Water cut-off protection device for mining dust removal system

Abstract

A water-break protection device for a mining dust removal system comprises a shell and a wiring port arranged on the shell, an anode and a cathode are arranged on the shell, the anode is connected with an anode wiring terminal in the shell, and the cathode is connected with a cathode wiring terminal in the shell. The anode wiring terminal and the cathode wiring terminal can be respectively connected with terminals on a liquid level relay in the local control box through leads penetrating through the wiring ports; as the device is connected with the liquid level relay, whether slime water flows out or not is monitored in real time, so that the working state of the negative-pressure dust removal main waterway electromagnetic valve is judged, and the problem that a large amount of dust is raised at an air outlet due to continuous operation of a fan after a waterway fault occurs is solved. The dust concentration exceeds the standard to pollute the environment, the high-temperature fault alarm of the motor is easily caused without waterway cooling, and the insulation is aged and damaged are solved, and the total dust removal efficiency can reach 99% or above; therefore, the fault rate and the maintenance rate of the dust removal fan can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of mine dust removal, in particular to a water cut-off protection device for a mine dust removal system. Background Art

[0002] At the mining site, due to the harsh use environment, the nozzles are often blocked or the solenoid valves are damaged. The above failures will cause the water circuit in the dust removal system to be blocked, and the fan will run idly and extract the sealed dust-containing air in the chute to the exhaust outlet. Not only does it not achieve the dust removal effect, but it also causes the dust concentration to exceed the standard.

[0003] The negative pressure wet dust removal fan cannot run without load for a long time. The negative pressure wet dust removal fan is completely enclosed in the pipeline, and without water circuit cooling, it is easy to cause the motor to overheat and malfunction, resulting in insulation aging and damage.

[0004] The technical difficulties and problems to be solved in the prior art mainly include three points: First, after the solenoid valve is damaged, since the water circuit in the chute cannot atomize the dust-containing air through spraying, the air discharged from the exhaust outlet causes dust pollution; Second, when a failure occurs due to the high temperature of the negative pressure induced dust removal fan during operation, the negative pressure induced dust removal fan is designed to be completely enclosed in the pipeline, and without water circuit cooling, it is easy to cause the motor to overheat and malfunction and the solenoid valve to be damaged, resulting in the electrical equipment running at high temperature for a long time, causing insulation aging and damaging the motor; Third, the no-load operation of the negative pressure induced dust removal fan equipment will cause environmental pollution.

[0005] Chinese Patent CN202020696171.3 discloses an efficient mine wet dust removal fan, including: a fan body, a support frame, a dust removal component and a circulation component. The fan body is matched and installed at the top end of the support frame, the dust removal component is installed on one side inside the fan body, the circulation component is installed at the bottom end of the fan body and the circulation component is matched and installed with the dust removal component. The utility model can synchronously adsorb and collect the dust in the gas by using the dust removal cavity, and at the same time, under the action of the diversion channel, the liquid can be stably diverted into the collection cavity, and by using two groups of diversion pipes, the gas can be uniformly diverted synchronously and effectively, ensuring the stable progress of the overall dust removal work. At the same time, under the action of the spraying part, the liquid is sprayed out through a plurality of nozzles, and the gas can be sprayed synchronously, and the dust in the gas is adsorbed and settled by the liquid, ensuring the stable progress of the overall dust removal work, and the cyclic sedimentation dust removal work can be stably carried out. However, this utility model cannot monitor the failure of the solenoid valve, resulting in the dust not being adsorbed and settled by the liquid, thus causing secondary pollution to the surrounding dust removal environment. Summary of the Invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present utility model is to provide a water cut-off protection device for a mine dust removal system. By setting a water cut-off protection device in the existing fan dust removal system, the possibility of coal dust combustion and explosion is fundamentally eliminated, the fan is also protected, and it can timely humidify, minimize the harm of coal dust to miners, reduce the no-load power consumption of the fan, and has the characteristics of improving the dust removal efficiency and saving energy.

[0007] In order to achieve the above purpose, the technical solution adopted by the present utility model is as follows:

[0008] A water cut-off protection device for a mine dust removal system includes a housing 2 and a wiring port 3 provided thereon. An anode 1 and a cathode 4 are provided on the housing 2. The anode 1 is connected to an anode terminal 5 inside the housing 2, and the cathode 4 is connected to a cathode terminal 6 inside the housing 2. The anode terminal 5 and the cathode terminal 6 can be respectively connected to the terminals on a liquid level relay LJ of a control circuit in a local control box through wires passing through the wiring port 3.

[0009] Further, the anode terminal 5 and the cathode terminal 6 can be respectively connected to the 4th terminal and the 5th terminal on the liquid level relay LJ of the control circuit in the local control box through wires passing through the wiring port 3.

[0010] Further, the control circuit includes a time relay KT1, a relay KA1, a relay KA2, a relay KA3, a relay KA4, a relay KA5, a reset button SS5, a thermal relay FR1, a contactor KM1, an indicator light HR, an indicator light HG1, an indicator light HG2, a start button SF1, a stop button SS1, a liquid level relay LJ, and a solenoid valve coil YV; where A is the live wire, N is the neutral wire, the main control switch QF3 is connected to the power supply side of the circuit, the power indicator light HR is connected in parallel below QF3, the change-over switch SA1 is switched to the remote position, the head end of the change-over switch SA1 is connected to phase A, and the tail end is locally controlled and sequentially connected in series with the stop button SS1, the start button SF1, and the relay coil KA1.

[0011] Further, the relay coil KA1 is connected to N, the normally open contact KA1-1 of the relay is connected in parallel with the stop button SF1; the tail end is remotely controlled and connected to the normally open contact KA4-1 of the relay, the tail end of the normally open contact KA4-1 of the relay is connected to the head end of the relay coil KA1, the normally closed contact KM1-1 of the contactor is connected in series with the time relay KT1 and connected in parallel on the relay coil KA1, and the relay coil KA4 is connected in series with the belt conveyor operation signal.

[0012] Further, the liquid level relay LJ is connected in parallel with the coil KA1. The head end of the reset button SS5 is connected to the tail end of the start button SF1, and the tail end is connected in series with the normally closed point LJ-1 of the liquid level relay and the time relay KT3. The tail end of the time relay KT3 is connected to N. The normally open point KT3-1 in series with the relay coil KA5 is connected in parallel with the time relay coil KT3. The relay normally open point KA5-1 is connected in parallel between the tail end of the reset button SS5 and the head end of the relay coil KA5.

[0013] Further, the head end of the relay normally closed point KA5-2 is connected to the tail end of the relay normally open point KA4-1. The tail end of the relay normally closed point KA5-2 is connected in series with the normally open point KT1-1 of the time relay, the contactor KM1, and the thermal relay FR1 in sequence. The tail end of the thermal relay normally closed point FR1 is connected to N. The relay normally open point KA1-2 is connected in parallel with the normally open point KT1-1 of the time relay. The head end of the fan operation indicator HG1 is connected to the tail end of the normally open point KT1-1 of the time relay, and the tail end is connected to N.

[0014] Further, the head end of the relay normally open point KA5-3 is connected to the head end of the relay normally closed point KA5-2, and the tail end is connected in series with the water cut-off protection indicator HG2. The tail end of the indicator HG2 is connected to N.

[0015] Further, the head end of the relay normally open point KA1-3 is connected to the head end of the relay normally open point KA5-3, and the tail end is connected in series with the solenoid valve YV. The tail end of the solenoid valve YV is connected to N.

[0016] Compared with the prior art, the utility model has the following beneficial effects:

[0017] After the electromagnetic is damaged, the dust-containing air and the water spray in the chute cannot be atomized by the fan, resulting in the dust-containing air being discharged from the exhaust port, causing dust pollution to the environment. However, since the anode terminal 5 and the cathode terminal 6 of the utility model can be respectively connected to the terminals on the liquid level relay in the local control box through the wires passing through the wiring port 3, the water cut-off protection device of the utility model will monitor in real time whether there is coal slime water flowing out to judge the working state of the solenoid valve for the total water path of the negative pressure dust removal. If no coal slime water is detected flowing out within 30 seconds, the system will determine that the solenoid valve for the total water path of the negative pressure dust removal is working abnormally and trigger a fault alarm to notify the maintenance personnel for timely maintenance to prevent secondary pollution, solving the problem that a large amount of dust is raised at the exhaust port and the dust concentration exceeds the standard and pollutes the environment due to the continuous operation of the fan after the water path fails; it can avoid the high-temperature fault and damage of the dust removal fan. Since the dust removal fan is completely enclosed in the pipeline after the solenoid valve is damaged and there is no water path for cooling, it is extremely easy to cause the motor high-temperature fault alarm and insulation aging and damage; the utility model enables the total dust removal efficiency to reach more than 99%.

[0018] Therefore, after adding the water cut-off protection device of the utility model, the failure rate and maintenance rate of the dust removal fan can be reduced. Brief Description of the Drawings

[0019] Figure 1 This is a perspective view of the present utility model.

[0020] Figure 2 This is a left view of the present utility model.

[0021] Figure 3 This is a front view of the present utility model.

[0022] Figure 4 This is a top view of the present utility model.

[0023] Figure 5 This is a schematic diagram of the internal structure of the present utility model.

[0024] Figure 6 This is an installation schematic diagram of the present utility model.

[0025] Figure 7 This is a partially enlarged view of the installation of the present utility model.

[0026] Figure 8 This is a circuit diagram of the present utility model.

[0027] Wherein: 1. Anode; 2. Outer shell; 3. Wiring port; 4. Cathode; 5. Anode terminal; 6. Cathode terminal; 7. Dust removal fan; 8. Water supply and spray pipeline; 9. Machine base; 10. Filter; 11. Separation port; 12. Drain port; 13. Sewage pipeline. Detailed Description of the Preferred Embodiments

[0028] In order to make the technical problems, technical solutions and beneficial effects solved by the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and do not limit the present utility model. The detailed description is as follows.

[0029] Referring to Figures 1-5 , a water cut-off protection device for a mine dust removal system includes an outer shell 2 and a wiring port 3 provided thereon. A parallel anode 1 and cathode 4 are provided on the front wall surface of the outer shell 2. The anode 1 is connected to an anode terminal 5 inside the outer shell 2, and the cathode 4 is connected to a cathode terminal 6 inside the outer shell 2. The anode terminal 5 and the cathode terminal 6 are fixed on the rear wall surface inside the outer shell 2. The anode terminal 5 and the cathode terminal 6 can be respectively connected to the 4th terminal and the 5th terminal on the liquid level relay LJ of the control circuit in the local control box through wires passing through the wiring port 3. For details, see Figure 8 .

[0030] See Figure 8, the control circuit in the local control box of the utility model includes a time relay KT1, a relay KA1, a relay KA2, a relay KA3, a relay KA4, a relay KA5, a reset button SS5, a thermal relay FR1, a contactor KM1, an indicator light HR, an indicator light HG1, an indicator light HG2, a start button SF1, a stop button SS1, a liquid level relay LJ, and a solenoid valve coil YV; among them, A is the live wire, N is the neutral wire, the main control switch QF3 is connected to the power supply side of the circuit, the power indicator light HR is connected in parallel below QF3, the change-over switch SA1 is switched to the remote position, the head end of the change-over switch SA1 is connected to the A phase, and the tail end for local control is sequentially connected in series with the stop button SS1, the start button SF1, and the relay coil KA1. The relay coil KA1 is connected to N, and the normally open contact KA1-1 of the relay is connected in parallel with the stop button SF1; the tail end for remote control is connected to the normally open contact KA4-1 of the relay, and the tail end of the normally open contact KA4-1 of the relay is connected to the head end of the relay coil KA1. The normally closed contact KM1-1 of the contactor is connected in series with the time relay KT1 and is connected in parallel with the relay coil KA1. The relay coil KA4 is connected in series with the running signal of the belt conveyor; the liquid level relay LJ is connected in parallel with the coil KA1. The head end of the reset button SS5 is connected to the tail end of the start button SF1, and the tail end is connected in series with the normally closed point LJ-1 of the liquid level relay and the time relay KT3. The tail end of the time relay KT3 is connected to N. The normally open delayed contact KT3-1 is connected in series with the relay coil KA5 and is connected in parallel with the time relay coil KT3. The normally open contact KA5-1 of the relay is connected in parallel between the tail end of the reset button SS5 and the head end of the relay coil KA5; the head end of the normally closed contact KA5-2 of the relay is connected to the tail end of the normally open contact KA4-1 of the relay, and the tail end of the normally closed contact KA5-2 of the relay is sequentially connected in series with the normally open delayed contact KT1-1 of the time relay, the contactor KM1, and the thermal relay FR1. The tail end of the normally closed contact FR1 of the thermal relay is connected to N. The normally open contact KA1-2 of the relay is connected in parallel with the normally open contact KT1-1 of the time relay. The head end of the fan running indicator HG1 is connected to the tail end of the normally open contact KT1-1 of the time relay, and the tail end is connected to N; the head end of the normally open contact KA5-3 of the relay is connected to the head end of the normally closed contact KA5-2 of the relay, and the tail end is connected in series with the water cut-off protection indicator light HG2. The tail end of the indicator light HG2 is connected to N. The head end of the normally open contact KA1-3 of the relay is connected to the head end of the normally open contact KA5-3 of the relay, and the tail end is connected in series with the solenoid valve YV. The tail end of the solenoid valve YV is connected to N.

[0031] See Figure 6 , Figure 7, during use, install the water cut-off protection device of the present utility model on the sewage pipe 13 at the bottom of the sewage discharge port 12. The specific installation structure is as follows: fix the outer shell 2 on the bracket through the bracket clamp, and at the same time tightly install the bracket clamp on the sewage pipe 13, with the anode 1 and the cathode 4 aligned with the bottom of the sewage pipe 13. The tail of the conveyor belt is a key node for the transportation of the belt conveyor and the falling point of coal transfer. During its operation, the falling of coal will raise a large amount of coal ash, forming significant dust, polluting the surrounding environment and bringing potential safety risks. The mine dust removal equipment includes an explosion-proof dust removal fan 7, a water supply spray pipeline 8, a machine base 9, a filter 10, a separation port 11 and a sewage discharge port 12. The mine dust removal equipment is accurately installed at a position 3 to 5 meters above the conveyor belt at the blanking port of the transfer station. The dust removal port of the explosion-proof dust removal fan 7 is completely wrapped by the material guiding trough. At the same time, water supply spray pipelines 8 are equipped on both sides of the material guiding trough. Spray nozzles are arranged on the water supply spray pipeline 8 and are uniformly controlled by the negative pressure dust removal total waterway solenoid valve. When the control cabinet of the explosion-proof dust removal fan 7 receives a start signal, the explosion-proof dust removal fan 7 starts to intake water, and after a 60-second delay, the explosion-proof dust removal fan 7 starts, and at the same time, the water supply spray pipelines 8 on both sides of the material guiding trough are also activated. When the control cabinet of the explosion-proof dust removal fan 7 receives a start signal (local manual start and remote automatic start), the water intake of the explosion-proof dust removal fan 7 is connected, and after a 60S delay, the explosion-proof dust removal fan 7 starts. The coal slime mixed water in the explosion-proof dust removal fan 7 flows out through the sewage discharge port 12, enters the sewage pipe 13 and then is discharged. The water cut-off protection device monitors. If the water cut-off protection device does not detect water flow for more than 30S continuously, the explosion-proof dust removal fan 7 will automatically stop.

[0032] At the blanking point of the transfer station, some dust may not be completely suppressed by the water supply spray pipelines 8 on both sides of the material guiding trough. This part of the dust will be extracted by the explosion-proof dust removal fan 7 into its air duct. The spraying device in the air duct combines with the dust-containing air to form coal slime mixed water, which is finally discharged through the sewage discharge port 12. The water cut-off protection device of the present utility model will monitor in real time whether there is coal slime water flowing out to judge the working state of the negative pressure dust removal total waterway solenoid valve. If no coal slime water is detected flowing out within 30 seconds, the system will determine that the negative pressure dust removal total waterway solenoid valve is working abnormally and trigger a fault alarm to notify the maintenance personnel for timely maintenance to prevent secondary pollution.

[0033] Refer to Figure 6 and Figure 7 , when the waterway solenoid valve is opened and the explosion-proof dust removal fan 7 is operating normally, high-speed steam mist jets ejected by the spray assembly in the air duct and the sealed chute are used to remove dust based on the mechanism of forming a negative pressure around the jets. The method is that each nozzle in the spray assembly can form a negative pressure area within a range with a diameter of 1 meter centered on the nozzle, sucking the dust-containing air into the mist column. The small mist particles hit the dust in the mist column, capture and wet it, causing it to fall. This method has fine mist particles and a large mist body range, and the dust removal effect is very significant.

[0034] After the dust removal in the first stage of the spray assembly, the wet air is then sucked into the explosion-proof dust removal fan 7 by the explosion-proof dust removal fan 7. The dust-containing air is moistened by the spray head in the explosion-proof dust removal fan 7 and then further filtered by the filter 10. At the same time, a water film is attached to the stainless steel positive rotation net on the filter 10 by the water mist sprayed by the spray head. When the dust-containing air passes through the water film, the dust is moistened and weighted or adsorbed. At the same time, the stainless steel positive rotation net vibrates under the action of the wind force, and the adsorbed dust is shaken off to achieve self-cleaning. The shaken-off dust particles and the weighted dust particles together enter the separation port 11. The dust particles and air are separated through the separation port 11, and the sewage is discharged from the sewage discharge port 12. After entering the sewage pipeline 13, it is judged by the water cut-off protection device arranged at the bottom of the sewage pipeline 13 that the negative pressure dust removal total waterway solenoid valve operates normally, and the purified air is discharged from the air outlet. On the contrary, if no wastewater is detected at the sewage discharge port 12 within 30 s after the mine dust removal equipment is started, the mine dust removal equipment will stop due to a fault, and it is necessary to check the fault of the negative pressure dust removal total waterway solenoid valve to ensure the safe and normal operation of the mine dust removal equipment.

[0035] A part of the spray assembly is also arranged at the chute feeding point of each transfer station for dust removal to achieve comprehensive dust removal at the chute feeding points of the entire transfer station. At the same time, the air humidity in the ventilation environment is controlled to prevent secondary dust generation and eliminate the possibility of coal dust participating in an explosion.

[0036] Refer to Figure 8 , the drainage pipeline is electrically transformed, and a liquid level electrode, namely the anode 1 and the cathode 4, is installed on the sewage pipeline 13. It is controlled in cooperation with the control schematic diagram and is connected to the on-site control box through the on-site explosion-proof junction box housing 2. A time relay is installed in the control circuit of the dust removal fan 7, and the water cut-off protection can start to detect 30 s after the fan is started, avoiding the start interval of the dust removal equipment process. The actual normal working time of the dust removal equipment is less than 30 s, avoiding the faults reported by the misjudgment of the water cut-off device during the equipment startup. When the QF3 control power supply is switched on, the change-over switch is switched to the remote position. The KA4 relay receives the start signal and closes. The KA1 start relay attracts and the dust removal fan spray solenoid valve opens. After a delay of 60 seconds, the dust removal fan motor starts. When the water cut-off protection device of the present invention does not detect the water flow signal, the KT3 time relay starts timing. After 30 seconds, the KA5 relay operates and self-locks to disconnect the motor start circuit of the explosion-proof dust removal fan 7, thus realizing the water cut-off protection function.

[0037] Refer to Figure 8, QF3 controls the power supply to close, the change-over switch is switched to the remote position, the KA4 relay receives the start signal and closes, the KA1 start relay pulls in, the dust removal fan spray solenoid valve opens, and the dust removal fan motor starts after a 60-second delay. When the water cut-off protection device of the present utility model does not detect a water flow signal, the KT3 time relay starts timing. After 30 seconds, the KA5 relay operates and self-locks to disconnect the motor start circuit of the explosion-proof dust removal fan 7, thus realizing the water cut-off protection function.

[0038] The cost of the water cut-off protection device of the present utility model is the liquid level electrode, that is, the anode 1 and the cathode 4, with a price of 20 yuan, the explosion-proof junction box, that is, the shell 2, with a price of 50 yuan each, and the time relay is 100 yuan. The cost price of an explosion-proof motor of a negative pressure induced mine dust removal fan is 5000 yuan per unit. To prevent damage, 3 units are purchased as spare parts. 10 units are replaced each year for motor spare parts replacement and damage replacement, and the damage repair cost is 800 - 1000 yuan. The annual maintenance cost is 8000 yuan - 10000 yuan. After the water cut-off protection transformation, the operation efficiency of the equipment has been significantly improved. As of August this year, there has been no damage to the motor winding, and the equipment maintenance cost can be reduced by about 10000 yuan, and the spare parts cost by 15000 yuan.

Claims

1. A water cut-off protection device for a mine dust removal system, comprising a housing (2) and a wiring port (3) provided thereon, characterized in that, An anode (1) and a cathode (4) are provided on the outer shell (2). The anode (1) is connected to the anode terminal (5) inside the outer shell (2), and the cathode (4) is connected to the cathode terminal (6) inside the outer shell (2). The anode terminal (5) and the cathode terminal (6) can be respectively connected to the terminals on the liquid level relay LJ of the control circuit in the local control box through wires passing through the wiring port (3).

2. The water cut-off protection device for a mine dust removal system according to claim 1, characterized in that, The anode terminal (5) and the cathode terminal (6) can be respectively connected to the No. 4 terminal and the No. 5 terminal on the liquid level relay LJ of the control circuit in the local control box through wires passing through the wiring port (3).

3. The water cut-off protection device for a mine dust removal system according to claim 1 or 2, characterized in that, The control circuit includes a time relay KT1, a relay KA1, a relay KA2, a relay KA3, a relay KA4, a relay KA5, a reset button SS5, a thermal relay FR1, a contactor KM1, an indicator light HR, an indicator light HG1, an indicator light HG2, a start button SF1, a stop button SS1, a liquid level relay LJ, and a solenoid valve coil YV; where A is the live wire and N is the neutral wire. The main control switch QF3 is connected to the power supply side of the circuit. The power indicator light HR is connected in parallel below QF3. The change-over switch SA1 is switched to the remote position. The head end of the change-over switch SA1 is connected to the A phase, and the tail end is connected to the stop button SS1, the start button SF1, and the relay coil KA1 in series for local control in sequence.

4. The water cut-off protection device of a mine dust removal system according to claim 3, characterized in that, The relay coil KA1 is connected to N, and the normally open contact KA1-1 of the relay is connected in parallel with the stop button SF1; The tail end is connected to the normally open contact KA4-1 of the relay for remote control. The tail end of the normally open contact KA4-1 of the relay is connected to the head end of the relay coil KA1. The normally closed contact KM1-1 of the contactor is connected in series with the time relay KT1 and in parallel with the relay coil KA1. The relay coil KA4 is connected in series with the running signal of the belt conveyor.

5. The water cut-off protection device for a mine dust removal system according to claim 3, characterized in that, The liquid level relay LJ is connected in parallel with the coil KA1. The head end of the reset button SS5 is connected to the tail end of the start button SF1, and the tail end is connected in series with the normally closed contact LJ-1 of the liquid level relay and the time relay KT3. The tail end of the time relay KT3 is connected to N. The normally open delayed contact KT3-1 is connected in series with the relay coil KA5 and then in parallel with the time relay coil KT3. The normally open contact KA5-1 of the relay is connected in parallel between the tail end of the reset button SS5 and the head end of the relay coil KA5.

6. The water cut-off protection device for a mine dust removal system according to claim 4, characterized in that The tail end of the normally open contact KA4-1 of the relay is connected to the head end of the normally closed contact KA5-2 of the relay. The tail end of the normally closed contact KA5-2 of the relay is connected in series with the normally open delayed contact KT1-1 of the time relay, the contactor KM1, and the thermal relay FR1 in sequence. The tail end of the normally closed contact FR1 of the thermal relay is connected to N. The normally open contact KA1-2 of the relay is connected in parallel with the normally open contact KT1-1 of the time relay. The head end of the fan running indicator HG1 is connected to the tail end of the normally open contact KT1-1 of the time relay, and the tail end is connected to N.

7. The water cut-off protection device for a mine dust removal system according to claim 6, characterized in that, The head end of the normally closed contact KA5-2 of the relay is connected to the head end of the normally open contact KA5-3 of the relay, and the tail end is connected in series with the water cut-off protection indicator light HG2. The tail end of the indicator light HG2 is connected to N.

8. The water cut-off protection device of a mine dust removal system according to claim 7, characterized in that, The head end of the normally open contact KA5-3 of the relay is connected to the head end of the normally open contact KA1-3 of the relay, and the tail end is connected in series with the solenoid valve YV. The tail end of the solenoid valve YV is connected to N.

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