Method of and apparatus for selectively controlling a plurality of remotely located loads

3,964,023

05/551,051

February 19, 1975

A master controller is connected via a pair of wires to a plurality of loads and is capable of generating pulses having either positive or negative polarity and a voltage level either above a first threshold or below a second threshold or above the second threshold. Some of the slave units connected via these two wires to the master controller are singly handicapped and have a single zener diode whose avalanche voltage corresponds to the first threshold so that the load is energized whenever this first threshold is exceeded. Other units have a second zener diode in series of the first diode and itself having an avalanche voltage equal to the second threshold so that only when this second threshold is exceeded is the load energized. In such a system it is possible to provide a memory circuit to short circuit this second zener diode if it is desired to remove the double handicap and partially emancipate the slave unit. This memory circuit may comprise a thyristor connected across the second zener diode so that if the voltage in the input lines to the slave unit drop to zero the emancipation command from the memory is eliminated. In addition some of the slave units are connected via full-wave rectification bridges to the two conductors so that regardless of the polarity of the pulses they are energized, whereas others of the units do not have such fall-wave rectification so that reversal of the signal polarity cuts these slave units out.

Fauchez, Jean-Jacques (Saint-Egreve, FR)

Anvar, Agence Nationale de Valorisation de la Recherche (Neuilly-sur-Seine, FR)

I claim

1. A system for operating a plurality of variously remotely located loads from a single master location, said system comprising

a master controller at said master location including means for generating a succession of voltage signals each of positive or negative polarity and of a voltage level either above or below a predetermined threshold;

at least four slave units connected in parallel to said master controller and each at and connected to a respective load;

means including a conductor extending between said master controller and all of said slave units for feeding said signals to all of said units;

priority means in one of said slave units for operating the respective load on reception over said conductor of a signal having either of said polarities;

handicap means in another of said slave units for operating the respective load only on reception over said conductor of a signal of at least one of said polarities and having a voltage level above said threshold;

negative-responsive means in yet another of said slave units for operating the respective load only on receptin over said conductor of a signal of negative polarity; and

positive-responsive means in yet another of said slave units for operating the respective load only on reception over said conductor of a signal of positive polarity.

2. The system defined in claim 1 wherein said priority determination means includes a bridge circuit connected to said conductor.

3. The system defined in claim 1 wherein said handicap means includes a zener diode.

4. The system defined in claim 1, further comprising switch means connected to said handicap means for changing the handicap thereof and operating the respective load on reception over said conductor of a signal having a voltage level below said threshold.

5. The system defined in claim 4 wherein said handicap means includes a zener diode, said switch means including a normally open switch connected across said zener diode.

6. The system defined in claim 5 wherein said switch means includes a thyristor connected across said zener diode and means for feeding a voltage pulse from said conductor into the gate of said thyristor, whereby after firing of said thyristor by said pulse a drop to zero potential in said conductor opens said switch means.

7. The system defined in claim 1, further comprising time-delay means in some of said units for preventing operation of the respective load until the operating signal therefor has lasted a predetermined length of time.

8. The system defined in claim 7 wherein said time-delay means includes a thyristor connected in series with the respective load and means including a time-constant circuit connected between the gate of said thyristor and said conductor for feeding a voltage pulse to said gate from said conductor after a signal on said conductor has lasted said predetermined length of time.

9. A method of operating a plurality of variously remotely located loads from a single master location, said method comprising the steps of

feeding to all of a plurality of slave units each provided at a respective load a succession of voltage signals each of positive or negative polarity and of a voltage level either above or below a predetermined threshold;

operating a first one of the loads with the respective slave unit on reception of a signal of either of said polarities;

operating a second one of the loads with the respective slave unit only on reception thereby of a signal of negative polarity;

operating a third one of the loads with the respective slave unit only on reception thereby of a signal of positive polarity; and

operating a fourth one of the loads with the respective slave units only on reception thereby of a signal of at least one of said polarities and having a voltage level above said threshold.

10. The method defined in claim 9, further comprising the step of delaying operation of any of the loads on reception of an appropriate signal until same has lasted a predetermined length of time.

11. The method defined in claim 9, further comprising the step of temporarily operating said fourth load with the respective slave unit on reception thereby of a signal having a voltage level below said threshold.

340/147PC; 340/310A

H04Q 900

2992366 July 1961 Veltfort
3310777 March 1967 Fosdick

edspgr.03964023