Electrical controller

An electrical controller for actuating a number of electrical devices in accordance with control inputs received from a number of control input sources includes a number of optical isolators having inputs coupled to the control input sources. The optical isolators function to electrically isolate each of the control input sources from each other and to provide individual control voltages corresponding to the control inputs received from the control input sources. The outputs of the optical isolators are coupled through a user-actuable matrix switch to the coils of a number of relays which, in turn, control the electrical devices. Through various settings of the matrix switch, various ones of the electrical devices can be actuated in response to control inputs received from particular ones of the control input sources. Electrical isolation is maintained among the control input sources to avoid the development of undesirable feedbacks to the non-actuated control input sources.

BACKGROUND OF THE INVENTION 
This invention relates generally to controllers for controlling a number of 
electrical devices in response to control inputs received from a number of 
control input sources, and, more particularly, to such an electrical 
controller wherein electrical isolation is maintained between each of the 
control input sources. 
The need to control a number of electrical devices in response to control 
inputs received from a number of sources, and, in particular, to control 
relatively few electrical devices in response to control inputs received 
from relatively many sources, can occur in a variety of control system 
installations. In automative gasoline and diesel-fuel filling stations, 
for example, several individual fuel hoses or dispensers are typically 
supplied with fuel provided from a single submersible pump fitted to a 
common underground storage tank. In larger filling stations, it is not 
uncommon for as many as eight underground storage tanks to supply fuel to 
as many as forty-eight hoses. Thus, several control input sources can 
exist for actuating the submersible pump of each storage tank. 
To provide for the selective actuation of individual submersible pumps in 
response to control inputs received from a number of sources, various 
systems have been developed. In one such system, individual electrical 
switches, associated with each of the hoses or dispensers supplied from a 
common tank, are commonly connected to each other and to the coil of an 
electrical relay which controls the application of power to a submersible 
pump fitted to the tank. Although this system is effective in 
inexpensively implementing the desired control effect, it suffers the 
serious disadvantage of promoting undesirable "feedbacks" which render all 
of the unused dispensers electrically "hot" whenever the switch of any one 
dispenser is closed. In the event it becomes necessary to remove a fuel 
dispenser from service for purposes of maintenance, repair, or to avoid 
the creation of a hazardous condition following, for example, an 
accidental collision between an automobile and a dispenser, the potential 
for the occurrence of such feedbacks requires that each of the remaining, 
functioning dispensers, which are connected to the common relay, be shut 
down also. In a busy station, the need to shut down otherwise fully 
functional dispensers can have serious adverse economic consequences for 
the filling station operator. 
To avoid the development of such undesirable feedbacks, individual relays, 
coupled to a common relay for actuating a single submersible pump, can be 
individually controlled by the switches associated with each hose or 
dispenser. Although effective, the cost of the relays and additional 
wiring associated with this approach can be considerable. 
In view of the foregoing, it is a general object of the invention to 
provide a new and improved electrical controller for controlling several 
electrical devices in response to control inputs received from several 
sources. 
It is a further object of the present invention to provide an electrical 
controller wherein undesirable feedbacks to unactuated ones of the control 
input sources are avoided. 
It is still another object of the present invention to provide an 
electrical controller which can be implemented without considerable 
expense in terms of parts, time and labor. 
SUMMARY OF THE INVENTION 
The invention provides an electrical controller for controlling a plurality 
of electrical devices in accordance with control inputs received from a 
plurality of control input sources. Isolating means, coupled to the 
control input sources, are provided for electrically isolating the control 
input sources from each other and for developing individual control 
voltages corresponding to the individual control inputs developed by the 
individual control input sources. A plurality of output means, uniquely 
associated with individual ones of the electrical devices, are provided 
for actuating individual ones of the electrical devices in response to the 
application of the control voltages. Selector means are provided for 
selectively coupling the isolating means to individual ones of the output 
means in order to apply the control voltages to the output means and 
thereby actuate individual ones of the electrical devices in response to 
generation of the control inputs by selected ones of the control input 
sources.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings and in particular to FIG. 1, a two-tank, 
four-hose, automotive filling or service station, having an electrical 
controller 10 constructed in accordance with the invention, is 
illustrated. To accomodate different types of vehicular fuels, such as 
diesel fuel and various grades of gasoline, the filling station is 
provided with a pair of underground main storage tanks 11 and 12 (labeled 
"Tank 1" and "Tank 2") which are each fitted with electrically driven 
submersible pumps 13 and 14 respectively. Each pump includes a input 
conduit, 16 and 17, extending into its associated storage tank, and an 
outlet conduit, 18 and 19, through which fuel is discharged when the pump 
is actuated. Above-ground, the filling station is provided with four hoses 
21, 22, 23 and 24 mounted to a pair of free-standing, dual-hose dispenser 
units 26 and 27. Preferably, outlet conduit 18 is coupled through 
individual solenoid-controlled valves 5 and 7 to the first and third 
dispensers (labeled #1 and #3), while outlet conduit 19 is coupled through 
individual solenoid controlled-valves 6 and 8 to the second and fourth 
dispensers (labeled #2 and #4) as shown, such that both fuel types are 
available at each of the dispenser units 26 and 27. 
The actuation of each of the first and second dispensers is independently 
controlled by means of a pair of double-pole switches 28 and 29 which, in 
turn, are acutated by means of a pair of user-actuable control handles 31 
and 32 mounted on opposite sides of dispenser unit 26 adjacent hoses 21 
and 22 respectively. Similar switches 33 and 34, for controlling the 
operation of the third and fourth dispensers respectively, are actuated by 
means of similar control handles 36 and 37 mounted on opposite sides of 
dispenser unit 27 adjacent hoses 23 and 24. 
When fuel is to be dispensed from underground tank 11 through either hose 
21 or hose 23, it is necessary that submersible pump 13 be actuated. 
Similarly, pump 14 must be actuated in order to dispense fuel from 
underground tank 12 through either hose 22 or hose 24. Actuation of pumps 
13 and 14 is controlled by means of switches 28, 29, 33 and 34 in 
conjunction with the electrical controller 10 constructed in accordance 
with the invention. Switches 28, 29, 33 and 34 are also coupled to 
solenoid valves 5, 6, 7 and 8 such that fuel can only be dispensed through 
a hose whose associated switch control handle has been actuated. 
As further illustrated in FIG. 1, one contact of each pole of each of the 
switches 28, 29, 33 and 34 is connected through a single common conductor 
38 to a single power source. The remaining contacts of switches 28, 29, 33 
and 34 are individually connected through separate conductors 41, 42, 43 
and 44 to separate control inputs 49, 48, 47 and 46 respectively on 
controller 10. Alternating current (AC) power, for operating controller 
10, is provided by an AC power source 51 which is coupled to controller 10 
through a pair of conductors 52 and 53. AC power source 51 is also coupled 
through the normally open contacts of a first double-pole single-throw 
relay 54 to submersible pump 13 and through the normally open contacts of 
a second double-pole single-throw relay 56 to submersible pump 14. The 
coils 57 and 58 of relays 54 and 56 respectively are coupled to a pair of 
"Pump Enable" outputs provided by controller 10 through output terminals 
61, 62, 63 and 64. 
When dispenser control switch 28 is closed, a current is applied to 
controller 10 through control input 49. Similarly, closure of dispenser 
control switches 29, 33 and 34 results in the application of individual 
control currents to control inputs 48, 47 and 46 respectively. 
In response to closure of switches 28 and 33, controller 10 functions to 
actuate submersible pump 13. To this end, a control current is developed 
at the "Pump 1 Enable" output of controller 10 and is passed through coil 
57 to actuate relay 54. When relay 54 is thus actuated, the normally open 
relay contacts close and thereby permit current from the AC power source 
51 to pass to the submersible pump 13. Similarly, when either dispenser 
switch 29 or 34 is closed, an actuating current is applied to the coil 58 
of relay 56 through the "Pump 2 Enable" output of controller 10 in order 
to close the contacts of relay 56 and thereby apply AC power to 
submersible pump 14. It is a feature of the present invention that 
conductors 41-44, and the switches to which they are connected, remain 
electrically isolated from each other at all times regardless of the 
position of switches 28, 29, 33 and 34, and regardless of whether pumps 13 
and 14 are actuated. 
In order to provide a means by which power to pumps 13 and 14 can be 
quickly removed in the event of an emergency, an "emergency shut-off" 
switch 66 is included. Switch 66 is connected, at one end, to one active 
or "hot" side L1 of power source 51 and is coupled to controller 10 
through an input terminal 67. When the normally closed contacts of switch 
66 are opened, current to relay coils 57 and 58 is removed regardless of 
the position of the dispenser control switches 28, 29, 33 and 34. 
The construction and operation of electrical controller 10 can best be 
understood by reference to the electrical schematic diagram of FIG. 2. As 
illustrated therein, controller 10 includes a regulated DC power supply 
69, of known construction, having its input connected through a fuse 70 to 
the AC power source 51. A regulated DC voltage (+V.sub.DC) is provided at 
the output of power supply 69 for operating various circuitry within 
controller 10. 
Referring further to FIG. 2, one active or "hot" side L1 of the AC power 
source 51 is coupled through conductor 38 to the commonly connected 
contacts of dispenser control switches 28, 29, 33 and 34. The remaining 
contacts of the switches are individually coupled to controller 10 through 
control input terminals 46-49. Individual control inputs, comprising 
alternating currents from AC power source 51, are thus applied to 
controller 10 through control input terminals 46-49 in response to closure 
of switches 28, 29, 33 and 34. 
To prevent the occurrence of "feedbacks" in response to closure of any one 
of the dispenser control switches 28, 29, 33 or 34, isolating means for 
electrically isolating the control input sources from each other and for 
developing control voltages corresponding to the individual control inputs 
received on control input terminals 46-49 are provided in the form of a 
plurality of optical isolators 71-74 which are individually coupled to 
control input terminals 46-49. To convert the alternating current control 
inputs into a form suitable for operating the optical isolators 71-74, a 
plurality of full-wave bridge rectifiers 76-79, of known construction, are 
also provided. As illustrated, one input terminal of bridge rectifier 76 
is connected through a resistor 81 to control input terminal 46, while 
single input terminals of the remaining rectifiers 77-79 are individually 
connected through resistors 82-84 to control input terminals 47-79 
respectively. Preferably, resistors 81-84 are connected to the "hot" side 
of power source 51 in order to minimize the presence of high voltages 
within controller 10. The remaining input terminals of rectifiers 76-79 
are individually coupled to the remaining neutral side of the AC power 
source 51 through terminals 46'-49' respectively. The outputs of 
rectifiers 76-79 are respectively coupled to the inputs of optical 
isolators 71-74 through individual, forward biased, light emitting diodes 
(LED's) 86-89. A plurality of filter capacitors 91-94 are individually 
connected across the outputs of rectifiers 76-79 and function to filter 
the output of each rectifier such that a substantially steady DC voltage 
is provided in response to closure of switches 28, 29, 33 or 34. 
When switches 28, 29, 33 and 34 are each open, bridge rectifiers 76-79 are 
each de-energized and the outputs of optical isolators 71-74 are each 
biased high. Upon closure of any one of the dispenser control switches 28, 
29, 33 or 34, a DC voltage is developed at the output of the associated 
bridge rectifier coupled thereto. This DC voltage, in turn, actuates the 
optical isolator to which it is applied with the further effect that the 
output of the isolator is biased low. Accordingly, a plurality of control 
voltages, individually indicative of the position of dispenser control 
switches 28, 29, 33 and 34, are provided at the outputs of optical 
isolator 71-74. The control voltages thus provide a logic transition or 
voltage level change in response to a change in the position of the 
dispenser control switches 28, 29, 33, and 34. LED's 86-89 illuminate in 
response to closure of their associated dispenser control switches and 
function to aid system repair by providing a visual indication in response 
to proper circuit operation. 
To enable controller 10 to actuate individual ones of a plurality of 
electrical devices in response to the generation of the control voltages 
at the outputs of optical isolators 71-74, output means are provided in 
the form of a plurality of single-pole single-throw relays 96-99. Each 
relay includes a coil 101-104 and a set of normally open switch contacts 
106-109 which close in response to the passage of current through the 
associated relay coil. 
As illustrated, one contact of relay contact set 106 is coupled through 
output terminal 62 to one end of the coil 57 of pump control relay 54. The 
other end of coil 57 is connected to the neutral line 39 of the AC power 
source 51. Similarly, one contact of relay contact set 107 is coupled 
through terminal 64 to one end of the coil 58 of pump control relay 56. 
The remaining end of coil 58 is connected to neutral line 39. The 
remaining contact of relay contact set 106 is connected to one position of 
a multiple position switch 111 while the remaining contact of relay 
contact set 107 is connected to one position of an additional multiple 
position switch 112. The wiper arms of switches 111 and 112 are each 
connected to on of the "hot" conductors L1 of the power source 51. 
As further illustrated, two sets of additional output terminals 116, 117 
and 118, 119 are included. Terminal 117 is connected to one contact of 
relay contract set 108, the remaining contact of which is coupled through 
one position of a multiple position switch 113 to terminal 116. Similarly, 
terminal 119 is connected to one contact of relay contract set 109, the 
remaining contact of which is coupled through one position of an 
additional multiple position switch 114 to output terminal 118. 
In the example illustrated, output terminals 116-119 are unused but provide 
the capability for expansion in the event additional electrical devices 
are to be operated by the controller. A plurality of voltage-sensitive 
variable resistors (Varistors) 121-124 are respectively connected across 
relay contacts 106-109 and function to suppress transient voltages 
developed in response to relay contact bounce. 
Relay contacts 106-109 close in response to the passage of current through 
their associated relay coils 101-104 and function to couple the AC power 
source 51 to particular pairs of the controller output terminals 61-64 and 
116-119. Such currents are generated in accordance with the logic 
transitions occurring at the outputs of the optical isolators 71-74. To 
this end, controller 10 includes a multiple relay driver 120 containing 
four individual inverting driver amplifiers 121-124. The outputs of driver 
amplilfiers 121-124 are respectively individually connected to one side of 
each of the relay coils 101-104. The opposite sides of the relay coils are 
connected to circuit ground. Diagnostic LED's 126-129, which provide a 
visual indication of normal circuit operation, are individually connected 
across relay coils 101-104. In response to the application of a low-logic 
voltage at its input, relay driver amplifier 121 functions to provide 
sufficient current at its output to energize relay coil 101, and thereby 
close relay contacts 106, and to actuate LED 126. Similarly, relay driver 
amplifiers 122-124 function to actuate relay contacts 107-109 and 
illuminate LED's 127-129. 
In order to enhance system flexibility and to permit various combinations 
of electrical devices to be controlled in response to various combinations 
of control inputs, selector means are provided for selectively coupling 
the control voltages developed by optical isolators 71-74 to the inputs of 
relay driver amplifiers 121-124. In the illustrated embodiment, such 
selector means are provided in the form of a user-actuable matrix switch 
125 of known construction. Switch 125 includes four input lines 126a-129a, 
five output lines 131-135 and four user-actuable switch position selectors 
136-139. Input lines 126a-129a are respectively connected to the outputs 
of optical isolators 71-74, and output lines 131-134 are respectively 
connected to the inputs of relay driver amplifiers 121-124. 
Matrix switch 125 functions to electrically connect individual ones of 
input lines 126-129 with individual ones of output lines 131-135 in 
accordance with the set positions of the switch position selectors 
136-139. When the switch position selectors 136-139 are positioned as 
shown, the outputs of optical isolators 72 and 74 are both connected to 
the input of relay driver amplifier 121, while the outputs of optical 
isolators 71 and 73 are both connected to the input of relay driver 
amplifier 122. Thus, closure of either dispenser control switch 33 or 28 
results in closure of relay contacts 106, while closure of either 
dispenser control switch 34 or 29 results in closure of relay contact 107. 
It will be appreciated that the switch position selectors can be set in 
various combinations such that some, all, or none of the relay contacts 
106-109 close in response to closure of any or all of the dispenser 
control switches 28, 29, 33 or 34. 
To provide a further measure of control over the electrical devices which 
are to be operated in accordance with the individual control inputs, 
switches 111-114 can be individually set in one of three positions. In one 
position, labeled "On" the wiper of the switch, which is coupled directly 
to one side L1 of the AC power source 51, causes the full AC voltage to 
appear across the associated controller output terminals and thereby 
continuously actuate the electrical device connected thereto regardless of 
the positions of the dispenser control switches 28, 29, 33 or 34 and 
regardless of the position of the switch position selectors 136-139. In 
the middle switch position, labeled "Off," the switch wiper is 
electrically disconnected from all circuitry and the electrical device 
connected to the associated controller output terminals remains 
continuously deactivated regardless of the positions of the other 
switches. In the lowermost position, labeled "Auto" the electrical devices 
are controlled in accordance with the closure of the associated relay 
contacts 106-109, which is, in turn, controlled by switches 28, 29, 33, 
and 34 and switch positions selectors 136-139. Preferably, the wipers of 
switches 111-114 are connected to the same power source 51 which provides 
power to the submersible pumps 13 and 14. This assures that when the 
source is disconnected for such purposes as pump repair, no power will be 
available which can accidently result in closure of relays 54 and 56. 
To facilitate system repair in the event of a malfunction, a diagnostic 
test position is provided. To this end, output line 135 of matrix switch 
125 is connected to the cathode of an LED 141, the anode of which is 
connected to the DC supply voltage +V.sub.DC. When one of the switch 
position selectors 136-139 is set to a position wherein output line 135 is 
electrically joined with one or more of the outputs of optical isolators 
71-74, actuation of the particular optical isolator(s) applies a low 
voltage to the cathode of LED 141 which then becomes forward biased. This 
provides a visual indication that the input channel(s) associated with the 
particular optical isolator(s) is functioning properly. An additional LED 
142 is connected across the DC supply voltage, as is a bypass capacitor 
143, and functions to provide a visual indication that power is applied to 
controller 10. 
To enable controller 10 to rapidly shut down operation of the electrical 
devices in the event of an emergency, controller 10 includes an additional 
full-wave bridge rectifier 144 and optical isolator 146. One input of 
bridge rectifier 144 is connected to the neutral side of the AC power 
source 51, while the other input is coupled through the normally closed 
contacts of emergency shut-off switch 66 and through a resistor 157 to a 
"hot" side L1 of the AC Power source. The outputs of bridge rectifier 144 
are connected through a diagnostic LED 152 to the input of optical 
isolator 146, and the output of optical isolator 146 is coupled through a 
first resistor 147 to the DC supply voltage and through a second resistor 
148 to the base electrode of a Darlington transistor pair 149. The emiter 
of transistor 149 is connected to the DC supply voltage and the collector 
is coupled through a resistor 151 to circuit ground. A forward biased LED 
153 is connected across resistor 151 and a filter capacitor 154 is 
connected across the output terminals of bridge rectifier 144. 
As long as the contacts of the emergency shut-off switch 66 remain closed, 
optical isolator 146 remains actuated and the base of the Darlington 
transistor pair 149 is grounded through resistor 148. The transistor is 
thereby biased on and the DC supply voltage is coupled through the 
transistor and appears at the juncture of the transistor collector and the 
resistor 151. The voltage appearing at the juncture of the transistor 
collector and resistor 151 is coupled to the relay driver 120 and 
functions to enable each of the relay driver amplifiers 121-124. The 
voltage also actuates LED 153 to provide a visual indication that the 
relay driver is enabled. LED 152 is also actuated as long as switch 66 
remains closed to provide a visual indication of proper circuit operation. 
In the event the contacts of the emergency shut-off switch 66 open, the 
voltage at the output of optical isolator 146 rises with the effect that 
transistor 149 is biased off. When this occurs, the voltage across 
resistor 151 drops, with the further effect that relay driver 120 becomes 
disabled and LED 153 is biased off. When relay driver 120 is so disabled, 
actuation of the electrical devices, connected to the controller output 
terminals 61-64 and 116-119, is prevented regardless of the position of 
the dispenser control switches 28, 29, 33 and 34. To bypass the emergency 
shut-off feature, a switch 156 is connected across the DC supply voltage 
and the collector of transistor 149. When switch 156 is closed, the DC 
supply voltage is applied directly to relay driver 120 and thereby enables 
the relay driver regardless of the position of emergency shut-off switch 
66. 
To provide a visual indication that proper supply voltage is being 
supplied, the controller further includes a line voltage monitor 158 
coupled to the input of DC power supply 69, which includes an LED (not 
shown). Preferably, the line voltage monitor is constructed similarly to 
the emergency shut-off circuitry which includes rectifier 144, capacitor 
154 and LED 152. 
It will be appreciated that the controller 10 provides a flexible and 
effective means for selectively operating various electrical devices in 
accordance with a plurality of control inputs. Although, in the embodiment 
shown and described, the capability exists for operating four independent 
electrical devices in accordance with control inputs received from four 
independent control input sources, it will be appreciated that additional, 
substantially identical control channels can be included to accomodate a 
greater or lesser number of control input sources and electrical devices. 
Furthermore, through selection of an appropriate matrix switch 125, the 
circuit can be easily configured such that relatively few control input 
sources control the actuation of a relatively large number of electrical 
devices or, in the alternative, such that relatively many control input 
source control actuation of relatively few electrical devices. 
Additionally, although the circuitry is preferably implemented through the 
use of CMOS semiconductor devices, it will be appreciated that other 
semiconductor devices can be successfully employed. Finally, although the 
controller has been described in the context of an automotive filling 
station, it will be appreciated that the invention is well suited for 
other applications wherein it is desired to control various electrical 
devices in accordance with various control inputs while maintaining 
electrical isolation among the many control inputs. 
While a particular embodiment of the invention has been shown and 
described, it will be obvious to those skilled in the art that changes and 
modifications may be made without departing from the invention in its 
broader aspects, and, therefore, the aim in the appended claims is to 
cover all such changes and modifications as fall within the true spirit 
and scope of the invention.