Control method and circuit of direct current contactor based on single-chip microcomputer

Abstract

The invention relates to the technical field of direct current contactor power consumption control, and discloses a control method and circuit of a direct current contactor based on a single-chip microcomputer, and the method comprises the steps: enabling the single-chip microcomputer to control a relay to be closed, enabling a contact of the relay to enable a current-limiting resistor to be in short circuit, and enabling the current-limiting resistor to stop working in the circuit; when an external power supply is connected, voltage is directly loaded on the direct-current contactor through a contact of the relay to drive the direct-current contactor to be closed; and after the state of the DC contactor is stable, the single-chip microcomputer controls the relay to be disconnected again, and the external power supply is supplied to the DC contactor after passing through the current-limiting resistor, thereby realizing current-limiting and voltage-dividing, and completing the control flow of the DC contactor. According to the invention, the relay is accurately controlled through the single-chip microcomputer, so that the closing and opening time of the DC contactor can be accurately mastered. Through the intelligent control of the single-chip microcomputer, the energy consumption can be effectively reduced and the overall efficiency can be improved on the premise of ensuring that the system meets the safety.

Description

Technical Field

[0001] The invention relates to the technical field of power consumption control of a DC contactor, and in particular to a control method and circuit of a DC contactor based on a single chip microcomputer. Background Art

[0002] At present, the power consumption of new energy vehicles, especially pure electric vehicles, is increasing, resulting in insufficient vehicle range and increasing user complaints. Since the DC contactors in the high-voltage control box of the power battery are directly controlled by 12V DC, there is currently no device on the market to reduce the power consumption of the contactors.

[0003] The internal control end of the current contactor is the coil. A 12V power supply is required only before the contactor is attracted to drive the coil to generate an attractive force. The maintenance voltage after attraction does not need to be maintained at 12V. Therefore, after the contactor is controlled to be attracted by a 12V power supply, if the 12V voltage is maintained, the contactor will generate useless power consumption and consume the power of the entire vehicle.

[0004] The invention with patent publication number CN113611572A is entitled "A method for energy-saving control of a contactor", comprising: contactor connection: after the control power supply is connected, the energy storage circuit works to charge the energy storage capacitor, and at the same time, the coil of the contactor KM generates an attractive magnetic force after receiving a pulse voltage signal, so that the actuating mechanism of the contactor KM is activated; contactor disconnection: when the control power supply is disconnected, the energy storage capacitor of the energy storage circuit discharges to provide release electric energy for the coil of the contactor KM, and the released electric energy is output through a full-bridge drive control circuit to output a pulse with a polarity opposite to the coil pull-in voltage of the contactor KM, and the coil of the contactor KM generates a reverse magnetic force, but the overall control structure is complex and cannot directly reduce the power consumption of the DC contactor. Summary of the invention

[0005] The object of the present invention is to provide a control method and circuit for a DC contactor based on a single chip microcomputer, so as to solve the technical problem of how to reduce the power consumption of the DC contactor by using a single chip microcomputer in the prior art.

[0006] The present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a control method for a DC contactor based on a single chip microcomputer, comprising: The single chip microcomputer controls the relay to close, so that the contacts of the relay short-circuit the current limiting resistor, causing the current limiting resistor to stop working in the circuit; Connect the external power supply, and the voltage is directly loaded on the DC contactor through the contacts of the relay, driving the DC contactor to close; After the state of the DC contactor stabilizes, the microcontroller controls the relay to disconnect again, and the external power is supplied to the DC contactor after passing through the current limiting resistor to achieve current limiting and voltage division.

[0007] Preferably, before controlling the relay to close, the single chip microcomputer first initializes the relay, the current limiting resistor and the DC contactor.

[0008] Furthermore, the specific process of initializing the relay is as follows: Connect the output interface of the single-chip microcomputer to the control signal input end of the relay, where one end of the relay control signal is connected to the single-chip microcomputer ground, and the other end is connected to the single-chip microcomputer IO port; According to the triggering mode of the relay, set the corresponding control signal level in the microcontroller; Detect the voltage difference across the contact switch of the relay, and determine whether the relay is closed based on the detection result.

[0009] Furthermore, the specific process of the microcontroller initializing the current limiting resistor is as follows: Connect the current limiting resistor in parallel with both ends of the relay contact switch, and test the working status of the entire circuit. When the relay contacts are disconnected, the current is limited.

[0010] Furthermore, the specific process of the microcontroller initializing the DC contactor is as follows: Connect the power supply end of the DC contactor to the power supply system; Connect the control signal input terminal of the DC contactor to another output port of the microcontroller; The test signal is sent through the single chip microcomputer to detect the control signal received by the DC contactor, and the initial state of the DC contactor is determined according to the detection result.

[0011] Preferably, the external power supply is a 12V DC power supply.

[0012] Preferably, in the step of waiting for the state of the DC contactor to stabilize, the state of the DC contactor is determined by a feedback signal provided by an auxiliary contact inside the DC contactor.

[0013] Furthermore, in the step of determining the state of the DC contactor through the feedback signal provided by the auxiliary contact inside the DC contactor, the specific process is as follows: When the single chip microcomputer controls the DC contactor to close, the state of the auxiliary contacts is monitored; If the auxiliary contact is successfully closed after the main contact is closed and maintains a stable closed state, it means that the DC contactor is working stably; on the contrary, if the auxiliary contact fails to close after the main contact is closed, or jitters or becomes unstable, it means that the DC contactor is unstable.

[0014] In a second aspect, the present invention provides a control circuit of a DC contactor based on a single-chip microcomputer, which is used to implement the above-mentioned control method of a DC contactor based on a single-chip microcomputer, wherein the control circuit includes a single-chip microcomputer and a DC contactor circuit; the DC contactor circuit includes a relay assembly, a DC contactor and a power supply; the relay assembly, the DC contactor and the power supply are connected in series in sequence to form a loop structure; the IO port of the single-chip microcomputer is connected to the control end of the relay assembly.

[0015] Preferably, the relay assembly includes a relay and a current-limiting resistor; the relay and the current-limiting resistor are arranged in parallel on the return structure; and the IO port end of the single-chip microcomputer is connected to the control end of the relay.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a control method for a DC contactor based on a single-chip microcomputer, wherein the single-chip microcomputer controls a relay to close, so that the contacts of the relay short-circuit a current-limiting resistor, causing the current-limiting resistor to not work in the circuit. When the relay is closed, an external power supply is connected, and at this time, the voltage is directly loaded on the DC contactor through the contacts of the relay, driving the DC contactor to close; after the state of the DC contactor is stable, the single-chip microcomputer controls the relay to disconnect again, and the external power supply is supplied to the DC contactor after passing through the current-limiting resistor, realizing current limiting and voltage division, and completing the control process of the DC contactor. The present invention can accurately grasp the closing and disconnecting timing of the DC contactor by using a single-chip microcomputer to precisely control the relay. The single-chip microcomputer has a high degree of integration and stability, and can work stably in a complex electrical environment, thereby improving the reliability and accuracy of the entire control system.

[0017] Furthermore, at the initial start-up of the DC contactor, the current limiting resistor is short-circuited by a relay, so that the voltage is directly loaded on the DC contactor, which can quickly drive it to close. This method can reduce the startup time and improve the system response speed. When the DC contactor is stable, the single-chip microcomputer controls the relay to disconnect, so that the external power supply is supplied to the DC contactor through the current limiting resistor. In this way, the current limiting resistor can play the role of current limiting and voltage dividing, effectively protecting the DC contactor and other circuit components from the impact of excessive current, and extending the service life of the equipment.

[0018] Furthermore, in the startup phase, a quick startup is achieved by short-circuiting the current limiting resistor, which reduces the energy consumption caused by the current limiting resistor. In the stable operation phase, although the current limiting resistor is still in the circuit, its role is to protect the circuit while also reducing the current and power consumption. Through the intelligent control of the single-chip microcomputer, it can ensure that the system effectively reduces energy consumption and improves overall efficiency while meeting safety requirements.

[0019] Furthermore, the present invention uses a single chip microcomputer as the control center, and different control programs can be written according to actual needs to achieve flexible adjustment of the DC contactor control process. This helps to meet the needs of different application scenarios and improve the versatility and flexibility of the system.

[0020] The present invention also provides a control circuit of a DC contactor based on a single chip microcomputer. The control circuit is composed of core components such as a single chip microcomputer, a DC contactor circuit, and a relay assembly, and the overall structure is simple and clear. The relay and the current limiting resistor in the relay assembly are arranged in parallel on the loop structure, which not only realizes the rapid start-up of the DC contactor, but also ensures the safety of the circuit during stable operation. This design reduces unnecessary circuit components and improves the overall efficiency of the circuit.

[0021] Furthermore, the single-chip microcomputer, as the core of the control circuit, has a high degree of integration and stability. By connecting its IO port to the control end of the relay, precise control of the relay can be achieved. This control method not only has a fast response speed, but also has high control accuracy, which can ensure that the DC contactor is accurately closed or opened when needed, thereby improving the reliability of the entire control system.

[0022] Furthermore, the single-chip microcomputer controls the relay to close, so that the external power supply is directly loaded on the DC contactor, thereby quickly driving it to close. This method reduces the startup time and improves the system response speed. At the same time, after the DC contactor is stable, the single-chip microcomputer controls the relay to disconnect, and the external power supply is supplied to the DC contactor through the current limiting resistor. The existence of the current limiting resistor plays the role of current limiting and voltage dividing, effectively protecting the DC contactor and other circuit components from the impact of excessive current. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of a control method for a DC contactor based on a single chip microcomputer in an embodiment of the present invention; Figure 2 Schematic diagram of the control circuit structure of a DC contactor based on a single chip microcomputer in an embodiment of the present invention; In the figure: 1. Microcontroller; 2. Relay; 3. Current limiting resistor; 4. DC contactor; 5. External power supply. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0025] The object of the present invention is to provide a control method and circuit for a DC contactor based on a single chip microcomputer, so as to solve the technical problem of how to reduce the power consumption of the DC contactor by using a single chip microcomputer in the prior art.

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1 In one embodiment of the present invention, a control method for a DC contactor based on a single chip microcomputer is provided, comprising the following steps: Step 1, controlling the relay 2 to close by the single chip microcomputer 1, so that the contact of the relay 2 short-circuits the current limiting resistor 3, causing the current limiting resistor 3 to stop working in the circuit; Specifically, before the control relay 2 is closed, the relay 2, the current limiting resistor 3 and the DC contactor 4 are initialized to ensure that each component is in a preset working state.

[0027] The specific process of initializing relay 2 is as follows: Connect the output interface of the single-chip computer 1 to the control signal input end of the relay 2, wherein one end of the relay 2 control signal is connected to the single-chip computer 1 ground, and the other end is connected to the single-chip computer IO port; According to the triggering mode of relay 2, the corresponding control signal level is set in single chip microcomputer 1; The voltage difference between the two ends of the contact switch of relay 2 is detected, and whether the relay is closed is determined based on the detection result.

[0028] The specific process of initializing the current limiting resistor 3 is as follows: Connect the current limiting resistor 3 in parallel with both ends of the contact switch of relay 2, and test the working state of the entire circuit. When the contact of relay 2 is disconnected, the current size is limited.

[0029] The specific process of the single chip microcomputer 1 initializing the DC contactor 4 is as follows: Connect the power supply end of the DC contactor 4 to the power supply system; Connecting the control signal input terminal of the DC contactor 4 to another output port of the single chip computer 1; The single chip microcomputer 1 sends a test signal to detect the control signal received by the DC contactor 4, and determines the initial state of the DC contactor 4 according to the detection result.

[0030] Step 2, when the relay 2 is closed, connect the external power supply 5, at this time the voltage is directly loaded on the DC contactor 4 through the contacts of the relay 2, driving the DC contactor 4 to close; Specifically, in this embodiment, the external power supply 5 is a 12V DC power supply.

[0031] Step 3, after the state of the DC contactor 4 is stable, the single chip computer 1 controls the relay 2 to be disconnected again, and the external power 5 is supplied to the DC contactor 4 after passing through the current limiting resistor 3 to achieve current limiting and voltage division.

[0032] Specifically, in the step after the state of the DC contactor 4 is stabilized, the state of the DC contactor 4 is determined by a feedback signal provided by an auxiliary contact inside the DC contactor 4 .

[0033] Among them, in the step of determining the state of the DC contactor 4 through the feedback signal provided by the auxiliary contact inside the DC contactor 4, the specific process is as follows: When the single chip microcomputer 1 controls the DC contactor 4 to close, the state of the auxiliary contact is monitored.

[0034] If the auxiliary contact is successfully closed after the main contact is closed and maintains a stable closed state, it means that the DC contactor is working stably; on the contrary, if the auxiliary contact fails to close after the main contact is closed, or jitters or becomes unstable, it means that the DC contactor is unstable.

[0035] In this embodiment, when the single chip microcomputer 1 sends a control signal, the control coil of the relay 2 is activated to generate a magnetic field, so that the contacts of the relay 2 are closed.

[0036] When the contacts of relay 2 are closed, a path is formed between the two contacts, allowing current to flow.

[0037] When the contacts of the relay 2 are closed, the positive electrode of the external power supply 5 (12V DC power supply) is connected to the control end of the DC contactor 4 through the contacts of the relay 2 .

[0038] At the same time, the negative pole of the external power source 5 is connected to the other control terminal (or common terminal) of the DC contactor 4 .

[0039] When the voltage of the external power source 5 is directly loaded on the control end of the DC contactor 4 through the contact of the relay 2, the electromagnetic mechanism inside the DC contactor 4 is activated.

[0040] The electromagnetic mechanism generates a magnetic field, attracting the moving iron core to move toward the static iron core, and driving the contact to move. At this time, the normally open contact of the DC contactor 4 is closed, and the normally closed contact is disconnected.

[0041] Closing of the DC contactor 4 forms a main circuit path, allowing a large current to pass through, thereby achieving control of the load.

[0042] After the state of the DC contactor 4 is stable, the single chip microcomputer sends a control signal again to deactivate the control coil of the relay 2, the magnetic field disappears, and the contacts of the relay 2 are disconnected.

[0043] After the contacts of the relay 2 are disconnected, the external power source 5 is no longer directly loaded on the control end of the DC contactor 4 through the contacts of the relay 2 , but is supplied to the DC contactor 4 after passing through the current limiting resistor 3 .

[0044] The function of the current limiting resistor 3 is to limit the current passing through the control end of the DC contactor 4 to prevent excessive current from damaging the DC contactor 4 or other circuit components.

[0045] After the current limiting resistor 3 is connected, although the current is limited within a certain range, the DC contactor 4 can still maintain a closed state (depending on its design and the voltage of the external power supply).

[0046] When the DC contactor 4 needs to be disconnected, the single chip microcomputer can cut off the power supply of the external power source 5 by controlling other circuits or components (such as another relay or switch), thereby realizing the disconnection of the DC contactor 4 .

[0047] This embodiment controls the power supply of the DC contactor 4 by the external power supply 5 by controlling the closing and opening of the relay 2 by the single chip microcomputer. When the relay 2 is closed, the external power supply 5 is directly loaded on the control end of the DC contactor 4 to drive it to close; after the relay 2 is disconnected, the external power supply 5 is supplied to the DC contactor 4 through the current limiting resistor 3 to achieve current limiting and voltage division. This method has the advantages of high control accuracy, good reliability, fast startup speed, etc., and is suitable for application scenarios that require precise control of the closing and opening of the DC contactor.

[0048] In summary, the present invention provides a control method for a DC contactor based on a single-chip microcomputer, by controlling the single-chip microcomputer 1 to close the relay 2, so that the contact of the relay 2 shorts the current limiting resistor 3, so that the current limiting resistor 3 does not work in the circuit. When the relay 2 is closed, the external power supply 5 is connected, and the voltage is directly loaded on the DC contactor 4 through the contact of the relay 2, driving the DC contactor 4 to close; after the state of the DC contactor 4 is stable, the single-chip microcomputer 1 controls the relay 2 to disconnect again, and the external power supply 5 is supplied to the DC contactor 4 after passing through the current limiting resistor 3, realizing current limiting and voltage division, and completing the control process of the DC contactor 4. The present invention can accurately control the relay 2 through the single-chip microcomputer 1, and can realize the accurate grasp of the closing and disconnecting timing of the DC contactor 4. The single-chip microcomputer 1 has a high degree of integration and stability, and can work stably in a complex electrical environment, thereby improving the reliability and accuracy of the entire control system.

[0049] Example 2 according to Figure 2As shown, this embodiment provides a control circuit of a DC contactor based on a single-chip microcomputer, which is used to implement the above-mentioned control method of a DC contactor based on a single-chip microcomputer, and the control circuit includes a single-chip microcomputer 1 and a DC contactor circuit; the DC contactor circuit includes a relay component, a DC contactor 4 and a power supply; the relay component, the DC contactor 4 and the power supply 5 are connected in series in sequence to form a loop structure; the IO port end of the single-chip microcomputer 1 is connected to the control end of the relay component.

[0050] Specifically, the relay assembly includes a relay 2 and a current-limiting resistor 3 ; the relay 2 and the current-limiting resistor 3 are arranged in parallel on the return structure; and the IO port end of the single-chip computer 1 is connected to the control end of the relay 2 .

[0051] In this embodiment, the relay 2 is used to control the short-circuit current limiting resistor; the current limiting resistor 3 is used to be connected in series with the DC contactor to play the role of current reduction and voltage division; the single chip computer 1 is used to control the relay to be closed and opened.

[0052] In this embodiment, the single chip microcomputer 1 is the core of the control circuit, which has high integration and stability. Through its IO port end connected to the control end of the relay 2, accurate control of the relay 2 can be achieved. This control method not only has a fast response speed, but also has high control accuracy, and can ensure that the DC contactor 4 is accurately closed or opened when needed, thereby improving the reliability of the entire control system.

[0053] In the present embodiment, during the startup phase, the single chip microcomputer 1 controls the relay 2 to close, so that the external power source is directly loaded on the DC contactor 4, thereby quickly driving it to close. This method reduces the startup time and improves the system response speed. At the same time, after the DC contactor 4 is in a stable state, the single chip microcomputer 1 controls the relay 2 to disconnect, and the external power source 5 is supplied to the DC contactor 4 through the current limiting resistor 3. The existence of the current limiting resistor 3 plays the role of current limiting and voltage dividing, effectively protecting the DC contactor 4 and other circuit components from the impact of excessive current.

[0054] In this embodiment, the relay 2 is mainly used to achieve the effect of controlling the large with the small. The voltage drop of the relay 2 is small, and the current limiting resistor 3 is short-circuited. First, it is ensured that the pull-in voltage of the DC contactor 4 reaches the 12V requirement. After ensuring that the DC contactor 4 can be pulled in, the relay 2 is disconnected to allow the current limiting resistor 3 to work, thereby reducing the power consumption of the DC contactor 4 and reducing the power consumption of the entire vehicle.

[0055] In the startup phase, this embodiment achieves rapid startup by short-circuiting the current limiting resistor 3, thereby reducing the energy consumption caused by the current limiting resistor. In the stable operation phase, although the current limiting resistor 3 is still in the circuit, its function is to protect the circuit rather than increase additional energy consumption. Through the intelligent control of the single-chip microcomputer, it can be ensured that the system reduces energy consumption as much as possible while meeting the safety requirements, which meets the energy-saving and environmental protection requirements of modern electronic equipment.

[0056] In summary, the present invention also provides a control circuit of a DC contactor based on a single-chip microcomputer. The control circuit is composed of core components such as a single-chip microcomputer 1, a DC contactor circuit, and a relay assembly, and the overall structure is concise and clear. The relay and the current limiting resistor in the relay assembly are arranged in parallel on the loop structure, which not only realizes the rapid start-up of the DC contactor, but also ensures the safety of the circuit during stable operation. This design reduces unnecessary circuit components and improves the overall efficiency of the circuit.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A control method for a DC contactor based on a single chip microcomputer, characterized in that: include: The single chip microcomputer controls the relay to close, so that the contacts of the relay short-circuit the current limiting resistor, causing the current limiting resistor to stop working in the circuit; Connect the external power supply, and the voltage is directly loaded on the DC contactor through the contacts of the relay, driving the DC contactor to close; After the state of the DC contactor stabilizes, the microcontroller controls the relay to disconnect again, and the external power is supplied to the DC contactor after passing through the current limiting resistor to achieve current limiting and voltage division.

2. A control method for a DC contactor based on a single chip microcomputer according to claim 1, characterized in that: Before the control relay (2) is closed, the relay (2), the current limiting resistor (3) and the DC contactor (4) are initialized.

3. The control method of a DC contactor based on a single chip microcomputer according to claim 2 is characterized in that: The specific process of initializing the relay (2) is as follows: Connecting the output interface of the single-chip computer (1) to the control signal input end of the relay (2), wherein one end of the control signal of the relay (2) is connected to the ground of the single-chip computer (1), and the other end is connected to the IO port of the single-chip computer; According to the triggering mode of the relay (2), the corresponding control signal level is set in the single chip microcomputer (1); The voltage difference between the two ends of the contact switch of the relay (2) is detected, and whether the relay is closed is determined based on the detection result.

4. The control method of a DC contactor based on a single chip microcomputer according to claim 2 is characterized in that: The specific process of initializing the current limiting resistor (3) is as follows: The current limiting resistor (3) is connected in parallel to both ends of the contact switch of the relay (2), and the working state of the entire circuit is tested. When the contact of the relay (2) is disconnected, the current is limited.

5. The control method of a DC contactor based on a single chip microcomputer according to claim 2, characterized in that: The specific process of the single chip microcomputer (1) initializing the DC contactor (4) is as follows: Connect the power supply terminal of the DC contactor (4) to the power supply system; Connecting a control signal input terminal of the DC contactor (4) to another output port of the single chip computer (1); A test signal is sent through the single chip computer (1) to detect the control signal received by the DC contactor (4), and the initial state of the DC contactor (4) is determined according to the detection result.

6. The control method of a DC contactor based on a single chip microcomputer according to claim 1, characterized in that: The external power supply (5) is a 12V DC power supply.

7. The control method of a DC contactor based on a single chip microcomputer according to claim 1, characterized in that: In the step of waiting for the state of the DC contactor (4) to stabilize, the state of the DC contactor (4) is determined by a feedback signal provided by an auxiliary contact inside the DC contactor (4).

8. The control method of a DC contactor based on a single chip microcomputer according to claim 7, characterized in that: In the step of determining the state of the DC contactor (4) through the feedback signal provided by the auxiliary contact inside the DC contactor (4), the specific process is as follows: When the single chip microcomputer (1) controls the DC contactor (4) to close, the state of the auxiliary contact is monitored; If the auxiliary contact is successfully closed after the main contact is closed and remains in a stable closed state, it means that the DC contactor is working stably; On the contrary, if the auxiliary contacts fail to close after the main contacts close, or if they jitter or become unstable, it means that the DC contactor is unstable.

9. A control circuit of a DC contactor based on a single chip microcomputer, characterized in that: A control method for a DC contactor based on a single-chip microcomputer is used to implement any one of claims 1 to 8, wherein the control circuit comprises a single-chip microcomputer (1) and a DC contactor circuit; the DC contactor circuit comprises a relay assembly, a DC contactor (4) and a power supply; the relay assembly, the DC contactor (4) and the power supply (5) are sequentially connected in series to form a circuit structure; and the IO port end of the single-chip microcomputer (1) is connected to the control end of the relay assembly.

10. A control circuit for a DC contactor based on a single chip microcomputer according to claim 9, characterized in that: The relay assembly comprises a relay (2) and a current-limiting resistor (3); the relay (2) and the current-limiting resistor (3) are arranged in parallel on a return structure; and the IO port end of the single-chip computer (1) is connected to the control end of the relay (2).

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