Patent Publication Number: US-8982515-B2

Title: Apparatus for a circuit interrupter

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to commonly assigned, copending U.S. patent application Ser. No. 13/477,497, filed May 22, 2012, 2012, entitled “Circuit Interrupter Including Indicator Circuit”. 
     BACKGROUND 
     1. Field 
     The disclosed concept pertains generally to power circuits and, more particularly, to power circuits protected by circuit interrupters. The disclosed concept further pertains to apparatus for installing, testing, operating and/or maintaining such power circuits and/or circuit interrupters. 
     2. Background Information 
     A conventional circuit breaker panel inputs, for example and without limitation, a conventional 120 VAC RMS , 60 Hz power line as distributed by a power company. This input is received by an electrical conductor, which is electrically connected to a hot buss bar. A line terminal of a main circuit breaker is electrically connected to the hot buss bar and a load terminal of the main circuit breaker is electrically connected to line terminals of a plurality of branch circuit breakers. Each branch circuit breaker protects a branch power circuit that is electrically connected to the load terminal of the corresponding branch circuit breaker. A neutral is used to complete the electrical power circuit of, for example, an electrical outlet or receptacle, and is electrically connected to a neutral buss bar in the circuit breaker panel. A ground is used as a safety precaution to protect against ground fault currents in the power circuit and is electrically connected to a ground buss bar in the circuit breaker panel. 
     A common problem in a building&#39;s electrical system is mislabeled or unmapped circuit breakers and outlets. While installing an electrical system in a building, power circuits can become confused and/or mislabeled. Because electricians can never be exactly sure which power circuit is electrically connected to an outlet, and, more importantly, which circuit breaker is electrically connected to the outlet, they continuously have to double check electrical connections. This could mean numerous trips between a circuit breaker panel room and the remote location of an outlet. This problem increases in a relatively large warehouse or commercial building. 
     One proposed solution for this problem uses two electricians, one at the remote location of the power circuit (e.g., an outlet) and the other in an electrical room where a circuit breaker panel is located, communicating with each other whether the power circuit in question is energized. For example, often equipped with hand held radios, one electrician turns off a circuit breaker at the circuit breaker panel, while the other electrician tests for voltage on the electrical outlet and relays back whether the power circuit is off or still energized. With some electrical panels having, for example, more than forty circuit breakers, this proposal can be time consuming and potentially hazardous. 
     Most circuit breakers, as employed in circuit breaker panels, do not incorporate any type of luminous indication of status (e.g., on; off; tripped). When looking at a circuit breaker panel with, for example, more than forty circuit breakers, it is difficult to distinguish between a circuit breaker that is on, one that is off and one that is tripped. 
     According to the Bureau of Labor Statistics, in 2007, there were 43,500 recorded non-fatal injuries in the electrical contracting industry. Among these statistics are a number of incidents that are a direct result of improper or non-thorough circuit detection procedures that cause unknown energized power circuits. 
     There is a need for an apparatus that can minimize time, effort and hazards associated with locating power circuits and circuit interrupters. 
     There is room for improvement in circuit interrupters operatively associated with such power circuits. 
     SUMMARY 
     These needs and others are met by embodiments of the disclosed concept. In accordance with one aspect of the disclosed concept, an apparatus comprises: an enclosure; a connector structured to mechanically and electrically engage a power circuit; a transmitter structured to transmit a signal having a frequency substantially greater than a power line frequency to the connector; and a user interface structured to cause the transmitter to transmit the signal to the connector. 
     The connector may be structured to mechanically and electrically engage the power circuit at an electrical outlet or receptacle. 
     The user interface may comprise a shorting circuit structured to short the power circuit; the shorting circuit may comprise a silicon controlled rectifier; the power circuit may comprise a hot line and a neutral; and the silicon controlled rectifier may be structured to short the hot line to the neutral. 
     As another aspect of the disclosed concept, an apparatus comprises: an enclosure; a connector disposed on or through the enclosure, the connector structured to mechanically and electrically engage a power circuit; and a transmitter enclosed by the enclosure, the transmitter structured to transmit a signal having a frequency substantially greater than a power line frequency to the connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full understanding of the disclosed concept can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: 
         FIG. 1  is a block diagram of a circuit interrupter in accordance with embodiments of the disclosed concept. 
         FIG. 2  is a block diagram of a circuit interrupter, power circuit, outlet and a portable apparatus in accordance with other embodiments of the disclosed concept. 
         FIG. 3  is a block diagram of two panel mounted circuit interrupters in accordance with another embodiment of the disclosed concept. 
         FIG. 4  is a block diagram in schematic form of a shorting circuit including a current limiting resistor in accordance with another embodiment of the disclosed concept. 
         FIG. 5  is a block diagram in schematic form of an indicator circuit of a circuit interrupter including two light emitting diodes (LEDs) in accordance with another embodiment of the disclosed concept. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality). 
     As employed herein, the statement that two or more parts are “connected” or “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts. Further, as employed herein, the statement that two or more parts are “attached” shall mean that the parts are joined together directly. 
     The disclosed concept will be described as applied to a miniature circuit breaker for use in alternating current (AC) systems, which are typically 60 Hz, but can also be used in direct current (DC) systems. It will also become evident that the disclosed concept is applicable to other types of circuit interrupters including those used in AC systems operating at other frequencies; to relatively smaller circuit breakers, such as subminiature, aircraft or aerospace circuit breakers; to relatively larger circuit breakers, such as commercial circuit breakers; and to a wide range of circuit interrupter applications, such as, for example and without limitation, residential, commercial, industrial, aerospace, and automotive. As further non-limiting examples, both AC (e.g., 110, 120, 208, 220, 240 or 480-600 VAC RMS ) operation at a wide range of frequencies (e.g., 50, 60, 120 or 400 Hz) and DC operation (e.g., 42 VDC) are possible. 
     The disclosed concept employs a circuit interrupter and an apparatus including a transmitter that assist, for example and without limitation, electricians in recognizing an electrical connection between a power circuit, such as an electrical outlet or receptacle thereof, and a corresponding circuit interrupter, and properly detecting the power circuit. For example and without limitation, the apparatus can plug into the electrical outlet or receptacle and transmit a suitable signal back through power circuit conductors of the power circuit to the corresponding circuit interrupter. The circuit interrupter includes an indicator circuit structured to indicate when the transmitted signal is received by the circuit interrupter. The apparatus can include an optional function to allow the user to trip the circuit interrupter directly from the power circuit. 
     It is believed that there is no known device that can safely and reliably trip a circuit interrupter by plugging such device into an electrical outlet or receptacle, as opposed to walking to a circuit breaker panel and manually turning the circuit interrupter off. Although a shorting wire could hypothetically be inserted into an electrical outlet or receptacle to trip a circuit interrupter, that approach is quite unsafe and must, therefore, not be used. 
     The combination of a circuit interrupter having a suitable indicator circuit and an apparatus that can remotely interact with the circuit interrupter from, for example and without limitation, a remote electrical outlet or receptacle, can solve the problem of identifying power circuits. 
     Referring to  FIG. 1 , a circuit interrupter  2  includes an enclosure  4 , a first terminal  6 , a second terminal  8 , separable contacts  10  electrically connected between the first and second terminals  6 , 8 , an operating mechanism  12  structured to open and close the separable contacts  10 , and an indicator circuit  14  electrically interconnected with the second terminal  8  and being structured to indicate occurrence of a signal  16  at the second terminal  8 . The signal  16  has a frequency substantially greater than a power line frequency  17  (e.g., at the first terminal  6 ). 
     Example 1 
     The power line frequency  17  is less than or equal to about 400 Hz (e.g., without limitation, 50 Hz; 60 Hz; 120 Hz; 400 Hz). 
     Example 2 
     The frequency of the signal  16  is about 8 MHz. Alternatively, the frequency of the signal  16  may range from about 7 MHz to about 9 MHz. 
     Example 3 
     The example indicator circuit  14  includes an inductor  18  (e.g., without limitation, 27 μH) electrically connected between the separable contacts  10  and one of the first terminal  6  and the second terminal  8 , an indicator device (e.g., without limitation, a light emitting diode (LED)  20 ), and a capacitor  22  (e.g., without limitation, 0.1 nF) electrically connected between the second terminal  8  and the LED  20 . The inductor  18  passes the power line frequency  17  and blocks the frequency of the signal  16 . The capacitor  22  blocks the power line frequency  17  and passes the frequency of the signal  16  to the LED  20 . 
     The indicator circuit  14  also includes a ground connection  24  that is structured to be electrically connected to, for example and without limitation, a grounded circuit interrupter panel  86  ( FIG. 3 ). The indicator circuit  14  further includes a diode  26 . The capacitor  22  is electrically connected between the second terminal  8  and the anode (A) of the LED  20 , the cathode of the diode  26  is electrically connected to the anode of the LED  20 , the anode of the diode  26  is electrically connected to the cathode (C) of the LED  20 , and the cathode of the LED  20  is grounded by the ground connection  24 . The capacitor  22  passes the frequency of the signal  16  to the anode of the LED  20 , in order to illuminate the LED  20 , and blocks the power line frequency  17  from the anode of the LED  20 . The diode  26  passes negative half cycles of the frequency of the signal  16 . 
     The indicator circuit  14  inputs the example high frequency signal  16  from an apparatus transmitter  30  ( FIG. 2 ) and responsively outputs light from the illuminated LED  20 , which is on when the apparatus transmitter  30  transmits the example 8 MHz signal  16  and, otherwise, is off. The capacitor  22  functions as an open circuit to the line frequency  17  and a short to the 8 MHz signal  16 . The diode  26  provides a path for the negative half cycle of the 8 MHz signal  16  and for the capacitor  22  to discharge. 
     Example 4 
     A current flowing between the first and second terminals  6 , 8  is less than or equal to about 20 A RMS  when the separable contacts  10  are closed. 
     Example 5 
     The indicator circuit  14  includes a suitable indicator device, such as the example LED  20 , structured to indicate the occurrence of the signal  16  at the second terminal  8  when the separable contacts  10  are opened or closed. 
     Example 6 
     A simple and suitable way to implement the circuit interrupter  2  includes adding a suitable indicator circuit  14  including the example LED  20  and a suitable filter, such as including a number of inductors  18  and capacitors  22  (only one inductor  18  and one capacitor  22  are shown in  FIG. 1 ). Since the line frequency  17 , such as 60 Hz, at an electrical outlet or receptacle, and the example 8 MHz frequency of the signal  16  are significantly different, these frequencies can be separated from each other without affecting the operation of a corresponding power circuit, such as  28  of  FIG. 2 . 
     The circuit interrupter  2  (e.g., without limitation, a circuit breaker) protects the power circuit  28  as shown in  FIG. 2 . The example LED  20  of the indicator circuit  14  is illuminated when a suitable signal  16  (e.g., without limitation, 8 MHz) is transmitted from the transmitter  30  of an apparatus  32  as shown in  FIG. 2 . The inductor  18  (which may be disposed at the load side of the separable contacts  10  as shown in  FIG. 2 ) passes the line frequency  17  (e.g., without limitation, 60 Hz) coming from the circuit interrupter  2  and blocks the example 8 MHz signal  16  transmitted by the apparatus transmitter  30 . This blocks the 8 MHz signal  16  from passing through the circuit interrupter  2  and reaching other circuit breakers (not shown, but see circuit interrupter  2 ′ of  FIG. 3 ) and their LEDs (not shown) of a circuit breaker panel (not shown, but see circuit interrupter panel  86  of  FIG. 3 ) via a hot buss bar (not shown) thereof. Also, the capacitor  22  acts as an open circuit to relatively low frequencies and blocks the line frequency  17 , in order to prevent the line frequency  17  from reaching and illuminating the LED  20 , while acting as a short to relatively high frequencies and passing the 8 MHz signal  16  to illuminate the LED  20 . The example LED  20  is illuminated when the apparatus  32  is installed and activated by a user, as will be described. This enables the user to detect which circuit breaker protects a specific electrical outlet or receptacle in a room or building. 
     The circuit interrupter  2  receives the example 8 MHz signal  16  from its load terminal  8  as transmitted by the apparatus  32 . The example circuit breaker LED  20  is illuminated when the apparatus  32  transmits the example 8 MHz signal  16 , regardless whether the circuit interrupter  2  is on, off or tripped. The example 8 MHz signal  16  is choked out by the inductor  18 , in order that it does not pass to other circuit breakers (not shown) via the hot buss bar (not shown) of a circuit breaker panel (not shown). Otherwise, the circuit interrupter separable contacts  10 , operating mechanism  12  ( FIG. 1 ) and trip mechanism  34  ( FIG. 1 ) are conventional. Since the LED  20  is only illuminated by the 8 MHz signal  16 , the LED  20  illuminates when the circuit interrupter  2  is in any position (e.g., on; off; tripped). Because the LED  20  and other components of the indicator circuit  14  are after the separable contacts  10  of the circuit interrupter  2 , the LED  20  still receives the 8 MHz signal  16  from the apparatus  32  over a load conductor  36 , which electrically connects the circuit interrupter  2  to an electrical outlet or receptacle  38 . 
       FIG. 2  shows the circuit interrupter  2 , the power circuit  28 , the electrical outlet or receptacle  38 , and the apparatus  32 . The apparatus  32  includes an enclosure  40 , a connector  42  structured to mechanically and electrically engage the power circuit  28 , the transmitter  30  structured to transmit the signal  16  having a frequency substantially greater than the power line frequency  17  to the connector  42 , and a user interface  44  structured to cause the transmitter  30  to transmit the signal  16  to the connector  42 . 
     Example 7 
     The connector  42  mechanically and electrically engages the power circuit  28  at the electrical outlet or receptacle  38 . The connector  42  forms part of a male three prong plug  46  that mechanically and electrically engages a hot contact  48 , a neutral contact  50  and a ground contact  52  of a female socket  54  of the electrical outlet or receptacle  38 . The ground contact  52  is electrically connected to the apparatus enclosure  40 . 
     Example 8 
     The transmitter  30  includes a battery  56  and an oscillator circuit  58  (e.g., without limitation, an 8 MHz crystal oscillator). The user interface  44  can energize the oscillator circuit  58  from the battery  56 . When energized, the oscillator circuit  58  transmits the signal  16  having the example 8 MHz frequency to the connector  42 . The transmitter  30  further includes a capacitor  60  (e.g., without limitation, 0.1 nF) electrically connected between the oscillator circuit  58  and the connector  42 , and a voltage regulator  62  that inputs a first direct current voltage  64  (e.g., without limitation 9 VDC) from the battery  56  and outputs a second direct current regulated voltage  66  (e.g., without limitation 5 VDC) to power the oscillator circuit  58 . The battery  56  permits the signal  16  to be transmitted regardless whether the power circuit  28  is energized by a line voltage having the power line frequency  17 . 
     The user interface  44  includes a switch  68  that when closed causes the oscillator circuit  58  to transmit the signal  16 . The oscillator circuit  58  inputs the regulated voltage  66  and transmits the signal  16  when the user turns on the apparatus  32  and plugs it into the electrical outlet or receptacle  38 . The capacitor  60  passes the signal  16  from the oscillator circuit  58  to the connector  42  and blocks the power line frequency  17  from the connector  42  to the oscillator circuit  58 . The transmitter  30  outputs the signal  16  to the power circuit  28  when the connector  42  mechanically and electrically engages the electrical outlet or receptacle  38  of the power circuit  28  and the user interface  44  causes the transmitter  30  to transmit the signal  16  to the connector  42  and, in turn, to the hot contact  48  of the female socket  54  of the electrical outlet or receptacle  38 . The high frequency signal  16  is then received from the power circuit  28  by the indicator circuit  14 , which illuminates the LED  20  of the corresponding circuit interrupter, such as  2 . 
     Example 9 
     The example 8 MHz signal  16  has a relatively low power level (e.g., without limitation, less than about 4.5 mA and less than about 3 V) to avoid causing any significant interference with other apparatus (not shown) commonly employed in or with a building, power distribution system or power circuit, and is subject to relatively little attenuation when transmitted over power circuit conductors, such as  36 . The example 8 MHz signal  16  has a sufficient power level to compensate for power circuit conductor losses and attenuation, in order to illuminate the LED  20  of the circuit interrupter  2 , but has an insufficient power level to illuminate other LEDs (not shown) of other circuit interrupters (not shown) in a circuit breaker panel (not shown) in the unlikely event that the 8 MHz signal  16  is leaked by the inductor  18 . 
     Example 10 
     For added security and convenience, an optional shorting circuit  70  having a suitable switch, such as a silicon controlled rectifier (SCR)  72 , can optionally be included with the transmitter  30  of the apparatus  32  to trip the circuit interrupter  2  from the corresponding electrical outlet or receptacle  38 . The user interface  44  may include the optional shorting circuit  70  to short the power circuit  28 . The shorting circuit  70  includes the SCR  72  structured to short the hot line at hot contact  48  to the neutral at neutral contact  50  of the power circuit  28 . The SCR  72  has an anode  74  electrically connected to the hot line, a cathode  76  electrically connected to the neutral, and a gate  78 . The SCR gate  78  is energized through resistor  80  (e.g., without limitation, 450Ω) by the battery  56  responsive to closure of a switch  82 , which causes the SCR  72  to short the hot line to the neutral. This causes an over-current fault, which causes a trip of the corresponding circuit interrupter, such as  2 . 
     Example 11 
     The disclosed apparatus  32  is relatively compact and can be enclosed in the suitably rigid enclosure  40  (e.g., without limitation, a plastic housing), which encloses the transmitter  30  and the optional shorting circuit  70 . 
     Example 12 
     If a user is trying to determine which circuit interrupter, such as  2 , corresponds to the electrical outlet or receptacle  38 , then they can enable the signal  16  from the apparatus  32  and walk to the circuit breaker panel (not shown) to see, for example, which circuit interrupter has illuminated the LED  20 . This can either be done when the power circuit  28  is live or on, or when off or tripped. 
     Example 13 
     If a user would like to work on the electrical outlet or receptacle  38  and doesn&#39;t care about the corresponding circuit interrupter, such as  2 , then the user can enable the SCR  72 , which trips the corresponding circuit interrupter  2 , electrically check to confirm that the power circuit  28  is dead (e.g., off; tripped), and then work on the electrical outlet or receptacle  38  or power circuit  28  without having to go to the circuit breaker panel (not shown) to check if the corresponding circuit interrupter, such as  2 , is tripped or whether the LED  20  is illuminated. The SCR  72  essentially creates a short at the electrical outlet or receptacle  38 , which trips the corresponding circuit interrupter, such as  2 , thereby eliminating the need for a user to go to the circuit breaker panel (not shown) and turn off the corresponding circuit interrupter, such as  2 . 
     Example 14 
     The example radio frequency (RF) signal  16  (e.g., having a frequency substantially greater than a line frequency, such as  17 ) of about 8 MHz is believed to be preferred for the apparatus transmitter  30 . 
     Example 15 
     After the apparatus  32  is plugged into the electrical outlet or receptacle  38 , the user enables the apparatus transmitter  30 , which transmits the example 8 MHz signal  16 . The 8 MHz signal  16  passes through the electrical outlet or receptacle  38  and then through the conductors, such as  36 , of the power circuit  28 . The 8 MHz signal  16  then enters the indicator circuit  14  of the corresponding circuit interrupter, such as  2 , which turns on and illuminates the LED  20 . 
     Example 16 
       FIG. 3  shows a simplified view of the circuit interrupter  2  including the indicator circuit  14  and a mechanical connection point  84  suitable for providing a ground  88  to the indicator circuit  14 . The mechanical connection point  84  of the circuit interrupter enclosure  4  retains the circuit interrupter  2  in a circuit interrupter panel  86  with a number of other circuit interrupters, such as  2 ′, and provides the ground  88  to the indicator circuit  14 . 
     The example mechanical connection point  84  is where the circuit interrupter  2  mechanically fastens to the circuit breaker panel  86 , which provides a suitable source for a ground  88 . This connection point  84  is electrically connected to a ground bus  90  in the circuit breaker panel  86 . The panel connection point  91  is, for example and without limitation, a conductive bar (e.g., a mechanical connection point) that the circuit interrupter  2  mechanically fastens to in the circuit breaker panel  86 . The conductive bar  91  is electrically connected to the ground bus  90  in the circuit breaker panel  86 . The ground  88  provides the ground connection  24  (also shown in  FIGS. 1 and 2 ) for the indicator circuit  14 . The LED  20  of the indicator circuit  14 , in turn, employs the ground connection  24 . For most circuit breakers (e.g., without limitation, for power circuits rated at 20 A or less), there is no ground in the circuit breaker. The ground connection  24  is, therefore, incorporated into the circuit interrupter  2  for the LED  20  of the indicator circuit  14  to function properly. 
     Example 17 
     As shown in  FIG. 4 , an optional current limiting resistor  92  can be employed on the hot line side of the SCR  72  of  FIG. 2 . The resistor  92  is electrically connected in series with the SCR  72  between the hot line and the neutral of the power circuit  28  ( FIG. 2 ). 
     Example 18 
       FIG. 5  shows another indicator circuit  94  that can be used in place of the indicator circuit  14  of  FIGS. 1 and 2 . The indicator circuit  94  includes a first indicator device, such as an LED  96 , to indicate the signal  16  at the second terminal  8  and a second indicator device, such as an LED  98 , which is conventional, to indicate when the separable contacts  10  are opened. Otherwise, the circuit interrupter  2  of  FIGS. 1 and 2  indicates the open and/or the tripped open positions of the operating mechanism  12  by the position of operating handle  100 , as is conventional. 
     While specific embodiments of the disclosed concept have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the disclosed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof.