Equipment control system safety monitoring circuit

Abstract

The present invention discloses a safety monitoring circuit for an equipment control system. The control contacts of a safety relay are connected in series in the control signal loop of the controller to the actuator. Only when the working condition of the safety relay is normal, its control contacts can be closed, and the actuator can act under the control of the control signal of the controller. The fault state of the controller and other emergency situations can be monitored and judged. When the controller fails, the safety relay can be automatically activated immediately to make the actuator shut down safely and automatically keep shutting down until the controller fault is eliminated and the reset button is pressed after manual confirmation. The actuator can work normally, and the actuator can be prevented from automatically re-acting after the controller fault is eliminated. The safety monitoring circuit of the equipment control system has simple circuit wiring, high safety and high reliability.

Description

Technical Field

[0001] The invention relates to a safety monitoring control technology, in particular to a safety monitoring circuit for an equipment control system. Background Art

[0002] With the development of automation technology, programmable logic controllers (PLC) have been widely used in the field of industrial control. Although programmable logic controllers have high feasibility, they have higher safety requirements in the control of equipment such as gas turbines. If a programmable logic controller fails, it may cause the equipment to lose control, resulting in equipment loss or even personal safety accidents.

[0003] Common gas turbine control system safety monitoring circuits generally use a series of relays and switch contacts such as watchdog relays, emergency stop buttons, reset buttons, redundant relays, etc. to maintain a fault-free (powered) state and form a self-holding circuit. The circuit wiring method is complicated, and the safety and reliability of ordinary relays are not high enough. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a safety monitoring circuit for an equipment control system, which can safely shut down the actuator and automatically keep it shut down when the controller fails, avoiding the actuator from automatically restarting after the controller failure is eliminated. It has high safety and reliability, and the circuit wiring is simple.

[0005] In order to solve the above technical problems, the present invention provides a device control system safety monitoring circuit, which includes a controller PLC1, a watchdog relay KT1, a reset button SB1, an emergency button SB2 and a safety relay U1;

[0006] The safety relay U1 includes a working power supply positive connection point A1, a working power supply negative connection point A2, a reset positive connection point Y1, a reset negative connection point Y2, and a control contact C3;

[0007] The control contact C3 is a normally open contact. When the working power positive connection point A1 of the safety relay U1 is powered off, the control contact C3 is disconnected. When the working power positive connection point A1 of the safety relay U1 is connected to the positive DC power supply, if the reset positive connection point Y1 is connected to the reset negative connection point Y2, the control contact C3 is closed, otherwise the control contact C3 remains disconnected.

[0008] The safety relay U1 has its working power supply negative connection point A2 grounded;

[0009] The control signal output terminal 3 of the controller PLC1 is connected to an actuator E1 via the control contact C3;

[0010] The watchdog relay KT1 includes a watchdog contact K1 and a delay control circuit K2;

[0011] The delay control circuit K2 controls the watchdog contact K1 to close when its input terminal jumps from 0 level to high level, and controls the watchdog contact K1 to open when its input terminal maintains the same level for more than the delay release time;

[0012] The watchdog contact K1 of the watchdog relay KT1 and the emergency contact S2 of the emergency button SB2 are connected in series between the positive connection point A1 of the DC power supply and the working power supply of the safety relay U1;

[0013] The delay control circuit K2 of the watchdog relay KT1 is connected between the fault signal output terminal 1 of the controller PLC1 and the ground;

[0014] The fault signal output terminal 1 of the controller PLC1 continuously outputs 0 voltage or continuously outputs a high level when the controller PLC1 fails, and outputs a periodic pulse signal when the controller PLC1 works normally;

[0015] The period of the pulse signal is shorter than the delayed release time;

[0016] The emergency button SB2 has an emergency contact S2 that is closed in a natural state and can be opened when pressed;

[0017] The reset button SB1 has a reset contact S1 that is open in a natural state and can be closed when pressed;

[0018] The reset contact S1 of the reset button SB1 is connected in series between the reset positive connection point Y1 and the reset negative connection point Y2 of the safety relay U1.

[0019] Preferably, the controller PLC1 is a programmable controller;

[0020] The equipment control system is a gas turbine control system.

[0021] Preferably, the actuator E1 is a fuel shut-off valve of a gas turbine, installed in a fuel system of the gas turbine.

[0022] Preferably, the controller PLC1, watchdog relay KT1, reset button SB1, emergency button SB2, and safety relay U1 are all installed in the gas turbine control panel.

[0023] Preferably, the DC power supply is a 24V DC power supply;

[0024] The pulse voltage value of the periodic pulse signal is greater than 4V.

[0025] Preferably, the period of the pulse signal is 300ms;

[0026] The delayed release time of the watchdog relay KT1 is set to 400ms.

[0027] The equipment control system safety monitoring circuit of the present invention can monitor and determine whether the fault state of the controller PLC1 and other emergency situations occur. When the controller PLC1 fails, the safety relay U1 can be automatically activated immediately to make the actuator E1 shut down safely and automatically keep shutting down until the controller PLC1 fails and the reset button SB1 is pressed after manual confirmation. The actuator E1 can work normally, avoiding the actuator E1 from automatically re-acting after the controller PLC1 fails. The equipment control system safety monitoring circuit has simple circuit wiring, high safety and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The present invention is a circuit diagram of a safety monitoring circuit of an existing gas turbine control system;

[0030] Figure 2 It is a schematic diagram of the left and right directions of an embodiment of a gas turbine control system safety monitoring circuit of the present invention;

[0031] Figure 3 This is a schematic diagram of the working principle of the watchdog relay.

[0032] Description of reference numerals in the figures:

[0033] PLC1 controller; 1 fault signal output terminal; 3 control signal output terminal; KT1 watchdog relay; K1 watchdog contact; K2 coil; SB1 reset button; S1 reset contact; SB2 emergency button; S2 emergency contact; U1 safety relay; A1 working power supply positive connection point; A2 working power supply negative connection point; Y1 reset positive connection point; Y2 reset negative connection point; C3 control contact; E1 actuator. DETAILED DESCRIPTION

[0034] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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 are within the scope of protection of the present invention.

[0035] Embodiment 1

[0036] like Figure 1 As shown, the equipment control system safety monitoring circuit includes a controller PLC1, a watchdog relay KT1, a reset button SB1, an emergency button SB2 and a safety relay U1;

[0037] The safety relay U1 includes a working power supply positive connection point A1, a working power supply negative connection point A2, a reset positive connection point Y1, a reset negative connection point Y2, and a control contact C3;

[0038] The control contact C3 is a normally open contact. When the working power positive connection point A1 of the safety relay U1 is powered off, the control contact C3 is disconnected. When the working power positive connection point A1 of the safety relay U1 is connected to the positive DC power supply, if the reset positive connection point Y1 is connected to the reset negative connection point Y2, the control contact C3 is closed, otherwise the control contact C3 remains disconnected.

[0039] The safety relay U1 has its working power supply negative connection point A2 grounded;

[0040] The control signal output terminal 3 of the controller PLC1 is connected to an actuator E1 via the control contact C3;

[0041] The watchdog relay KT1 includes a watchdog contact K1 and a delay control circuit K2;

[0042] The delay control circuit K2 controls the watchdog contact K1 to close when its input terminal jumps from 0 level to high level, and controls the watchdog contact K1 to open when its input terminal maintains the same level for more than the delay release time;

[0043] The watchdog contact K1 of the watchdog relay KT1 and the emergency contact S2 of the emergency button SB2 are connected in series between the positive connection point A1 of the DC power supply and the working power supply of the safety relay U1;

[0044] The delay control circuit K2 of the watchdog relay KT1 is connected between the fault signal output terminal 1 of the controller PLC1 and the ground;

[0045] The fault signal output terminal 1 of the controller PLC1 continuously outputs 0 voltage or continuously outputs a high level when the controller PLC1 fails, and outputs a periodic pulse signal when the controller PLC1 works normally;

[0046] The period of the pulse signal is shorter than the delayed release time;

[0047] The emergency button SB2 has an emergency contact S2 that is closed in a natural state and can be opened when pressed;

[0048] The reset button SB1 has a reset contact S1 that is open in a natural state and can be closed when pressed;

[0049] The reset contact S1 of the reset button SB1 is connected in series between the reset positive connection point Y1 and the reset negative connection point Y2 of the safety relay U1.

[0050] In the equipment control system safety monitoring circuit of Example 1, when the controller PLC1 works normally, the delay control circuit of the watchdog relay KT1 applies a periodic pulse signal, and the watchdog contact K1 of the watchdog relay KT1 is closed. Under normal circumstances, the emergency contact S2 of the emergency button SB2 is closed, and the working power supply positive connection point A1 of the safety relay U1 is connected to the positive DC power supply. At this time, pressing the reset button SB1 briefly closes its reset contact S1, and the reset positive connection point Y1 of the safety relay U1 is briefly connected to the reset negative connection point Y2, and the control contact C3 of the safety relay U1 is closed, so that the safety relay U1 starts to work normally. At this time, the controller PLC1 can normally control the actuator E1.

[0051] After the controller PLC1 fails, its fault signal output terminal 1 continuously outputs 0 voltage or continuously outputs high level, the watchdog contact K1 of the watchdog relay KT1 is disconnected, the working power positive connection point A1 of the safety relay U1 is powered off, its control contact C3 is disconnected, the control signal output terminal 3 of the controller PLC1 is disconnected from the control terminal of the actuator E1, and the actuator E1 is shut down;

[0052] Similarly, when there is an emergency, the emergency button SB2 is pressed to disconnect its emergency contact S2, the working power positive connection point A1 of the safety relay U1 is de-energized, its control contact 13 is disconnected, the connection between the control signal output terminal 3 of the controller PLC1 and the control terminal of the actuator E1 is disconnected, and the actuator E1 is shut down;

[0053] After the controller PLC1 fails, when the working power positive connection point A1 of the safety relay U1 is powered off, or when the working power positive connection point A1 is connected to the DC power supply but the reset button SB1 is not pressed, the control contact C3 of the safety relay U1 remains disconnected; only after the fault of the controller PLC1 is eliminated, the watchdog relay KT1 and the emergency button SB2 are restored to normal working state, and the operator needs to manually press the reset button SB1, can the control contact C3 of the safety relay U1 be closed, the safety relay U1 is reset, and the controller PLC1 can control the actuator E1 to work normally.

[0054] In the equipment control system safety monitoring circuit of the first embodiment, the control contact C3 of the safety relay U1 is connected in series in the control signal loop of the controller PLC1 to the actuator E1. Only when the working conditions of the safety relay U1 are normal, its control contact C3 can be closed, and the actuator E1 can act under the control of the control signal of the controller PLC1. When the working conditions of the safety relay U1 cannot be met, the actuator E1 also loses power and closes, forcing the equipment to shut down.

[0055] The equipment control system safety monitoring circuit of the first embodiment can monitor and determine whether the fault state of the controller PLC1 and other emergency situations occur. When the controller PLC1 fails, the safety relay U1 can be automatically activated immediately to make the actuator E1 shut down safely and automatically keep shutting down until the controller PLC1 fault is eliminated and the reset button SB1 is pressed after manual confirmation. The actuator E1 can work normally to avoid the actuator E1 automatically re-acting after the controller PLC1 fault is eliminated. The equipment control system safety monitoring circuit of the first embodiment has simple circuit wiring, high safety and high reliability.

[0056] Embodiment 2

[0057] Based on the equipment control system safety monitoring circuit of the first embodiment, the controller PLC1 is a programmable controller;

[0058] The equipment control system is a gas turbine control system.

[0059] Preferably, the actuator E1 is a fuel shut-off valve of a gas turbine, installed in a fuel system of the gas turbine.

[0060] Preferably, the controller PLC1, watchdog relay KT1, reset button SB1, emergency button SB2, and safety relay U1 are all installed in the gas turbine control panel.

[0061] Preferably, the DC power supply is a 24V DC power supply;

[0062] The pulse voltage value of the periodic pulse signal is greater than 4V.

[0063] The equipment control system safety monitoring circuit of the second embodiment can close the fuel shut-off valve through the action of the safety relay U1 when the gas turbine control system fails or an emergency occurs, thereby cutting off the gas turbine fuel and shutting down the gas turbine safely.

[0064] Embodiment 3

[0065] Based on the control system safety monitoring circuit of the first embodiment, the period of the pulse signal is 300 ms, and the delayed release time of the watchdog relay KT1 is set to 400 ms.

[0066] The watchdog relay KT1 is a delayed release relay, and the delayed release time can be set. When the controller PLC1 works normally, its fault signal output terminal 1 outputs a periodic pulse signal. Every time the watchdog relay KT1 receives a rising pulse, the watchdog contact K1 remains closed within the delayed release time. Therefore, the controller PLC1 must output at least one pulse within the delayed release time to ensure that the watchdog contact K1 is continuously closed. When the period of the pulse signal is less than the delayed release time of the watchdog relay KT1, the watchdog contact K1 of the watchdog relay KT1 remains closed when the controller PLC1 works normally. When the controller PLC1 causes its fault signal output terminal 1 to be unable to send a pulse signal normally, its fault signal output terminal 1 continuously outputs 0 voltage or a continuous high level, and the watchdog contact K1 of the watchdog relay KT1 is disconnected. Figure 3 As shown, the purpose of monitoring whether the controller PLC1 fails is achieved.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device control system safety monitoring circuit, characterized in that: It includes a controller (PLC1), a watchdog relay (KT1), a reset button (SB1), an emergency button (SB2) and a safety relay (U1); The safety relay (U1) comprises a working power supply positive connection point (A1), a working power supply negative connection point (A2), a reset positive connection point (Y1), a reset negative connection point (Y2), and a control contact (C3); The control contact (C3) is a normally open contact. When the working power positive connection point (A1) of the safety relay (U1) is powered off, the control contact (C3) is disconnected; when the working power positive connection point (A1) of the safety relay (U1) is connected to the positive DC power supply, if the reset positive connection point (Y1) is connected to the reset negative connection point (Y2), the control contact (C3) is closed; otherwise, the control contact (C3) remains disconnected; The safety relay (U1) has a negative connection point (A2) of the working power supply connected to ground; The control signal output terminal (3) of the controller (PLC1) is connected to an actuator (E1) via the control contact (C3); The watchdog relay (KT1) comprises a watchdog contact (K1) and a delay control circuit (K2); The delay control circuit (K2) controls the gate contact (K1) to close when its input terminal jumps from 0 level to high level, and controls the gate contact (K1) to open when its input terminal maintains the same level for more than the delay release time; The watchdog contact (K1) of the watchdog relay (KT1) and the emergency contact (S2) of the emergency button (SB2) are connected in series between the positive connection point (A1) of the DC power supply and the working power supply of the safety relay (U1); A delay control circuit (K2) of a watchdog relay (KT1) is connected between a fault signal output terminal (1) of the controller (PLC1) and ground; The fault signal output terminal (1) of the controller (PLC1) continuously outputs a 0 voltage or continuously outputs a high level when the controller (PLC1) fails, and outputs a periodic pulse signal when the controller (PLC1) works normally; The period of the pulse signal is shorter than the delayed release time; The emergency button (SB2) has an emergency contact (S2) that is closed in a natural state and can be opened when pressed; The reset button (SB1) has a reset contact (S1) that is open in a natural state and can be closed when pressed; The reset contact (S1) of the reset button (SB1) is connected in series between the reset positive connection point (Y1) and the reset negative connection point (Y2) of the safety relay (U1); The equipment control system is a gas turbine control system; The pulse voltage value of the periodic pulse signal is greater than 4V.

2. The equipment control system safety monitoring circuit according to claim 1, characterized in that: The controller (PLC1) is a programmable controller.

3. The equipment control system safety monitoring circuit according to claim 2, characterized in that: The actuator (E1) is a fuel shut-off valve of a gas turbine and is installed in a fuel system of the gas turbine.

4. The equipment control system safety monitoring circuit according to claim 3, characterized in that: The controller (PLC1), the watchdog relay (KT1), the reset button (SB1), the emergency button (SB2), and the safety relay (U1) are all installed in the gas turbine control panel.

5. The equipment control system safety monitoring circuit according to claim 1, characterized in that: The DC power supply is a 24V DC power supply.

6. The equipment control system safety monitoring circuit according to claim 1, characterized in that: The period of the pulse signal is 300ms; The delayed release time of the watchdog relay (KT1) is set to 400ms.

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