Abstract:
Disclosed are advances in the arts with novel methods and apparatus for detecting faulty connections in an electrical system. Exemplary preferred embodiments include basic, ASIC, AC, DC, and RF monitoring techniques and systems for monitoring signals at one or more device loads and analyzing the monitored signals for determining fault conditions at the device loads and/or at the main transmission lines. The invention preferably provides the capability to test and monitor electrical interconnections without fully activating the host system.

Description:
PRIORITY ENTITLEMENT 
       [0001]    This application is entitled to priority based on Provisional Patent Application Ser. No. 61/154,704 filed on Feb. 23, 2009, which is incorporated herein for all purposes by this reference. This application and the Provisional Patent Application have at least one common inventor. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to monitoring the status of device connections in electrical systems for addressing concerns related to system reliability, quality, and safety. More particularly, the invention relates to monitoring the status of systems that include multi-wire interconnects and/or long transmission lines, especially systems that may be deployed in rough environmental conditions. 
       BACKGROUND OF THE INVENTION 
       [0003]    In systems requiring that multiple loads be electrically coupled to one or more main lines, many connection approaches known in the arts may be used. The load lines may be connected off a main line in a linear transmission line configuration, star configuration, or daisy chain configuration, for example. An example familiar in the arts is a system configuration in which load lines are connected off the main line in a two-wire system with a transmission line configuration. A matrix configuration is also known in the arts, in which loads are connected to main lines using a web of load lines arranged in rows and columns. Those familiar with the arts will recognize that various combinations of such configurations may also be used, such as a linear transmission line connected with one or more star configuration, for example. The complexity of the connections may in some instances be very high and the connections may extend over a very large physical area. 
         [0004]    Regardless which arrangement of system connections are used, the status of device connections in electrical systems can be outside acceptable limits due to poor installation, environment conditions, external conditions, and/or operational errors. If faulty connections are not detected, the individual device or entire system performance can be affected resulting in potential quality, reliability, and/or safety problems. Due to various challenges, monitoring the status of the interconnect system can be difficult at times. For example, when the connection lines are extremely long, on the order of kilometers, it becomes a challenge to find the locations of faulty connections or loads. Other challenges are environmental conditions that could directly contribute to the increased likelihood of faulty loads due to sharp objects, corrosive materials, extreme temperatures, wind, ice, etc. It would therefore be useful to have the capability to conveniently and reliably monitor the status of an interconnect system. One example that demonstrates a need for monitoring a complex interconnect system is in the mining industry, where electronic apparatus is used to control a substantially precisely timed string of detonations. Such a system often uses a multi-wire interconnect where all the device loads are tapped into the same signals at different points of the interconnect system. Marginal interconnect status of the tap wires and connections can affect performance of one or more devices. Conventional integrity check methods often fail to detect such marginal conditions. Due to these and other problems and potential problems, improved status monitoring of an interconnect system would be useful and advantageous in the arts. Reliable yet easy to use detection systems and methods would be particularly beneficial contributions to the art. 
       SUMMARY OF THE INVENTION 
       [0005]    In carrying out the principles of the present invention, in accordance with preferred embodiments, the invention provides advances in the arts with novel methods and apparatus directed to detecting faulty connections in an electrical system. According to aspects of the invention, preferred embodiments include a basic connector type, a smart connector type, a DC monitoring system, an AC monitoring system, an RF monitoring system, a transmission line monitoring system, and a multi-wire monitoring system. Examples of each of various preferred embodiments of such monitoring systems are described. 
         [0006]    According to one aspect of the invention, an example of a preferred method is disclosed for detecting and reporting faults, and the locations of faults, in an electrical interconnect with a main line and a number of loads. The method includes steps for monitoring signals at one or more device loads and analyzing the monitored signals for determining fault conditions at the device loads. In further steps, faulty loads are isolated from the main lines and load fault conditions are reported to a system master. 
         [0007]    According to another aspect of the invention, in an exemplary embodiment, the method includes steps for monitoring signals at the main lines and analyzing the monitored signals for determining fault conditions at the main lines. In further steps, faults in the main lines are reported to a system master. 
         [0008]    According to another aspect of the invention, an embodiment described includes steps for disabling all but one device load, transmitting a DC signal on the main lines, and measuring voltages at the enabled load. The measured voltages are compared to expected values and the existence of fault conditions is indicated when the voltage measured at that load is less than the expected value. 
         [0009]    According to another aspect of the invention, an embodiment of a method for detecting and reporting faults includes the step of transmitting an AC signal on the main line. The AC signal has one or more pulses of known magnitude, width, and frequency parameters, at least one of which is monitored. Reflected pulse signals at the main line are measured and compared with one or more of the expected parameters for determining whether fault conditions exist. 
         [0010]    According to another aspect of the invention, in an example of a preferred embodiment, a method includes monitoring signals at device loads by sending command signals from a system master to one or more loads to command the loads to enter a diagnostic mode. In a further step, radio frequency (RF) signals are generated and transmitted at one or more of the loads operating in diagnostic mode. The RF signals are detected and received at the main line, and fault conditions at the loads as well as on the main line are identified by comparing parameters of the received RF signals, such as the amplitude, frequency, and phase, with expected values. 
         [0011]    According to another aspect of the invention, an example of a preferred method is disclosed for detecting and reporting faults, and the locations of faults, in an electrical interconnect system having a main line and a number of loads. In the method, one or more additional wire lines connected to one or more device loads is used for monitoring the current flow through the one or more additional wire lines. Fault conditions in one or more device loads are indicated by increases or decreases in current in the one or more additional wire lines relative to the main lines and are reported to a system master. 
         [0012]    According to another aspect of the invention, in an embodiment of the methods described, the steps of monitoring signals at device loads further includes using one or more additional wire lines each connected to one or more device loads through a switch. The steps include monitoring current flow through the one or more additional wire lines while operating all device loads in a quiescent mode in which the loads do not draw current. By switching on each of the device loads individually, current detected in the one or more additional wire line or lines may be used to detect fault conditions. 
         [0013]    According to another aspect of the invention, a preferred embodiment of a system for detecting faults, reporting faults, and detecting the locations of faults in an electrical interconnect system having a main line and a plurality of device loads is disclosed. The system includes monitoring modules at device loads for monitoring signals at the load lines and analyzing modules for determining fault conditions at the device loads based on the monitored signals. A communication module is provided for reporting fault conditions and locations to a system master. 
         [0014]    According to yet another aspect of the invention, a preferred embodiment of the fault detecting system provides one or more monitoring modules at the main line for monitoring signals at the load lines and main line. Also included are one or more analyzing modules at the main line for determining fault conditions at device loads and main line based on the monitored signals. Communication modules at the main line for reporting fault conditions at the device loads or at the main line to a system master. 
         [0015]    According to yet another aspect of the invention, in a preferred embodiment of a electrical interconnect status monitoring system, a DC transmitter is included for transmitting the DC signals from the main line to device loads for monitoring and analyzing fault conditions. 
         [0016]    According to another aspect of the invention, a preferred embodiment of a electrical interconnect status monitoring system includes an AC transmitter for transmitting AC signals from the main line to device loads for use in monitoring and analyzing fault conditions. 
         [0017]    According to another aspect of the invention, preferred embodiments are described in which one or more RF transmitters at one or more device loads in the system may be used for transmitting RF signals to monitoring devices at the main line. 
         [0018]    The invention has advantages including but not limited to providing one or more of the following features; improved accuracy and safety in monitoring the status of device connections in electrical systems, including the ability to test and monitor connections without fully activating the system. These and other advantageous features and benefits of the present invention can be understood by one of ordinary skill in the arts upon careful consideration of the detailed description of representative embodiments of the invention in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The present invention will be more clearly understood from consideration of the following detailed description and drawings in which: 
           [0020]      FIG. 1  is a simplified schematic diagram illustrating an example of a preferred embodiment of an electrical interconnect status monitoring system and method utilizing a resistance placed between the load and the main line for the purpose of fault detection; 
           [0021]      FIG. 2  is a simplified schematic diagram illustrating an example of a preferred embodiment of an electrical interconnect status monitoring system and method using an ASIC placed between the load and the main line for the purpose of fault monitoring; 
           [0022]      FIG. 3  is a simplified schematic diagram illustrating an example of a preferred embodiment of an electrical interconnect status monitoring system and method with a DC monitoring module for detecting fault conditions; 
           [0023]      FIG. 4  is a simplified schematic diagram illustrating an example of a preferred embodiment of an electrical interconnect status monitoring system and method using an AC monitoring module for detecting fault conditions; 
           [0024]      FIG. 5  is a simplified schematic diagram illustrating an example of a preferred embodiment of an electrical interconnect status monitoring system and method utilizing a transmission line configuration for monitoring signals observed on the main line for detecting fault conditions; 
           [0025]      FIG. 6  is a simplified schematic diagram illustrating an example of a preferred embodiment of an electrical interconnect status monitoring system and method with an RF signal generator and RF detector for detecting fault conditions; 
           [0026]      FIG. 7  is a simplified schematic diagram illustrating an example of a preferred embodiment of an electrical interconnect status monitoring system and method with an RF signal generator external to the device load paired with an RF signal detector at the load for detecting fault conditions; and 
           [0027]      FIG. 8  is a simplified schematic diagram illustrating an example of a preferred embodiment of an electrical interconnect status monitoring system and method with a wire connected to the load through a switch to one side of a bridge diode placed between the inputs of the load for detecting fault conditions. 
       
    
    
       [0028]    References in the detailed description correspond to like references in the various drawings unless otherwise noted. Descriptive and directional terms used in the written description such as front, back, top, bottom, upper, side, et cetera, refer to the drawings themselves as laid out on the paper and not to physical limitations of the invention unless specifically noted. The drawings are not to scale, and some features of embodiments shown and discussed are simplified or amplified for illustrating principles and features, as well as anticipated and unanticipated advantages of the invention. 
       DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0029]    While the making and using of various exemplary embodiments of the invention are discussed herein, it should be appreciated that the present invention provides inventive concepts which can be embodied in a wide variety of specific contexts. It should be understood that the invention may be practiced with various electronic circuits, systems, system components, and subsystems without altering the principles of the invention. For purposes of clarity, detailed descriptions of functions, components, and systems familiar to those skilled in the applicable arts are not included. In general, the invention provides electrical connection status monitoring of multiple connections within an electrical system, providing capabilities for identifying and locating faulty connections. Preferably, the connection status monitoring may be performed with the system in a test mode, facilitating the making of repairs prior to full activation of the system. 
         [0030]    In one preferred embodiment, illustrated in  FIG. 1 , a smart connector  100  placed at the connection point between main lines  102  and device loads  104  includes one or more resistive elements  106 . Optionally, another resistive element  108  is placed between the two input wires of the load  104  for the purpose of detecting short and soft short conditions. In this preferred embodiment, the purpose of the resistors  106  is to provide isolation of the load  104  from the main line  102 . In case of a short in the load  104 , the resistors  106 , prevent the short from disturbing the main line  102 . This maintains functionality of the main line and any other loads also connected to it. During system query, a shorted load cannot respond, while a properly connected load can. This facilitates identifying the failure location. 
         [0031]    Now referring primarily to  FIG. 2 , in another preferred embodiment, a smart connector  200  includes an ASIC (Application Specific Integrated Circuit)  202  placed between the main lines  102  and device loads  104 . The purposes of the ASIC  202  is to detect, analyze and report fault conditions associated with the loads  104  or main line  102 . In the case of a short at a load, e.g.,  104 , higher currents are pulled from the main line  102 . The ASIC  202  then latches off and isolates the faulty load  104  from the main line  102 . The ASIC  202  also preferably includes a communication module that is used to report which load(s) are faulty once the faulty loads are identified and isolated. 
         [0032]    In another preferred embodiment, an example of which is illustrated in  FIG. 3 , an electrical interconnect system  300  using a transmission line configuration  302  includes multiple loads  104 A,  104 B,  104 C, etc., and preferably, multiple DC monitoring modules  304  for monitoring the lines  302  and detecting short and soft short conditions in the loads  104 A,  104 B,  104 C, as shown. The DC monitoring module  304 C, shown in the inset, preferably includes a diagnostic mode to disable all but one load, e.g.,  104 C. The enabled load  104 C monitoring module  304 C measures the signals at its inputs, thus determining the status of the connection from the main line  302  to the inputs of the load  104 C, and reports its status to the system master  306 . If a faulty condition exists, the device, e.g.  304 C, would either not communicate back to the master  306  or be disabled, thereby making it known to the master  306 , which load is faulty. Preferably, internal diagnostics  308 B at the load circuitry  304 C is used to detect and report the existence of soft short conditions where a voltage drop can be detected across the faulty load. Preferably, one or more diagnostic modes may be implemented in which selected loads may be placed in an autonomous mode in order to mimic isolation from the main line. This can preferably be achieved by utilizing an internal capacitor to supply the load circuitry operating in diagnostic mode, whereby power from the main line is not required for testing. 
         [0033]      FIG. 4  illustrates a transmission line configuration  400  for an electrical equipment system main line  402 , and AC checks  404 A,  404 B,  404 C . . . , monitoring signals for detecting short and soft short conditions in the loads. AC checks are used to monitor the status of an interconnect system relying on the AC characteristics of the main line and load lines. Preferably, a pulse or group of pulses of defined magnitude, width, and frequency are transmitted on the main line  402 . Each load monitor, e.g.,  404 C, measures the resulting signals at its respective inputs, and compares them to a set of fixed expected values, or configurable expected values, and reports back its status to the master  406 . If faulty, the monitoring devices would either not communicate back to the master or be disabled, thereby making it known to the master which loads are faulty. In preferred embodiments of an AC monitoring system, each load would alternatively, report back what it had measured for one or more of pulse width, magnitude, and frequency and allow the master to determine the status of the loads. In presently preferred embodiments, the use of pulse width evaluation is predominant. 
         [0034]    In an example of another preferred embodiment,  FIG. 5  illustrates a transmission line configuration  500  for an electrical equipment system, and transmission line monitoring signals observed on the main line that consist of transmitted as well as reflected waveforms for detecting short and soft short conditions in the loads. Using this approach, master circuitry  506  is used to directly monitor the reflections off the main line  502 . Preferably, a signal pulse such as a sine wave or single pulse is transmitted on the main line  502 . The reflected wave returning from the main line  502  is then sensed by the master  506 . The resulting reflected signal is a function of the integrity of the main line  502 . The signal characteristics and time delay of the reflected signal give indications of where faults in the line exist. Preferably in the transmission line approach, a termination impedance may be utilized both on the main line and load lines to optimize the line impedance. 
         [0035]    Now referring primarily to  FIG. 6 , an RF monitoring system  600  is illustrated that is capable of detecting short or soft short conditions. Preferably, each load to be monitored is equipped with a module  602  capable of generating an RF signal on the load terminals, and each load and monitoring device may be operated in a diagnostic mode. In the diagnostic mode, a monitoring device RF signal generator transmits one or more RF signals to a nearby RF detector. If a load has a fault such as a short or soft short, the RF detector in turn either receives no signal or a small signal relative to the expected signal for conditions wherein the load is without fault. This technique may also be used for detecting the existence of faults on the main line  604 . 
         [0036]    In another example of an alternative RF monitoring system  700  and method, as depicted in  FIG. 7 , an RF signal generator  702  is preferably located external to the loads, and an RF signal detector is located at the load(s) to be monitored. If a monitored load has a soft short or short, the detected RF signal at the load is small, or nonexistent, compared with expected normal signal levels when the circuit is without fault. The monitored load condition can then in turn be reported to indicate the status of particular loads. 
         [0037]      FIG. 8  illustrates a multi-wire monitoring system  800  and method for detecting short or soft short fault conditions. One or more wires  802  is deployed to connect to each of the monitored loads through a switch to one side of one or more bridge diodes  804  placed between the inputs of the load. If one or more faulty loads exists, the current in the additional wire(s) increases or decreases relative to the current in the main line(s)  806 , indicating the existence and location of the faulty loads. Preferably, in a multi-wire monitoring system as described above, each of the monitored load circuits may be independently placed in a quiescent diagnostic mode with no current load. In this mode, only one load circuit has the monitoring switch turned on at any given time. In the event that current is observed in the monitoring wire(s), the presence of a fault is indicated for that particular load. 
         [0038]    The methods and apparatus of the invention provide one or more advantages including but not limited to, electrical interconnect status monitoring efficiency, safety, convenience, and reduced cost. While the invention has been described with reference to certain illustrative embodiments, those described herein are not intended to be construed in a limiting sense. For example, variations or combinations of steps or materials in the embodiments shown and described may be used in particular cases without departure from the invention. Various modifications and combinations of the illustrative embodiments as well as other advantages and embodiments of the invention will be apparent to persons skilled in the arts upon reference to the drawings, description, and claims.