resistor R1, the diode D1 is connected in parallel with the main relay RL1, the anode of the diode D1 and the control end of the main relay RL1 are connected to the collector of the transistor Q1, the cathode of the diode D1 and the wiring terminal of the main relay RL1 are connected to the positive electrode of the first DC power supply, the emitter of the transistor Q1 is connected to the DC ground, and the base of the transistor Q1 and the emitter of the transistor Q1 are connected in series with a resistor R2. Preferably, the resistance of the resistor R1 is 1K ohms. Preferably, the resistance of the resistor R2 is 10K ohms. Preferably, the diode D1 adopts a 1N4148 small high-speed switching diode. Preferably, the transistor Q1 adopts a S8050 low-power NPN silicon tube. Preferably, the voltage of the first DC power supply is +12V.

[0025] See also Figure 3As shown, the adhesion detection circuit 2 includes resistors R3-R6, a diode D3, a transistor Q2 and a photocoupler U1, the main relay control signal interface RL1 CTL is connected to the base of the transistor Q2 through a resistor R5, the emitter of the transistor Q2 is connected to the positive electrode of the second DC power supply, the input pin 1 of the photocoupler U1 is connected in series with the load power output interface OUT1 through the series resistors R3 and R4 between the loop formed by the live wire ACL and the neutral line ACN, the input pin 2 of the photocoupler U1 is connected to the anode of the diode D3, the cathode of the diode D3 is connected to the neutral line ACN, the output pin 3 of the photocoupler U1 is connected to the DC ground through the resistor R6, and the output pin 4 of the photocoupler U1 is connected to the collector of the transistor Q2. Preferably, the resistor R4 is directly connected to the load power output interface OUT1. Preferably, the resistance value of the resistor R3 is 51K ohms. Preferably, the resistance value of the resistor R4 is 51K ohms. Preferably, the resistance value of the resistor R5 is 1k ohms. Preferably, the resistance of resistor R6 is 10K ohms. Preferably, the voltage of the second DC power supply is +5V. Preferably, diode D3 adopts 1N4007 plastic package type general silicon material rectifier diode. Preferably, transistor Q2 adopts S8550 ordinary PNP type silicon transistor. Preferably, photocoupler U1 adopts EL817 linear photocoupler.

[0026] See also Figure 3As shown, the cut-off control protection circuit 5 includes resistors R7-R9, capacitors C1-C2, transistor Q3 and unidirectional thyristor Q5, the main relay control signal interface RL1 CTL is connected to the base of the transistor Q3 through the resistor R7, the emitter of the transistor Q3 is connected to the output pin 3 of the photoelectric coupler U1, the collector of the transistor Q3 is connected to the gate of the unidirectional thyristor Q5 through the resistor R8, the cathode of the unidirectional thyristor Q5 is connected to the DC ground, the gate of the unidirectional thyristor Q5 and the DC ground are connected in parallel with resistor R9 and capacitor C1, and the base of the transistor Q3 is connected to the DC ground through capacitor C2. In the present application, the emitter of the transistor Q3 is connected between the output pin 3 of the photoelectric coupler U1 and the resistor R6. In the present application, the base of the transistor Q3 is connected to the resistor R7 and the capacitor C2 respectively. The charge and discharge circuit composed of the resistor R7 and the capacitor C2 can charge the capacitor C2 when the main relay control signal interface RL1CTL outputs a high level; when the main relay control signal interface RL1 CTL outputs a low level, discharge is performed to maintain the base voltage of the transistor Q3, that is, delay judgment, to ensure that when the signal switching speed of the main relay control signal interface RL1 CTL is fast, the voltage at the input end of the photocoupler U1 cannot follow the change in time. It can also be stably detected. Preferably, the resistance of the resistor R7 is 10K ohms. Preferably, the resistance of the resistor R8 is 1K ohms. Preferably, the resistance of the resistor R9 is 10K ohms. Preferably, the capacitor C1 adopts a 104 capacitor. Preferably, the capacitor C2 adopts a 106 capacitor. Preferably, the transistor Q3 adopts an S8550 ordinary PNP silicon transistor. Preferably, the unidirectional thyristor Q5 adopts a BT169 unidirectional thyristor.

[0027] See also Figure 3 As shown, the protection relay circuit 4 also includes a diode D2, which is connected in parallel with the protection relay RL2, and the anode of the diode D2 and the control end of the protection relay RL2 are connected to the anode of the unidirectional thyristor Q5. Preferably, the diode D2 is a 1N4148 small high-speed switching diode.

[0028] See also Figure 3As shown, the alarm circuit 3 includes resistors R10-R12, transistor Q4 and buzzer BUZ1, the base of transistor Q4 is connected to the control end of the protection relay RL2 or the anode of the unidirectional thyristor Q5 through the resistor R10, the emitter of transistor Q4 is connected to the third DC power supply, and the collector of transistor Q4 is connected to the DC ground after being connected in series with the parallel resistor R12 and buzzer BUZ1 through the resistor R11. Preferably, the base of transistor Q4 is connected to the control end of the protection relay RL2 through the resistor R10, and the control end of the protection relay RL2 is connected to the anode of the unidirectional thyristor Q5. Preferably, the voltage of the third DC power supply is +12V. Preferably, when the voltage of the first DC power supply is the same as the voltage of the third DC power supply, the first DC power supply and the third DC power supply can be shared, that is, only one DC power supply with a voltage value that meets the requirements is used to supply power. Preferably, the resistance value of resistor R10 is 10K ohms. Preferably, the resistance value of the resistor R11 is 100 ohms. Preferably, the resistance value of the resistor R12 is 2K ohms. Preferably, the transistor Q4 is a S8550 common PNP silicon transistor.

[0029] An electric heating device uses the above relay anti-adhesion protection system. In the present application, the electric heating device includes a heating load, and the heating load is connected to the load power supply output interface OUT1.

[0030] The above scheme works as follows:

[0031] When the main relay control signal interface RL1 CTL of the main control system outputs a high level, that is, the main relay RL1 is controlled to open, the transistor Q1 is saturated and turned on to control the main relay RL1 contacts to close, the load power output interface OUT1 is energized, and there is a voltage signal input to the input pin 1 of the photocoupler U1, then the output end of the photocoupler U1 is turned on, and the high level signal of the main relay control signal interface RL1 CTL quickly turns off the transistors Q2 and Q3, the gate of the unidirectional thyristor Q5 has no voltage, the normally closed protection relay RL2 does not operate, and the transistor Q4 is turned off. At this time, the buzzer does not alarm.

[0032] When the main relay control signal interface RL1 CTL of the main control system outputs a low level, that is, the contact of the control main relay RL1 is released, the load power output interface OUT1 is powered off, and there is no voltage signal input to the input pin 1 of the photoelectric coupler U1, the output end of the photoelectric coupler U1 is not conducting, the transistors Q2 and Q3 are cut off, the gate of the unidirectional thyristor Q5 has no voltage, the normally closed protection relay RL2 does not operate, and the transistor Q4 is cut off. At this time, the buzzer does not alarm.

[0033] If the main relay control signal interface RL1 CTL of the main control system outputs a low level, the main relay RL1 has a sticking fault and cannot release the contact in time, then the input end of the photocoupler U1 will have a continuous voltage to turn on the output end of the photocoupler U1, and at the same time, the transistors Q2 and Q3 are turned on, and the unidirectional thyristor Q5 is triggered and locked, thereby controlling the protection relay RL2 to cut off the power supply circuit to achieve the cut-off protection effect, avoiding the heating load from getting out of control and continuing to power on for heating, thereby causing safety accidents such as fire and explosion of the electric heating equipment. At this time, the base voltage of the transistor Q4 is about 0.7V, and the transistor Q4 is turned on, thereby controlling the buzzer BUZ1 to alarm, and promptly reminding the user of the abnormality, with a higher safety factor.

[0034] Although the specific implementation modes of the present invention have been described above, those skilled in the art may modify the present invention without departing from the spirit and principle of the present invention. The protection scope of the present invention is defined by the claims and their equivalents.

Claims

1. A relay anti-adhesion protection system, comprising a main relay circuit, an adhesion detection circuit and an alarm circuit, wherein the main relay circuit comprises a main relay RL1 configured with a live line ACL, characterized in that: It also includes a protection relay circuit and a cut-off control protection circuit. The protection relay circuit includes a protection relay RL2 configured with the live wire ACL. The contacts of the protection relay RL2 are of normally closed type. The adhesion detection circuit detects the on-off state of the contacts of the main relay RL1 in real time and when adhesion occurs, controls the protection relay circuit through the cut-off control protection circuit to disconnect the contacts of the protection relay RL2 and triggers the alarm circuit to sound an alarm.

2. The relay anti-adhesion protection system according to claim 1, characterized in that: The main relay circuit, the adhesion detection circuit and the cut-off control protection circuit are connected in parallel on the main relay control signal interface RL1 CTL, the adhesion detection circuit is connected to the cut-off control protection circuit, and the cut-off control protection circuit is connected to the protection relay circuit and the alarm circuit connected in series.

3. The relay anti-adhesion protection system according to claim 2, characterized in that: The main relay circuit also includes resistors R1-R2, a diode D1 and a transistor Q1. The main relay control signal interface RL1 CTL is connected to the base of the transistor Q1 through the resistor R1. The diode D1 is connected in parallel with the main relay RL1. The anode of the diode D1 and the control end of the main relay RL1 are connected to the collector of the transistor Q1. The cathode of the diode D1 and the connection terminal of the main relay RL1 are connected to the positive electrode of the first DC power supply. The emitter of the transistor Q1 is connected to the DC ground. The resistor R2 is connected in series between the base of the transistor Q1 and the emitter of the transistor Q1.

4. The relay anti-adhesion protection system according to claim 2 or 3, characterized in that: The adhesion detection circuit includes resistors R3-R6, a diode D3, a transistor Q2 and a photocoupler U1. The main relay control signal interface RL1 CTL is connected to the base of the transistor Q2 through the resistor R5, the emitter of the transistor Q2 is connected to the positive electrode of the second DC power supply, the input pin 1 of the photocoupler U1 is connected in series between the loop formed by the live wire ACL and the neutral wire ACN through the resistors R3 and R4 connected in series and the load power supply output interface OUT1, the input pin 2 of the photocoupler U1 is connected to the anode of the diode D3, the cathode of the diode D3 is connected to the neutral wire ACN, the output pin 3 of the photocoupler U1 is connected to the DC ground through the resistor R6, and the output pin 4 of the photocoupler U1 is connected to the collector of the transistor Q2.

5. The relay anti-adhesion protection system according to claim 4, characterized in that: The cut-off control protection circuit includes resistors R7-R9, capacitors C1-C2, transistor Q3 and unidirectional thyristor Q5. The main relay control signal interface RL1CTL is connected to the base of the transistor Q3 through the resistor R7. The emitter of the transistor Q3 is connected to the output pin 3 of the photocoupler U1. The collector of the transistor Q3 is connected to the gate of the unidirectional thyristor Q5 through the resistor R8. The cathode of the unidirectional thyristor Q5 is connected to the DC ground. The resistor R9 and the capacitor C1 are connected in parallel between the gate of the unidirectional thyristor Q5 and the DC ground. The base of the transistor Q3 is connected to the DC ground through the capacitor C2.

6. The relay anti-adhesion protection system according to claim 5, characterized in that: The protection relay circuit further includes a diode D2, which is connected in parallel with the protection relay RL2, and an anode of the diode D2 and a control end of the protection relay RL2 are connected to an anode of the unidirectional thyristor Q5.

7. The relay anti-adhesion protection system according to claim 5 or 6, characterized in that: The alarm circuit includes resistors R10-R12, a transistor Q4 and a buzzer BUZ1. The base of the transistor Q4 is connected to the control end of the protection relay RL2 or the anode of the unidirectional thyristor Q5 through the resistor R10, the emitter of the transistor Q4 is connected to a third DC power supply, and the collector of the transistor Q4 is connected in series with the resistor R12 and the buzzer BUZ1 in parallel through the resistor R11 and then connected to a DC ground.

8. An electric heating device, characterized in that: Use the relay anti-adhesion protection system described in any one of claims 1 to 7.

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