Abstract:
A device and method for detecting the imminent disconnection of electrical connectors before such an event occurs, thereby minimizing or eliminating the production of an electrical arc upon disconnection. The method detects the imminent disconnection of the connectors by use of a device located in the connector to signal the power source to cease sending electrical current through the connectors prior to the actual disconnecting event.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims subject matter that was disclosed in Provisional Application No. 61/090,250, filed 20 Aug. 2008, and in Provisional Application No. 61/099,294, filed 23 Sep. 2008, both entitled “A Method and Device for Detecting an Unexpected Disconnection of Connectors in a Circuit Carrying Electrical Current”. Applicant hereby claims the benefit under 35 USC §119(e) of the U.S. provisional applications, and hereby incorporates the aforementioned applications by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention pertains to the field of electrical transmitting circuitry. More particularly, the invention pertains to connectors used to link segments of electrically conductive circuits. Specifically, the invention of a device and method by which current flowing through the connectors is rapidly terminated before any disconnection occurs. 
       BACKGROUND OF THE INVENTION 
       [0003]    Electrical circuits often carry tens of thousands of volts, especially in large industrial operations or within municipal electrical transmission lines. Since the circuits or electrical lines that carry the voltage are installed in a wide range of locations, it is necessary that they be made in a wide range of lengths. These different lengths are then connected to each other to an appropriate length by use of terminal connectors on each end of each cable. 
         [0004]    Connecting and disconnecting the connectors is a serious operation and must be performed under carefully controlled conditions. If not done carefully, arcing may occur between one connector and the other during either connection or disconnection. These “arcs” of electricity can be extremely hazardous to equipment and personnel. An especially dangerous condition might exist if volatile solvents or gases are present in the area around the connectors. The size of the arc is influenced by factors such as circuit inductance, current (amperage), voltage and the speed of disconnection. 
         [0005]    This invention is directed at preventing the production of such electrical arcs by anticipating the imminent disconnection and reducing the amount of current flowing through the connection should certain unexpected conditions begin to occur, such as an accidental disconnection. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a device by which the imminent disconnection of at least one electrical connector is detected before such an event might occur. The output from such a device mounted to the connector is transmitted to a second device that substantially instantaneously terminates the current flowing through the connector(s) before disconnection occurs. The decay time for the source of the current may be so long that the reduction of the current to zero may not have been completed by the time the disconnection occurs. Nonetheless, even under these circumstances, the current will have been reduced substantially enough such that any arcing that does result is less than that which might have occurred under full current conditions, thus minimizing potentially catastrophic results from the electrical arc or the igniting of volatile gases that may be present around the connector(s). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  shows a block diagram of an electrical circuit from the power generating source, through the lines and connectors to the load, or end user of the electricity. 
           [0008]      FIG. 2  is a detailed schematic of one embodiment of the electrical circuitry of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0009]    Referring to  FIG. 1 , a power generating source PSI ( 21  in  FIG. 2 ) transmits electrical current through wires and an electrical control unit D 2 . D 2  allows the current to flow to one of the connectors, generally indicated as  20  ( FIG. 2 ), and in this example identified as a socket S 2  which is non-permanently engaged with a plug, in this case designated as P 1 . The electrical current continues on to the load, or final end user, L 1   30  ( FIG. 2 ). 
         [0010]    The invention consists of at least one detecting device, associated with each point of connection. In the example shown in  FIG. 1 , two detection devices are indicated. Detection device D 1 P is securely connected to plug P 1  and detection device D 1 S is securely connected to socket S 2 . When either or both of the detectors D 1 P and D 1 S senses that the connectors are about to be disconnected, one or both of the detectors sends a signal to the electrical control unit D 2 , which substantially instantaneously signals the power source PS 1  to cease current flow through this circuit. The result is that the current flowing through the connectors P 1  and S 2  is cut to zero or substantially zero to either prevent or substantially minimize the formation of an electrical arc upon connector disconnection. Note that as an alternative to switching off the power source, the load could be switched off. 
         [0011]    The detectors D 1 P and D 1 S may consist of but are not limited to any of the following devices. These devices consist of accelerometers, strain gauges, thermal or optical sensors and electrical or capacitance measuring device. An accelerometer circuit  22  is shown schematically in  FIG. 2 . 
         [0012]    Further embodiments of the present invention might include inserting the electrical control unit within the power generating source PSI. In another embodiment, the power source PSI ( 21 ) may be a battery charger and the load L 1  ( 30 ) may be a battery. These embodiments are within the contemplation of the present invention. 
         [0013]    Prior to disconnection, some movement of the connector housing occurs, with a large connector  20 ; many milliseconds may elapse before the electrical disconnection takes place. If the movement is detected, and the circuit can be switched off before the disconnection takes place, arcing can be substantially reduced or altogether eliminated. 
         [0014]    An accelerometer  22  can be used to sense any movement in connector  20  and its electrical output fed to a detecting circuit, such as a microprocessor  24 , which can switch off the power source. 
         [0015]    One application for such an invention is any environment where an arc may be hazardous. For example, but not limited to, the gases emitted when a large battery is being charged. The invention also increases the lifetime of connectors since damage caused by arcing is reduced or eliminated. 
         [0016]    Referring now to one embodiment of the invention shown in  FIG. 2 , an accelerometer  22  and detecting circuit  24 , which is mounted in a housing  25 , are fitted to the connector  20 , which therefore moves with the connector  20 . When movement is detected, the circuit transmits a signal via wires or wireless transmitter to a receiving circuit which switches off the power generating source  21  or other similar device prior to the actual unintentional disconnection of the connector  20 . 
         [0017]    U 3  is the motion detecting integrated circuit  26  of accelerometer  22 ; the sensitivity is set by the state of the two-pole switch SW 1 . Since each section of the switch can be closed or open, the voltage applied to the g-Select  1  and g-Select  2  pins can be high or low. In binary terms, the options are 00, 01, 10, and 11. Each of the four states program U 3  sensitivity. C 17  provides filtering; R 45  keeps U 3  enabled whenever 3.3V is present. 
         [0018]    U 3  ( 26 ) provides a voltage output at the X Out, Y Out and Z Out pins which is proportional to the magnitude of the acceleration experienced by U 3  in the X, Y and Z plane. Positive acceleration results in an increase in voltage; negative acceleration results in a reduction in voltage. 
         [0019]    R 2 -C 20 , R 6 -C 18  and R 21 -C 19  filter out clock noise from the accelerometer output which might otherwise cause the detector  24  to give erratic results. 
         [0020]    This embodiment of the invention uses a microprocessor U 1  ( 24 ), but a comparator and timer components would work equally well. The X Out, Y Out and Z Out voltages from the accelerometer  22  are fed into three analog to digital inputs of the microprocessor. If the voltage levels on these inputs exceed a programmable high level internal reference or go below a programmable low level internal reference, pin B 1  goes high, which turns on bipolar transistor Q 1  and P 1  (typically connected to 5V via a 1-10 k Ohm resistor) is taken low via the resistor, R 1 . This level change can in turn be used to disable the electrical power source  21  before the physical disconnection of the connector occurs. 
         [0021]    Since in most cases the connectors would lie in one plane, if the sensitivity of the U 3  ( 26 ) is set to a level where 1 g or less produces an output voltage which causes the microprocessor to give a high voltage output on pin B 1  within detector  24 , the electrical source will be disabled under static conditions. To avoid this problem, the output from the microprocessor is pulsed, the output occurs only for a defined time after which the output from B 1  returns low and no further output will result from acceleration with this polarity in this plane. Acceleration of the opposite polarity or output resulting from the other two planes will however still produce an output pulse. After a reasonable amount of time, the circuit can be tested to see if a load is present. If no load is present, the source remains off; if a load is present the source can be re-enabled. Alternatively the output from this circuit could be ignored at initial power up. 
         [0022]    C 6  filters out electrical noise from the 5V supply to prevent it disturbing U 1 . The network consisting of D 201 , R 5  and C 5  resets the microprocessor on power up. C 4  improves noise immunity. R 6  and R 7  modify the output from the microprocessor to match Q 1 . The resistor R 1  limits the current that flows to ground if connected to a capacitive load when Q 1  changes to the on state. 
         [0023]    Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.