APPARATUS FOR TESTING WIRING

The present invention relates to apparatus for testing the safety of the electrical wiring, particularly within buildings.

Wiring regulations in various countries requires that the electrical wiring within buildings must be regularly checked to determine whether or not the wiring meets certain minimum standards of safety. In general, buildings that are open to members of the public and licensed for public assembly, either on a daily basis or for particular events only, are required by law to have their electrical wiring tested on a regular basis. It is also good practice in respect of other buildings for such testing to be carried out on a regular basis.

The regular testing of electrical wiring in buildings is therefore important not only to maintain and ensure the safety of those persons frequenting such buildings, but also in verifying that the subsequent installation or replacement of electrical components has been carried out properly, thereby helping to avoid or mitigate against installation of dangerous or faulty electrical components that may lead to failure of the wiring at a later date. Additionally, by providing the evidence that regular testing has taken place building owners can demonstrate that they have shown due diligence and have therefore complied with the law.

The three most commonly used tests test the insulation resistance of the wiring, the continuity of the wiring and the earth fault loop impedance. The insulation resistance test involves applying a test voltage to both the live and neutral conductors, the voltage being typically of the order of 500 to 1,000 V and measuring the leakage current through Ground, thereby deriving a value of the insulation resistance. The value of the insulation resistance provides an indication of the integrity of the wiring insulation. The earth fault loop impedance determines the current that could flow if a phase-to-earth fault occurs and as such determines compliance with the disconnection times for protective devices. Both the earth fault loop impedance test and the continuity test require, under conventional test procedures, for the point in each circuit furthest from the distribution board to be found and accessed, which in most instance is at best very laborious and time consuming and at worst

is extremely difficult due to physical access problems to ducted wiring and/or high level fittings. The conventional insulation resistance test is also time consuming since, individual fittings across which it is inadvisable to apply the test voltage must be physically isolated from the circuit being tested.

To reduce the problems associated with performing the above mentioned conventional tests, the present applicants have developed an apparatus for testing electrical wiring within buildings that includes an electrical device located at the end of each radial lighting or power circuit. The device is capable of altering an electrical circuit for testing, this being done in response to a signal sent to the device from a command console . The device is also arranged to restore the electrical circuit of the supply wires at the end of a test. This allows the electrical circuit to be automatically made ready for testing simply in response to an appropriate control signal from a command console, thus alleviating the electrician from the time consuming task of manually locating EOL (End of Line) positions and manually altering the various electrical circuits.

However, the electrician performing the various tests must still perform and record the results of the various tests on each of the circuits within the building wiring. Not only is the manual activation of each test tedious and time consuming, where the actual test results require manual transcription to a paper record or manual input to an electronic record of some description, the possibility for human error in that transcription or manual input is present. Furthermore, the manual transcription or recordal of the test results precludes the ability to conduct any analysis of the test results at the time of testing and in particular precludes the possibility of comparing the results of the current test with the results of previously conducted tests. The comparison of current test results with previously recorded test results is a useful tool in determining fault trends in the wiring system and also can be used to identify precursors of certain faults before the fault occurs.

The current applicants have thus developed a new test apparatus that substantially alleviates the disadvantages identified above.

According to a first aspect of the present invention there is provided a test system comprising a plurality of line modules, each line module being connected to a respective

electrical circuit comprising at least one electrical load, a command console and a test port, wherein the test port is arranged to be coupled between the command console and each line module and includes a memory module arranged to store data received from the command console.

Preferably, the test port is further arranged to transmit the stored data to the command console.

The stored data preferably comprises test result data associated with a most recently conducted test. Additionally, the stored data may further comprise test result data associated with a plurality of previously conducted tests. Additionally or alternatively, the stored data may comprise commissioning data associated with the electrical circuits coupled to the test port. This may include the layout information of each circuit, with information on the location of devices, equipment, wiring sizes, circuit lengths and routing or any combination thereof.

Additionally or alternatively, the test port may further comprise at least one auxiliary output device arranged to transmit the stored data to an auxiliary device. Preferably, the auxiliary output unit of the test interface may comprise one or more of a RS232 port, USB port, network port, wireless transceiver (including either radio or infrared transmissions) or a printer port.

Additionally, the command console may be arranged to provide control signals in accordance with a signalling protocol, such as DTMF or other suitable protocol. The control signals are provided via one or more conductors of the respective electrical circuits.

Additionally or alternatively, the command console of the test system may comprise at least one measurement unit, or meter, arranged to measure one or more parameters of the electrical circuits coupled to the test port and provide said test data.

Additionally or alternatively the command console may comprise a data processor arranged to perform one or more analysis routines on the test data provided by the measurement unit, or meter. In addition, the command console may be arranged to receive

stored test data from the test port and the data processor may be further arranged to perform one or more analysis routines on said stored test data.

In preferred embodiments of the present invention, the command console may be arranged to transmit the test data provided by the or each measurement unit to the test port.

Additionally or alternatively, the command console may comprise a display unit and is arranged to display a plurality of user prompts on the display unit.

According to a second aspect of the present invention there is provided a test port arranged to be connected between a plurality of line modules, each line module being connected to a respective electrical circuit comprising at least one electrical load, and a command console, wherein the test port comprises a memory module arranged to store data received from the command console.

According to a third aspect of the present invention there is provided a command console for use in combination with the test port, comprising a test unit arranged to remotely perform a plurality of tests on the electrical circuits connected to the test port.

An embodiment of the present invention will now be described by way of illustrative example only, with reference to the accompanying figures, of which:

Figure 1 schematically represents the test apparatus of the present invention in combination with a building wiring layout;

Figure 2 schematically illustrates a single spur circuit and a line module connected in accordance with an embodiment of the present invention;

Figure 3 schematically represents the arrangement of a test port according to an embodiment of the present invention; and

Figure 4 schematically represents the arrangement of a test port according to a further embodiment of the present invention.

Figure 1 schematically illustrates an embodiment of the present invention in combination with a typical building wiring installation. The building wiring installation comprises four individual radial circuits number 2. Each radial circuit comprises a number of individual electrical loads 4, which may for example be light fittings or power sockets. At one end of each of the radial circuits 2 a line module 6 is installed. Each line module may be fitted as an accessory during the fit out of a new building or during a refurbishment project, or fitted as an add-on retro fit component to an existing installation. The arrangement and operation of the line modules is described in more detail below. The opposite end of each radial circuit 2 is connected to a distribution board 8 within the building. The distribution board is arranged and constructed as is well known in the prior art, and therefore allows the radial circuits 2 to be individually isolated from the main incoming electricity supply to the building.

Connected to the distribution board 8 is a test port 10, which in various embodiments of the present invention may be integrated within the distribution board as a factory fitted accessory provided by the distribution board manufacturer, or may be fitted as a separate bolt-on retro fit component. The test port 10 provides the point of connection into the radial circuit 2 of the building wiring system. The arrangement and operation of the test port will be described in more detail below.

Also provided is a command console 12. The command console includes a display unit 14 on which the status and operation of the test system can be displayed. The display unit 14 may, for example, comprise an LCD panel or any other display device known to the person skilled in the art. Also included in the command console is a plurality of input buttons 16 that allow the operation of the test and command console to be controlled by the test electrician. Various output devices and interfaces may also be provided as part of the command console. For example, the command console 12 may optionally include a printing mechanism for providing the results of one or more of the conducted tests as a hard copy. The printer mechanism may include an output slot 18 as illustrated in Figure 1. Additionally or alternatively various output interface sockets 20, such as a USB socket or RS232 socket may be provided to allow the command console to be connected to one or more alternative input or output devices. In further embodiments, the output interface

sockets 20 may be replaced or supplemented by alternative communication means, such as infrared or wireless communication devices.

Figure 2 schematically illustrates the arrangement of a line module 6 within an embodiment of the present invention. The line module is shown as part of a radial circuit 2 comprising two individual loads 4. The circuit includes live, neutral and earth conductors connected at one end to the main distribution board 8 and connected at their opposite ends to the line module 6, with the individual loads 4 being appropriately connected in between. The line module comprises a control and communication unit 22 that controls the operation of two switches 24, 25 that are arranged to connect together the live and neutral conductors and the live and earth conductors respectively. The switches 24, 25 may comprise any appropriate switching devices, such as solenoids, conductors or power transistors. The purpose of the switch 24 is to allow the raised DC voltage, such as 1000V, to be applied to both the live and neutral conductors during an insulation resistance test. By connecting the live and neutral conductors together there is no need to physically disconnect the individual loads 4, since the potential difference between the live and neutral wires is the same and therefore is not actually placed across a load at any point. Similarly, switch 25 allows the earth fault loop impedance and continuity tests to be performed from the distribution board. The communication and control unit 22 of the line module 6 operates the switch 24 in response to receiving an appropriate control signal from the central command console 12 via the distribution board 8 and individual conductors, hi preferred embodiments of the present invention, the control signals are transmitted along one or more of the individual conductors using an appropriate communication protocol, such as dual tone signalling. Each end of line module has a unit ID/address so that individual modules can be controlled by the central command console 12. The individual addressability of each line module also allows some of the test to be automatically conducted under the control of the control command console, with a number of line modules, and hence their associated circuits, being addressed/tested sequentially. In preferred embodiments the communication protocol employed communicate with the line modules requires that the line modules acknowledge the receipt of any received signal, thus ensuring that signals are received. This hand shaking by the line modules is managed by the communication and control unit 22.

Figure 3 schematically illustrates the arrangement of a test port in accordance with embodiments of the present invention. The test port 10 enables the command console 12 to be connected to the fixed wiring circuits 2 under test. The test port 10 is connected to the incoming mains power supply represented in Figure 3 by the 3-core (Live, Neutral, Earth) cable 30, and also to the individual circuits 2, which in Figure 3 is represented by a single circuit 32 for the purpose of clarity, although it will be appreciated that in fact many such circuits will be connected to the test port in parallel. The incoming mains cable 30 and the connection to the building circuits 32 are terminated at a connection socket 34 to which a multi-core cable can be connected to provide a connection between the test port 10 and the command console 12 and thus carrying both power to the command console and control and test signals between the command console and the circuits 2 under test. Also provided in the test port is a memory module 36, which preferably comprises any known nonvolatile memory unit and associated read/write circuitry, although in other embodiments volatile memory maintained by means of an appropriate power supply and/or battery may be used. In the embodiment shown in Figure 3 a power supply unit 38 is provided to convert the incoming mains supply 30 to an appropriate voltage for the memory module 36, typically 5V DC. The memory module 36 is connected to a data socket 40 by means of a multi-core databus 42. This allows a data connection to be made via an appropriate data cable between the memory module 36 and the command console 12. This allows the results of one or more tests to be stored in the test port 10 and subsequently be accessed by a connected command console. In the embodiment shown in Figure 3, a further output port and/or device 44 is provided in connection with the memory module 36, thus allowing the contents of the memory module to be output other than via a connected command console 12. Examples of suitable output devices include a USB port, an RS 232 port or a wireless communication port.

In addition to the incoming power lines 30 and the connection to the circuits 32, in some embodiments further data/control cables may be connected to the connection socket 34, as shown in Figure 3 by control line 46. An example of the use such additional control lines is to bypass a residual current device (RCD) connected to one of the radial circuits 2 to be tested. The RCD may be bypassed by the use of a solenoid, or other appropriate switching device, enabled by a control signal received via the additional control line 46. The bypassing of the RCD is desired to prevent the RCD from tripping during an earth fault

loop test and to allow the earth fault loop test to be performed without limiting the leakage current to below that at which the RCD would trip, such a limited leakage current not providing an adequately robust test.

The command console 12, as shown in Figure 1, preferably comprises an integrated microprocessor controlled testing unit that has all the functionality of a dedicated digital multi-meter. The test unit is further arranged to control the operation of the other components of the central command console, such as an input keyboard 16, display 14, output devices 18 and communication ports 20, together with the communication between the central command console and the test port 10. In alternative embodiments of the present invention, the actual test instruments required to conduct the desired tests and measure the results may be provided separately, in which case the command console 12 is arranged to be in communication with such test instruments and, where appropriate, control their operation. In further embodiments of the present invention the command console also includes a switch arranged to connect together the live and neutral conductors via the connection between the command console and the test port. The switch (not illustrated) may comprise any appropriate switching device. The switch is arranged to be activated when the insulation test is being performed and it's purpose is twofold. Firstly, it ensures that no test voltages are mistakenly applied to sensitive electronic components that are still connected to live and neutral. Secondly, in the example of lighting circuits, the light switches themselves break the live conductor of the circuit being tested. By bridging the live and neutral conductors at both the line modules and the command console it is ensured that the maximum amount of wiring is included in the insulation test.

In operation a test engineer will be provided with a portable command console 12. On arrival at a building to conduct scheduled testing of the building circuits the test engineer will connect the command console to the test port provided in conjunction with the distribution board of the building's electrical system, having first isolated the distribution board from the incoming main power supply. As noted previously, this connection may be made using individual data and power cables or by other means, such as wireless communication, thus powering up the command console. If the building circuits have not been tested previously, it will be necessary for the test engineer to input various commissioning data into the test system via the input device 16 provided on the command

console. As noted previously input device 16 may be a dedicated keyboard, or may alternatively be provided by a touch sensitive functionality of the display screen 14. The commissioning data includes the number of individual radial circuits within the building's wiring system the number of devices included within each radial circuit, the type and nature of those devices and other such relevant information. This allows the command console to create a logical mapping between itself and the electrical system of the building under test, such that, for example, each end of line module 6 can be individually addressed by the command console. This commissioning data is subsequently stored in the memory module of the test port such that on subsequent visits to the building this commissioning data can be retrieved from the test port and uploaded to the command console to allow testing to proceed without undue delay.

The desired tests are then performed by the test engineer, who is guided through the appropriate sequence of steps, including preliminary safety checks and safeguards, by means of the display screen 14 of the command console, the operation of the command console being controlled by the microprocessor based test unit. In preferred embodiments the command console is arranged to display one or more help, or 'tutorial', pages by means of the display screen 14 so as to assist the test engineer in performing the tests. Preferably the menu options and/or the tutorial pages displayed or made available will be controlled by the command console in response to either the arrangement of the circuit or circuits under test, as detailed by the stored commissioning data, and/or the results of previously performed tests. Full flexibility of operation is afforded to the test engineer, such that the results of all the tests may be displayed via the display screen as required, or alternatively the test may be conducted automatically under the operation of the microprocessor controlled test unit and the test engineer simply notified when the test is complete, or when an anomalous test result is obtained. In the case that the testing is performed automatically the command console is preferably arranged to perform the desired tests on each circuit to be tested in a sequential manner, the order of the tests preferably being programmable in advance or alternatively following a default order. In other words the command console is arranged to automatically scroll through the circuits to be tested at high speed (relative to manual testing), performing the desired tests on each circuit in turn. In this mode of operation the command console is preferably arranged to commence the testing sequence as soon as it has detected that all the test circuits are in a condition fit for testing, the

detection being accomplished by means of appropriate communication between the command console and each appropriate line module. To enable anomalous results to be identified it is preferred that a data set specifying acceptable test result data for each circuit is stored in the test port memory at the time of commissioning. In preferred embodiments in which the integrated test unit also comprises the appropriate test instruments, there is no need for the test engineer to manually input individual test results obtained, since those results may be directly communicated from the integrated test instruments. In other embodiments in which the test instruments are provided separately in the communication with the command console, it may be necessary for the test engineer to manually input the results via the keyboard 16, although this depends on the functionality of the separately provided test instruments and whether or not they are capable of communicating the test results obtained to the command console without the test engineer's intervention.

The test results are communicated from the command console to the test port and are stored in the memory module 34 of the test port. The storage of test results in the test port allows the test results to be subsequently uploaded to a connected command console at a later point of time such that the command console can perform analysis and comparison of the most recently obtained test results with corresponding test results obtained previously. This allows analysis of fault trends, which can be used to diagnose likely future faults before their actual occurrence. For example, the gradual deterioration in the results for the insulation resistance test for a particular circuit over the period of a number of separate tests may provide an indication of deteriorating insulation and prompt the replacement of that insulation before actual breakdown, and result in damage occurs.

The addition of any test leads to a circuit to be tested changes the circuit's impedance, thus potentially altering the results of most tests. To avoid this problem many prior art test meters include a "zeroing" function, whereby the ends of the test leads are manually shorted together and their impedance measured. The test meter subsequently automatically deducts this impedance value from the test readings, thus providing a true reading for the circuit under test. In the test system of the present invention, in addition to the conventional test leads, further wiring has been included in the form of the multicore cable connecting the command console and test port and this further wiring, which is integral to the test system, has its own impedance that adds to the impedance of the engineer's test

leads. Therefore, to allow accurate zeroing to be performed in preferred embodiments of the present invention an equivalent impedance (not shown) is provided within the command console that can be selectively (in response to a zero function of the command console) introduced across the terminals used to connect the test meter test leads, the equivalent impedance being equal in value to the system wiring and components of the test system. The impedance of the actual test leads and the equivalent impedance can then be measured together in the conventional manner to perform the necessary 'zeroing' function.

Figure 4 schematically illustrates a test port according to an embodiment of the present invention in which power consumption at the distribution board of the electrical system can be measured and preferably controlled. The test port 10 shown in Figure 4 shares many elements in common with the embodiment shown in Figure 3 and those common elements are numbered the same in Figure 4. In addition a power unit 50 for measuring the voltage applied to each radial circuit 32 and current being drawn are included within the test port 10. Appropriate measuring sensors 52 are connected to each electrical circuit that it is desired to monitor and these provide data on the voltage and current to the power unit 50, thus enabling the power consumption of that circuit to be monitored. In preferred embodiments the power unit 50 is further connected to the output port 44, thus enabling the power consumption data to be extracted from the power unit 50. It will be appreciated that depending on the nature of the output port 44 the power consumption data may be output on a continual basis, periodically, or only when interrogated by an external device. In those embodiments in which the output port 44 comprises a wireless transceiver, remote monitoring of the power consumption is possible. In alternative embodiments (not illustrated) the power unit 50 may comprise its own dedicated output port. Furthermore, to facilitate the periodic retrieval of the power consumption data the power unit 50 may include a memory device (not illustrated) in which collected data is stored.

The power unit 50 may also comprise switching means 54 arranged to allow one or more electrical loads connected to the electrical circuit 32 being monitored to be turned off in response to a control signal generated by the power unit 50. In preferred embodiments the control signal will address the line model associated with the respective load to be turned off. The control signal may be generated either in response to the power consumption exceeding predefined parameters stored and monitored by the power unit 50 (by means of

appropriate microprocessor control) or in response to a further control signal remotely generated and transmitted to the power unit 50 via the output port 44. Consequently, the energy consumption of devices connected to the test port can be monitored and preferably controlled remotely of the devices.

The integration of the dedicated test unit to the command console, in conjunction with the acquired commissioning data, allows the command console to automatically conduct a sequence of tests on a number of different circuits without intervention of the test engineer. This can significantly reduce the time taken to conduct the tests, and since the tedious and repetitive tasks are no longer required of the test engineer there is a significantly reduced risk of human error being introduced either the test procedure or in the recordal of the test results. Additionally, since the command console has the capability of being in communication with individual circuit elements, such as the end of line units, via the test port and the applied communication protocol transmitted through the conductors of the individual circuits, certain safeguards can be automatically enforced in the test procedures. For example, certain of the required tests can only be performed on a single radial circuit at any one time, thus requiring the remaining circuits to be physically isolated by means of their associated circuit breakers on the distribution board. Since this command console is capable of communicating with each of the end of line units via the test port and distribution board, it can issue a polling signal before commencing other test to ascertain which end of line units are in communication with the command console. If more than one end of line unit responds to the polling signal, it is an indication that more than one circuit is still connected to the distribution board and the command console may be arranged to inhibit the further operation of the test apparatus and to provide a visible or audible warning to the test engineer by providing test apparatus including a memory module of the present invention allows the storage of previous test results or subsequent retrieval and analysis, either by subsequent test unit or by provision to a remote analysis device. Additionally, the integration of the dedicated test unit within the command console allows a significant proportion of the testing operations to be automated, thus improving both the accuracy of the test procedures and significantly reducing the time taken to complete them.