Communication via an electricity supply main

• US 4,348,582 A
• Filed: 03/14/1979
• Issued: 09/07/1982
• Est. Priority Date: 03/14/1978
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Budek, Jerzy A.
• Primary Examiner(s): Reynolds, B. A.
• Assistant Examiner(s): PASCHALL, MARK H
• Application Number:
  US06/020,298
• Time in Patent Office: 1,273 Days
• Field of Search: 219/494, 219/492, 219/483, 219/486, 219/501, 219/508, 219/519, 219/507, 219/509, 340/310 A, 340/147 R, 340/147 F, 340/310 R, 307/38-41, 307/140, 307/34
• US Class Current: 219/483
• CPC Class Codes: H02J 13/00009 using pulsed signals
• CPC Class Codes: H02J 13/0001 using modification of a parameter of the network power signal
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation
• CPC Class Codes: H04B 2203/542 using zero crossing information
• CPC Class Codes: H04B 2203/5458 Monitor sensor; Alarm systems
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 3/542 the information being in digital form
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/52 Outage or fault management, e.g. fault detection or location
• CPC Class Codes: Y04S 40/121 using the power network as support for the transmission

Abstract

Control signals are transmitted through a.c. mains supply lines to control operation of electrical equipment powered from the supply lines. A near short-circuit condition is introduced across the a.c. mains supply lines, for example, by firing a thyristor connected in series with a fuse across the supply lines, for the final portion of positive half cycles of the mains supply voltage, thus holding the voltage to a near zero value for this length of time. A receiver coupled to the mains supply lines includes a zero crossing detector circuit which responds to the near zero voltage conditions across the supply lines to perform a particular control operation on an associated appliance connected to the receiver. Different control operations may be effected by defining the control signals over a group of half cycles of the a.c. supply mains and selecting one or more half cycles of the group during which the supply voltage is reduced to the near zero level, thereby producing a sequence of selected and non-selected half cycles within the group so that by changing the sequence the particular control operation can be changed accordingly.

Claims

1. A control system for remotely controlling at least one alternating current electric-mains-operated appliance, including:

a controller having electronic switch means for superimposing a control signal on an alternating current mains supply by interrupting the mains supply for a period adjacent a zero crossing in one or more selected half-cycles of the mains supply and substantially less than the mains supply cycle period thereby to hold the mains supply voltage substantially at zero during said interruption;

at least one receiver means for monitoring the mains supply and for controlling said electrical appliance said receiver having

(A) interruption detector means including a full wave rectifier means for providing a full-wave rectified signal from said mains supply;

voltage threshold detector means for receiving said full-wave rectified signal and producing an output whenever the voltage of said full-wave rectified signal is lower than a threshold voltage; and

means for responding to the durations of said outputs from said voltage threshold detector means to produce an indication of the occurrence of a said interruption; and

(b) means responsive to said indications of the occurrence of an interruption to produce outputs for controlling said electric appliance in accordance with the control signal from the controller.

2. A control system for remotely controlling one or more alternating current electric-mains-operated appliances, including:

a controller having electronic switch means for superimposing a control signal on an alternating current mains supply by interrupting the mains supply for a period adjacent a zero crossing in one or more selected half-cycles of a group of half-cycles of the mains supply and substantially less than the mains supply cycle period thereby to hold the mains supply voltage substantially at zero during the or each said interruption for producing a control signal comprising a sequence of selected and non-selected half-cycles in said group, the particular sequence characterizing an individual control signal;

at least one receiver means for monitoring the mains supply and for controlling the or each electrical appliance to which it is connected;

said receiver having;

(A) interruption detector means including a full wave rectifier means for providing a full-wave rectified signal from said mains supply;

voltage threshold detector means for receiving said full-wave rectified signal and producing an output whenever the voltage of said full-wave rectified signal is lower than a threshold voltage; and

means for responding to the duration of said outputs from said voltage threshold detector means to produce an indication of the occurrence of a said interruption; and

(B) means responsive to said indication of the occurence of an interruption to produce outputs for controlling said electric appliance in accordance with the control signal from the controller.

3. A control system according to claim 2, wherein the controller includes:

detector means for detecting when the mains supply phase is within a predetermined phase difference from a zero crossing;

counter means for counting half-cycles or integral multiples of half-cycles of the mains supply;

selector means connected to the counter means and the detector means for selecting particular half-cycles in a sequence dependent on the control operation and the appliance to be controlled and for producing a trigger signal to initiate an interruption in each selected half-cycle;

and wherein the electronic switch means is a semiconductor switching device connected to receive and respond to the trigger signal to short-circuit the mains supply until the next occuring zero crossing.

4. A system according to claim 3, wherein the controller includes manually settable means representing various control operations and/or appliances in response to setting of which the said sequence is selected.

5. A control system according to any of claims 2, 3 or 4, further including clock means programmable to instruct the controller to signal to the or each receiver to perform a control operation on its associated appliance(s) at a particular time.

6. A control system according to claim 2, wherein said electronic switch means comprises a gate controlled semiconductor device.