Safety device for control circuit

Abstract

The utility model discloses a safety device for a control circuit. The safety device comprises a power supply module, a control module and a safety output module, the power supply module supplies power to the control circuit through an external power supply; the control module comprises a first channel circuit, a second channel circuit, a first driving allowing circuit and a second driving allowing circuit, wherein the first channel circuit and the second channel circuit control the two forced guiding relays to be switched on and switched off respectively. The first channel circuit is connected with the first forced guide relay, and the second channel circuit is connected with the second forced guide relay; the first driving permission circuit is connected with the first channel circuit and the second driving permission circuit; the second driving permission circuit is connected with the power supply module, the first driving permission circuit and the second channel circuit; the first driving allowing circuit is conducted according to the state of the first channel circuit, the second driving allowing circuit conducts the second channel circuit according to the conducting state of the first driving allowing circuit, and the starting state of the second channel circuit is fed back to the first channel circuit to maintain the first channel circuit to be conducted; and the safety output module is formed by connecting contacts of two forced guide relays in series in a redundant manner. The opening of the first channel circuit and the second channel circuit forms a heterogeneous action form, so that the simultaneous failure of the first channel circuit and the second channel circuit can be avoided to the greatest extent, and the safety performance of the circuit is higher.

Description

Technical Field

[0001] This application belongs to the field of safety control technology, specifically referring to a safety device for control circuits. Background Technology

[0002] In existing technologies, the application of safety circuits, such as the control of wind turbines, elevators, and safety doors, mostly consists of several forced-guide relays forming the safety circuit. At the same time, the safety circuit is set up with dual-channel redundant emergency stop applications. However, they are all designed to start both channel circuits at the same time, or to start the first channel circuit or the second channel circuit randomly. Moreover, the first channel circuit and the second channel circuit are completely identical circuits. Therefore, it is difficult to avoid the same problem in the circuit causing both channel circuits to fail, resulting in safety problems. Utility Model Content

[0003] Therefore, in view of the above problems, this utility model proposes a safety device for control circuits.

[0004] This utility model is achieved using the following technical solution:

[0005] This utility model provides a safety device for a control circuit, including at least two forced-guide relays and a control circuit connected to the forced-guide relays. The control circuit includes a power supply module, a control module, and a safety output module.

[0006] The power module provides power to the control circuit via an external power source;

[0007] The control module includes a first channel circuit and a second channel circuit that control the on and off of the two forced-guided relays respectively, a first drive enable circuit, and a second drive enable circuit. The first channel circuit is connected to the first forced-guided relay, and the second channel circuit is connected to the second forced-guided relay. The first drive enable circuit is connected to the first channel circuit and the second drive enable circuit. The second drive enable circuit is connected to the power module, the first drive enable circuit, and the second channel circuit. Both the first channel circuit and the second channel circuit are connected to the power module and the safety output module. The first drive enable circuit is turned on according to the state of the first channel circuit, and the second drive enable circuit is turned on according to the on state of the first drive enable circuit, and feeds back the start state of the second channel circuit to the first channel circuit to maintain the first channel circuit on.

[0008] The safety output module consists of redundant contacts of two forced-guide relays connected in series.

[0009] In one embodiment, the first drive enable circuit includes at least a first switch unit, the controlled input terminal of the first switch unit is connected to the first channel circuit, and the switch output terminal of the first switch unit is connected to the power module and the second drive enable circuit respectively.

[0010] The first switching unit is turned on according to the voltage control signal of the first channel circuit.

[0011] In one embodiment, the second drive enable circuit includes at least a second switch unit. The controlled input terminal of the second switch unit is connected to the first drive enable circuit, and the switch output terminal of the second switch unit is connected to the second channel circuit and the power module, respectively. The second switch unit turns on the switch according to the conduction status of the first switch unit, and the second switch unit turns on the second channel circuit.

[0012] In one embodiment, the first channel circuit includes a third switch unit and a fourth switch unit, the second channel circuit includes a fifth switch unit and a sixth switch unit, and the second drive enable circuit is connected to the sixth switch unit; the switching states of the third switch unit and the sixth switch unit are always opposite, and the switching states of the fifth switch unit and the fourth switch unit are always opposite.

[0013] The third switch unit is initially open, the fourth switch unit is initially closed, the fifth switch unit is initially open, and the sixth switch unit is initially closed.

[0014] When the first drive enable circuit and the second drive enable circuit are turned on, the second channel circuit is energized and turned on, the fifth switch unit is turned on and the fourth switch unit is turned off; when the first channel circuit is energized and turned on, the third switch unit is turned on and the sixth switch unit is turned off, and the first channel circuit is maintained on.

[0015] In one embodiment, the third switching unit is a first normally open switching circuit, the fourth switching unit is a second normally closed switching circuit, the fifth switching unit is a second normally open switching circuit, and the sixth switching unit is a first normally closed switching circuit.

[0016] The first channel circuit includes a first normally open switch circuit and a second normally closed switch circuit, the second channel circuit includes a second normally open switch circuit and a first normally closed switch circuit, and the second drive enable circuit is connected to the first normally closed switch circuit; the switching states of the first normally open switch circuit and the first normally closed switch circuit are opposite, and the switching states of the second normally open switch circuit and the second normally closed switch circuit are opposite.

[0017] The first drive enable circuit and the second drive enable circuit are turned on, the second channel circuit is energized and turned on, the second normally open switch circuit is turned on and the second normally closed switch circuit is turned off; the first channel circuit is energized and turned on, the first normally open switch circuit is turned on and the first normally closed switch circuit is turned off, and the first channel circuit is kept on.

[0018] In one embodiment, the first channel circuit further includes a first channel driving circuit unit, and the second channel circuit further includes a second channel driving circuit unit.

[0019] The second drive enable circuit is connected to the sixth switch unit, the first drive enable circuit and the power module. The second drive enable circuit turns on the switch according to the detected conduction state of the first drive enable circuit, and provides a positive power supply loop for the second channel circuit.

[0020] The sixth switch unit is connected to the second drive enable circuit, the second channel drive circuit unit and the third switch unit. The sixth switch unit is used to perform a loop self-test on the first channel circuit and determine whether the sixth switch unit is in the initial state of conduction.

[0021] The second channel drive circuit unit is connected to the sixth switch unit and the fifth switch unit, and the second channel drive circuit unit is used to complete the contact closing action of the second forced guide relay;

[0022] The fifth switching unit is connected to the power module, the second channel drive circuit unit and the fourth switching unit, and maintains the contact closing action of the second forced guide relay;

[0023] The first drive enable circuit is connected to the power module, the second drive enable circuit and the first channel drive circuit unit. The first drive enable circuit detects whether the voltage control signal of the first channel drive circuit unit reaches the conduction standard and turns on the first drive enable circuit.

[0024] The fourth switching unit is connected to the first channel driving circuit unit, the third switching unit, and the fifth switching unit. The fourth switching unit is used for loop self-testing of the second channel circuit to determine whether the fourth switching unit is in the initial state of conduction.

[0025] The first channel drive circuit unit is connected to the fourth switch unit, the third switch unit, the first drive enable circuit and the power module. The first channel drive circuit unit is used to complete the contact closing action of the first forced guide relay.

[0026] The third switching unit is connected to the power module, the first channel drive circuit unit and the sixth switching unit, and maintains the contact engagement of the first forced-guided relay.

[0027] In one embodiment, the first channel driving circuit unit includes a coil K1 of a first forced-guided relay, a second diode D2, a receiving terminal TR1-B of a first photoelectric relay, and a first capacitor C1. The switching output terminal of the receiving terminal TR1-B of the first photoelectric relay is connected to the positive terminal of the second diode D2, the negative terminal of the second diode D2 is connected to the coil K1 of the first forced-guided relay, the other end of the coil K1 of the first forced-guided relay is connected to the power supply module, and the switching input terminal of the receiving terminal TR1-B of the first photoelectric relay is connected to the fourth switching unit. The first capacitor C1 is connected in parallel with the circuit in which the coil K1 of the first forced-guided relay, the second diode D2, and the receiving terminal TR1-B of the first photoelectric relay are connected in series.

[0028] In one embodiment, the third switching unit is composed of the normally open contact of the first forced-guided relay and a first Zener diode ZD1 connected in series. In the third switching unit, the anode of the first Zener diode ZD1 is connected to the cathode of the second diode D2, the cathode of the first Zener diode ZD1 is connected to the normally open contact of the first forced-guided relay, and the other end of the normally open contact of the first forced-guided relay is connected to the power module.

[0029] In one embodiment, the fourth switching unit includes a first resistor R1 and a normally closed contact of a second forced-guided relay. The first resistor R1 and the normally closed contact of the second forced-guided relay are connected in series to the third switching unit and the first channel drive circuit unit, respectively.

[0030] In one embodiment, the first drive enable circuit includes a second transistor Q2, a second resistor R2, and a third resistor R3. The base of the second transistor Q2 is connected to the second resistor R2 and the third resistor R3, respectively. The other ends of the second resistor R2 and the third resistor R3 are connected to the two ends of the first capacitor C1, respectively. The collector of the second transistor Q2 is connected to the second drive enable circuit, and the emitter of the second transistor is connected to the power module.

[0031] In one embodiment, the second drive enable circuit includes a first transistor Q1, the base of the first transistor Q1 is connected to the collector of the second transistor Q2, the emitter of the first transistor Q1 is connected to the power module, and the collector of the first transistor Q1 is connected to the sixth switching unit.

[0032] In one embodiment, the second channel driving circuit unit includes a coil K2 of a second forced-guide relay and a light-emitting terminal TR1-A of a first photoelectric relay. The coil K2 of the second forced-guide relay and the light-emitting terminal TR1-A of the first photoelectric relay are connected in series. The intersection of the coil K2 of the second forced-guide relay and the light-emitting terminal TR1-A of the first photoelectric relay is connected to the sixth switching unit. The other end of the light-emitting terminal TR1-A of the first photoelectric relay is connected to the fifth switching unit. The other end of the coil K2 of the second forced-guide relay is connected to the power supply module.

[0033] In one embodiment, the sixth switching unit includes the normally closed contact of the first forced-guided relay, the second Zener diode ZD2, and the fourth resistor R4;

[0034] One end of the normally closed contact of the first forced-guided relay is connected to the collector of the first transistor Q1, and the other end of the normally closed contact of the first forced-guided relay is connected to the negative terminal of the second Zener diode ZD2. The positive terminal of the second Zener diode ZD2 is connected to the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the intersection of the coil K2 of the second forced-guided relay and the light-emitting terminal TR1-A of the first photoelectric relay.

[0035] In one embodiment, the fifth switching unit includes a normally open contact of the second forced-guided relay and a third Zener diode ZD3; one end of the normally open contact of the second forced-guided relay is connected to one end of the light-emitting terminal TR1-A of the first photoelectric relay, the other end of the normally open contact of the second forced-guided relay is connected to the positive terminal of the third Zener diode ZD3, and the negative terminal of the third Zener diode ZD3 is connected to the power supply module.

[0036] In one embodiment, the safety device further includes an emergency stop button and a start switch;

[0037] The emergency stop button includes several dual-channel switches, which are respectively connected to the first channel circuit and the second channel circuit. The emergency stop button is located between the power module and the first channel circuit and the second channel circuit.

[0038] The start switch is located between the power module and the second drive enable circuit.

[0039] In one embodiment, the power module includes a positive power input terminal A1, a negative power input terminal A2, a first channel power input S11, a second channel power input S21, and an external startup power supply S33, as well as a first diode D1 connected to the positive power input terminal, a first fuse PTC1 connected to the first diode D1, and the other end of the first fuse PTC1 connected to the first channel power input S11; the negative power input terminal A2 is connected to a second fuse PTC2, and the second fuse PTC2 is connected to the first channel circuit.

[0040] The beneficial effects of this utility model are as follows: The safety device for a control circuit provided by this utility model includes a first channel circuit and a second channel circuit in the control circuit to control the opening and closing of the two forced-guided relays respectively. It also includes a first drive enable circuit and a second drive enable circuit. The first drive enable circuit detects the activation state of the first channel circuit to determine whether the second channel circuit can be activated, while the second drive enable circuit activates the second channel circuit based on the activation state of the first channel circuit. The activation of the first channel circuit and the second channel circuit constitutes a heterogeneous action mode, which can minimize the possibility of simultaneous failure of the first channel circuit and the second channel circuit, thus improving the safety performance of the circuit. Attached Figure Description

[0041] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0042] Figure 1 This is a structural block diagram of the safety device for the control circuit provided in this embodiment.

[0043] Figure 2 This is a schematic diagram of the circuit structure of the safety device for controlling the circuit provided in this embodiment.

[0044] The components in the diagram are labeled as follows: Power module 11, Second drive enable circuit 12, First drive enable circuit 13, Fourth switch unit 14, First channel drive circuit unit 15, Third switch unit 16, Sixth switch unit 17, Second channel drive circuit unit 18, Fifth switch unit 19, Safety output module 20, Safety device 10, External sensor input signal 102, External start signal 103, First channel circuit 30, Second channel circuit 40. Detailed Implementation

[0045] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention and are mainly used to illustrate the embodiments, and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0046] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0047] like Figure 1 and Figure 2 As shown, this utility model provides a structural schematic diagram of an embodiment of a safety device 10 for a control circuit. The safety device 10 for the control circuit specifically includes: at least two forced-guide relays and a control circuit connected to the forced-guide relays. The control circuit includes: a power supply module 11, a control module, and a safety output module 20.

[0048] The power module 11 provides power to the control circuit through an external power supply. The power module 11 can also provide reverse protection, overvoltage protection, overcurrent protection and filtering of the input voltage of the external power supply, thereby providing a stable voltage for the control circuit.

[0049] The control module includes a first channel circuit 30 and a second channel circuit 40, respectively controlling the on and off states of the two forced-guided relays, a first drive enable circuit 13, and a second drive enable circuit 12. The first channel circuit 30 is connected to the first forced-guided relay, enabling and maintaining the first forced-guided relay in a conducting state. The second channel circuit 40 is connected to the second forced-guided relay, enabling and maintaining the second forced-guided relay in a conducting state. The first drive enable circuit 13 connects to the first channel circuit 30 and the second channel circuit 40, and the second drive enable circuit 12 connects to... The first channel circuit 30 and the second channel circuit 40 are connected, and both the first channel circuit 30 and the second channel circuit 40 are connected to the power module 11 and the safety output module 20. The first drive enable circuit 13 is turned on according to the state of the first channel circuit 30, and the second drive enable circuit 12 is turned on according to the on state of the first drive enable circuit 13, and feeds back the start state of the second channel circuit 40 to the first channel circuit 30 to maintain the conduction of the first channel circuit 30. Both the first channel circuit 30 and the second channel circuit 40 are connected to an external sensor input signal 102, and the second drive enable circuit 12 is connected to an external start signal 103. The external sensor input signal 102 can be the input signal of an emergency stop button, and the external start signal 103 can be the start signal of the circuit.

[0050] The safety output module 20 is composed of redundant contacts of two forced-guided relays connected in series, and is connected to an external circuit device. When the relay in either the first channel circuit 30 or the second channel circuit 40 loses power, the safety output module 20 immediately disconnects, achieving a redundancy design with a fault margin of 1. Furthermore, in the safety device 10 provided in this embodiment, after the second drive enable circuit 12 enables the first channel circuit 30 to start, the second channel circuit 40 is then started according to the state of the first channel circuit 30. This creates a heterogeneous operating mode for the first channel circuit 30 and the second channel circuit 40; that is, the first channel circuit 30 can be used for current carrying, while the second channel circuit 40 is used for switching. This minimizes the possibility of simultaneous failure of the first channel circuit 30 and the second channel circuit 40, significantly improving safety performance.

[0051] The first drive enable circuit 13 includes at least a first switching unit. The controlled input terminal of the first switching unit is connected to the first channel circuit 30, and the switching output terminal of the first switching unit is connected to the power module 11 and the second drive enable circuit 12, respectively. The first switching unit is turned on according to the voltage control signal of the first channel circuit 40. The second drive enable circuit 12 includes at least a second switching unit. The controlled input terminal of the second switching unit is connected to the first drive enable circuit 13, and the switching output terminal of the second switching unit is connected to the second channel circuit 40 and the power module 11, respectively. The second switching unit turns on the switch according to the conduction status of the first switching unit, thereby enabling the second channel circuit 40.

[0052] In this embodiment, the first channel circuit 30 includes a third switch unit 16 and a fourth switch unit 14, the second channel circuit 40 includes a fifth switch unit 19 and a sixth switch unit 17, and the second drive enable circuit 12 is connected to the sixth switch unit 17; the switching states of the third switch unit 16 and the sixth switch unit 17 are always opposite, and the switching states of the fifth switch unit 19 and the fourth switch unit 14 are always opposite.

[0053] The third switch unit 16 is initially open, the fourth switch unit 14 is initially closed, the fifth switch unit 19 is initially open, and the sixth switch unit 17 is initially closed.

[0054] When the first drive enable circuit 13 and the second drive enable circuit 12 are turned on, the second channel circuit 40 is energized and turned on, the fifth switch unit 19 is turned on and the fourth switch unit 14 is turned off; when the first channel circuit 30 is energized and turned on, the third switch unit 16 is turned on and the sixth switch unit 17 is turned off, and the first channel circuit 30 is kept on.

[0055] In another embodiment, the third switching unit 16 is a first normally open switching circuit, the fourth switching unit 14 is a second normally closed switching circuit, the fifth switching unit 19 is a second normally open switching circuit, and the sixth switching unit 17 is a first normally closed switching circuit.

[0056] That is, the first channel circuit includes a first normally open switch circuit and a second normally closed switch circuit, the second channel circuit includes a second normally open switch circuit and a first normally closed switch circuit, and the second drive enable circuit is connected to the first normally closed switch circuit; the switching states of the first normally open switch circuit and the first normally closed switch circuit are opposite, and the switching states of the second normally open switch circuit and the second normally closed switch circuit are opposite.

[0057] The first drive enable circuit and the second drive enable circuit are turned on, the second channel circuit is energized and turned on, the second normally open switch circuit is turned on and the second normally closed switch circuit is turned off; the first channel circuit is energized and turned on, the first normally open switch circuit is turned on and the first normally closed switch circuit is turned off, and the first channel circuit is maintained on. Specifically, in this embodiment, the first channel circuit 30 includes: a first channel drive circuit unit 15, a third switch unit 16 and a fourth switch unit 14; the second channel circuit 40 includes: a second channel drive circuit unit 18, a fifth switch unit 19 and a sixth switch unit 17.

[0058] The second drive enable circuit 12 is a switching circuit. The control terminal of the second drive enable circuit 12 is connected to the first drive enable circuit 13. The switching terminal of the second drive enable circuit 12 is connected to the sixth switching unit 17 and the power module 11 respectively. The second drive enable circuit 12 turns on the switch according to the detected conduction state of the first drive enable circuit 13, so as to provide a positive power circuit for the second channel circuit 40.

[0059] The sixth switch unit 17 is a normally closed switch circuit. The sixth switch unit 17 is connected to the output port of the switch terminal of the second drive enable circuit 12, the third switch unit 16, and the second channel drive circuit unit 18. After the second drive enable circuit 12 is turned on, the output port of the switch terminal of the second drive enable circuit 12 is turned on. The sixth switch unit 17 can detect whether the first forced guide relay in the first channel circuit 30 is in a de-energized state and whether the normally closed contact function of the first forced guide relay is normal by whether the normally closed switch circuit is in a closed state. That is, the sixth switch unit 17 is used for loop self-test of the first channel circuit 30.

[0060] The second channel driving circuit unit 18 is a diode driving circuit. The second channel driving circuit unit 18 is connected to the sixth switch unit 17 and the fifth switch unit 19 respectively. When the sixth switch unit 17 detects that the normally closed contact of the first forced guiding relay is functioning normally and is closed, the second channel driving circuit unit 18 turns on the fifth switch unit 19, and the fifth switch unit 19 is energized. The second channel driving circuit unit 18 is used to complete the normally open contact closing action of the second forced guiding relay.

[0061] The fifth switching unit 19 is a normally open switching circuit. The fifth switching unit 19 turns the switch on or off according to the conduction control of the second channel driving circuit unit 18. The fifth switching unit 19 is connected to the second channel driving circuit unit 18, the power module 11 and the fourth switching unit 14. After the fifth switching unit 19 is powered on, the switch is turned on. The power module 11 supplies power to the second channel driving circuit unit 18 to maintain the closing action of the normally open contact of the second forced guide relay.

[0062] The first drive enable circuit 13 is a switching circuit. The controlled input terminal of the first drive enable circuit 13 is connected to the first channel drive circuit unit 15. The switch output terminal of the first drive enable circuit 13 is connected to the second drive enable circuit 12 and the power module 11. The first drive enable circuit 13 detects whether the voltage control signal of the first channel drive circuit unit 15 reaches the conduction standard and turns on the first drive enable circuit 13.

[0063] The fourth switching unit 14 is a normally closed switching circuit. The fourth switching unit 14 is connected to the first channel driving circuit unit 15, the third switching unit 16, and the fifth switching unit 19. When the contacts of the fourth switching unit 14 are functioning normally and closed, the first channel driving circuit unit 15 is energized. The switching states of the fourth switching unit 14 and the fifth switching unit 19 are opposite. That is, when the fourth switching unit 14 is in the closed state, the fifth switching unit 19 is in the open state, and when the fourth switching unit 14 is in the open state, the fifth switching unit 19 is in the closed state. The fourth switching unit 14 is used for loop self-testing of the second channel circuit 40 to determine whether the fourth switching unit 14 is in the initial conducting state.

[0064] The first channel drive circuit unit 15 is a switching circuit. The first channel drive circuit unit 15 controls the opening or closing of the switch according to the status signal of the fourth switch unit 14. The first channel drive circuit unit 15 is connected to the fourth switch unit 14, the third switch unit 16, the first drive enable circuit 13 and the power module 11. After the fifth switch unit 19 is energized and closed, the first channel drive circuit unit 15 will also be energized and turned on. The first channel drive circuit unit 15 is used to complete the closing action of the normally open contact of the first forced guide relay.

[0065] The third switching unit 16 is a normally open switching circuit. The third switching unit 16 is connected to the first channel driving circuit unit 15, the sixth switching unit 17, and the power module 11. After the first channel driving circuit unit 15 is energized and turned on, the third switching unit 16 will also be energized and close the normally open switching circuit. Moreover, the switching states of the third switching unit 16 and the sixth switching unit 17 are opposite. That is, when the third switching unit 16 is in the closed state, the sixth switching unit 17 is in the open state, and when the third switching unit 16 is in the open state, the sixth switching unit 17 is in the closed state to maintain the energizing action of the normally open contact of the first forced guide relay.

[0066] Specifically, such as Figure 2 As shown, in this embodiment, the power module 11 includes an external power input positive terminal A1, a power input negative terminal A2, a first channel power input S11, a second channel power input S21, and an external startup power supply S33, as well as a first diode D1 connected to the power input positive terminal A1, a first PTC fuse PTC1 connected to the first diode D1, and the other end of the first PTC fuse being connected to the first channel power input S11; the power input negative terminal A2 is connected to a second PTC fuse PTC2, and the other end of the second PTC fuse PTC2 is connected to the first channel drive circuit unit 15 in the first channel circuit 30.

[0067] An emergency stop button is located between the power module 11 and the safety device 10. The emergency stop button comprises several emergency stop switches S1...Sn connected in series. In this embodiment, these emergency stop switches S1...Sn collectively form the external sensor input signal 102. The first channel power input S11 is connected to the input terminal S12 of the first channel circuit 30 via the emergency stop switches S1...Sn, and the second channel power input S21 is connected to the input terminal S22 of the second channel circuit 40 via the emergency stop switches S1...Sn. If any of the emergency stop switches S1...Sn are pressed, both the input terminals S12 of the first channel circuit 30 and S22 of the second channel circuit 40 are disconnected. A start switch RS is connected between the external start power supply S33 and the input terminal S34 of the external start signal 103. The input terminal S34 of the external start signal 103 is connected to the second drive enable circuit 12.

[0068] Specifically, the first channel driving circuit unit 15 includes a coil K1 of a first forced-guided relay, a second diode D2, a receiving terminal TR1-B of a first photoelectric relay, and a first capacitor C1. The switching output terminal of the receiving terminal TR1-B of the first photoelectric relay is connected to the positive terminal of the second diode D2, and the negative terminal of the second diode D2 is connected to the coil K1 of the first forced-guided relay. The other end of the coil K1 of the first forced-guided relay is connected to the second PTC fuse PTC2 of the power module 11. The switching input terminal of the receiving terminal TR1-B of the first photoelectric relay is connected to the second channel status detection circuit unit 14. The first capacitor C1 is connected in parallel with the circuit in which the coil K1 of the first forced-guided relay, the second diode D2, and the receiving terminal TR1-B of the first photoelectric relay are connected in series.

[0069] The fourth switching unit 14 includes a first resistor R1 and a normally closed contact of a second forced-guided relay. The first resistor R1 and the normally closed contact of the second forced-guided relay are connected in series and then connected to the third switching unit 16 and the first channel drive circuit unit 15, respectively. Since the fourth switching unit 14 is a normally closed switching circuit, after the start switch RS is connected, the first channel power input S11 charges the first capacitor C1 through the input terminal S12 of the first channel circuit 30 and through the fourth switching unit 14.

[0070] The third switching unit 16 is composed of the normally open contact of the first forced-guided relay and a first Zener diode ZD1 connected in series. In the third switching unit 16, the positive terminal of the first Zener diode ZD1 is connected to the negative terminal of the second diode D2, the negative terminal of the first Zener diode ZD1 is connected to the normally open contact of the first forced-guided relay, and the other end of the normally open contact of the first forced-guided relay is connected to the power module 11.

[0071] The second drive enable circuit 12 includes a first transistor Q1, the base of the first transistor Q1 is connected to the first drive enable circuit 13, the emitter of the first transistor Q1 is connected to the input terminal S34 of the external start signal 103, and the collector of the first transistor Q1 is connected to the sixth switching unit 17.

[0072] The first drive enable circuit 13 includes a second transistor Q2, a second resistor R2, and a third resistor R3. The base of the second transistor Q2 is connected to the second resistor R2 and the third resistor R3, respectively. The other ends of the second resistor R2 and the third resistor R3 are connected to the two ends of the first capacitor C1, respectively. The collector of the second transistor Q2 is connected to the base of the first transistor Q1 in the second drive enable circuit 12, and the emitter of the second transistor Q2 is connected to the power module 11.

[0073] The sixth switching unit 17 includes the normally closed contact of the first forced-guided relay, the second Zener diode ZD2, and the fourth resistor R4;

[0074] One end of the normally closed contact of the first forced-guided relay is connected to the collector of the first transistor Q1, and the other end of the normally closed contact of the first forced-guided relay is connected to the negative terminal of the second Zener diode ZD2. The positive terminal of the second Zener diode ZD2 is connected to the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the intersection of the coil K2 of the second forced-guided relay and the light-emitting terminal TR1-A of the first photoelectric relay.

[0075] The second channel driving circuit unit 18 includes the coil K2 of the second forced guidance relay and the light-emitting terminal TR1-A of the first photoelectric relay. The coil K2 of the second forced guidance relay and the light-emitting terminal TR1-A of the first photoelectric relay are connected in series. The intersection of the coil K2 of the second forced guidance relay and the light-emitting terminal TR1-A of the first photoelectric relay is connected to the sixth switching unit 17. The other end of the light-emitting terminal TR1-A of the first photoelectric relay is connected to the fifth switching unit 19. The other end of the coil K2 of the second forced guidance relay is connected to the input terminal S22 of the second channel circuit 40 in the power module 11.

[0076] Specifically, after the first capacitor C1 has finished charging, the second transistor Q2 is turned on, thereby turning on the first transistor Q1. Since the sixth switch unit 17 is the normally closed contact of the first forced-guided relay, the sixth switch unit 17 is in the on state, and the second channel drive circuit unit 18 is energized, that is, the coil of the second forced-guided relay of the second channel drive circuit unit 18 is energized.

[0077] The fifth switching unit 19 includes a normally open contact of the second forced-guided relay and a third Zener diode ZD3; one end of the normally open contact of the second forced-guided relay is connected to one end of the light-emitting terminal TR1-A of the first photoelectric relay, the other end of the normally open contact of the second forced-guided relay is connected to the positive terminal of the third Zener diode ZD3, and the negative terminal of the third Zener diode ZD3 is connected to the power module 11.

[0078] When the coil K2 of the second forced-guided relay is energized, the normally open contact of the second forced-guided relay located in the fifth switching unit 19 will close, and simultaneously the normally closed contact of the second forced-guided relay located in the fourth switching unit 14 will open. After the normally open contact of the second forced-guided relay closes, the light-emitting terminal TR1-A of the first photoelectric relay is energized and emits light, and the receiving terminal TR1-B of the first photoelectric relay located in the first channel driving circuit unit 15 receives the light and becomes conductive. At this time, the first channel driving circuit unit 15 is turned on, the coil K1 of the first forced-guided relay located in the first channel driving circuit unit 15 is energized, the normally open contact of the first forced-guided relay located in the third switching unit 16 closes, and simultaneously the normally closed contact of the first forced-guided relay located in the sixth switching unit 17 opens.

[0079] After both the first forced-guide relay and the second forced-guide relay are energized and their normally open contacts are closed, the third switch unit 16 and the fifth switch unit 19 respectively maintain the closed state of the first forced-guide relay and the second forced-guide relay.

[0080] This utility model provides a safety device 10 for a control circuit. The control circuit includes a first channel circuit 30 and a second channel circuit 40 to control the opening and closing of two forced-guided relays, respectively. It also includes a first drive-enabled circuit 13 and a second drive-enabled circuit 12. The first drive-enabled circuit 13 detects the activation state of the first channel circuit 30 to determine whether the second channel circuit 40 can be activated, while the second drive-enabled circuit 12 activates the second channel circuit 40 based on the activation state of the first channel circuit 30. The activation of the first channel circuit 30 and the second channel circuit 40 constitutes a heterogeneous action mode, which can minimize the possibility of simultaneous failure of the first channel circuit 30 and the second channel circuit 40, thus improving the safety performance of the circuit.

[0081] In this embodiment, the first forced-direction relay K1 and the second forced-direction relay K2 are forced-direction relays conforming to the IEC / EN 61810-3 standard. Figure 2As shown, when the positive power input terminal A1 and the negative power input terminal A2 are energized, the power module 11 achieves reverse protection through the first diode D1, and overcurrent protection against short circuits through the first PTC fuse PTC1 and the second PTC fuse PTC2, thereby providing a stable power supply to each functional module. In this embodiment, both the first PTC fuse PTC1 and the second PTC fuse PTC2 are resettable PTC fuses.

[0082] like Figure 2 As shown, the fourth switching unit 14 includes a normally closed contact of the second forced-guided relay, and the fourth switching unit 14 is connected in series with the first capacitor C1. Therefore, the first capacitor C1 can only be charged when the second forced-guided relay is de-energized and its normally closed contact functions normally. A fully charged first capacitor C1 becomes one of the closing conditions for the first channel drive circuit unit 15.

[0083] Before the second channel drive circuit unit 18 is powered on, the first drive enable circuit 13 monitors whether the first capacitor C1 in the first channel circuit 30 has finished charging and entered the ready state. If the first capacitor C1 has finished charging, the first transistor Q1 and the second transistor Q2 will be turned on, that is, the second drive enable circuit 12 is powered on. When the external start signal 103 is connected, S11-S12-S33-S34 in the first channel are connected in series, where S11 is the power supply of the first channel circuit 30, S12 is the input of the first channel circuit 30, S33 is the power supply of the external start signal 103, and S34 is the input of the external start signal 103. After S11-S12-S33-S34 in the first channel are connected in series, they provide drive power to the second channel circuit 40. The sixth switching unit 17 is connected to the second channel drive circuit unit 18 and is used to detect whether the first forced-guided relay K1 is in a de-energized state and whether the contact function of the first forced-guided relay K1 is normal. When the first forced-guided relay K1 is detected to be normal, the second channel drive circuit unit 18 is energized, and then the second forced-guided relay K2 is energized. The normally open contact of the second forced-guided relay K2 is closed, and the normally open contact is kept closed by the fifth switching unit 19. The charging circuit of the first capacitor C1 is then disconnected.

[0084] The second channel circuit 40 keeps the circuit energized, and the light-emitting terminal TR1-A of the first photorelay is energized, thereby turning on the receiving terminal TR1-B of the first photorelay, providing the second closing condition for the first channel drive circuit unit 15.

[0085] Therefore, after both closing conditions of the first channel drive circuit unit 15 are met, the first forced-guide relay K1 is energized and remains closed through its normally open contact. At this time, both the first forced-guide relay K1 and the second forced-guide relay K2 are energized and their normally open contacts are closed, maintaining their closed operation through the third switch unit 16 and the fifth switch unit 19. The safety output module 20 closes, and the safety device 10 enters the operating state. When either the first forced-guide relay K1 or the second forced-guide relay K2 loses power, the safety output module 20 will disconnect.

[0086] In this embodiment, the first drive enable circuit monitors the startup state of the first channel circuit, and the second drive enable circuit starts the second channel circuit according to the startup state of the first channel circuit, and feeds back the startup state of the second channel circuit to the first channel circuit to control the on / off state of the first channel circuit.

[0087] Alternatively, when an emergency power cut is required for safety reasons, the emergency stop buttons S1...Sn are pressed, meaning the external sensor input signal 102 is disconnected, inputs S12 and S22 are de-energized, all functional modules of the first channel circuit 30 and the second channel circuit 40 are de-energized, the first forced-guide relay K1 and the second forced-guide relay K2 are both disconnected, and the safety output module 20 is disconnected. Here, S12 is the input of the first channel circuit 30, and S22 is the input of the second channel circuit 40.

[0088] If, at this time, the normally open contact of the first forced-guide relay K1 fails to adhere, and an emergency power cut is required for safety, the emergency stop buttons S1...Sn are pressed. This disconnects the external sensor input signal 102, de-energizes inputs S12 and S22, de-energizes all functional modules of the first channel circuit 30 and the second channel circuit 40, and disconnects both the first forced-guide relay K1 and the second forced-guide relay K2. The normally open contact of the second forced-guide relay K2 also disconnects, and the safety output module 20 disconnects. In the next operating cycle, since the normally open contact of the first forced-guide relay K1 remains adhered, and the normally closed contact of the sixth switch unit 17 is open, the second forced-guide relay K2 in the second channel circuit 40 cannot be energized, and the safety output module 20 disconnects, enabling circuit self-diagnosis.

[0089] Similarly, if the normally open contact of the second forced-guide relay K2 fails to adhere and an emergency power cut is required for safety, the emergency stop buttons S1...Sn are pressed. This disconnects the external sensor input signal 102, de-energizes inputs S12 and S22, de-energizes all functional modules of the first channel circuit 30 and the second channel circuit 40, disconnects both the first forced-guide relay K1 and the second forced-guide relay K2, opens the normally open contact of the first forced-guide relay K1, and disconnects the safety output module 20. In the next operating cycle, since the normally open contact of the second forced-guide relay K2 remains adhered, the normally closed contact of the fourth switch unit 14 is open. At this time, the first capacitor C1 cannot be charged, the first channel drive circuit unit 15 is de-energized, the first forced-guide relay K1 in the first channel circuit 30 cannot be energized, and the safety output module 20 disconnects, enabling circuit self-diagnosis.

[0090] When an emergency power cut is required for safety, if the contacts of the emergency stop button S11-S12 circuit fail due to adhesion, when the emergency stop button S1...Sn is pressed, if the S12 input is not de-energized (i.e., the external sensor input signal 102 remains closed), the third switch unit 16 still has a current loop, and the first forced-guided relay K1 remains closed. However, if the S22 input is de-energized, all functional modules of the second channel circuit 40 lose power, the second forced-guided relay K2 opens, and the safety output module 20 disconnects. When the emergency stop button is restored, since the first forced-guided relay K1 in the first channel circuit 30 remains closed, the sixth switch unit 17 is in an open state (normally closed contact). At this time, the second channel drive circuit unit 18 is open, the second forced-guided relay K2 in the second channel circuit 40 cannot be energized, and the safety output module 20 disconnects, thereby enabling the detection of the external input sensor.

[0091] Similarly, when an emergency power cut is required for safety reasons, if the contacts of the emergency stop button S21-S22 circuit fail due to sticking, when the emergency stop button S1...Sn is pressed, if the S22 input is not de-energized (i.e., the external sensor input signal 102 is still closed), the fifth switch unit 19 still has a current loop, and the second forced-guided relay K2 remains closed. However, if the S12 input is de-energized, all functional modules of the first channel circuit 30 are de-energized, the first forced-guided relay K1 is disconnected, and the safety output module 20 is disconnected. When the emergency stop button is restored, since the second forced-guided relay K2 in the second channel circuit 40 remains closed, the fourth switch unit 14 is in an open state with its normally closed contacts open. At this time, the first capacitor C1 cannot be charged, the first channel drive circuit unit 15 is de-energized, the first forced-guided relay K1 in the first channel circuit 30 cannot be energized, and the safety output module 20 is disconnected, thereby realizing the detection of the external input sensor.

[0092] If a cross short circuit occurs in the input signal lines of the emergency stop button, specifically a short circuit between lines S11-S12 and S21-S22 (where S11-S12 is connected to the positive power input terminal A1 and S21-S22 is connected to the negative power input terminal A2), then the power module 11 will short-circuit, the first PTC fuse PTC1 and the second PTC fuse PTC2 will open, and all functional blocks of the first channel circuit 30 and the second channel circuit 40 will lose power. In other words, the safety output module 20 will disconnect, thus enabling the diagnosis of the input signal lines of the emergency stop button.

[0093] The safety device 10 for control circuits provided in this embodiment includes a power module 11, a first drive enable circuit 13, a second drive enable circuit 12, a first channel drive circuit unit 15, a third switch unit 16, a sixth switch unit 17, a second channel drive circuit unit 18, a fifth switch unit 19, and a fourth switch unit 14. It can monitor and shut down any component in case of dangerous failure, achieving highly reliable safety control. Furthermore, safety control and high reliability are achieved through a simple circuit, significantly reducing the cost of the device. The simple circuit also enables mutual and self-testing of the functions of each circuit, improving the safety and reliability of the device. It also effectively avoids using normally closed contacts of relays as safety outputs, improving vibration resistance.

[0094] Although the present invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the present invention without departing from the spirit and scope of the present invention as defined in the appended claims, and all such changes shall be within the scope of protection of the present invention.

Claims

1. A safety device for controlling an electrical circuit, characterized in that The application relates to a control circuit for at least two force-guided relays, comprising a power supply module, a control module and a safety output module. The power supply module provides power supply for the control circuit through an external power supply. The control module comprises a first channel circuit and a second channel circuit for controlling the opening and closing of the two force-guided relays respectively, a first drive allowing circuit and a second drive allowing circuit; the first channel circuit is connected with the first force-guided relay, the second channel circuit is connected with the second force-guided relay; the first drive allowing circuit is connected with the first channel circuit and the second drive allowing circuit, the second drive allowing circuit is connected with the power supply module, the first drive allowing circuit and the second channel circuit, the first channel circuit and the second channel circuit are connected with the power supply module and the safety output module; the first drive allowing circuit is turned on according to the state of the first channel circuit, the second drive allowing circuit turns on the second channel circuit according to the on-off state of the first drive allowing circuit, and feeds back the starting state of the second channel circuit to the first channel circuit to maintain the on state of the first channel circuit. The safety output module is composed of the contacts of the two force-guided relays in series redundancy.

2. The safety device for controlling an electrical circuit according to claim 1, characterized in that, The first drive allowing circuit comprises at least a first switch unit, the controlled input end of the first switch unit is connected with the first channel circuit, and the switch output end of the first switch unit is connected with the power supply module and the second drive allowing circuit respectively. The first switch unit is turned on according to the voltage control signal of the first channel circuit.

3. The safety device for controlling an electrical circuit according to claim 2, characterized in that, The second drive allowing circuit comprises at least a second switch unit, the controlled input end of the second switch unit is connected with the first drive allowing circuit, the switch output end of the second switch unit is connected with the second channel circuit and the power supply module respectively, the second switch unit is turned on according to the on-off state of the first switch unit, and the second switch unit turns on the second channel circuit.

4. The safety device for controlling an electrical circuit according to claim 1, wherein The first channel circuit comprises a third switch unit and a fourth switch unit, the second channel circuit comprises a fifth switch unit and a sixth switch unit, and the second drive allowing circuit is connected with the sixth switch unit; the on-off states of the third switch unit and the sixth switch unit are always opposite, and the on-off states of the fifth switch unit and the fourth switch unit are always opposite; The initial state of the third switch unit is off, the initial state of the fourth switch unit is on, the initial state of the fifth switch unit is off, and the initial state of the sixth switch unit is on; When the first drive allowing circuit and the second drive allowing circuit are turned on, the second channel circuit is powered on, the fifth switch unit is turned on and the fourth switch unit is turned off; The first channel circuit is powered on, the third switch unit is turned on and the sixth switch unit is turned off, and the on state of the first channel circuit is maintained. The first channel circuit is powered on, the third switch unit is turned on and the sixth switch unit is turned off, and the on state of the first channel circuit is maintained.

5. The safety device for controlling an electrical circuit according to claim 4, characterized in that, The third switch unit is a first normally open switch circuit, the fourth switch unit is a second normally closed switch circuit, the fifth switch unit is a second normally open switch circuit, and the sixth switch unit is a first normally closed switch circuit. The first channel circuit includes a first normally open switch circuit and a second normally closed switch circuit, the second channel circuit includes a second normally open switch circuit and a first normally closed switch circuit, and the second drive permission circuit is connected to the first normally closed switch circuit; the switch states of the first normally open switch circuit and the first normally closed switch circuit are opposite, and the switch states of the second normally open switch circuit and the second normally closed switch circuit are opposite; The first drive permission circuit and the second drive permission circuit are turned on, the second channel circuit is powered on and turned on, the second normally open switch circuit is turned on and the second normally closed switch circuit is turned off; The first channel circuit is powered on and turned on, the first normally open switch circuit is turned on and the first normally closed switch circuit is turned off, and the first channel circuit is maintained in the turned-on state.

6. A safety device for controlling an electrical circuit according to claim 4 or 5, characterized in that The first channel circuit further includes a first channel drive circuit unit, and the second channel circuit further includes a second channel drive circuit unit; The second drive permission circuit is connected to the sixth switch unit, the first drive permission circuit, and a power supply module, and the second drive permission circuit is turned on according to the turned-on state of the first drive permission circuit detected, to provide a forward power supply loop for the second channel circuit; The sixth switch unit is connected to the second drive permission circuit, the second channel drive circuit unit, and a third switch unit, and is used for loop self-checking of the first channel circuit to determine whether the sixth switch unit is in an initially turned-on state; The second channel drive circuit unit is connected to the sixth switch unit and the fifth switch unit, and is used for completing a contact attraction action of the second forced direction relay; The fifth switch unit is connected to the power supply module, the second channel drive circuit unit, and the fourth switch unit, to maintain the contact attraction action of the second forced direction relay; The first drive permission circuit is connected to the power supply module, the second drive permission circuit, and the first channel drive circuit unit, and the first drive permission circuit detects whether a voltage control signal of the first channel drive circuit unit reaches a turned-on standard and turns on the first drive permission circuit; The fourth switch unit is connected to the first channel drive circuit unit, the third switch unit, and the fifth switch unit, and is used for loop self-checking of the second channel circuit to determine whether the fourth switch unit is in an initially turned-on state; The first channel drive circuit unit is connected to the fourth switch unit, the third switch unit, the first drive permission circuit, and the power supply module, and is used for completing a contact attraction action of the first forced direction relay. The third switch unit is connected with the power module, the first channel drive circuit unit and the sixth switch unit, and maintains the contact attraction action of the first forced-oriented relay.

7. The safety device for controlling an electrical circuit according to claim 6, characterized in that, The first channel drive circuit unit comprises a coil K1 of the first forced-oriented relay, a second diode D2, a receiving end TR1-B of the first photoelectric relay, and a first capacitor C1. The switch output end of the receiving end TR1-B of the first photoelectric relay is connected with the anode of the second diode D2. The cathode of the second diode D2 is connected with the coil K1 of the first forced-oriented relay. The other end of the coil K1 of the first forced-oriented relay is connected with the power module. The switch input end of the receiving end TR1-B of the first photoelectric relay is connected with the fourth switch unit. The first capacitor C1 is connected in parallel with the circuit in which the coil K1 of the first forced-oriented relay, the second diode D2 and the receiving end TR1-B of the first photoelectric relay are connected in series.

8. The safety device for controlling an electrical circuit according to claim 7, characterized in that, The third switch unit is composed of a normally open contact of the first forced-oriented relay and a first voltage stabilizing diode ZD1 connected in series. The anode of the first voltage stabilizing diode ZD1 in the third switch unit is connected with the cathode of the second diode D2. The cathode of the first voltage stabilizing diode ZD1 is connected with the normally open contact of the first forced-oriented relay. The other end of the normally open contact of the first forced-oriented relay is connected with the power module.

9. The safety device for controlling an electrical circuit according to claim 8, characterized in that, The fourth switch unit comprises a first resistor R1 and a normally closed contact of the second forced-oriented relay. The first resistor R1 and the normally closed contact of the second forced-oriented relay are connected in series and connected with the third switch unit and the first channel drive circuit unit respectively.

10. The safety device for controlling an electrical circuit according to claim 9, wherein, The first drive permission circuit comprises a second triode Q2, a second resistor R2 and a third resistor R3. The base of the second triode Q2 is connected with the second resistor R2 and the third resistor R3 respectively. The other ends of the second resistor R2 and the third resistor R3 are connected with the two ends of the first capacitor C1 respectively. The collector of the second triode Q2 is connected with the second drive permission circuit. The emitter of the second triode is connected with the power module.

11. The safety device for controlling an electrical circuit according to claim 10, wherein, The second drive permission circuit comprises a first triode Q1. The base of the first triode Q1 is connected with the collector of the second triode Q2. The emitter of the first triode Q1 is connected with the power module. The collector of the first triode Q1 is connected with the sixth switch unit.

12. The safety device for controlling an electrical circuit according to claim 11, wherein, The second channel drive circuit unit comprises a coil K2 of the second forced-oriented relay and a light-emitting end TR1-A of the first photoelectric relay. The coil K2 of the second forced-oriented relay and the light-emitting end TR1-A of the first photoelectric relay are connected in series. The intersection of the coil K2 of the second forced-oriented relay and the light-emitting end TR1-A of the first photoelectric relay is connected with the sixth switch unit. The other end of the light-emitting end TR1-A of the first photoelectric relay is connected with the fifth switch unit. The other end of the coil K2 of the second forced-oriented relay is connected with the power module.

13. The safety device for controlling an electrical circuit according to claim 12, wherein, The sixth switch unit comprises the normally closed contact of the first forced guide relay, a second voltage stabilizing diode ZD2 and a fourth resistor R4. One end of the normally closed contact of the first forced guide relay is connected to the collector of the first triode Q1, the other end of the normally closed contact of the first forced guide relay is connected to the negative pole of the second voltage stabilizing diode ZD2, the positive pole of the second voltage stabilizing diode ZD2 is connected to the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the intersection of the coil K2 of the second forced guide relay and the light-emitting end TR1-A of the first photoelectric relay.

14. The safety device for controlling an electrical circuit according to claim 13, wherein, The fifth switch unit comprises the normally open contact of the second forced guide relay and a third voltage stabilizing diode ZD3; one end of the normally open contact of the second forced guide relay is connected to one end of the light-emitting end TR1-A of the first photoelectric relay, the other end of the normally open contact of the second forced guide relay is connected to the positive pole of the third voltage stabilizing diode ZD3, and the negative pole of the third voltage stabilizing diode ZD3 is connected to the power supply module.

15. The safety device for controlling an electrical circuit according to claim 1, wherein, The safety device further comprises an emergency stop button and a start switch. The emergency stop button comprises a plurality of double switches, the double switches of the emergency stop button are respectively connected to the first channel circuit and the second channel circuit, and the emergency stop button is arranged between the power supply module and the first channel circuit and the second channel circuit. The start switch is arranged between the power supply module and the second drive permission circuit.

16. The safety device for controlling an electrical circuit according to claim 1, wherein, The power supply module comprises a power input positive end A1 of an external power supply, a power input negative end A2, a first channel power input S11, a second channel power input S21 and an external start power S33, a first diode D1 connected to the power input positive end, a first fuse PTC1 connected to the first diode D1, and the other end of the first fuse PTC1 is connected to the first channel power input S11; the power input negative end A2 is connected to a second fuse PTC2, and the second fuse PTC2 is connected to the first channel circuit.

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