Large-scale equipment safety switch device

Abstract

The utility model provides a safety switch device for large-scale equipment, and the device comprises a pre-starting circuit which comprises a pre-starting switch of which one end is connected with a positive electrode / live wire power line; the motor control circuit comprises a coil of a motor control relay and a motor starting switch connected with the coil in series, and the motor control relay is a relay used for controlling a controlled motor in the large-scale equipment to start and stop; one end of the motor control circuit is connected with the other end of the pre-starting switch, and the other end is connected with a negative electrode / zero line power line; the alarm circuit comprises a normally closed contact of the motor control relay and an alarm connected in series with the normally closed contact; one end of the alarm circuit is connected with the other end of the pre-starting switch, and the other end is used for connecting a negative electrode / zero line power line. The safety switch device is used for reducing the equipment cost and the structural complexity of the safety switch device under the condition of ensuring the safety of the starting process of the motor in the large-scale equipment.

Description

Technical Field

[0001] This utility model relates to the field of motor start-stop control technology, specifically to a safety switch device for large equipment. Background Technology

[0002] In certain specific applications, such as coal conveying equipment in mines, large pieces of equipment may not be encased due to application requirements or construction difficulties, leaving moving parts like motors directly exposed. If the motor is started directly during the operation of this large equipment, its rotation could potentially cause injury to people in the vicinity.

[0003] Chinese utility model patent CN219970951U discloses a coal conveyor belt start-up early warning system based on a microcomputer protection device. The system includes a motor control protector and an alarm bell. After receiving a start signal, the motor control protector first issues an alarm signal through the alarm bell but does not start the motor. Instead, it starts the motor after a certain delay, so that people around the motor can receive the alarm signal and move away from the equipment during the delay period to prevent the motor from starting and injuring people around them.

[0004] The aforementioned utility model patent relies on the motor control protector for both the start-up delay and the alarm signal during the motor startup process. Therefore, this approach not only increases the structural complexity of the early warning device but also increases its equipment cost. Utility Model Content

[0005] This utility model provides a safety switch device for large equipment, which reduces the equipment cost and structural complexity of the safety switch device while ensuring the safety of the motor starting process of large equipment.

[0006] A further objective of this invention is to improve the reliability and convenience of motor control in large-scale equipment.

[0007] Specifically, this utility model provides a safety switch device for large equipment, comprising:

[0008] A pre-start circuit includes a pre-start switch with one end for connecting to the positive / live power line;

[0009] A motor control circuit includes a coil of a motor control relay and a motor start switch connected in series with the coil, wherein the motor control relay is a relay used to control the start and stop of the controlled motor in the large equipment; one end of the motor control circuit is connected to the other end of the pre-start switch, and the other end is used to connect to the negative / neutral power supply line;

[0010] The alarm circuit includes a normally closed contact of the motor control relay and an alarm connected in series with the normally closed contact; one end of the alarm circuit is connected to the other end of the pre-start switch, and the other end is used to connect to the negative / neutral power supply line.

[0011] Furthermore, a normally open contact of the motor control relay is connected in parallel with the motor start switch to form a self-locking circuit for the motor control relay.

[0012] Furthermore, the motor control circuit includes a time delay relay, the coil of which is connected in parallel with the coil of the motor control relay, and a normally closed contact is provided in the line between the motor control circuit and the pre-start switch.

[0013] Furthermore, the motor control circuit includes a forward rotation control circuit and a reverse rotation control circuit connected in parallel with the forward rotation control circuit, wherein:

[0014] The forward rotation control circuit includes a coil of a forward rotation relay and a forward rotation start switch connected in series with the coil, wherein the forward rotation relay is a relay used to control the forward rotation of the controlled motor.

[0015] The reversing control circuit includes a coil of a reversing relay and a reversing start switch connected in series with the coil, wherein the reversing relay is a relay used to control the controlled motor to reverse.

[0016] Furthermore, a normally open contact of the forward rotation relay is connected in parallel with the forward rotation start switch to form a self-locking circuit for the forward rotation relay;

[0017] One normally open contact of the reversing relay is connected in parallel with the reversing start switch to form a self-locking circuit for the reversing relay.

[0018] Furthermore, the forward rotation control circuit includes a forward rotation time delay relay, the coil of which is connected in parallel with the coil of the forward rotation relay;

[0019] The reversing control circuit includes a reversing time-delay relay, the coil of which is connected in parallel with the coil of the reversing relay; and

[0020] The normally closed contacts of the forward delay relay and the reverse delay relay are connected in series and are located on the line between the motor control circuit and the pre-start switch.

[0021] Furthermore, the normally closed contact of the forward rotation relay is located in the reverse rotation control circuit and connected in series with the coil of the reverse rotation relay; the normally closed contact of the reverse rotation relay is located in the forward rotation control disconnect circuit and connected in series with the coil of the forward rotation relay, so that the forward rotation control circuit and the reverse rotation control circuit are mutually exclusive.

[0022] Furthermore, the pre-start circuit includes a pre-start relay, whose normally open contact is connected in parallel with the pre-start switch, one end of the coil is connected to the other end of the pre-start switch, and the other end is used to connect to the negative / neutral power line.

[0023] Furthermore, the pre-start circuit includes a power-off switch connected in series with the coil of the start relay, and the power-off switch is a normally closed switch.

[0024] Furthermore, an emergency stop switch is provided on the line connecting the pre-start switch to the alarm circuit and the motor control circuit; and / or

[0025] A stop switch is provided on the line connecting the motor control circuit to the pre-start switch.

[0026] This utility model discloses a safety switch device for large equipment. After the pre-start switch is closed, the alarm in the alarm circuit is energized and emits an alarm signal to alert personnel around the equipment to stay away. After the motor start switch is closed, the coil of the motor control relay is energized and its contacts actuate to control the controlled motor in the large equipment to start running. The alarm in the alarm circuit is de-energized and stops emitting alarm signals. Because this utility model emits an alarm signal through the alarm after the pre-start switch is closed, but does not directly control the controlled motor to start running, but only controls the controlled motor to start running after the motor start switch is closed, it can prevent the controlled motor from causing harm to personnel around the equipment during startup, thus improving the safety of the controlled motor startup process in large equipment. Furthermore, this utility model improves equipment safety by designing the electrical connection between the relay, switch, and alarm, eliminating the need for logic control devices such as motor control protectors. Therefore, it can reduce the structural complexity of the safety switch device and achieve the goal of saving equipment costs.

[0027] Furthermore, after the coil of the motor control relay is energized, the coil of the time-delay relay is also energized. After the coil of the time-delay relay is energized for a period of time, the normally open contact opens, de-energizing the coil of the motor control relay and stopping the controlled motor. Therefore, this invention can further enable the controlled motor to automatically stop working after running for a period of time, and the running time of the controlled motor is the delay time of the time-delay relay, thereby further improving the convenience of controlling the controlled motor. Attached Figure Description

[0028] The following sections will describe some specific embodiments of the present invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0029] Figure 1This is a circuit diagram of a safety switch device for large equipment according to an embodiment of the present invention;

[0030] Figure 2 This is a circuit diagram of a safety switch device for large equipment according to another embodiment of the present invention;

[0031] Figure 3 This is a circuit diagram of a safety switch device for large equipment according to another embodiment of the present invention;

[0032] Figure 4 A circuit diagram of a safety switch device for large equipment and a controlled motor according to an embodiment of the present invention;

[0033] Figure 5 This is a circuit diagram of a safety switch device for large equipment according to another embodiment of the present invention;

[0034] Figure 6 This is a circuit diagram of a safety switch device for large equipment according to another embodiment of the present invention;

[0035] Figure 7 This is a circuit diagram of a safety switch device for large equipment according to another embodiment of the present invention;

[0036] Figure 8 This is a circuit diagram of a safety switch device for large equipment according to another embodiment of the present invention;

[0037] Figure 9 This is a circuit diagram of a safety switch device for large equipment and a controlled motor according to another embodiment of the present invention. Detailed Implementation

[0038] The following reference Figures 1 to 9 This invention describes a safety switch device for large equipment according to an embodiment of the present invention. In this description, it should be understood that "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically described, this indicates that other features are not excluded and may be further included.

[0039] Unless otherwise expressly specified and limited, the terms "set," "install," "connect," "link," "fix," and "couple" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art should be able to understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0040] In the description of this embodiment, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] Example 1:

[0042] Please see Figure 1 , Figure 1 The diagram shown is a schematic circuit diagram of a safety switch device for large equipment according to an embodiment of the present invention. This safety switch device is used to control the motor in large equipment, such as coal conveying equipment in a coal mine. The controlled motor M in the large equipment is a three-phase four-wire AC motor. This AC motor is connected to the AC bus of the large equipment to draw power from the AC bus. A circuit breaker QF0 is installed on the line connecting the controlled motor M to the AC bus.

[0043] exist Figure 1 In the structure shown, the safety switch device of this embodiment includes a pre-start circuit, a motor control circuit, and an alarm circuit. The pre-start circuit includes a pre-start switch SA0 and a pre-start relay KA. The pre-start switch SA0 can be a manual switch, and the user can manually control the pre-start switch SA0 to close or open.

[0044] The motor control circuit includes a motor start switch SB and a motor control relay KM. The motor control relay KM has multiple normally open contacts and multiple normally closed contacts, with three normally open contacts connected to the three-phase power supply lines of the controlled motor M. The motor start switch SB can be a manual switch, connected in series with the coil of the motor control relay KM, and the user can manually control the motor start switch SB to close or open. In this embodiment, one end of the motor control circuit is connected to a pre-start switch SA0, and the other end is connected to the neutral power supply line.

[0045] The alarm circuit includes a normally closed contact of the motor control relay KM and an alarm XL, which can be an alarm light, and the normally closed contact is connected in series with the alarm XL. In this embodiment, the alarm circuit is connected in parallel with the motor control circuit, and one end of the alarm circuit is connected to one end of the pre-start switch SA0, and the other end is connected to the neutral power supply line.

[0046] The working principle of the safety switch device in this embodiment is as follows:

[0047] When the controlled motor needs to be started, if the user manually operates the pre-start switch SA0 to close it, the alarm XL in the alarm circuit will be energized and send an alarm signal to notify the surrounding personnel that the controlled motor is in the pre-start state.

[0048] After the user manually operates the motor start switch SB to close it, the coil of the motor control relay KM is energized, causing the normally open contact of the motor control relay KM to close and the normally closed contact to open.

[0049] After the normally closed contact of the motor control relay KM opens, the alarm XL is de-energized and stops emitting alarm signals, and the controlled motor M is energized and starts working.

[0050] As described above, in this embodiment, after the pre-start switch is closed, the alarm in the alarm circuit is energized and emits an alarm signal to alert personnel around the equipment to stay away. After the motor start switch is closed, the coil of the motor control relay is energized and its contacts actuate to control the controlled motor in the large equipment to start running. The alarm in the alarm circuit is then de-energized and stops emitting alarm signals. Because this embodiment emits an alarm signal through the alarm after the pre-start switch is closed, but does not directly control the controlled motor to start running, but only controls the controlled motor to start running after the motor start switch is closed, it can prevent the start of the controlled motor from causing harm to personnel around the equipment, thus improving the safety of the controlled motor start-up process in large equipment. Furthermore, this embodiment improves equipment safety by designing the electrical connection between the relay, switch, and alarm, eliminating the need for logic control devices such as motor control protectors. Therefore, it can reduce the structural complexity of the safety switch device, achieving the goal of saving equipment costs.

[0051] In this embodiment, the safety switch device for large equipment uses AC power and can draw power from the controlled motor M, such as... Figure 4As shown, in the large equipment safety switch device, the moving end of the pre-start switch SA0 is connected to the A-phase busbar via relay QF1, so that the A-phase busbar is used as the live wire in the power supply of the large equipment safety switch device, and the N-phase busbar is used as the neutral wire in the large equipment safety switch device. In other embodiments, the large equipment safety switch device can be powered by a DC power supply.

[0052] In some embodiments of this utility model, a normally open contact of the motor control relay KM is connected in parallel with the motor start switch SB to form a self-locking circuit for the motor control relay KM.

[0053] In this embodiment, the motor start switch SB can be a self-resetting manual switch that closes when pressed and opens when released. After the motor start switch SB closes to energize the coil of the motor control relay KM, the normally open contact connected in parallel with the motor start switch SB closes to self-lock the motor control relay KM. Even if the motor start switch SB is opened, the coil of the motor control relay KM can still be continuously powered, thereby improving the reliability of the power supply to the coil of the motor control relay KM.

[0054] In some embodiments of this utility model, the motor control circuit includes a time delay relay KT, the coil of which is connected in parallel with the coil of the motor control relay KM, and the normally closed contact of the time delay relay KT is located on the line between the motor control circuit and the pre-start switch SA0, that is, on the line where the motor start switch SB is connected to the pre-start switch SA0.

[0055] When the controlled motor is in the pre-start state, if the user operates the motor start switch SB to close it, the coil of the motor control relay KM and the coil of the time delay relay KT will be energized simultaneously. After the coil of the time delay relay KT is energized, its normally closed contact will open after the delay ends. After the normally closed contact of the time delay relay KT opens, the coil of the motor control relay KM will be de-energized, its normally closed contact will return to the closed state, and its normally open contact will be in the open state.

[0056] When the normally open contact of the motor control relay KM opens, the controlled motor stops working; when the normally closed contact of the motor control relay KM returns to the closed state, the alarm XL is energized and begins to emit an alarm signal to remind the user that the controlled motor M is in a pre-start state.

[0057] In this embodiment, a time-delay relay is set in the motor control circuit, which can enable the controlled motor to stop running automatically. The running time of the controlled motor is the delay time of the time-delay relay. Therefore, it can prevent the controlled motor M from working for a long time and improve the convenience of controlling the controlled motor.

[0058] Example 2:

[0059] In this embodiment, the motor control circuit includes a forward rotation control circuit and a reverse rotation control circuit. The forward rotation control circuit includes a forward rotation start switch SB1 and a forward rotation relay KM1. The forward rotation relay KM1 has multiple normally open contacts and multiple normally closed contacts. Three normally open contacts are connected to the forward rotation power line of the controlled motor M, and one normally closed contact is connected in parallel with the alarm circuit and the alarm XL. The forward rotation start switch SB1 is a normally open manual switch and is connected in series with the coil of the forward rotation relay KM1.

[0060] The reverse control circuit is connected in parallel with the forward control circuit. The reverse control circuit includes a reverse start switch SB2 and a reverse relay KM2. The reverse relay KM2 has multiple normally open contacts and multiple normally closed contacts. Three normally open contacts are connected to the reverse power supply line of the controlled motor M, and one normally closed contact is connected in parallel with a normally closed contact of the forward relay KM1 and the alarm XL in the alarm circuit. The reverse start switch SB2 is a normally open manual switch connected in series with the coil of the reverse relay KM2.

[0061] After the user manually operates the forward start switch SB1 to close it, the coil of the forward relay KM1 is energized, causing the normally open contact of the forward relay KM1 to close and the normally closed contact to open. After the normally closed contact of the forward relay KM1 opens, the alarm XL loses power and stops emitting alarm signals. After the normally open contact on the forward power line closes, the controlled motor starts to be energized and begins to work.

[0062] After the user manually operates the reverse start switch SB2 to close it, the coil of the reverse relay KM2 is energized, causing the normally open contact of the reverse relay KM2 to close and the normally closed contact to open. After the normally closed contact of the reverse relay KM2 opens, the alarm XL loses power and stops emitting alarm signals. After the normally open contact on the reverse power line closes, the controlled motor starts to be energized and begins to work.

[0063] This embodiment includes a forward rotation control circuit and a reverse rotation control circuit, which can control the controlled motor to rotate forward or in reverse, thereby improving the flexibility of motor control.

[0064] In some embodiments of this utility model, a normally open contact of the forward rotation relay KM1 is connected in parallel with the forward rotation start switch SB1 to form a self-locking circuit for the forward rotation relay; a normally open contact of the reverse rotation relay KM2 is connected in parallel with the reverse rotation start switch SB2 to form a self-locking circuit for the reverse rotation relay.

[0065] In this embodiment, both the forward start switch SB1 and the reverse start switch SB2 can be self-resetting manual switches that close when pressed and open when released. After the forward start switch SB1 is closed to energize the coil of the forward relay KM1, the normally open contact connected in parallel with the forward start switch SB1 closes to self-lock the forward relay KM1. Even if the forward start switch SB1 is opened, the coil of the forward relay KM1 can still be continuously powered, thereby improving the reliability of the power supply to the coil of the forward relay KM1.

[0066] After the reverse start switch SB2 is closed to energize the coil of the reverse relay KM2, the normally open contact connected in parallel with the reverse start switch SB2 closes to lock the reverse relay KM2. Even if the reverse start switch SB2 is opened, the coil of the reverse relay KM2 can be continuously powered, thereby improving the reliability of the power supply to the coil of the reverse relay KM2.

[0067] In some embodiments of this utility model, the forward rotation control circuit includes a forward rotation delay relay KT1, the coil of which is connected in parallel with the coil of the forward rotation relay KM1, and the normally closed contact of the forward rotation delay relay KT1 is located on the line between the forward rotation control circuit and the pre-start switch SA0, that is, on the line where the forward rotation start switch SB1 is connected to the pre-start switch SA0.

[0068] When the controlled motor is in the pre-start state, if the user operates the forward start switch SB1 to close it, the coils of the forward relay KM1 and the forward delay relay KT1 will be energized simultaneously. After the coil of the forward delay relay KT1 is energized, its normally closed contact will open after the delay ends. After the normally closed contact of the forward delay relay KT1 opens, the coil of the forward relay KM1 will be de-energized, its normally closed contact will return to the closed state, and its normally open contact will be in the open state.

[0069] When the normally open contact of the forward relay KM1 opens, the controlled motor stops working; when the normally closed contact of the forward relay KM1 returns to the closed state, the alarm XL is energized and begins to emit an alarm signal to remind the user that the controlled motor is in a pre-start state.

[0070] In this embodiment, the reversing control circuit includes a reversing time delay relay KT2. The coil of the reversing time delay relay KT2 is connected in parallel with the coil of the reversing relay KM2. The normally closed contact of the reversing time delay relay KT2 is located on the line between the reversing control circuit and the pre-start switch SA0, that is, on the line where the reversing start switch SB2 is connected to the pre-start switch SA0.

[0071] When the controlled motor is in the pre-start state, if the user operates the reverse start switch SB2 to close it, the coils of the reverse relay KM2 and the reverse delay relay KT2 will be energized simultaneously. After the coil of the reverse delay relay KT2 is energized, its normally closed contact will open after the delay ends. After the normally closed contact of the reverse delay relay KT2 opens, the coil of the reverse relay KM2 will be de-energized, its normally closed contact will return to the closed state, and its normally open contact will be in the open state.

[0072] When the normally open contact of the reverse relay KM2 opens, the controlled motor stops working; when the normally closed contact of the reverse relay KM2 returns to the closed state, the alarm XL is energized and begins to emit an alarm signal to remind the user that the controlled motor is in a pre-start state.

[0073] In this embodiment, a forward rotation delay relay is set in the forward rotation control circuit and a reverse rotation delay relay is set in the reverse rotation control circuit. This allows the controlled motor to automatically stop running. Furthermore, the forward rotation duration of the controlled motor is equal to the delay duration of the forward rotation delay relay, and the reverse rotation duration is equal to the delay duration of the reverse rotation delay relay, thereby improving the reliability and convenience of controlling the controlled motor.

[0074] In some embodiments of this utility model, a normally closed contact of the forward rotation relay KM1 is disposed in the reverse rotation control circuit and connected in series with the coil of the reverse rotation relay KM2; a normally closed contact of the reverse rotation relay KM2 is disposed in the forward rotation control circuit and connected in series with the coil of the forward rotation relay KM1.

[0075] When the coil of the forward relay KM1 is energized and its normally closed contact opens, the reverse relay KM2 disconnects from the pre-start switch SA0; when the coil of the reverse relay KM2 is energized and its normally closed contact opens, the forward relay KM1 disconnects from the pre-start switch SA0. Therefore, the forward control circuit and the reverse control circuit in this embodiment are mutually exclusive circuits.

[0076] In this embodiment, the forward control circuit and the reverse control circuit are set as mutually exclusive circuits, which can prevent the forward and reverse relays from being energized at the same time and causing damage to the controlled motor, thereby improving the safety of the controlled motor.

[0077] Example 3:

[0078] Based on the above embodiment 1 or embodiment 2, the pre-start circuit of this embodiment also includes a pre-start relay KA. The normally open contact of the pre-start relay KA is connected in parallel with the pre-start switch SA0. One end of the coil is connected to the other end of the pre-start switch SA0, and the other end is used to connect to the neutral power line.

[0079] In this embodiment, the pre-start switch SA0 can be a self-resetting manual switch that closes when pressed and opens when released. After the pre-start switch SA0 is closed, the coil of the pre-start relay KA is energized, and the normally open contact of the pre-start relay KA, which is connected in parallel with the pre-start switch SA0, closes, so that the start relay KA is self-locked and its normally open contact is in the closed state, ensuring the reliability of the power supply to the coil of the start relay KA.

[0080] Furthermore, in some embodiments of this utility model, a power-off switch SA1 connected in series with the coil of the pre-start relay KA is provided in the pre-start circuit.

[0081] In this embodiment, the power-off switch SA1 is a manually operated normally closed switch. When the controlled motor is in the pre-start state or in the working state, if the user operates the power-off switch SA1 to disconnect it, the coil of the pre-start relay KM1 will be de-energized and released from its self-locking state, thus de-energizing the motor control circuit and the alarm circuit. After the motor control circuit is de-energized, the controlled motor will be de-energized and exit the working state. After the alarm circuit is de-energized, the alarm XL will stop emitting alarm signals and the controlled motor will exit the pre-start state.

[0082] In this embodiment, a power-off switch is set in the pre-start circuit. By operating the power-off switch, the pre-start relay KM1 can be released from its self-locking state, so that the controlled motor can exit the pre-start state, thereby improving the reliability of the controlled large motor control.

[0083] In some embodiments of this utility model, an emergency stop switch SA2 is provided on the cable connecting the pre-start switch SA0 to the motor control circuit and the alarm circuit. One end of the emergency stop switch SA2 is connected to the pre-start switch SA0, and the other end is connected to the motor control circuit and the alarm circuit.

[0084] In this embodiment, the emergency stop switch SA2 can be a manual switch that can be pressed to open and pressed again to close, and the emergency stop switch SA2 is in a normally closed state; after the emergency stop switch SA2 is pressed to open it, the coil of the motor control relay KM is de-energized, causing the controlled motor M to stop running, and the alarm XL is de-energized and will not issue an alarm signal.

[0085] In this embodiment, a stop switch SA3 can also be installed on the cable connecting the pre-start switch SA0 to the motor control circuit. The stop switch SA3 can be a manual switch that can be opened by pressing and closed by releasing. After the stop switch SA3 is pressed to open, the coil of the motor control relay KM is de-energized, and the controlled motor M stops running.

[0086] In this embodiment, an emergency stop switch and a shutdown switch are provided in the safety switch device. In case of an emergency shutdown, the controlled motor can be stopped manually, thereby improving the reliability and controllability of the controlled motor.

[0087] Therefore, those skilled in the art should recognize that although many exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A safety switch device for large equipment, characterized in that, include: A pre-start circuit includes a pre-start switch with one end for connecting to the positive / live power line; A motor control circuit includes a coil of a motor control relay and a motor start switch connected in series with the coil, wherein the motor control relay is a relay used to control the start and stop of the controlled motor in the large equipment; one end of the motor control circuit is connected to the other end of the pre-start switch, and the other end is used to connect to the negative / neutral power supply line; The alarm circuit includes a normally closed contact of the motor control relay and an alarm connected in series with the normally closed contact; one end of the alarm circuit is connected to the other end of the pre-start switch, and the other end is used to connect to the negative / neutral power supply line.

2. The safety switch device for large equipment according to claim 1, characterized in that, One normally open contact of the motor control relay is connected in parallel with the motor start switch to form a self-locking circuit for the motor control relay.

3. The safety switch device for large equipment according to claim 2, characterized in that, The motor control circuit includes a time delay relay, the coil of which is connected in parallel with the coil of the motor control relay, and a normally closed contact is provided on the line between the motor control circuit and the pre-start switch.

4. The safety switch device for large equipment according to claim 1, characterized in that, The motor control circuit includes a forward rotation control circuit and a reverse rotation control circuit connected in parallel with the forward rotation control circuit, wherein: The forward rotation control circuit includes a coil of a forward rotation relay and a forward rotation start switch connected in series with the coil, wherein the forward rotation relay is a relay used to control the forward rotation of the controlled motor. The reversing control circuit includes a coil of a reversing relay and a reversing start switch connected in series with the coil, wherein the reversing relay is a relay used to control the controlled motor to reverse.

5. The safety switch device for large equipment according to claim 4, characterized in that, One normally open contact of the forward rotation relay is connected in parallel with the forward rotation start switch to form a self-locking circuit for the forward rotation relay; One normally open contact of the reversing relay is connected in parallel with the reversing start switch to form a self-locking circuit for the reversing relay.

6. The safety switch device for large equipment according to claim 5, characterized in that, The forward rotation control circuit includes a forward rotation delay relay, the coil of which is connected in parallel with the coil of the forward rotation relay; The reversing control circuit includes a reversing time-delay relay, the coil of which is connected in parallel with the coil of the reversing relay; as well as The normally closed contacts of the forward delay relay and the reverse delay relay are connected in series and are located on the line between the motor control circuit and the pre-start switch.

7. The safety switch device for large equipment according to any one of claims 4-6, characterized in that, The normally closed contact of the forward rotation relay is located in the reverse rotation control circuit and is connected in series with the coil of the reverse rotation relay; the normally closed contact of the reverse rotation relay is located in the forward rotation control disconnect circuit and is connected in series with the coil of the forward rotation relay, so that the forward rotation control circuit and the reverse rotation control circuit are mutually exclusive.

8. The safety switch device for large equipment according to any one of claims 1-6, characterized in that, The pre-start circuit includes a pre-start relay, whose normally open contact is connected in parallel with the pre-start switch. One end of the coil is connected to the other end of the pre-start switch, and the other end is used to connect to the negative / neutral power line.

9. The safety switch device for large equipment according to claim 8, characterized in that, The pre-start circuit includes a power-off switch connected in series with the coil of the pre-start relay, and the power-off switch is a normally closed switch.

10. The safety switch device for large equipment according to any one of claims 1-6, characterized in that, An emergency stop switch is provided on the line connecting the pre-start switch to the alarm circuit and the motor control circuit; and / or A stop switch is provided on the line connecting the motor control circuit to the pre-start switch.

Images