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Title:
MECHANICALLY OPERATED PRESSURE SWITCH HAVING SOLID STATE COMPONENTS
Document Type and Number:
WIPO Patent Application WO/1985/000464
Kind Code:
A1
Abstract:
A pressure switch having mechanical and solid state components. The switch includes mechanical components that are arranged so the mechanical components provide the electrical connections between a motor and an electric source for the motor. The mechanical components include a fluid pressure responsive mechanism which causes contacts of the switch to move with a snap action in response to pressure variations in a fluid system. The solid state components detect variations in the motor current, voltage and power factor as well as the duration of the intervals during which the motor is energized and interrupts or prevents energization of the motor when at least one of the variations exceeds a preprogrammed value. The switch includes a calibration switch which programs the switch operation for use with the particular motor controlled by the switch and coded diodes that function to indicate the cause of a malfunction detected by the switch.

More Like This:
JPS5370375PRESSURE SWITCH
Inventors:
Kierstead, Bruce E.
Noth, Myron A.
Application Number:
PCT/US1984/001091
Publication Date:
January 31, 1985
Filing Date:
July 11, 1984
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SQUARE D COMPANY.
International Classes:
H01H35/24; H02H7/08; (IPC1-7): H01H35/24; H02H7/08
Foreign References:
US3466978A
FR1355293A
US4370098A
EP0027843A1
FR1556653A
US4020308A
US3340372A
Download PDF:
Claims:
CLAIM
1. 1 A pressure switch comprising: a support, a cover having a rear end positioned on the support, side walls extending forwardly from the rear end, a front wall extending between a front end of the side walls and a cavity extending between the support, the side walls and the front wall, a pressure responsive snap acting switch mechanism mounted on the support within the cavity and including terminals connected to an A.C. source and terminals connected to an A.C. motor, a plurality of components including a programmable microcomputer positioned in the cavity, and a manually operable switch mounted on the front wall to have an operator accessible externally of the cover and contacts in circuit with the microcomputer for entering a data point into the microcomputer that reflects a desired operating condition of the motor when the motor is > energized and the switch is operated.
2. CLAIM.
3. A pressure switch comprising: a support, a pressure responsive snap acting switch mechanism mounted on the support and including terminals connected to an A.C. source and terminals connected to and A.C. motor, a cover having a rear end positioned on the support, side walls extending forwardly from the rear end to a front end, a front wall extending between the front end of the side walls and a cavity extending between the support, the side walls and front wall and enclosing the pressure responsive snap acting switch mechanism; a wall extending between the side walls dividing the cavity into a rear chamber wherein the switch mechanism is enclosed and a front chamber, a plurality of ccmponents including a prograirmable microcomputer chip positioned in the front chamber? and a manually operable switch mounted on the front wall to have an operator accessible externally of the cover and contacts in circuit with the microcomputer for entering a data point into the microcomputer that reflects a desired condition of operation of the motor when the motor is energized and the switch is actuated.
4. CLAIM.
5. The pressure switch as recited in CLAIM 1 wherein a wall extending between the side walls divides the cavity into a front chamber and a rear chamber and the snap acting switch mechanism is positioned in the rear chamber and the ccmponents are positioned in the front chamber.
6. CLAIM.
7. The pressure switch as recited in CLAIM 3 wherein at least one illurn__na ing device is positioned on the front wall and externally visible and connected in circuit with the ccmponents to have coded multiple illurciipating states to indicate the operating state of the motor.
8. CLAIM.
9. The pressure switch as recited in CLAIM 1 OMP wherεin at least one illuminating device is visible externally of the front wall to indicate an operating condition of the motor.
10. CLAIM.
11. The pressure switch as recited in CLAIM 3 wherein at least one illuminating device is visible externally of the front wall to indicate an operating condition of the motor.
12. CLAIM.
13. The pressure switch as recited in CLAIM 2 wherein at least one illuminating devicε is visible externally of the front wall to indicate an operating condition of the motor.
14. CLAIM.
15. The pressure switch as recited in CLAIM 5 wherein two illuminating devices having contrasting colors are positioned on the front wall.
16. CLAIM.
17. The pressurε switch as rεcitεd in CLAIM 2 wherein the terminals and components arε electrically connected by a separable connection.
18. CLAIM.
19. The pressurε switch as rεcitεd in CLAIM 1 wherein the terminals and components arε electrically connected by a separable connection.
20. CLAIM.
21. The pressure switch as recitεd in CLAIM 6 wherεln the terminals and components are elεctrically connεcted by a separable connection.
22. CLAIM.
23. The pressure switch as recited in CLAIM 8 wherein the terminals and components are electrically connected by a separable connection. OMPI CLAIM.
24. a motor control switch comprising: a mechanically operated pressure responsive switching means having contacts for closing and opening a circuit to a motor in response to pressure changes in a fluid, system, means for detecting and providing a signal indicative of current in the circuit, means for detecting and providing a signal indicative of a voltage across the motor, means responsive to the signals from the current and the voltage detecting means for providing a signal indicative of the power factor of the current in the circuit, and means responsive to the signals for interrupting the circuit when at least one of the signals changes by an amount greater than a preprogrammed value.
25. CLAIM.
26. The motor control switch as recited in CLAIM 13 where in the contacts operate with a snap action. OMPI CLAIM.
27. The motor control switch as recited in CLAIM 13 wherein the means for interrupting the circuit includes an electrcxnagnetically operating device. CLAIM.
28. motor control switch comprising: mechanically operating pressure responsive means having switching contacts for opening and closing a circuit between an A.C. source and an A.C. motor in response to pressure changes in a fluid syst m, means for detecting and providing a signal indicative of a voltage across the motor, means for detecting and providing a signal indicative of current in the circuit, means responsive to the current and the voltage signals for producing a signal indicative of the power factor of the current in the motor, iϊπiing means for measuring the duration of intervals when the motor is energized and the duration of int_rvals between intervals when the motor is energized and providing an output indicative of the duration of the intervals, and means responsive to the output and the signals for interrupting the circuit when the preselected output and signals changes by an amount greater than a preprc>gra τιπ__d value.
29. CLAIM.
30. A motor control switch comprising: a mechanically operated pressure responsive switching means having contacts for closing and opening a circuit between an A.C. source and an A.C. motor in response to pressure changes in a fluid system, means for detecting and providing a voltage signal indicative of an A.C. voltage across the motor, means for detecting and supplying a current signal indicative of an A.C. current in the circuit, means responsive to the voltage signal and the current signal providing a power factor signal that is indicative of the duration of intervals between the instants when the polarity of the A.C. voltage and the polarity of the A.C. current reverses, timing means for measuring and providing a run signal that is indicative of the duration of intervals when the motor is energized, timing means for measuring and providing an off signal that is indicative of the duration of intervals between the occurrance of successive run signals, and means including a microcomputer for interrupting the circuit in response to the voltage and current signals and to the duration of the power factor, the run time and the off time signals.
31. CLAIM.
32. The motor control switch as recited in CLAIM 17 wherein the means for interrupting the circuit includes a relay having normally closed contacts in the circuit and a coil winding having its energization controlled by the rd<Ξrocαπputer.
33. CLAIM.
34. The motor control switch as recited in CLAIM 18 wherein the means for closing and opening the circuit includes a switch having snap acting contacts.
35. CLAIM.
36. The motor control switch as recited in CLAIM 13 wherein the means for closing and opening the circuit includesaswitch having snap acting contacts.
37. CLAIM.
38. The motor control switch as recited in CLAIM 17 wherein the motor drives a submersed pump.
39. CLAIM.
40. The motor control witch as recited in CLAIM 20 wherein the snap acting contacts, the voltage detecting means, the current detecting means, the means providing the power factor, the means providing the run signal, the means providing the off signal and the micxc xπputer are enclosed with a cσrmon cover and a pair of light emitting devices positioned in a front wall of the cover are coded to indicate a detected malfunction of the motor and pump.
41. CLAIM.
42. The motor control switch as recited in CLAIM 22 wherein the pair of light anitting diodes that are mounted in the cover and have contrasting colors.
43. CIAIM.
44. The motor control switch as recited in CLAIM 23 wherein the code of the diodes is provided by the microcαnputer so that diodes selectively are switched to an off state, a steady on state and a flashing state.
45. CLAIM.
46. The motor control switch as recited in CLAIM 19 wherein the motor drives a submersed pump.
47. CLAIM.
48. The motor control switch as recited in CIAIM 25 wherein the snap acting contacts, the voltage detecting means, the current detecting means, the means providing the power factor, the means providing the run signal, the means providing the off signal and the rtάcroccmputer are enclosed with a cσrmon cover and a pair of light emitting devices positioned in a front wall of the cover are coded to indicate a detected malfunction of the motor and pump.
49. CLAIM.
50. The motor control switch as recited in CLAIM 26 wehrein the pair of light emitting diodes that are mounted in the cover and have contrasting colors.
51. CLAIM.
52. The motor control switch as recited in CLAIM 27 wherein the code of the diodes is provided by the microcomputer so th 'diodes selectively are switched to an off state, a steady on state and a flashing state. _ OΛ1PI CLAIM.
53. A motor control comprising: a support, a first housing part detachably mounted on the support, a second housing part mounted on the first housing part, a pressure responsive snap acting switch mechanismmounted on the support and enclosed within a cavity provided by the first housing part, solid state control ccmponents enclosed within a cavity provided by the second housing part and means extending through openings betweεn the cavities providing a separable electrical connection between the switch mec±anism. and the solid state ccmponents.
54. CLAIM.
55. The motor control as recited in CIAIM 29 wherein the separable electrical connection is provided by plugin type elenrents.
56. CLAIM.
57. The motor control as recited in CLAIM 29 wherein the pressure responsive snap acting switch mechanism comprises: a pressure responsive diaphragm mounted on the support, a stationary contact assembly including a plurality of stationary contacts mounted on OMPI the support and a movable contact assembly including contacts that are movable with a snap action in response to movements of the diaphragm into and out of engagement with the stationary contacts.
58. CIAIM.
59. The motor control as recited in CLAIM 29 wherein the components enclosed within the second housing part include a relay, a current responsive means and a voltage responsive means.
60. CLAIM.
61. The motor control as recited in CLAUM 31 wherein the mponents enclosed within the second housing part include a relay, a current responsive means and a voltage responsive means.
62. CIAIM.
63. The motor control as recited in CLAIM 30 wherein the pressure responsive snap acting switch mechanism includes a pressure responsive diaphragm mounted on the support, a stationary contact assembly including a plurality of stationary contacts mounted on the support and a movable contact assanbly including contacts that are movable with a snap action in response to movements of the diaphragm into and out of engagement with the stationary contacts.
64. CLAIM.
65. The motor control as recited in CLAIM 30 wherein the ccmponents enclosed within the second housing part include a relay, a current responsive means and a voltage responsive means.
66. CLAIM.
67. The motor control as recited in CIAIM 34 wherein the ccmponents enclosed within the second housing part include a relay, a current responsive means and a voltage responsive means.
68. CIAIM.
69. A motor control switch cαnprising: a support, a mechanical switch mechanism mounted on the support, said mechanism including wire connecting terminals connecting the switch mechanism to an electric source and a motor to be energized by the source, a cover detachably mounted on the support enclosing the switch mechanism when the cover is positioned on the support and providing access to the terminals when the cover is detached frcm the support, components including solid state control cαrgponents enclosed within the cover and means providing a separable electrical connection between the terminals and solid state ccmponents.
70. CLAIM.
71. The motor control switch as recited in CLAIM 37 wherein the separable electrical connection is provided by plugin type elements.
72. CLAIM.
73. The motor control switch as recited in CIAIM 37 wherein the pressure responsive snap acting switch mechanism includes a pressure responsive diaphragm mounted on the support, a stationary contact assembly including a plurality of stationary contacts and a movable contact assembly including contacts that are movable with a snap acting in response to movements of the diaphragm into and out of engagement with the stationary contacts.
74. CLAIM.
75. The motor control switch as recited in CLAIM 37 wherein the components enclosed within the housing include a relay, current responsive means and voltage responsive means.
76. CLAIM.
77. Hie motor control switch as recited in CLAIM 37 wherein the cover has an internal dividing wall with the control components positioned within the cover on a side of the wall remote from the switch mechanism and the means providing the separable electrical connection extends through the dividing wall.
78. CLAIM.
79. The motor control switch as recited in CLAIM 41 wherein the separable electrical connection is provided by cooperating and connectors that are carried by the terminals and a printed circuit board enclosed wi hin the cover and extend through openings in the dividing wall.
80. CLAIM.
81. A motor control switch including a mechanically operated switch portion comprising a support having a periphery, a lever pivotally mounted on the support, a post having an end secured to the support and extending through an opening in the lever to a threaded end, a spring seat positioned on the threaded end, a compression spring surrounding the post and positioned between the spring seat and the lever, a pressure responsive mechanism positioned by the support to urge the lever in a direction to compress the spring, an insulating block positioned by the support, a plurality of stationary contact structures positioned by the block with each contact structure including a stationary contact and a terminal member, a plurality of movable contacts moved by the lever into and from engagement with the stationary contacts, a cover for the switch, said cover having an interior area and including a peripheral skirt positioned adjacent the periphery of the support and a dividing wall separating a front chamber frcm a rear chamber in the interior area of the cover, with the rear chamber enclosing the mechanically operated switch portion and the front chamber enclosing a plurality of electronic components, a plurality of separable connectors extending through openings in the dividing wall and arranged to connect components in the front chamber with selected stationary contact structures in the rear chamber, and means extending from a front end of the cover through the front chamber into a threaded engagement with the threaded end of the post for securing the cover to the support.
82. CLAIM.
83. The motor control as recited in CLAIM 39 wherein the separable electrical connection is provided by a block of insulating material that is mounted on the support and provides a support for the stationary contacts, and a separate block of insulating material that is secured to the block of insulating material and provides a support for one of the wire connecting terminals and a bayonet portion of the separable connector associated with the said one wire connecting terminal.
84. CLAIM.
85. The motor control as recited in CIAIM 44 wherein a stationary contact associated with the said one termirial includes a bayonet portion of the separable connector associated IjUREA.
Description:
MECHANICALLY OPERATED PRESSURE SWITCH

HAVING SOLID STATE COM P ONENTS

The present invention relates to controls for electric motors and more particularly to a control switch having mechanical and solid state components for controlling the energization of a submersible pump motor.

BACKGROUND OF THE INVENTION

Fluid pressure responsive switches are well known and have long been used to control the energization of electric motors driving submersible pumps that deliver fluids under pressure from a well to a receiving tank during periods when the fluid pressure within the tank is lower than a preset pressure. An example of a control of this type is disclosed in an expired U.S. patent 2,741,678 and a U.S. patent 3,340,372. While controls incorporating features of these patents are presently extensively used, in certain pumping installations pump motors may be unprotected against damage which results when the recovery rate of the well from which the fluid is pumped is less than the rate at which the fluid is removed from the well. A pressure switch as disclosed in the U.S. patent 3,345,480 is intended to prevent motor damage under low water pumping conditions by permitting the motor to be energized as long as the well conditions permit the pump to maintain the fluid pressure of the system within a preset pressure range. The switch operates to prevent pump motor operation when the fluid level in the well is below the level which will permit the pump to maintain the desired system pressure. A further improvement in pressure switches for submersible pump motors appears in a U.S. patent 4,020,308, which discloses an arrangement for providing an indicating light in a cover of a fluid

prεssure switch. Pressure switches of the type included in the '308 patent are particularly suited for use in pumping systems where it is desirable to visually indicate periods when the pump motor is energized.

SUMMARY OF THE INVENTION

The mechanical pressure and other switch components according to the present invention are housed within a single enclosure. In the preferred embodiment of the invention, the enclosure is provided by a pair of housing parts with one of the parts, termed the lower housing part enclosing fluid pressure responsive components and snap acting switch parts and the other or upper housing part enclosing solid state and other electrical components that are connected to terminations on the snap switch in the lower housing parts by a separable or plug-in type connection to provide a convenient access to the pressure responsive components and wire terminals in the lower housing part for iring and adjustment purposes. The upper housing part encloses solid state components, a relay and current and voltage detectors. The upper housing part also includes a calibrating button which is accessible from the top.or front of the upper housing part and is provided to program the operation of the solid state circuits. The upper housing part also positions indicating lights which are coded to indicate the type of an operative malfunction of the pump motor.

It is an object of the present invention to provide a control for a pump motor with a segmented housing wherein one segment encloses a pressure responsive snap acting mechanism and the other segment contains solid state switching components and to electrically interconnect the snap switch with other components of the control by a plug-in type electrical connection.

A further object is to provide a control for a pump -motor with a housing that encloses solid state components which are provided to monitor the operative condition of the motor and provide the housing with a switch button and indicating lamps which are respectively usable to calibrate the solid state ccmponents within the enclosure and indicate the operative state of the pump motor.

An additional object is to provide a control for a pump motor with components that detect variations in fluid pressure delivered by the pump, detect when the load on the motor is less than a normal value, detect when the motor is operating under locked rotor or overload conditions, detect when the duration of the pumping cycles are excessively long or short and when the input voltage to the motor is excessively high or low.

Another object is to provide a control for a pump motor with components that detect and provide signals indicative of the voltage, current and power factor of the motor current and control the operation of the motor in response to the signals.

A still further object is to provide a control for a pump motor with ccmponents that detect and provide signals -uidicative of the pressure output of a pump driven by the motor and the current and voltage as well as the power factor of the motor current and provide a snap acting mechanical-switchmechanism that is controlled by the pressure output and a means including electronic ccmponents for controlling the operation of the motor in response to the voltage, current and power factor.

Further objects and features of the invention will be readily apparent to those skilled in the art frcm the specification and the appended drawings illustrati-ng a preferred e bodiinent in which a mechanically operated pressure switch having solid state components

incorporating the features of the present invention is diagra matically shown.

DESCRIPTION OF THE DRAWINGS

FIG. 1 and 1A are cross section elevation views of a pump motor controller that incorporates the present invention;

FIG. 2 is another cross section elevation view of the switch in FIG. 1;

FIG. 3 is a diagram illustrating the functional relationship of certain of the components of the control in FIG. 1;

FIG. 4 is a chart showing the interrelation of the components in the control illustrated in FIG. 1.

FIG. 5 is a diagram showing the range of the operation of the control in FIG. 1.

FIG. 6 is a block diagram of a flow chart utilized by the control logic in the motor controller in FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the drawings, a control 10 incorporating a pressure switch mechanism 12 and a microprocessor type control includes mechanical and pressure responsive components as disclosed in U.S. patent 3,340,372, which was granted to Carl A. Schaefer and is incorporated herein by reference. The control 10 is particularly suited for use in submersible pump installations wherein a pump and a motor driving the pump are submersed in the fluid within a well and delivers fluid under pressure to a receptacle located above ground.

As disclosed in the Schaefer patent, the pressure switch mechanism 12 includes a diaphragm mechanism 14 that is mounted on a support 16 and operates a snap action mechanism 18 including movable contacts 20 in response to

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mechanism 18 including movable contacts 20 in response to variations in pressure imposed on the diaphragm mechanism 14. The diaphragm mechanism 14 includes a flexible diaphragm 22 that is moved in response to variations in fluid pressure imposed thereon through a fluid conduct, not shown, that is connected between a fluid receptacle, not shown, and a coupling 24. The snap acting mechanism 18 includes a member 26 that moves in response to movements of the diaphragm 22 and causes a snap acting movement of a member 30. The member 30 through an arm portion, an insulating contact carrier 66 and conducting member 68 provides a support for movable contacts 20 and causes the contacts 20 to engage pairs of stationary contacts 32 with a snap action when the diaphragm 22 responds to a pressure less than a selected pressure. Tne member 30 also causes the contacts 20 to move out of engagement with the contacts with a snap action when the pressure imposed on the diaphragm 22 is greater than a preselected value.

The stationary contacts 32 are carried on an insulating terminal block 34 that is in turn carried on the support 16, As most clearly shown in FIGS. 1A and 3, the stationary contacts comprises four contacts 36-39 that are positioned on the block 34 as two pairs of contacts with contacts 36 and 37 providing one pair and the contacts 38 and 39 providing the second pair. The contacts 36-39 are mounted on -shaped terminal members 40-43 respectively with each terminal member 40-43 having a leg portion whereon its associated contact 36-39 is secured and a leg portion threadedly receiving terminal screws 44-47 respectively. One of the terminal members 40-43, e.g. terminal 43 is provided with a bayonet connector 48 and an additional or a fifth terminal, i.e., a terminal 50 is mounted on its own individual insulating block 51 and includes a terminal screw 52 as well as a

me bers 40-43, e.g. terminal member 40 is engaged by a prong 56 that electrically engages the terminal member 40 as will be later described. The insulating block 51 is secured to the block 34 by a screw 53.

As shown in FIGS. 1A and 3, the contact carrier 66 is substantially V-shaped with each of its arms carrying a bridging conducting member 68 having a pair of the contacts 36-39 disposed at each end thereof. The contacts 36-39 are positioned to cooperate and engage adjacent pairs of the stationary contacts 32.

Referring to FIG. 1 and 3, the pressure switch 10 is wired when a cover 70, as will be later described in detail, is removed to provide access to the terminal screws 44-46 and the terminal screw 50. As shown, one side of an alternating current source, not shown, is connected through a conductor 72 and tightened terminal screw 44 to the terminal 40 and the other side of the A.C. source is connected via a conductor 74 and the tightened screw 52 to the fifth terminal 50. An alternating current motor 76 in the embodiment disclosed herein is connected by conductors 78 and 80 and tightened terminal screws 45 and 46 to the terminals 44 and 42 respectively.

As more fully described in the U.S. patent 3,340,372 the support 16 has a pair of posts.- A range spring 79 is disposed about one of the posts 81 and a differential spring 82 is disposed about the other post of the pair. The range spring 79 has its ι-pper end bearing against a cap washer 84 that is captivated by a nut 86 threaded on a threaded end 88 of the post 81 and is used to adjust the pressure operating range of the switch 10. The lower end of the range spring 79 abuts against and applies a force to a free end portion of the member or lever 26 that has relatively large openings through which the pair of posts including the post 81 extend. The amount of force applied by the spring 79 on the lever 26 is determined by the

adjustment of the nut 86. The movement of the member 26 through a toggle echanim including a toggle spring 90 is transmitted to the member 30.

As shown in FIG. 1A a post, not shown, is provided with a shoulder against which a cup washer 92 normally is biased by the differential spring 82. The spring 82 is compressed by a nut 94 bearing against a cup 96 which is positioned on the upper end of the spring 82.

The cover 70, in the preferred embodiment is formed of a pair of parts identified as a rear or lower cover part 100 and a front or upper cover part 102 which are formed as distinct parts 100 and 102 for manufacturing purposes. The cover 70 provides maximum protection to components mounted within the cover 70 and accessibility to the mechanical components and electrical terminations carried on the support 16 and enclosed within the cover part 100. The cover part 100 has a peripheral skirt or rear end 104 positioned adjacent the peripheral edge of the support 16 and a front wall 106 which acts as a dividing wall and separates the interior of the cover 70 into two chambers identified as a rear chamber 108 and a front chamber 110 when the cover parts 100 and 102 are assembled to each other. The wall 106 includes a pair of openings 112 and 114 which are located to receive the bayonet connectors 48 and 54 respectively and expose the ends of the connectors 48 and 54 in the front chamber 110. The wall 106 also includes an opening 116 which is provided in a bore extending through a post 118 that extends rεarwardly from the wall 106. The post 118 and the opening 116 are located to receive the prong 56 that extends rearwardly from the chamber 110 through the opening 116 into engagement with the terminal 40.

The connectors 48 and 54 extend into the openings 112 and 114 respectively where the connectors 48 and 54 are engaged by a pair of spring biased plug-In

OMPI

connector type conductors, one of which is designated as 178 in FIG. 2 and represented by numerals 178 and 180 in FIG. 3. The pair of condutors 178 and 180 are secured to circuits in printed circuit borads 176 as will be later described. The bayonet connectors 48 and 54 as well as the prong 56 provide plug-in type interruptable connections and completeandinterrupt electric circuits when the cover 70 is removed and secured to the pressure switch mechanism 12.

The front or upper cover part 102 has a rear peripheral edge or -skirt 120 engaging the front side of the periphery of the wall 106 so the parts 100 and 102, when secured to each other, will provide a unitary assanbly or cover 70 which may be removed or secured as an assembly on the support 16. To provide this assembly, the front part 102 includes suitably tapped bosses which receive screws 124, one of which is shown in FIG. 1, which secure the rear end of the front part 102 to the front end of the part 100. ' When the parts 100 and 102 are assαnbled, the prong 56 extends through the opening 116 into engagement with the teiππinal 40. The prong 56 preferably includes an outer cylinder that is secured through a member to a printed circuit board 122, positioned in the chamber 110, and a plunger that is telescoped in the cylinder and engages the terminal 40 with a spring biased pressure engagement. Also when the cover parts 100 and 102 are assembled, a boss 127 extending forwardly frcm the wall 106 is aligned wit a boss 128 extending rearwardly frcm a front wall 130 on part 102 and a bore 132 extending through the bosses 127 and 128 is aligned with the front threaded end of the post 81. When the cover parts 100 and 102 are thus assembled, a rod-like member 134 having a fanale threaded

end 136 threaded on the post 81 extends through the bore 132 to a threaded front end 138 that extends through an opening in the front wall 130. A suitable nut 140 when threaded on the end 138 secures the cover 70 to the support 16.

In addition to the on and off pressure switch function provided by the switch mechanism 12, the pressure switch 10 includes components enclosed within the front chamber 110 that are provided to protect the motor 76 against water system failures. Among the failures to which the pump motor may be subjected is a condition where no load is imposed on the motor as a result of a broken pump shaft or coupling, or an insufficient well recovery water flow, an air locked pump or a blocked pump intake. Another type of failure that can manifest itself is an overload condition which occurs as the pump is gradually clogged as when the pump gradually takes up sand. Additionally, the motor may be subjected to an overload resulting from excessive back pressure as caused by scaled and corroded discharge pipes, a failure of the check valve to open or an improper combination of the motor and the pump because of differences in their ratings. Other failures that may occur include extended run operation as caused by over usage of water, worn pump parts or leaks in the service piping and rapid cycling of the pump as maybe occasioned because of a water logged tank, a check valve leak or leaks in the sevice piping. The components within chamber 110 are provided to detect these failures and institute a proper response to minimize damage resulting from the failures.

The components of the control 10, as shown in FIG. 3, that are in the front chamber 110 include a control relay 150, a current detector 152, and solid state elements identified as control logic 154. Additionally, the components include a pair of light emitting diodes

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(LEDS) 156 &πd 158 and a recessed calibration switch 160 having normally open contacts. The diodes 156 and 158 as well as the recessed switch 160 are mounted in the front wall 130 so as to be respectively visible and accessible from the front side of the cover 70.

Referring to the FIGS. 3 and 4, the control 10 includes the pressure switch mechanism 12, a power supply 162, the control relay 150 having normally closed contacts 150a and a coil winding 150b, a current detector 152, a voltage detector 166, a single chip microcomputer 168, the calibration switch 160, the LED diodes 156 and 158, a non-volitile memory 170, associate control circuitry 172 and a high/low voltage detector 174.

The power supply 162, the current detector 152, the voltage detector 166, the microcomputer 168, the memory 170, the control circuitry 172 are provided by solid state components mounted on printed circuit boards 122 and 176, in a manner well known to those skilled in the art. The boards 122 and 176 are maintained in parallel spaced relation by the cover 102. The relay 150 is mounted between the boards 122 amd 176 and is enclosed along with the current detector 152 within the chamber 110.

The pressure switch mechanism 12 is mechanical and switches the movable contacts 20 into a circuit closing position or a circuit opening position in response to changes in the input pressure on the diaphragm 22. When the pressure falls below a preset pressure setting, the contacts 20 move with a snap action to a circuit closing position with the stationary contacts 32 and the motor 76 and a pump, not shown, is energized. The energized pump causes a pressure increase on the diaphragm 22 and the contacts 20 are moved with a snap action to a circuit opening position to deenergize the motor 76 when the pressure on the diaphragm 22 exceeds a reset value.

OMPI

As shown in FIG. 3, an alternating current source is connected via conductors 72 and 74 to the terminals 40 and 50 respectively. The terminal 50 is connected to the bayonet conductor 54 and components within the front chamber 110 by the plug-in type connector 178. The terminal 40 is connected to components within the front chamber 110 by the prong 56 and the plug-in type connector 180.

The connector 54 is connected through the closed contact 150a, a suitable conductor surrounded by a pick up coil, not shown, of the current detector 152 to the bayonet connector 48. The connector 54 also supplies an input to the control logic 154. The probe 56 is connected to the supply lead 72 and supplies an input to the control logic 154. In FIG. 4, the pressure switch mechanism 12 is shown as having an input 162 which represents the conductors 72 and 74 in FIG. 3. The mechanism 12 is also shown as having an output 163 which represents the conductors 78 and 80 in FIG. 3. The ' fluid pressure which is imposed upon the coupling 24 in FIG. 1 is represented by the arrow 182 which desiginates the pressure imposed on the pressure switch mechanism 12. As shown in FIG. 4, the power supply 162, the power relay 150, the current detector 152, the voltage detector 166, the high/low voltage detector 174, the microcomputer 168, the non-volitile memory 170 and the control circuitry 172 are all enclosed within the front chamber 110. The calibration switch 160 and the visual indicators 156 and 158 are positioned by the front wall 130.

The pressure switch mechanism 12 is totally mechanical and switches the two sets of movable contacts 20 to energize or deenergize the motor 76 in response to the input pressure 182. When the pressure 182 falls below a low pressure setting, the contacts 20 engage the stationary contact 32 and energize the motor 78. The

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prεssure increases until a high pressure setting is exceeded whereat the contacts 20 open with a snap action to deenergizε the motor 76. The power supply 162, as included within the front chamber 110, supplies the energizing current and voltage to the other previously mentioned components included within the front chamber 110. The power relay 150 has normally closed contacts 150a in series between the connectors 54 and 48 and an operating coil 150b connected to receive an output from the microcomputer 168. The microcomputer 168 monitors the operation of the motor 76 and thereby the operation of the pump in the system. When a proper output signal is received from the microcomputer 168, the relay 150 opens the contact 150a and thereby inhibits the pump from running even though the contacts of the switch mechanism 12 are closed due to a low pressure signal input 182. During normal operation when the conditions in the the motor fluid circuit are normal, the contacts 150a are closed. The current detector 152 includes a current transformer not shown, that converts the motor current sine wave into a logic level square wave that Is inputted through a lead 184 to the microcomputer 168. The edge of the output pulse from the current detector 152 corresponds to the zero crossing of the motor current.

The voltage detector 166 has an output 186 which is supplied as an input to the microcomputer 168. the microcomputer 168 also receives an input from the power supply 162. The voltage detector 166 converts the voltage sine wave of the A.C. supply into a logic level square wave which is supplied to the microcomputer 168. The edge of the square wave output 162 corresponds to the zero crossing of the voltage across the motor 76. The microcomputer 168 is arranged to count the time Interval between the zero crossing of the voltage signal on the lead 186 and the zero crossing of the current on lead 184

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and thereby provide a measure of the power factor of the current to the motor 76.

The high/low voltage dete ' ctor 174 converts the line voltage on the line 162 into two logic level outputs that are supplied as an input 188 to the microcomputer 168. The microcomputer 168 ignores the input 188 as long as the voltage on line 162 is within preset high and low limits. When the output of the voltage detector 174 is present due to a voltage higher or lower than the preset limits, the detector 174 through the microcomputer 168 provides a signal to the power relay 150 which causes the relay to open its contacts 150a and thereby deenergize the motor 76. The microcomputer 168 is the central and controlling device in control 10. The microcomputer 168 monitors the pumps operation that is conveyed by signals from the motor as previously described. The microcomputer 168 provides an output to the relay 150 in response to signals indicative of the motor conditions as will be subsequently described.

The control 10 includes a non-volitile memory 170. The memory 170 is an EEPROM (Electrically Eraseable Programmable Read Only Memory). The memory is of the type which will retain any information stored In it in event of power removal or failure. An important piece of data which is to be stored in he memory 170 is the calibration value as will be hereafter described. All other data values will be programmed into the memory when the control 10 is manufactured. The item designated as control circuitry 172 includes components that are required to support the microcomputer 168, i.e., a suitable clock crystal, not shown.

The switch 160 is mounted in the front wall of the cover 70 and is thus readily available for calibration purposes. After the electrical and plumbing connections of the pump system associated with the control 10 are

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otor is running under normal operating conditions, the calibration switch 160 contacts are closed and an input is supplied to the microcomputer 168 which jumps to a software routine and stores the calibration reading value in the the non-volitile memory 170 for future use. The arrangement of the switch 160 in the cover 70 is such that the switch 160 is in a recess and after the calibration procedure is completed, an adhesive sticker can be applied to the front wall 106 to conceal the switch 160. If desired, the date of calibration maybe inscribed on the applied sticker.

The memory in which the calibration value is stored is of the non-volitile type that does not require power to retain its data and has its data available each time power is applied to the control 10. Thus, even- if power is removed from the control 10, the calibration data in the memory remains so that re-calibration of the switch is not required. The normal operating power factors of electric motors vary not only with load and voltage but also with the design of the motor and horsepower rating. The calibration feature is included in the controller 10 to compensate for these variations. According to FIG. 5, POINT A on a curve 190 is a normal operating power factor or calibration-value which was entered into the memory of the control 10 when the switch 160 was operated. The value of POINT A on the curve 190 is used for comparison with an actual running power factor value, desiginated as a POINT D. The location of POINT D on the curve 190 will vary for reasons such as variations in load, voltage and pressure of the motor and pump system and is constantly checked and.compared with POINT A. When POINT D moves away from POINT A by a plus value greater than a value "M"or less than a "N" value, the power relay 150 is energized and the motor is deenergizεd and proper signals are indicated by the illuminated state of the diodes 156

and 158. The and N values are fixed in the software of the irάcroccraputer 168 so that normal variation in the motor operating characteristics will not cause false tripping when the control 10 is properly calibrated. The section containing the visual indicators designated as diodes 156 and 158 is arranged to have the diodes 156 and 158 located in the front wall 130 so the diodes are visible frcm the exterior of the control 10. The light emitting diodes 156 and 158 are preferably chosen to have contrasting colors such as a color red for the diode 156 and a yellow for the diode 158. As shown in the table below, "F", "S" and "OFF" indicate the illuminating state or condition of the diodes 156 and 158 and thereby are coded to indicate the irtproper operating condition of the motor and pump. The diodes, when operating in the manner indicated, will provide an indication of the type of failure occurring in the systan. In the present embcx3iment, the coding of the diodes is as follows with "F" indicating a flashing diode, and "S" designating a diode that is continuously energized and "OFF" designating a deenergized diode.

Condition Red LED Yellow LED

Noload ' F F

Rapid Cycling S S

Low Voltage F S

High Voltage S F

Overload F OFF

Extended Run OFF S

Normal On/Off OFF OFF

When a low water condition or a motor or pump noload occurs, the power factor of the motor will drop below .45 and the motor current will decrease. The reduced motor current reduces the urgency to deenergize the motor and

pεrmits attempts to restart the motor several times before the motor is finally deenergized. When a noload condition occurs, the pump controller will detect the change in power factor and deenergize the motor. After a short delay, the microcomputer will attempt to restart the motor. If the noload condition persists, the microcomputer will progressively increase the delay interval of subsequent restarts and after a fixed number of preprogrammed delayed restarts, the microcomputer will cease its attempts to restart the motor. By detecting the power factor change, the motor is thus protected from damage. In case of a broken shaft or plugged inlet of the pump, the motor will not be damaged even though the pump requires service.

Overload conditions of the pump and motor may be the result of different causes. A motor overload occurs under locked rotor conditions and a pump overload occurs when an incrεasε in back pressure causes the fluid flow of the pump to be decreased. The distinction is made between these two overload conditions because the current and voltage parameters of the motor change differently for the two conditions and therefore different protection features are required to protect the pump and motor under the two different overload conditions. Motor overload can occur when the pump is plugged with sand or the motor is stalled. In this case, the timing of the motor going to a locked rotor condition is the important factor in the protection of thε pump controller. When the pump is slowly clogged by sand, the controller will have time to detect the power factor increase and deenεrgize the motor. In contrast, when the pump and motor are locked, the pump and motor will require a removal from the well to clear the pump, and any protection additional to the protection offered by the conventional circuit breaker in the circuit would be superflous. Additionally, if the

controller did sense the locked rotor or pump plugged condition, the restarting of the pump and motor would aggravate the situation. For this reason, time delays and restarts are not attempted under locked rotor or plugged pump conditions.

When the pump is subjected to an overload that is caused by excessive back pressure, the flow output of the pump is reduced and the power factor and current to the motor both decrease. When this type of failure is detected, ample time will permit the motor to be deenergized before the pump and motor are damaged. If the pump ovεrload conditions continue, a noload signal may be given because the controller cannot distinguish between a noload and excessive back pressure conditions.

When the pump system is subjected to extended run conditions, the microcomputer times the interval beginning with the pump energization and if pressure is not restored within a preset time limit, a visual signal will be given.

Rapid cycling results from a water logged tank, a check valve leak, or leaks in the plumbing. The controller 10 detects a low pressure signal and energizes the motor to restore the proper pressure. If after the motor is deenergized, a low pressure signal is prematurεly detected, a signal will prevent the motor from being energized until the system is reset. This function protects the motor from overheating due to repeated high starting currents in the motor. The control also detects over voltage conditions which causes excessive stress in the motor windings and under voltage conditions which cause overheating of the- otor windings. Good motor design dictates that a motor should not be subjected to voltages 10% greater or 10% less than its nominal voltage rating. In the controller according to the present invention when an incorrect voltage level is detected, the

invention wnen an incorrect voltage level is detεcted, the controller will inhibit the motor from being energized and in this manner, extend the life of the motor being controlled.

The operation of the control 10 as illustrated in FIG. 6 is believed to be self-evident and the construction of the control to be readily apparent to those skilled in the art to which the present invention pertains. As shown in FIG. 3, the control logic 154 is continuously energized from the source connected to conductors 72 and 74, the connector 178 and the conductor 180. Further as shown in FIG. 4, the power supply 162 supplies an Input to the voltage detector 166 and the microcomputer 168. The current detector 152 and the high/low voltage detector 174 provide inputs to the microcomputer 168.

Initially, when the motor 76 is energizεd, as a rεsult of a reduced fluid pressure signal 182, the output of the high/low voltage detector 174 is interrogated by the microcomputer 168. If the voltage of the supply is too low, control is transferred from a block 200 to a control 202 which provides an energizing signal to the relay coil 150b to deenergize the motor 76 and providε a toggle signal which causεs thε rεd LED 156 to flash and the yellow LED 158 to have a steady glow to indicate a low voltage condition across conductors 72 and 74. If the low voltage condition is absent, control is transferred to the block 204 and the control 206 which determine if the supply voltage is too high. If the supply voltage Is too high, a control 206 provides an output which energizes the relay coll 150b to deenergize the motor 76 and toggles the rεd LED 156 to a steady state and a the yellow LED 158 to a flashing state to indicate a high voltage condition.

In the event a high voltage condition is not present, control transfers to a block 208 which checks if thε motor 76 is operating as indicated by a proper motor

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current. If the motor is not running, control returns to the block 200 via an input A to reinitiate the starting current to the motor. If the block 208 determines that the motor 76 is energized, a control signal is initiated after a preset time delay by a control 210 that permits a block 212 to interrogate signals from the current detector 164 and the voltage detector 166 to determine the power factor of the motor current.

After reading of the power factor by the control 212 is inititated, control transfers to a block 214 which determines if the motor has turned off. In the event the block 214 determines that the motor is turned off, control transfers to a block 216 that deter inεs if the interval of an on/off operating cycle of the motor is less than a preset value. In the event that the operating cycle of the motor is less than the preset value, control is transferred to a control 218 which energizes the relay coil 150b to deenergize the motor 76 and toggles the red LED 156 to a steady state and the yellow LED 158 to a steady state to indicate rapid cycling of the motor. If the block 216 deteimines that the operating cycle is not less than the preprogrammed value, control is returned to POINT A.

After the reading of the power factor on the motor is initiated by the control 212 and the block 214 has determined that the motor is not turned off, control is transferred to a block 220 that determines if the power factor of the motor current has been read. If the reading of the power factor is not completed, control is returned to block 214 which again determines if the motor is turned off before control is rεtransfεrrεd to thε block 220. If the reading of the power factor of the motor is completed, block 220 transfers control to a block 222. Block 222 determinεs if a calibration rεquest has been initiated by closure of the contacts of switch 160. In event that a

a control 224 which causes the entry of the parameters of the calibration into the microcomputer 168 and returns control to the block 212 at POINT B.

In the event that a calibration value has beεn entered, control transfers to a block 226. Block 226 determines if a noload condition is present as may be caused by a low water condition. Thε low water condition is indicated by a drop in the power factor below .45 and a motor current decrease. When a low water condition is present, control transfers to a block 228 that detεrmines if the condition sensεd is thε first low water condition. If the low water condition sεnsed by block 228 is the first low water condition, control is transferred to a control 230 which aftεr a short dεlay energizεs thε rεlay 150 to dεεnεrgizε thε motor 76 and togglεs thε red LED 156 to a flashing state and the yellow LED 158 to a steady state to indicate a low water or noload condition is present. After a short delay, control is transferred from the control 230 to a block 232 which dεεnergizes the rεlay 150 and restarts the motor 76. Thε block 228 rεsponds to successive Indications of a low water or noload conditions and supplies an input to a block 234 for each occurrance. After the block 234 dεte miπεs that four succεssive noload conditions have occurred, it transfers control to a control 236 which energizεs the relay coil 150b and toggles the LEDS 156 and 158 to indicate a low watεr or noload condition is present as previously described. In the event that the condition sensεd by the block 234 is not thε fourth low water condition, control is transferred to a control 238 which progrεssivεly increases thε delay of the signal supplied to the block 232 as second and third low water conditions are sεnsεd by thε block 226. Thus after four low watεr conditions have beεn sεnsεd by the block 226 the rεlay 150 is energizεd to interrupt the motor circuit and the diode

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LEDS 156 and 158 are energized in the manner previously described.

If the system does not have a low water or a noload condition, control is transferred from block 226 to a block 240. If a motor and/or pump overload condition is present, the power factor of the motor current will increase above POINT C in FIG. 5 and the block 240 transfers control to a control 242. The overload condition causes the control 242 to energize the relay 150 which deεnergizes the motor 76 and toggles the red LED 156 to have a flashing output and the yellow LED 158 to be off.

If an overload condition is not present the block 240 transfers thε control to a block 244. Block 244 responds to a low voltage signal from the detεctor 174 and if a low voltage signal is present, transfers to control via the POINT A to block 200 which energizes the relay 150 to stop thε motor and toggles the red LED 156 to have a flashing output and the yellow LED 158 to have a steady or continuous output.

In the event that the voltage detected by the block 244 is higher than the preprogrammed value, control is transferred to a block 246 which interrogates a signal from the detector 174 and supplies an output indicating a- high voltage through POINT A and through the low voltage block 200 to the high voltage block 204. The block 204 in response to thε detected high voltage transfers control to control 206 which enεrgizεs thε rεlay 150 to stop the motor 76 and toggles thε LEDS so that the red LED 156 is continuously illuminated and the yellow LED 158 has a flashing output.

If the signal from the voltage detector 174 to the block 246 discloses that the motor is operating within the presεt voltage limits, control is transferrεd to block 248. Thε block 248 times the period that the pump

is running and if the running time of the pump is excessive, control is transferred to a control 250. If the time period of the pumping cycle is excessive, the transfer of the control to the control 250 causes the control 250 to toggle the LEDS so that the red LED 156 is not illuminated and the yellow LED 158 has a steady output.

If an extended run is not detected by the block 248, control is transferred from the block 248 to the POINT B and another cycle of interrogating operation of the motor voltage and current in the manner described occurs.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.