Electronic circuit for identifying circuit breaker associated with selected branch circuit

A system for locating the particular circuit breaker associated with a branch circuit. The system includes a transmitter is connected to the hot lead of the branch circuit to inject a signal having a predetermined frequency. The system further includes identification circuits permanently associated with each circuit breaker. The identification circuit includes an indicator powered by a rectifier connected to the hot lead of the associated branch circuit. A band pass filter within the identification circuit passes the predetermined frequency, which when present biases the gate of a controlled switch which is placed in series with the indicator lamp such that when the predetermined frequency is present on the hot lead the indicator lamp is turned on. Each identification circuit may also include a low pass filter connected in series between the hot lead of the branch circuit and the bus so as to block the predetermined frequency signal from being distributed via the bus bar into the identifying circuits associated with other branch circuits. In one embodiment, the identification circuit and circuit breaker are enclosed within a single enclosure, which may further include a socket for simplified connection to at least the hot lead and bus bar.

BACKGROUND OF THE DISCLOSURE 
1. Field of the Invention 
The present invention relates in general to electrical power distribution 
design, implementation and repair devices and, in particular, to a system 
and circuit for identifying which one of a group of circuit breakers is 
associated with a particular, selected branch circuit within a facility. 
2. Background Art 
When electrical work needs to be performed on an electrical system in a 
building or facility, it is usually necessary to trace and identify which 
circuit interrupter device (i.e., circuit breaker or fuse) is supplying 
power to a specific AC power branch circuit. 
Manual identification of the fuse or circuit breaker can be accomplished by 
removing each fuse or opening each circuit breaker, thereby disrupting the 
power flow through the circuit. Each test point must subsequently be 
examined to determine whether the power to the test point has been 
disconnected. This method is not only time consuming, but also may not be 
feasible in situations where it would be hazardous to interrupt the power 
flow to certain branch circuit outlets, i.e., in a hospital or in 
environments where there are computers in use without backup power. 
Alternatively there are currently available a number of circuit testers for 
identifying the circuit interrupting device that is supplying power to a 
specific outlet receptacle. These testers employ a variety of techniques 
to differentiate one circuit breaker from the rest. All of these 
pre-existing devices have at least one thing in common, they all consist 
of two separate units, a identification signal generator (referred to as a 
transmitter) and a signal receiver, which inject and then receive this 
signal over the AC wiring. 
Consequently, it is an object of the present invention to provide a circuit 
location device that is simpler to couple to one of a plurality of branch 
circuits of a facility. 
One pre-existing tester pair creates a magnetic field on the AC wiring and 
then detects that magnetic field proximate the circuit interrupter 
devices. Unfortunately, the magnetic fields created are easily coupled 
between AC wire lines, thus creating potentially false identification 
signals. Further, using magnetic fields as signal medium, in turn, 
necessitates the use of a radio frequency receiver for detection at the 
circuit interruptor devices box. 
Accordingly, it is another object of the present invention to provide a 
device that provides more reliable identification of circuit selection. It 
is an associated object of the present invention to obviate the need for 
radio frequency receiver by eliminating the use of magnetic field 
identification. As a result, detection can be accomplished at 
significantly larger distances and with less error in noisier environments 
than with the magnetic field approach. 
Depending upon the type of tester device used, the end user may also be 
required to calibrate for the sensitivity of the device either by manually 
adjusting same or by allowing for differences in sensitivity by 
independent observation of sensitivity data provided via a signal strength 
meter, bar graph display or other approach in order to properly identify 
the correct circuit interrupting device. Receivers with manual adjustment 
as well as those with analogue or digital readouts (signal strength 
meters) can be quite difficult to use especially if the end user has no 
prior experience with such instruments. Furthermore, since the strength of 
the identification signal is a function of permanently altering line 
impedance and capacitance, the amplitude of the identification signal 
varies. However, pre-existing receiving devices always detect the breaker 
in question by determining which breaker is reflecting the largest signal 
amplitude. 
Accordingly, it is yet another object of the present invention to provide 
easier operation and time savings to an end user by eliminating the need 
for manual calibration and thereby also eliminating the potential for user 
error associated with same. 
These and other objects will be apparent to those of ordinary skill in the 
art having the present drawings, specification and claims before them. 
SUMMARY OF THE INVENTION 
The present invention is directed to a system for locating the circuit 
breaker (or other similar circuit interrupter device) associated with a 
selected branch circuit from a group of circuit breakers (possibly 
contained within the same breaker panel). The system includes a 
transmitter and at least one identification circuit. The transmitter is 
connected to the hot lead of the branch circuit for which circuit breaker 
association is desired. The transmitter injects a signal having a 
predetermined frequency into the hot lead of the branch circuit. No 
particular design is required for the transmitter so long as it generates 
a signal at the predetermined frequency. In fact, the identification 
circuit can be used alone so long as a signal of predetermined frequency 
exists on the line for which circuit breaker location is desired. 
An identification circuit is connected to a unique branch circuit and 
associated with each one of the circuit breakers from the group of circuit 
breakers. Each identification circuit includes an indicator lamp and 
preferably further includes a fuse to protect the components of the 
identification circuit. Operably connected to one side of the indicator 
lamp is a rectifier which draws power from the hot lead of the unique 
branch circuit. The identification circuit further includes a band pass 
filter with its input being operably connected to the hot lead of the 
unique branch circuit. The output of the band pass filter is connected to 
the gate of a controlled switch toward controlling same. In a preferred 
embodiment, this gate may be protected by a reverse bias protection 
circuit. The first and second terminals of the controlled switch are 
operably connected in series with the indicator lamp wherein upon receipt 
of the predetermined frequency signal on the hot lead of the unique branch 
circuit, the band pass filter output biases the gate causing current to 
flow through the controller switch and, in turn, the indicator lamp. In 
this way the target circuit breaker is identified via its association with 
the indicator lamp. 
In a preferred embodiment of the present invention, each identification 
circuit further includes a low pass filter operably connected in series 
between the hot lead of the unique branch circuit and the bus bar and in 
parallel with other circuits in the identification circuit. The low pass 
filter substantially prevents the predetermined frequency signal injected 
in one particular branch circuit from bleeding into one or more of the 
other branch circuits connected to the same bus bar as the indicated 
circuit, thus, substantially precluding the possibility of false 
positives. 
In a preferred embodiment of the present invention the identification 
circuit and circuit breaker are enclosed within a single enclosure. This 
enclosure may further include a socket which operably connects the 
enclosed identification circuit and circuit breaker to at least the hot 
lead and the bus bar and may further include an additional connector which 
connects the identification circuit to the neutral lead (alternatively the 
hot/bus bar socket may also connect to the neutral lead). Thus the circuit 
breaker manufacturer can install the identification circuit directly into 
the circuit breaker enclosure. Thus, from an end user's stand point, this 
process would be "single ended" (i.e. connection of transmitter only) and 
would not require any type of hand held receiver unit.

BEST MODE OF CARRYING OUT THE PRESENT INVENTION 
While the present invention may be embodied in many different forms, there 
is shown in the drawings and discussed herein a few specific embodiments 
with the understanding that the present disclosure is to be considered 
only as an exemplification of the principles of the invention and is not 
intended to limit the invention to the embodiments illustrated. 
The system for locating the circuit breaker associated with a desired 
branch circuit from a group of circuit breakers is shown in FIG. 1 in 
association with a group of circuit breakers. As would be understood by 
those of ordinary skill in the art, the present system will operate in the 
manner disclosed herein in combination with any type of circuit 
interrupter device, which have been referred to generically as circuit 
breakers in the present application. In particular, circuit breakers 10, 
11, 12, 13, 14 and 15 within a group of circuit breakers are operably 
connected in series between an associated unique branch circuit 20, 21, 
22, 23, 24 and 25, respectively, and bus bar 16 to provide overload 
protection to each respective unique branch circuit. Branch circuits 20, 
21 and 25 are shown as having associated therewith hot leads 20a, 21a and 
25a, respectively, and neutral leads 20b, 21b and 25b, respectively. Each 
branch circuit includes a hot lead and a neutral lead. Some are not shown, 
however, merely to simplify disclosure of the present invention without 
obscuring same. 
As further shown in FIG. 1, the system also includes transmitters 31 and 35 
(other transmitters are not shown to simplify disclosure of the present 
invention without obscuring same). Of course, as would be understood by 
those of ordinary skill in the art, any number of transmitters (from one 
up to the numbers of circuit breakers) may be used without departing from 
the scope of the present invention. It is contemplated that the 
transmitters will be removably connected to a branch circuit via standard 
electrical outlets or some other means of simple removable connection. As 
shown, the transmitters are operably connected to the hot lead of a 
desired branch circuit, such that the transmitter can actively inject a 
signal 50 having a predetermined frequency. This predetermined frequency 
should generally be in the range of 300 kHz to 500 kHz because there are 
several other types of signals which may be present within an AC wiring 
system. For instance, electrical noise may be introduced by the weather or 
by electrical devices on one of the branch circuits. 
As further shown in FIG. 1, the system may include one or more 
identification circuits 100, wherein each identification circuit is 
associated with a particular circuit breaker such as circuit breaker 10. 
As shown, identification circuit 100 includes indicator lamp 101, 
rectifier 110, band pass filter 120, controlled switch 130, 
current-limiting resistor 135, low pass filter 140, reverse bias 
protection diode 150, and fuse 160. With these elements, a predetermined 
frequency signal received on hot lead 20a of branch circuit 20 is passed 
by band pass filter 120, the output of which biases controlled switch 130 
causing current to flow there through and, in turn, through indicator lamp 
101. In this manner, the particular circuit breaker associated with a 
branch circuit is identified. 
In particular, indicator lamp 101 preferably comprises an LED having first 
and second terminals wherein indicator lamp 101 illuminates when current 
flows between its terminals. Other types of lighting elements which 
illuminate when current flows therethrough and operate with the available 
voltage can be readily substituted for the preferred LED device. Of 
course, low power consuming devices are preferred. 
Rectifier 110 is operably connected between hot lead 20a of branch circuit 
20 and the first terminal of indicator lamp 101. As disclosed, rectifier 
110 preferably comprises a simple half wave rectifier circuit 
comprising--in the particularly disclosed embodiment--diode D1, resistor 
R2 and capacitor C4. Simpler half-wave circuits (comprising even just a 
diode) could similarly be utilized within the present disclosure. It is 
also contemplated that rectifier 110 could even be constructed as a 
full-wave rectifier. It should be noted that the present design is such 
that identification circuit 100 could be operated solely from the power 
provided by the predetermined frequency signal. Such operation is highly 
desirable in a facility during wiring but prior to electrical hook-up. As 
shown, identification circuit 100 may further comprise fuse 160 operably 
connected in series between the hot lead and the rectifier to provide 
overcurrent protection to identification circuit 100. 
Band pass filter 120 comprises--in the particularly disclosed 
embodiment--resistor R1, capacitor C1 and capacitor C2. As such, the input 
to band pass filter 120 is at the connection between the cathode of diode 
D1 and the first terminal of R1. In this manner, the input of the band 
pass filter is operably connected to the hot lead of the associated branch 
circuit. It should be noted that identification circuit 100 would operate 
if the band pass filter input were connected to the anode of diode D1 
rather than its cathode. However, it has been found that diode D1 provides 
desirable noise rejection which improves the operation of band pass filter 
120 and potentially simplifies the design of that filter when the input is 
taken from the diode's cathode. The output of band pass filter 120 is 
drawn at the tap between capacitors C1 and C2. As is known, the values for 
R1, C1 and C2 are selected such that band pass filter 120 passes the 
predetermined frequency from its input to its output while substantially 
blocking all other frequencies. 
Controlled switch 130 has gate 131, first terminal 132 and second terminal 
133 wherein current flows between the first and second terminals and 
through the controlled switch upon application of appropriate bias to the 
gate. Accordingly, although controlled switch 130 preferably comprises a 
SCR it could comprise a Triac or other similarly operated gate-controlled 
switching device. As shown, first terminal 132 is in series with the 
indicator lamp and second terminal 133 is connected to neutral lead 20b of 
branch circuit 20. Gate 131 is operably connected to the output of band 
pass filter 120. In a preferred embodiment, capacitor C3 is interposed 
between gate 131 and the output of the band pass filter and selected such 
that C3 substantially blocks any harmonic frequency noise from reaching 
the gate to prevent inadvertent triggering. Also connected to this circuit 
is second diode 150, which provides reverse bias protection for the gate 
of the controlled switch. 
In a preferred embodiment of the present invention, identification circuit 
further includes low pass filter 140, which is operably connected in 
series between hot lead 20a of branch circuit 20 and bus bar 16 and in 
parallel with other circuits in said identification circuit. 
In a preferred embodiment, identification circuit 100 is manufactured such 
that it is contained in the same enclosure as its associated circuit 
breaker so as to provide for ease of installation. This enclosure may 
further include a socket which operably connects the enclosed 
identification circuit and circuit breaker to at least the associated hot 
lead and bus bar terminals. A further removably connectable lead may be 
used to connect to the neutral lead (or alternatively the socket may also 
include a connection to the neutral lead in addition to the hot lead/bus 
bar connections). 
In operation, an end user connects (usually a standard branch receptacle) 
transmitter 31 to hot lead 21a of branch circuit 21. Then the end user or 
another user assisting the end user merely visually scans the breaker 
panel looking for the particular indicator lamp that lights to correctly 
identify the circuit breaker protecting selected branch circuit 21. Of 
course, a similar procedure could be conducted for each branch circuit and 
circuit breaker within the group of circuit breakers. 
As shown in FIG. 1, transmitters 31 and 35 are directly coupled to a 
particular hot lead of a particular branch circuit, thus injecting a 
predetermined frequency signal into the hot lead. It should be emphasized 
that any circuit that can inject (or directly couple) a signal at the 
predetermined frequency onto the hot lead of a branch circuit can be used 
as the transmitter in the present invention. 
FIG. 2 shows one potential embodiment of the transmitters for use in the 
present invention. In particular, this transmitter, in addition to having 
frequency generator circuit 200 also includes receptacle analyzer 
circuitry and ground fault condition tester circuit, as well. Frequency 
generator circuit 200 includes timer circuit 201, resistor R15, resistor 
R16, capacitor C12, capacitor C15, switch S2, and booster/isolation 
circuit 202. Generally, resistors R15 and R16 and capacitor C12 are the 
frequency determining components for timer circuit 201. Additionally, 
though, by closing switch S2, capacitor C15 further determines the 
frequency by increasing the capacitance in the frequency determinative 
branch, in turn lowering the frequency of the resulting output signal. 
Accordingly, this particular transmitter is capable of generating one of 
two frequencies depending on the position of switch S2. The default 
frequency (generated with S2 open) is the standard predetermined frequency 
discussed throughout the present disclosure. The second, lower frequency 
(generated with S1 closed), would be used to pass through low pass filter 
140 and onto the particularly connected phase of bus bar 16 such that an 
end user could identify all circuit breakers within the group of circuit 
breakers that are on the same phase. Of course, in such a design the band 
pass filter of 120 would be designed with sufficient bandwidth to pass 
both signal frequencies. 
The foregoing description and drawings merely explain and illustrate the 
invention and the invention is not limited thereto. Those of the skill in 
the art who have the disclosure before them will be able to make 
modifications and variations therein without departing from the scope of 
the present invention.