Abstract:
An interface apparatus is disclosed for interfacing a testing device to a plurality of safety switches at a switch location, wherein each safety switch is connected to an electrical load circuit including at least an active line and a neutral return line. The interface apparatus comprises a plurality of actuating devices each being connectable to a respective safety switch, and a controller for controlling each actuating device to selectively connect the associated safety switch to the testing device. Each safety switch may include an RCD or RCCB device. A method of interfacing a testing device to a plurality of safety switches is also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national phase entry under 35 U.S.C. §371 of International Patent Application PCT/AU2013/001179, filed Oct. 10, 2013, designating the United States of America and published in English as International Patent Publication WO 2014/056042 A1 on Apr. 17, 2014, which claims the benefit under Article 8 of the Patent Cooperation Treaty to Australian Application Serial No. 2012904478, filed Oct. 12, 2012, the disclosure of each of which is hereby incorporated herein in its entirety by this reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates broadly to safety devices known as residual current devices (RCDs) or residual current circuit breakers (RCCBs) and in particular relates to an interface apparatus for interfacing a testing device to a plurality of safety switches or circuit breakers. 
       BACKGROUND 
       [0003]    An RCD or RCCB is a device that disconnects an associated load circuit whenever it detects that an electric current is leaking out of the circuit, such as current leaking to earth through a ground fault. Such devices are intended to operate quickly so that when a person contacts a live conductor, the circuit is isolated before electric shock can drive the heart into ventricular fibrillation, which may cause death in some circumstances. Most RCD/RCCB devices are designed to trip when a leakage current that exceeds a threshold such as 30 mA (milliamps) is detected. 
         [0004]    Because RCD/RCCB devices are important in saving people&#39;s lives, their integrity is required to be tested on a regular basis. Although RCD devices have built-in testing circuits these generally require a user to push and hold a button on the RCD device which bleeds off approximately 200% of rated leakage current over a period of time that the button is pressed or until the associated circuit is tripped by simulating a current leaking to earth. This may indicate that the RCD trips but it may not trip at the rated leakage current thereby placing lives at risk. 
         [0005]    In Australia, RCD device manufacturers typically require that a “push-button” test be performed monthly in the case of fixed equipment, or in the case of portable equipment, each time that the equipment is used. This may be a time-consuming process which can cause significant inconvenience to commercial premises or households. 
         [0006]    Australian Occupational Health and Safety (OH&amp;S) Regulations recommend that a “push-button” test be performed every 6 months. Recommendations and regulations may differ in other jurisdictions around the world. 
         [0007]    Applicants have identified the time-consuming nature of RCD/RCCB device field testing and the expense and personal risk of an electrician testing at a live open switchboard as significant factors contributing to the inconvenience and risk involved in testing of RCD/RCCB devices. 
         [0008]    The present invention may at least alleviate the aforementioned disadvantages by providing a quicker, more convenient and safer alternative to traditional testing of RCD/RCCB devices. 
         [0009]    A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge in Australia or elsewhere as at the priority date of any of the disclosure or claims herein. Such discussion of prior art in this specification is included to explain the context of the present invention in terms of the inventor&#39;s knowledge and experience. 
         [0010]    Throughout the description and claims of this specification the words “comprise” or “include” and variations of those words, such as “comprises,” “includes” and “comprising” or “including,” are not intended to exclude other additives, components, integers or steps. 
       BRIEF SUMMARY 
       [0011]    According to one aspect of the present invention there is provided an interface apparatus for interfacing a testing device to a plurality of safety switches at a switch location, wherein each safety switch is connected to an electrical load circuit including at least an active line and a neutral return line, the interface apparatus comprising:
       a plurality of actuating devices each being connectable to a respective safety switch; and   a controller for controlling each actuating device to selectively connect the associated safety switch to the testing device.       
 
         [0014]    Each safety switch may include an RCD or RCCB device or other safety switch or Ground Fault Interrupter device. Each actuating device may include a controllable relay for selectively connecting the associated safety switch to the testing device. The controller may include a microprocessor or microcontroller. 
         [0015]    The interface apparatus may include a line monitoring circuit for detecting an active line associated with a safety switch. The line monitoring circuit may be associated with the controller to prevent a safety switch from being connected to the testing device until the safety switch is clear of active line voltage. 
         [0016]    The testing device may be adapted to measure and/or record a trip time and/or a trip current associated with a safety switch. The testing device may include a manual or an automatic device. The switch location may include a mains switchboard or the like. In some embodiments the interface apparatus may include means for interfacing to another like interface apparatus. 
         [0017]    The testing device may be adapted to communicate with a digital computer such as a portable PC or tablet computer. The digital computer may include computer software including a control application for controlling the interface apparatus. 
         [0018]    The digital computer and control application may communicate with the interface apparatus to select a particular RCD or RCCB device to allow it to be tested. The apparatus may include a facility to record the results of a test. 
         [0019]    According to a further aspect of the present invention, there is provided a method of interfacing a testing device to a plurality of safety switches at a switch location, wherein each safety switch is connected to an electrical load circuit including at least an active line and a neutral return line, the method comprising:
       providing a plurality of actuating devices each being connectable to a respective safety switch; and   controlling each actuating device to selectively connect the associated safety switch to the testing device.       
 
         [0022]    The present invention may also provide a method of testing a safety switch such as an RCD or RCCB device including a method of interfacing a testing device to one or more safety switches as described herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Preferred embodiments of the present invention will now be described with reference to the accompanying drawings wherein: 
           [0024]      FIG. 1  shows a safety switch being tested at a switchboard in accordance with an embodiment of the present invention; 
           [0025]      FIG. 2  shows testing apparatus connected to RCD devices in accordance with an embodiment of the present invention; 
           [0026]      FIG. 3  shows a block diagram of one form of interface apparatus according to the present invention; 
           [0027]      FIG. 4  shows a flow chart of associated software; and 
           [0028]      FIGS. 5 through 8  show block diagrams of various testing protocols including interface apparatus, according to the present invention 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    The following detailed description of a preferred embodiment of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible and changes may be made to described embodiments without departing from the spirit and scope of the invention. 
         [0030]      FIG. 1  shows RCD device  15  associated with switchboard  10  being tested by a technician  11 . Switchboard  10  includes pre-installed testing module  12  and one or more pre-installed interface modules  13  in accordance with the present invention. Testing module  12  and interface modules  13  interact with RCD devices installed to switchboard  10  to allow each RCD device to be tested via testing module  12 . A testing sequence may be initiated via handheld tablet computer  14  with control software, which communicates with testing module  12  via a wireless link such as Wi-Fi LAN or Bluetooth. In some embodiments the wireless communications link may be replaced with a communications cable which may include a serial, LAN or other standard interface. 
         [0031]      FIG. 2  is a diagram showing a plurality of RCD devices  21 - 28  installed to switchboard  10  and connected to interface module  13  via conducting lines  29 . Testing module  12  and interface module  13  may include a configurable printed circuit board (PCB) populated with actuating devices/relays, solid state devices and/or other controllable devices. Testing module  12  is connected to interface module  13  via a communication cable  16 . Testing module  12  is powered from local circuit protection device  20 , as well as earth wire E and neutral wire N associated with switchboard  10 . Interface module  13  is adapted via communications from testing module  12  to select each RCD device ( 21 - 28 ) in turn for testing under control of tablet computer  14 . 
         [0032]    Because each RCD device ( 21 - 28 ) is connectable to testing module  12  via interface module  13  at switchboard  10 , the requirement for a technician to perform local testing or time-consuming field testing may be avoided. Once tested, the associated load circuits may be immediately reset and returned to service thereby minimizing down time and/or a requirement for testing after hours. 
         [0033]      FIG. 3  shows a block diagram of one form of interface apparatus, according to the present invention, connected at switchboard  10  to a plurality of RCD devices  20 - 43 . RCD devices  20 - 43  are installed at switchboard  10  between 3 phase active lines A 1 -A 3  and respective loads circuits (not shown). The interface module  12  communicates with testing module  13  via communications cable  16 . Testing module  13  is connected to digital (tablet) computer  14  via wireless communications with control software for controlling interface module  12 . In some embodiments testing module  13  may include a stand-alone testing device with inbuilt intelligence. 
         [0034]    Interface module  12  includes  24  controllable actuating devices  44 - 67  each comprising a relay. In some embodiments actuating devices  44 - 67  may comprise solid state devices such as transistors. Interface module  12  also includes line test circuit  68 , power enable circuit  69 , driver modules  70 - 73 , microprocessor unit  74  and communications bus  75 . 
         [0035]    Microprocessor unit  74  is adapted to perform data storage, monitoring and control functions. Relays  44 - 67  are adapted to connect RCD devices  20 - 43 , respectively, to testing module  13  when actuated under control of testing module  13  and microprocessor  74 . 
         [0036]    Line test circuit  68  ensures that status of line  77  is known prior to activating a relay ( 44 - 67 ) associated with RCD devices  20 - 43 . Line test circuit  68  may detect status of line  77  regardless of which relay ( 44 - 67 ) or which interface module  12  (assuming that multiple interface modules are used) is supplying line voltage. Power enable circuit  69  prevents a relay channel associated with relays  44 - 67  from being activated without the control software first enabling interface module  12 . 
         [0037]    Microprocessor unit  74  associated with interface module  12  and/or microprocessor unit  76  associated with testing module  13  may be programmed with data identifying each relay channel ( 44 - 67 ) and its association with a specific RCD device ( 20 - 43 ). This data may be required because typically RCD devices may not occupy an entire switchboard and some RCD devices may be added at a later time. 
         [0038]    Microprocessor unit  74  communicates with testing module  13  via communications bus  75  and cable  16 . Testing module  13  may facilitate selection of each RCD device ( 20 - 43 ) to be tested in turn, reset and the results recorded in a database. A relay channel may not be activated until a line test has been performed ensuring that status of line  77  is not already active due to it not being turned off under a fault condition. 
         [0039]    Interface module  12  may be connected in daisy chain fashion to one or more like interface modules  12 A and  12 B, etc. Multiple interface modules  12 ,  12 A,  12 B etc., may be installed in a networked configuration facilitating extension of switchboard capacities beyond that of an individual interface module  12  ( 24  in the example given in  FIG. 3 ). 
         [0040]    Digital computer  14  may include software having a control application which may initiate a test sequence and automatically record the results, as distinct to a manual test sequence. The results may be transmitted via a communications network such as the internet to a remote database facility allowing for detailed reports to be compiled about RCD devices. In some embodiments digital computer  14  or at least some of its functions may be integrated with interface module  12  and/or testing module  13 . 
         [0041]      FIG. 4  shows a flow chart for an associated software application. The software application includes device selection step  80  during which an operator selects an RCD device (from devices  20 - 43 , for example) to be tested. Step  81  is a relay power enable step during which power to coils of relays  44 - 67  is enabled via power enable circuit  69 . 
         [0042]    Step  82  is test line voltage step during which line test circuit  77  samples the voltage on line  68 . If no voltage is detected at step  83  the selected relay ( 44 - 67 ) is activated at step  84  via a corresponding driver ( 70 - 73 ). At this stage active voltage should be present on line  68  and this is confirmed at step  85 . If active voltage is present at step  85  test module  13  trips the selected RCD device ( 20 - 43 ) at step  86 , which corresponds to the selected relay ( 44 - 67 ) and the result is recorded in a data base. At this stage active voltage should not be present on line  68  and this is confirmed at step  87 . If no active voltage is present at line  68  power to relays  44 - 67  is disabled at step  88  and the software loops back to step  80 . 
         [0043]    If active voltage is detected at step  83 , power to relays  44 - 67  is disabled at step  83 A, status message is displayed at step  83 B and the software loops back to step  80 . If no active voltage is detected at step  85 , power to relays  44 - 67  is disabled at step  85 A, status message is displayed at step  85 B and the software loops back to step  80 . If active voltage is detected at step  87 , power to relays  44 - 67  is disabled at step  87 A, status message is displayed at step  87 B and the software loops back to step  80 . 
         [0044]      FIG. 5  is a block diagram showing multiple interface modules (relay units)  90 ,  91  communicating via a communication link  92  and adapted to interface with a plurality of RCD devices at a switchboard or the like (not shown). Each interface module  90 ,  91  may include an interface such as interface module  13  and communicates with testing device  93  via communication link  94 . Testing device  93  includes a battery power supply and smart selection of RCD devices for testing. Once tested, the associated load circuit may be immediately reset minimizing down time. 
         [0045]      FIG. 6  is a block diagram showing multiple interface modules (relay units)  100 ,  101  communicating via communication link  102  and adapted to interface with a plurality of RCD devices at a switchboard or the like (not shown). Each interface module  100 ,  101  may include an interface such as interface module  13  and communicates with testing device  103  via communication link  104 . Testing device  103  includes a battery power supply and communicates with digital computer  105  via communication link  106 . Digital computer  105  includes control software to facilitate smart or automatic selection of RCD devices for testing. Once tested, the associated load circuit may be immediately reset minimizing down time. 
         [0046]      FIG. 7  is a block diagram showing multiple interface modules (relay units)  120 ,  121  communicating via communication link  122  and adapted to interface with a plurality of RCD devices at a switchboard or the like (not shown). Each interface module  120 ,  121  may include an interface such as interface module  13  and communicates with testing device  123  via communication link  124 . Testing device  123  includes a battery power supply and communicates with digital computer  125  via communication link  126 . Digital computer  125  includes control software incorporating advanced data gathering to facilitate smart or automatic selection of RCD devices for testing. Once tested, an associated load circuit may be immediately reset minimizing down time. 
         [0047]      FIG. 8  is a block diagram showing multiple interface modules (relay units)  131 ,  133  communicating via communication link  132  and adapted to interface with a plurality of RCD devices at a switchboard or the like (not shown). Each interface module  131 ,  133  communicates with testing module  135  via communication link  134 . Testing module  135  communicates with digital computer  137  via wireless communication link  136 . Digital computer  137  includes control software incorporating advanced data gathering to facilitate smart or automatic selection of RCD devices for testing and data reporting. Once tested, the associated load circuit may be immediately reset minimizing down time. 
         [0048]    Each testing device/module  13 ,  93 ,  103 ,  123 ,  135  may include trip test equipment developed by the present applicant, although the interface apparatus of the present invention may also be used with test equipment that meets required specifications and functionality produced by other manufacturers. Furthermore, although not shown, trip test equipment which includes analogue and digital displays, etc., may be incorporated into a bypass device to form a single unit which an operator can simply carry around from job to job. 
         [0049]    Thus, it may be apparent that the present invention may provide for testing of RCD/RCCB devices without time-consuming field testing or the need for a technician or electrician. In this particular case, the means of selecting the protection device to be tested may be performed via control software interfaced to the appropriate relay board or boards. The apparatus may facilitate selective testing of devices and recording of results. Results may be made available either locally or remotely via an internet reporting site/facility. 
         [0050]    Finally, it is to be understood that various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or ambit of the invention.