Mechanically operated pressure switch having solid state components

• US 4,998,097 A
• Filed: 12/17/1985
• Issued: 03/05/1991
• Est. Priority Date: 07/11/1983
• Status: Expired due to Fees

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Kierstead, Bruce E., Noth, Myron A.
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): Hofsass, Jeffery A.
• Application Number:
  US06/810,823
• Time in Patent Office: 1,904 Days
• Field of Search: 340/648, 340/660, 340/664, 361/79, 361/90, 324/114, 318/474, 318/473, 318/452, 318/447, 417/44, 364/571
• US Class Current: 340/648
• CPC Class Codes: H01H 35/24 Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow wherein the change of pressure is caused by change of temperature H01H37/36
• CPC Class Codes: H02H 7/08 for dynamo-electric motors

Abstract

A motor control having mechanical switching and pressure reponsive components for connecting and intercepting a circuit between an A.C. source and an A.C. motor in response to pressure changes in a pressure system. The control includes a microcomputer chip and components that detect a voltage across the motor and a current through the motor and provide signals indicative of the level of the motor voltage and current. The control in response to the signals determines the power factor of the current and in response to the detected signals protects the motor from operating malfunctions when the voltage is too high or low, the current is too high or too low, the time of operation of the motor is too long or too short and in response to the character of the malfunction provides a visual coded lamp indication of the cause of the malfunction.

Claims

1. A motor control switch for selectively energizing a motor to drive a desired load and de-energizing the motor during abnormal operating conditions comprising:

a mechanically operated pressure responsive switching means having contact 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,

non-volatile memory means for storing desired signal values;

a microcomputer for storing a desired value of said power factor in said non-volatile memory as a stored desired value of the power factor, said stored desired value being transferred by said microcomputer from said means for providing a measurement indicative of the power factor to said non-volatile memory;

means for commanding said microcomputer to store, in said non-volatile memory, desired signal values of a motor parameter measured while said motor is driving a desired load;

means for comparing said stored desired value of the power factor with a value provided by said means for providing a measurement indicative of the power factor to obtain a difference signal;

means responsive to the signals for interrupting the cirucuit when at least one of the signals changes by an amount greater than a preprogrammed value, and,

a cover for housing said motor control switch.

2. The motor control switch as recited in claim 1 wherein the contacts operate with a snap action.

3. The motor control switch as recited in claim 1 wherein the means for interrrupting the circuit includes an electromagnetically operating device.

8. The motor control switch as recited in claim 1 wherein the means for closing and opening the circuit includes a switch having snap acting contacts.

10. The motor control switch as recited in claim 8 wherein the snap acting contacts, the voltate 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 microcomputer are enclosed with a common cover and a pair of light emitting devices positioned in a front wall of the cover are coded to indicate a detected malfucntion of the motor and pump.

11. The motor control switch as recited in claim 10 wherein the pair of light emitting diodes are mounted in the cover and have contrasting colors.

12. The motor control switch as recited in claim 11 wherein the code of the diodes is provided by the microcomputer so the diodes selectively are switched to an off state, a steady on state and a flashing state.

17. The apparatus as in claim 1 wherein said means for commanding said microcomputer to store further comprises:

a manually operated push button arranged so that closing of contacts of said push button commands said microcomputer to read a value of the power factor from said means for providing a signal indicative of the power factor.

4. A motor control switch for selectively energizing a motor to drive a desired load and de-energizing the motor during abnormal operating conditions comprising:

mechanically operated 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 system,

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,

non-volatile memory means for storing desired signal values;

a microcomputer for storing a desired value of said power factor in said non-volatile memory as a stored desired value of the power factor, said stored desired value being transferred by said microcomputer from said means for providing a measurement indicative of the power factor to said non-volatile memory;

means for commanding said microcomputer to store, in said non-volatile memory, desired signal values of a motor parameter measured while said motor is driving a desired load;

means for comparing said stored desired value of the power factor with a value provided by said means for providing a measurement indicative of the power factor to obtain a difference signal; and

,

timing means for measuring the duration of intervals when the motor is energized and the duration of intervals between intervals when the motor is energize and providing an output indicative of the duration of the intervals,

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 preprogrammed value in order to control a motor operating a pump in a fluid system, and,

a cover for housing said motor control switch.

5. A motor control switch for selectively energizing a motor to drive a desired load and de-energizing the motor during abnormal operating conditions 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 a 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 for providing a signal indicative of the power factor of the current in the circuit,

non-volatile memory means for storing desired signal values;

a microcomputer for storing a desired value of said power factor in a memory as a stored desired value of the power factor, said stored desired value being transferred by said microcomputer from said means for providing a measurement indicative of the power factor to said non-volatile memory;

means for commanding said microcomputer to store, in said non-volatile memory, desired signal values of a motor parameter measured while said motor is driving a desired load;

means for comparing said stored desired value of the power factor with a value provided by said means for providing a measurement indicative of the power factor to obtain a difference signal; and

,

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 occurrence of successive runs signals,

means including said 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, and,

a cover for housing said motor control switch.

6. The motor control switch as recited in claim 5 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 microcomputer.

7. The motor control switch as recited in claim 6 wherein the means for closing and opening the circuit includes a switch having a snap acting contacts.

9. The motor control switch as recited in claim 5 wherein the motor drives a submersed pump.

13. The motor control switch as recited in claim 7 wherein the motor drives a submersed pump.

14. The motor control switch as recited in claim 13 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 microcomputer are enclosed with a common cover and a pair of light emitting devices positioned in a front wall of the cover are coded to indicate a detected malfucntion of the motor and pump.

15. The motor control switch as recited in claim 14 wherein the pair of light emitting diodes are mounted in the cover and have contrasting colors.

16. The motor control switch as recited in claim 15 wherein the code of the diodes is provided by the microcomputer so the diodes selectively are switched to an off state, a steady on state and a flashing state.