AC/DC two-wire control techniques

• US 5,081,411 A
• Filed: 12/20/1990
• Issued: 01/14/1992
• Est. Priority Date: 12/20/1990
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Walker, James M.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): Davidson, Ben
• Application Number:
  US07/630,829
• Time in Patent Office: 390 Days
• Field of Search: 363/89, 363/53, 363/, 323/285, 323/286, 323/287, 323/324, 323/319, 361/100, 361/101
• US Class Current: 323/326
• CPC Class Codes: H02M 1/10 Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from ac or dc
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 5/293 using semiconductor devices only
• CPC Class Codes: H03K 17/18 Modifications for indicating state of switch
• CPC Class Codes: H03K 17/687 the devices being field-effect transistors
• CPC Class Codes: H03K 17/951 Measures for supplying operating voltage to the detector circuit

Abstract

An apparatus and method is disclosed for controlling a load capable of functioning for a predetermined purpose in response to a predetermined amount of electrical power. The load can be operated from either an AC or DC source using a two-wire connection. The predetermined amount of electrical power is applied to the load if a sensor senses a triggering event. During the time period when a triggering event is sensed, power is cycled on and off to the load in order to enable continuous monitoring of the trigger event. During most of the time period, the sensor receives power to maintain its operations from a storage circuit. If the charge in a capacitor decreases to a predetermined value, the predetermined amount of electrical power is removed from the load momentarily to allow replenishment of the capacitor charge.

Claims

1. In an electrical system including a load capable of functioning for a predetermined purpose in response to transmission of at least a predetermined quantity of AC or DC electrical power through the load from an AC or DC source, an improved method for controlling transmission of the electrical power through the load in response to a predetermined condition comprising in combination the steps of:

conducting the predetermined quantity of electrical power through said load during a first operational state for causing the load to function for the predetermined purpose;

preventing the conduction of said predetermined quantity of electrical power through said load during a second operating state for preventing the load from functioning for the predetermined purpose;

storing electrical energy in response to said AC or DC source for enabling the monitoring of said predetermined condition;

detecting the presence of said predetermined condition;

cyclically during a time period when the presence of said predetermined condition is detected, switching to said first operating sate for causing the functioning of said load for the predetermined purpose, monitoring said predetermined condition by using the stored electrical energy, switching to the second operating state in response to the decrease of the stored electrical energy, switching to the second operating state in response to the decrease of the stored electrical energy below a predetermined value, replenishing the stored electrical energy during the second operating state for enabling the continued monitoring of said predetermined condition, and switching to said first operating state in response to the increase of the stored electrical energy for continuing the functioning of the load for the predetermined purpose, whereby the predetermined condition can be monitored in both the first and second operating states from an AC or DC source, wherein an electronic switch is connected in series with the load and the source, wherein said conducting step comprises the step of gating said electronic switch on in response to a first gating signal;

generating pre-regulated DC power from said AC or DC source;

generating regulated DC power in response to said pre-regulated DC power;

charging said capacitor in response to said pre-regulated DC power;

generating a reference signal in response to said sensing signal; and

generating said first gating signal in response to a predetermined relationship between said reference signal and a signal proportional to the value of said stored electrical energy, wherein preventing step comprises a step of gating off said electronic switch in response to a second gating signal, wherein said detecting step comprises a step of generating a sensing signal for indicating the presence of said predetermined condition by use of said regulated DC power.

2. The method, as claimed in claim 1 wherein the step of switching to said second operating state comprises the steps of:

generating a second reference signal in response to the sensing signal; and

generating the second gating signal in response to a predetermined relationship between the second reference signal and a signal proportional to the decreased value of said stored electrical energy.