Abstract:
Disclosed are advances in the arts with novel methods and apparatus for detecting faulty connections in an electrical system. Exemplary preferred embodiments include 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. 61/434,696 filed on Jan. 20, 2011, 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. In preferred embodiments, the invention relates to the more efficient utilization of energy resources. 
       BACKGROUND OF THE INVENTION 
       [0003]    For various power systems, the power source may be limited in the amount of current that can be supplied to the system. As such, if a short or soft-short occurs, the loading on the power supply line increases, which will then reduce the voltage on the line and disabling all the circuitry that is to be powered on the line. 
         [0004]    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. 
         [0005]    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 line 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 
       [0006]    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 transmission line monitoring system. Examples of various preferred embodiments of such monitoring systems are described. 
         [0007]    According to one aspect of the invention, an example of a preferred embodiment of a method for monitoring the status of an electrical line includes a step for monitoring current between a source and a load. Detection of a current level above a first threshold indicates the existence and location of a fault and results in the disconnection of the load from the power source. In a further step, absent a current level above the first threshold, power is provided to the load and current is monitored. In the event a current level above a second threshold is detected, the load is disconnected and the existence and location of a fault is indicated. 
         [0008]    According to another aspect of the invention, a preferred embodiment of the electrical line status monitoring method includes steps as summarized above, modified to perform the same functions by monitoring voltage instead of current. 
         [0009]    According to an aspect of the invention, in an exemplary embodiment the electrical line status monitoring method further includes steps for monitoring one or more local parameters at the location of a load. 
         [0010]    According to one aspect of the invention, an example of a preferred embodiment of a system for monitoring the status of an electrical line includes circuitry configured to monitor current or voltage levels between a power source and a load. Switches are provided for causing the load to be disconnected from the source upon detection of a level above a first threshold, indicating the existence and location of a fault. In the absence of a current or voltage level above the selected threshold, the switches enable power to be provided to the load. The circuit is equipped to continue to monitor current or voltage between the source and load, and upon detection of a voltage level above a second threshold, to activate a switch to disconnect the load from the power supply, indicating the existence and location of a fault. 
         [0011]    According to another aspect of the invention, in an exemplary embodiment the electrical line status monitoring system further includes one or more sensors for monitoring one or more local parameters at the location of a load. 
         [0012]    According to another aspect of the invention, in an exemplary embodiment the electrical line status monitoring system is preferably implemented as an application-specific integrated circuit (ASIC). 
         [0013]    The invention has advantages including but not limited to providing one or more of the following features; improved efficiency, 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 host 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 
         [0014]    The present invention will be more clearly understood from consideration of the following detailed description and drawings in which: 
           [0015]      FIG. 1  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 monitoring the status of the line; 
           [0016]      FIG. 2  is a simplified schematic diagram depicting an example of a preferred embodiment of an electrical interconnect status monitoring system and method; and 
           [0017]      FIG. 3  is a simplified schematic diagram showing an example of a preferred embodiment of an electrical interconnect status monitoring system and method deployed in association with a system array of monitored loads. 
       
    
    
       [0018]    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 advantages of the invention. 
       DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0019]    The present patent application is related to U.S. patent application Ser. No. 12/710,307 which shares at least one common inventor with the present application and has a common assignee. Said related application is hereby incorporated herein for all purposes by this reference. 
         [0020]    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, host systems, 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 connections within an associated host 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 host system. 
         [0021]    Referring primarily to  FIG. 1 , an electrical line status monitoring system  100  is shown. This system  100  provides a connection between the power line  102  of associated electronics and an electrical load  104 . In this particular application, the electronic load  104  may preferably be held in reset during initial power sequencing. For other applications, an alternative current limit or voltage detection may be used to detect a short or soft short as further described herein. For this exemplary system  100 , the sequence of operation is preferably as follows. Upon power up, a short detection application-specific integrated circuit (ASIC)  202  monitors the supply current going to the electronic load  104  via the main line  102 . This electronic load  104  remains in a low power state. The short detection ASIC  202  then measures the current supplied to the electronic load  104 . Placed between the main lines  102  and device loads  104 , the purpose 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 and/or voltages are drawn 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 functionality that is used to report when a fault is identified and isolated. In this example, if the current detected at the load  104  is larger than a selected threshold level, e.g., 2 mA, then a soft-short is suspected, assuming 28V across the main line wires  102  and a 10 kOhm short. The values herein are given by way of example representative of an implementation of the practice of the invention. The threshold value of the soft short current can be tailored to each system, and be higher or lower than this example. 
         [0022]    Now also referring to  FIG. 2 , preferably switches  204  are provided in the short detection ASIC  202 . Upon detection of a short condition, the switches  204  are caused to open, disconnecting the electronic load  104  from the power VIN 1 , VIN 2  ( 102  in  FIG. 1 ). In this scenario, when the system is activated upon powering up a host system, the faulty electronic load  104  is prevented from being able to power up, and hence no communication would be possible to this electronic load  104 , giving indication which load, potentially among numerous loads in a larger system, has a short or soft-short. In the event no soft-short is detected, then the short detection ASIC&#39;s  202  switches  204  remain “on”, and permit the electronic load  104  to be powered in a fully operational state. Preferably, after the lapse of a selected interval of time, the short detection ASIC  202  then switches over to a higher current detection state, for example, greater than 50 mA, although any level may be chosen that is higher than the selected soft-short detection threshold. In this higher current detection state, the short detection ASIC  202  monitors the current supplied to the electronic load  104 . If a current condition higher than the selected threshold is detected, then the switches  204  in the soft-short detection ASIC  202  are opened, and communication and power to the electronic load  104  is interrupted. A query of each electronic load in a larger system then indicates which load location, if any, e.g.,  104 , has not communicated, which pinpoints the location of the failure. 
         [0023]    Instead of or in addition to monitoring current, the short detection ASIC  202  may also be adapted to monitor voltage in a similar manner in order to detect shorts by measuring the voltage difference on the VOUT 1  and VOUT 2  outputs. In the event the voltage difference is below a selected threshold, this indicates a fault condition and the ASIC  202  switches  204  open in the manner described above. Similarly, a comparison may also be made between the voltages on the input VIN nodes and the VOUT nodes. These voltages may be compared single-ended (as an example, VIN 1  compared with VOUT 1 ), or differentially to determine whether the difference is significant in comparison to a selected threshold, indicating the existence of a fault. The short detection ASIC  202  may also monitor power to detect the short by measuring voltage or current supplied to the load  104 . In the event the power level is too high in comparison with an acceptable threshold, then this indicates a fault condition and the switches  204  open. 
         [0024]    Once a fault is detected, the ASIC  202  may also indicate the fault condition by providing an electronic alert such as an audio tone and/or visual display. This is illustrated in  FIG. 2  by showing an LED representative of a visual display, although various alternative visual, audio, haptic, or other alerts or displays may instead or also be used without departure from the invention. 
         [0025]    The electrical interconnect status monitoring system  100  may be deployed for a single electronic load, e.g., load  104  in  FIG. 1 , or for a group of electronic loads, or in combinations with various network configurations such as a branched network system  300  as shown in the example of  FIG. 3 . The electrical interconnect status monitoring system  302  may include individual ASICs  202  for numerous loads as well as ASICs  304  situated for serving as junction connectors when more than one electronic loads are connected in a larger system  300 . The fault detection threshold for these junction connectors  304  may be the same as other short detection ASICs  202  deployed in the system  300  or may be identical or unique, and may be configurable either in the field and/or during system manufacturing. 
         [0026]    A host system may be monitored using the ASIC  202  to perform impedance measurements at the outputs of the system (e.g.,  300 ) over various voltages. It should be noted that soft-short conditions may not be linear and may change significantly with voltage. In alternative embodiments of electrical interconnect status monitoring systems, either comparators may be used to measure selected voltage levels or a signal conditioning interface with a look-up table may be used to store data and flag potential system problems. This information may then be transmitted to an operator, and/or to additional control apparatus deployed with the electrical interconnect status monitoring system, using suitable wired or wireless communication circuitry. A digital and/or analog protocol may be provided to the ASIC  202  and be adapted for dynamically adjusting a variety of parameters which may include, but are not necessarily limited to current limit level, impedance evaluation over voltage potential, communication validation of a host system, and other various safety and hardware functions. The ASIC  202  may be configured to detect temperature, humidity levels, alkalinity/acidity, or other local conditions in the operating environment. Monitored data relating to these conditions can then be sent back to an operator, control equipment, or other recipient. 
         [0027]    The ASIC  202  and electrical line status monitoring system  100  and methods can be used in association with a host system in a variety of ways. Star configurations, multi-star configurations, multiple series configurations, ring configurations, grid configurations, parallel configurations, and figurations having an electrical interconnect status monitoring system as a central control unit may be employed, as well as other network configuration schemes. Deploying multiple ASIC  202  and electrical line status monitoring systems  100  and suitable control units in combination with series, parallel, star, ring, grid, or other network schemes is also possible within the scope of the invention. 
         [0028]    The threshold levels for monitored parameters may be preselected and/or reprogrammed in the ASIC  202  and electrical line status monitoring system  100  depending upon application specific requirements. Time intervals may also be adjusted either longer or short for soft-short/short circuit detection times. This attribute can preferably be programmed either in the field or at the factory through on-chip memory, external components, pin configurations, and other circuit configuration techniques. Time duration can also be used in conjunction with other events, such as the detection of communication pulse down the line, voltage or current levels, temperature, or other types of events. 
         [0029]    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.