Remote switch position indicator

• US 4,578,669 A
• Filed: 09/12/1983
• Issued: 03/25/1986
• Est. Priority Date: 09/12/1983
• Status: Expired due to Term

• Current Assignee: Hydril Company L P (General Electric Company)
• Original Assignee: Hydril Company L P (General Electric Company)
• Inventors: Woods, Allan O.
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US06/530,962
• Time in Patent Office: 925 Days
• Field of Search: 340/518, 340/500, 340/506, 340/512, 340/513, 340/514, 340/505, 340/825.05, 340/825.06-825.1, 340/825.11, 340/825.29, 340/825.42, 340/825.43 , 340/825.54, 340/825.59, 340/825.88-825.91, 340/509, 340/524, 340/525, 340/644, 340/645
• US Class Current: 340/518
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles
• CPC Class Codes: G08B 26/002 only replying the state of the sensor

Abstract

A remote sensing and indicating system for monitoring and displaying at a central operating location the state or position of a remotely located multiple state element. The multiple state element may be a subsea valve which may be either in an open state or a closed state. The system electronically scans valve position switches, stores data indicating the position and drives lamps to display valve position. Switches at the remotely located valve are selectively closed in response to the state of the valve. The switches are connected to the central location by only two leads.

Claims

1. An indicator system for remotely sensing and indicating first and second status conditions of a two state element comprising:

a first switch means responsive to the two state element for closing when the element is in a first state and for opening when the element is in a second state,

a second switch means responsive to the element for opening when the element is in a first state and for closing when the element is in a second state,

a first diode means connected in series with the first switch means for conducting only current of a first direction through the closed first switch means,

a second diode means connected in series with the second switch means for conducting only current of a second direction through the closed second switch means,

the first diode-first switch series connection connected in parallel with the second diode-second switch series connection forming a parallel connection,

a first conductor connected to one end of the parallel connection and a second conductor connected to the other end of the parallel connection, the first and second conductors extending from the location of the remotely disposed element to a central location,

circuit means disposed at the central location for applying a driving oscillating signal that is substantially symmetrical about a reference level to the first conductor,

circuit means disposed at the central location responsive to half cycles of a first direction on the second conductor for generating a first continuous output signal indicative that the element is in the first state, and

circuit means disposed at the central location responsive to half cycles of a second direction on the second conductor for generating a second continuous output signal indicative that the element is in the second state.

2. The indicator of claim 1 further comprising,

a first lamp circuit means responsive to said first continuous output signal when present for lighting a first lamp means indicative that the element is in the first state, and

a second lamp circuit means responsive to said second continuous output signal for lighting a second lamp means indicative that the element is in the second state.

3. The indicator system of claim 1 wherein the two state element is a valve operator stem of a subsea valve, wherein the stem is in a first state when the valve is closed and in the second state when the valve is open.

4. The indicator system of claim 3 wherein the first and second switch means each comprise at least one reed switch, the first and second switch means being disposed axially apart in a housing through which the valve stem moves axially from the valve open state to the valve closed state, the valve operator stem including two magnets, wherein in the open state of the valve, one magnet of the valve operator stem is disposed adjacent the second switch means, the magnet acting to close only the second switch means, and in the closed state of the valve, the other magnet of the valve operator stem is disposed adjacent the first switch means, acting to close only the first switch means.

5. The indicator system of claim 4 wherein the first and second switch means are each a set of four reed switches comprising a series connection of two groups of two parallel connected switches.

6. The indicator system of claim 4 wherein the first diode means is a set of four diodes comprising a parallel connection of two sets of two series connected diodes, the diodes connected to conduct current of a positive direction but to prevent current of a negative direction through the first switch means.

7. The indicator system of claim 4 wherein the second diode means is a set of four diodes comprising a parallel connection of two sets of two series connected diodes, the diodes connected to conduct current of a negative direction but to prevent current of a positive direction through the second switch means.

8. The indicator system of claim 1 in which the circuit means for applying an oscillating signal to the first conductor comprises,

an oscillator circuit means for generating a rectangular signal,

a flip flop means responsive to the rectangular signal for generating a square wave signal,

a level shifter means responsive to the square wave signal for generating a square wave signal substantially symmetrical about a reference level, and

a current limited driver means responsive to the symmetrical square wave signal for generating an oscillating current signal substantially symmetrical about a reference level.

9. The indicator system of claim 1 in which the circuit means for generating a first continuous output signal comprises,

an inverter/amplifier circuit means for inverting and amplifying the half cycles of a positive direction received on the second conductor indicative that the element is in the first state, the output of said inverter circuit being negative half cycles corresponding to said positive half cycles,

a level shifter circuit means responsive to said negative half cycles for generating a doubly inverted positive half cycle signal,

a quadrature signal generator means responsive to said driving oscillating signal that is substantially symmetrical about a reference level for generating a lagging oscillating signal that is ninety degrees trailing behind said driving oscillating signal, and

a flip flop circuit means responsive to said lagging oscillating signal and to said doubly inverted positive half cycle signal for generating said first continuous output signal indicative that the element is in the first state so long as said doubly inverted positive half cycle signal is present.

10. The indicator system of claim 1 in which the circuit means for generating a second continuous output signal comprises,

an inverter/amplifier circuit means for inverting and amplifying the half cycles of a negative direction received on the second conductor indicative that the element is in the second state, the output of said inverter circuit being an inverted signal of positive half cycles corresponding to said negative half cycles,

limiter circuit means for generating a clamped inverter signal by clamping the amplitude of the inverted signal of positive half cycles to a prespecified level,

a quadrature signal generator means responsive to said driving oscillating signal that is substantially symmetrical about a reference level for generating a leading oscillating signal which is ninety degrees ahead of said driving oscillating signal, and

a flip flop circuit means responsive to said leading oscillating signal and to said clamped inverted signal for generating said second continuous output signal indicative that the element is in the second state.

11. The indicator system of claim 2 wherein

said first lamp means comprises a first lamp in a first closed circuit with an alternating cycle voltage source and a first triac element, and wherein said first continuous output signal when present is applied to a first emitter follower circuit, the output of which is applied to the control terminal of the first triac element, for allowing alternating current to flow in said closed first series circuit and lighting the lamp indicating that the element is in the first state, and

said second lamp means comprises a second lamp in a second closed circuit with said alternating cycle voltage source and a second triac element, and wherein said second continuous output signal when present is applied to a second emitter follower circuit, the output of which is applied to the control terminal of the second triac element, for allowing alternating current to flow in said closed second series circuit and lighting the lamp indicating that the element is in the second state.

12. An indicator system for remotely sensing and indicating first, second and third conditions of a three state element comprising,

a first switch means responsive to the three state element for closing when the element is in a first state and for opening when the element is in a second or third state,

a second switch means responsive to the three state element for closing when the element is in a second state and for opening when the element is in a first or third state,

a first diode means connected in series with the first switch means for conducting only positive current through the first switch means when said first switch means is closed,

a second diode means connected in series with the second switch means for conducting only negative current through the second switch means when said second switch means is closed,

the first diode-first switch series connection connected in parallel with the second diode-second switch series connection forming a parallel connection,

a first conductor connected to one end of the parallel connection and a second conductor connected to the other end of the parallel connection, the first and second conductors extending from the location of the remotely disposed element to a central location,

circuit means disposed at the central location for applying a driving oscillating signal that is substantially symmetrical about a reference level to the first conductor,

circuit means disposed at the central location responsive to positive half cycles on the second conductor for generating a first continuous output signal indicative that the element is in the first state,

circuit means disposed at the central location responsive to negative half cycles on the second conductor for generating a second continuous output signal indicative that the element is in the second state, and

wherein neither the first continuous output signal nor the second continuous output signal are generated when the element is in the third state.

13. The system of claim 12 further comprising

a first lamp circuit means responsive to said first continuous output signal when present for lighting a first lamp means indicative that the element is in the first state,

a second lamp circuit means responsive to said second continuous output signal for lighting a second lamp means indicative that the element is in the second state, and

wherein the absence of lighting of the first lamp means and the second lamp means is indicative that the element is in the third state.

14. The system of claim 12 wherein the three state element is a valve operator stem of a subsea valve, wherein the stem is in a first state when the valve is closed, in a second state when the valve is open, and in a third state when the valve is in transit between being open and closed.

15. The system of claim 14 wherein

the first and second switch means each comprise at least one reed switch, the first and second switch means being disposed axially apart in a housing through which the valve stem moves axially from the valve open state to the valve closed state, the valve operator stem including two magnets, wherein the open state of the valve, a magnet of the valve operator stem is disposed adjacent the second switch means, the magnet acting to close only the second switch means, and in the closed state of the valve, the other magnet of the valve operator stem is disposed adjacent the first switch means, acting to close only the first switch means, and

when the valve is in transit between being open and closed, the magnets of the valve operator stem are displaced either side of the first switch means and the second switch means whereby neither the first switch means nor the second switch means are closed.

16. The system of claim 15 wherein the first and second switch means are each a set of four reed switches comprising a series connection of two groups of two parallel connected switches.

17. The system of claim 15 wherein the first diode means is a set of four diodes comprising a parallel connection of two sets of two series connected diodes, the diodes connected to conduct positive current but to prevent negative current current through first switch means.

18. The system of claim 15 wherein the second diode means is a set of four diodes comprising a parallel connection of two sets of two series connected doides, the diodes connected to conduct negative current but to prevent positive current through the second switch means.

19. The system of claim 13 in which the circuit means for applying an oscillating signal to the first conductor comprises,

an oscillator circuit means for generating a rectangular signal,

a flip flop means responsive to the rectangular signal for generating a square wave signal,

a level shifter means responsive to the square wave signal for generating a square wave signal substantially symmetrical about a reference level, and

a current limited driver means responsive to the symmetrical square wave signal for generating an oscillating current signal substantially symmetrical about a reference level.

20. The system of claim 13 in which the circuit means for generating a first continuous output signal comprises,

an inverter/amplifier circuit means for inverting and amplifying the positive half cycles received on the second conductor indicative that the element is in the first state, the output of said inverter circuit being negative half cycles corresponding to said positive half cycles,

a level shifter circuit means responsive to said negative half cycles for generating a doubly inverted positive half cycle signal,

a quadrature signal generator means responsive to said driving oscillating signal that is substantially symmetrical about a reference level for generating a lagging oscillating signal that is ninety degrees trailing behind said driving oscillating signal, and

a flip flop circuit means responsive to said lagging oscillating signal and to said doubly inverted positive half cycle signal for generating said first continuous output signal indicative that the element is in the first state so long as said doubly inverted positive half cycle signal is present.

21. The system of claim 13 in which the circuit means for generating a second continuous output signal comprises,

an inverter/amplifier circuit means for inverting and amplifying the negative half cycles received on the second conductor indicative that the element is in the second state, the output of said inverter circuit being an inverted signal of positive half cycles corresponding to said negative half cycles,

limiter circuit means for generating a clamped inverter signal by clamping the amplitude of the inverted signal of positive half cycles to a prespecified level,

a quadrature signal generator means responsive to said driving oscillating signal that is substantially symmetrical about a reference level for generating a leading oscillating signal which is ninety degrees ahead of said driving oscillating signal, and

a flip flop circuit means responsive to said leading oscillating signal and to said clamped inverted signal for generating said second continuous output signal indicative that the element is in the second state.

22. The system of claim 15 wherein said first lamp means comprises a first lamp in a first closed series circuit with an alternating cycle voltage source and a first triac element, and wherein said first continuous output signal when present is applied to a first emitter follower circuit, the output of which is applied to the control terminal of the first triac element, for allowing alternating current to flow in said closed first series circuit and lighting the lamp indicating that the element is in the first state, and

said second lamp means comprises a second lamp in a second closed series circuit with said alternating cycle voltage source and a second triac element, and wherein said second continuous output signal when present is applied to a second emitter follower circuit, the output of which is applied to the control terminal of the second triac element, for allowing alternating current to flow in said closed second series circuit and lighting the lamp indicating that the element is in the second state, and

wherein when the element is in the third state, no continuous output signal is applied to either the control terminal of the first triac element or to the control terminal of the second triac element and neither the first lamp nor the second lamp is lit.