What is AST solenoid valve

What is AST solenoid valve?

In the working process of AST solenoid valve, AST solenoid valve is charged, and the solenoid valve drives the valve core down, closing the oil discharge passage X chamber of HP, and the pressure of the high-pressure oil supply pressure rises, which overcomes the pulling force of Spring 1, push the piston to move right, and cut off the discharge passage of AST critically off oil to block the oil pressure of AST critically off oil. When AST solenoid valve loses power, the spool of solenoid valve will move up under the action of the tension of Spring 2, and the pressure in cavity X of oil discharge passage opening HP of high-pressure oil supply will decrease. It is not enough to overcome the tension of Spring 1, the piston moves left under the action of spring pulling force, and opens the discharge passage of AST critically cut off oil to critically off the pressure loss of oil.
20210223030547 40312 - What is AST solenoid valve

How is AST oil pressure established?

AST oil pressure refers to the oil that EH oil passes through the throttle of quick unloading valve. As long as EH oil pump runs, it always exists, but AST solenoid valve drain is open and it is unloaded, when the AST solenoid valve of the unit is reset and the oil drain is closed, the AST oil pressure is established.

  • After passing through a throttle hole of 0.8, the pressure oil enters the main valve and the bottom of the unloading valve on the integration block of the main valve and the engine; each main valve oil motivation overcomes the friction of the valve, the steam force, the dead weight of the valve and the spring force of the control seat under the action of anti-fuel oil pressure, and opens each main valve; At the same time, the pressure oil, which is sent to the bottom of the unloading valve, forms the automatic shutdown to cut off the control oil (and AST control oil) after it is checked by a flow hole on the unloading valve, after passing through an internal throttle hole of the unloading valve, the control oil acts on the upper part of the cup-shaped slide valve of the unloading valve. The force generated by the control oil combines with the spring force of the small spring inside the unloading valve, press the cup-shaped slide valve of the unloading valve on the valve seat, and sealed the bottom of each main valve, the oil cylinder of the engine and the Channel with pressure and oil return; when the main valve switch solenoid valve gets electricity to open or the AST solenoid valve on the AST solenoid valve assembly is open due to power loss, the AST control oil on the top of the discharge valve cup-shaped slide valve will be connected to the non-pressure return oil, the cup-shaped sliding valve of the unloading valve acts under the action of the oil pressure at the bottom, connecting the pressure oil in the lower space of the oil motivation oil of each main valve to the pressure return oil, thus, each main steam door can be closed quickly under the action of spring force of operating seat. In addition, slowly turning the needle valve adjusting handle on the unloading valve counterclockwise can drop the oil pressure part in the inferior cavity of the main valve oil cylinder. Under the action of the control seat spring force, close a certain stroke to achieve the purpose of the main valve activity test;
  • The pressure oil is sent to the front of MOOG J761-003 servo valve by an oil filter with a precision of 3μm. Under the action of the control signal after the servo amplifier of DEH control system, send pressure oil into the lower chamber of the oil motivation piston of each regulating valve, and at the same time, send to the lower part of the unloading valve on the integrated block of the oil motivation of each regulating valve; Under the action of the anti-flammable oil pressure, overcome the friction of the valve, the steam force, the dead weight of the valve and the spring force of the control seat, and open each regulating valve; At the same time, the pressure oil that is sent to the lower part of the unloading valve is throttle through a small orifice below the unloading valve, over-speed protection control oil (OPC control oil) is formed, which acts on the upper part of the cup-shaped slide valve of the unloading valve after passing through a throttle hole inside the unloading valve, the acting force generated by the oil pressure is combined with the spring force of the small spring inside the unloading valve, pressing the cup-shaped slide valve of the unloading valve onto the valve seat, and sealing off the bottom of each regulating steam door oil cylinder and the pressure oil return channel; when the OPC solenoid valve on the OPC solenoid valve assembly is electrically opened, connect the OPC control oil on the top of the cup-shaped slide valve of the unloading valve to the pressure return oil, and the unloading valve will act under the action of the oil pressure on the bottom, connect the pressure oil in the inferior space of the oil master cylinder of each regulating valve to the non-pressure return oil, in this way, each regulating valve will be closed quickly under the action of the spring force of the control seat; In addition, when the DEH control cabinet loses power or the servo amplifier is damaged (namely the input of the servo valve is zero), the servo valve will turn back to the zero position of the machine, at this time, the pressure oil in the inferior chamber of the oil motivation oil cylinder is fully drained to the pressure oil return pipe through the servo valve, and the oil motivation of each regulating valve is closed;
  • After passing through a throttle hole of 0.8, the pressure oil is added into the OPC control oil mother tube, and then the two check valves between the OPC electromagnetic valve assembly and the AST electromagnetic valve assembly are added into the AST control oil mother tube. The system is designed in this way to consider: the OPC and AST control oil of the unloading valve on the integrated block of all the engine is relatively small, and the OPC and AST control oil of the oil cylinder is relatively slow to fill, so the pressure oil is directly filled into the OPC and AST control oil cylinder, make the unloading valves of the main valve oil motivation and the oil motivation of each regulating door close quickly, so that the unit has the ability to start quickly; When the OPC or AST solenoid valve acts, due to the role of the throttle hole, it will not cause the pressure oil mother pipe to lose pressure;
  • AST control oil and OPC control oil are both formed after the pressure oil passes through the throttle hole of the oil unloading valve and the pressure oil passes through a throttle hole of 0.8; AST control oil is for the main valve oil motivation, OPC control oil is for the regulating valve oil motivation. There are two check valves between the assembly of AST electromagnetic valve and OPC electromagnetic valve. The function of the two check valves is that when the oil pipe of OPC control oil mother is out of pressure, AST control the oil pressure of oil mother pipe will not be affected; however, when AST control oil pipe loses its pressure, OPC control oil of oil mother pipe will enter AST mother pipe through these two check valves, and then drain back to the non-pressure oil return pipe of EH control system, return EH tank directly.

The oil pressure of AST control oil mother pipe is also controlled by the membrane valve. When the steam turbine generator unit encounters mechanical trip, the low pressure oil added to the top of the membrane valve will be lost. The membrane valve will be opened under the action of the spring on the valve body, what’s the difference between the trip of AST control oil mother pipe to the non-pressure return oil mother pipe of EH control system and the loss of pressure of AST control oil mother pipe?

OPC: overspeedprotection controller

The OPC is overspeedprotection controller, is a solenoid valve, which is usually closed by power loss and open with electricity. As 103% overspeed. And AST is to interrupt the electromagnetic valve of the unit in a critical way, and when the unit loses power, it opens and removes the safety oil, thus realizing the shutdown of the unit.

OPC oil: idle oil

  • Two parallel connections: any action, turn off the oil drain door.
  • Accept Post OPC logic loop control.
  • (103% 3000 r/min) OPC action, OPC solenoid valve on.
  • (BR=0) & (Δ N > 15% MCR ) OPC action, OPC solenoid valve is on.
  • Action principle: electric action, power off and off. “It is better to refuse to move than to mistakenly move”.

OPC solenoid valve

  • Accept Post OPC logic loop control
  • (103% 3000 r/min) OPC action, OPC solenoid valve on.
  • (BR=0) & (Δ N > 15% MCR ) OPC action, OPC electromagnetic valve is on.
  • Action principle: electric action, power off and off. “It is better to refuse to move than to mistakenly move”.

AST: autumn shift trip crisis interrupt

AST oil: Stop oil

  • Control the quick unloading valve of the TV and RSV to make it close quickly.
  • Control the OPC oil to make the GV,IV, extraction backstop door close quickly.

Discharge control of AST oil: 4 AST solenoid valves; Diaphragm valves.

  • AST oil drain, shutdown. Hang Up, AST oil recovery.

AST solenoid valve

  • 4 series and hybrid: it can prevent misoperation, and there are a variety of action methods to avoid rejection due to individual valve failure.
  • Accept ETS control :ETS action AST solenoid valve power off, open, drain oil, unit stop.
  • Action principle: power off action, live off. Anti-logic. “It is better to make mistakes than to refuse to move”.
  • ASP: an AST oil pressure protection measuring point, located in a oil pressure point between 1,3, 2,4 of the series and mixed, convenient trip test-the whole trip block adopts the principle of “dual channel.

Source: China Solenoid Valve Manufacturer– Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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what is ast solenoid valve - What is AST solenoid valve
Article Name
What is AST solenoid valve
Description
In the working process of AST solenoid valve, AST solenoid valve is charged, and the solenoid valve drives the valve core down, closing the oil discharge passage X chamber of HP, and the pressure of the high-pressure oil supply pressure rises.
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www.steeljrv.com
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