Related Applications

This application claims priority from Australian provisional patent no. 2013901231 filed in 10 April 2013, the contents of which are incorporated herein by reference.

Technical Field

[001] The invention relates to a flag relay system, a flag relay device and an associated method of operating a flag relay system and device.

Background

[002] A standard relay typically includes a magnetic coil and a set of switching contacts. When the coil is energised the contacts switch to a switched state and when the coil is de-energised the contacts revert hack.

[003] Similarly to a standard relay, a latching relay will switch between contacts to a switched state when the coil is energised. However, unlike a standard relay, a latching relay will remain in the switched state or "latched" until the latching relay is reset. The reset may be undertaken by another coil or manually by an operator. The reason for using a latching relay is that the latching relay will remain in the switched state indefinitely, even in the event of a power failure.

[004] Electrical protection systems used in switchyards, substations and switching stations often have several electrical protection devices protecting each circuit, these devices may include a number of trip relay devices including over current (overload), short circuit, earth fault (earth leakage), temperature, pressure and transformer trip relays. [005] The protection devices are generally powered up from a reliable control power supply such as a battery bank. If a major fault occurs and/or the power is lost upstream (towards the point of supply) the batteries can keep the protection devices and indication lamps powered up until power is restored.

[006] However, in some circumstances, the protection device is placed remote locations where it may not be able to be accessed quickly and there is the risk of the batteries not providing enough charge to keep the control system powered up until tin operator arrives. Furthermore, in underground coal mining, batteries and other electrical stored energy are generally not allowed and as such power to the protection devices cannot be guaranteed. Tn these circumstances, latching relays may be used as latching relays maintain a switched state even in the even of power failure.

[007] In addition, electrical protection systems often contain a number of latching relays in circuit with the protection devices. Each latching relay includes a flag to display the state of the relay. Accordingly, latching relays are put into the protection systems to signal which protection device has tripped the circuit, particularly in instances where backup power is limited or unavailable.

[008] A disadvantage of traditional latching relays is that latching relays are mechanical relays requiring moving parts and after years of heavy use, can become unreliable.

[009] Another disadvantage is tiiat latching relays are generally individual relays. For example, a panel with five protection devices will require five latching relays which each having to be wired separately. The use of multiple latching relays may result in increased cost, increase maintenance and have associated reliability issues. Furthermore, each relay needs to be individually inspected to check the state of the relay.

[0010] Another disadvantage with traditional latching relays is that visual inspection of mechanical pans of the latching relays is required determine which protection function has tripped. [0011] Another disadvantage traditional latching relays, is that traditional relays do not record, transmit or concisely display information in relation to the status of the latching relay and/or other components to which the latching relays are electrically connected.

[0012] The below described invention seeks to improve or overcome one or more of the above identified disadvantages and/or at least provide a useful alternative.

Summary

[0013] In accordance with a first main aspect there is provided, a system for identifying a trip signal from trip relays, the trip relays being moveable between a normal state and tripped state in which a trip signal is provided, the system including: trip inputs which are each configured to receive the trip signal from one of the trip relays; a latching relay in electrical communication with each of the trip inputs, tire latching relay being moveable between a latched state and an unlatched state in response to the receipt of the trip input signal received at one or more of the trip inputs; and a controller in electrical communication with the trip inputs, wherein the controller is configured to detect which of the trip relays generated the trip input signal thereby enabling identification of which of the trip relays has moved between the normal state and tripped state.

[0014] hi an aspect, the controller is in electrical communication with the latching relay, the controller being configured detect the latching relay being in at least one of the latched state and an unlatched state.

[0015] In an aspect, the controller is configured to generate an output trip signal to the latching relay when the trip signal is received by one or more of the trip inputs.

[0016] In an aspect, the system includes a trip output, wherein the trip input and latching relay are electrically connected to the trip output. [0017] In an aspect, each of the trip inputs include a first electrical connection to the controller and a second electrical connection to a current control system configured to enable current flow from the trip inputs to the latching relay and the trip output.

[0018] In an aspect, the current control system is a diode, each diode being associated with a respective one of the trip inputs.

[0019] In an aspect, outputs of each diode are electrically connected in common with the each other, the trip output and the latching relay.

[0020] In an aspect, the first electrical connection includes an opto-isolator between the trip input and the controller.

[0021] In an aspect, the system includes a display in electrical communication with the controller, the display being configured to indicate the state of each of the trip relays based on receipt of a display signal from the controller.

[0022] In an aspect, the display is a liquid crystal display adapted to maintain a displayed image in the event of a power loss.

[0023] In an aspect, the display is an E-iiik display.

[0024] In an aspect, the controller is configured to maintain the display whilst at least one of the trip relays is in the tripped state.

[0025] In an aspect, the controller includes a reset output in electrical communication with the latch relay, the controller being configured to selectively generate a reset signal at the reset output to move the latch relay between the latched state and the unlatch state.

[0026] In an aspect, the controller is configured to enable the output trip signal when the input trip signal is greater than a threshold value. [0027] In an aspect, the system includes a trip relay voltage supply in electrical communication with the controller and wherein the threshold value is 50% above the trip relay voltage.

[0028] In an aspect, the input trip signal is greater than 50% of a supply voltage to the electrical protection system.

[0029] In an aspect, the system includes under voltage trip inputs configured to receive under voltage trip signals from the trip relays, wherein the under voltage trip inputs are in electrical communication with the controller.

[0030] In an aspect, the controller is configured to generate an output trip signal when at least one of the under voltage trip inputs receives an under voltage trip signal.

[0031] In an aspect, the controller is configured to enable the output trip signal when the under voltage trip input is less than a threshold value.

[0032] In an aspect, the system includes an under voltage supply in electrical communication with the controller, the threshold value is 50% below a supply voltage to the electrical protection system.

[0033] In an aspect, the controller includes a processor and memory.

[0034] In accordance with a second main aspect there is provided, an electrical device including a system as defined above.

[0035] In accordance with a third main aspect there is provided, an electrical protection system including an electronic flag relay sub-system provided in accordance with the system as defined above, the electrical protection system including flag relays in electrical communication with the flay relays inputs of the electronic flag relay sub-system.

[0036] In accordance with a fourth main aspect there is provided, a method of operation of a device for an electrical protection system including trip relays, the device including: trip inputs which are each configured to receive a trip signal from a respective one of the trip relays; a controller electrically connected to the trip inputs; and a latching relay in electrical communication with the trip inputs, the method including the steps of: the controller undertaking a monitoring routine in which the trip inputs are monitored for the trip signal and; on receipt of the trip signal, the controller undertakes a determination routine in which trip information is provided to identify which one or more of the trip inputs received the trip signal.

[0037] In an aspect, the device includes a display in electrical communication with the controller, the method including the steps of: the controller providing a display signal based on the trip information, and the display receiving a display signal and displaying the state of the trip relays.

[0038] hi an aspect, the latching relay is in electrical communication with the controller, the method including the step of: the controller providing a trip output to the latching relay based in the trip information thereby moving he latching relay between the unlatched state and the latched state.

[0039] hi an aspect, the method further includes the step of: the controller inhibiting the latching relay from being reset from the latched state to the unlatched state when the trip signal is received at one or more of the trip inputs.

[0040] In an aspect, the method including the steps of: the controller maintaining the display until the latching relay is reset.

[0041] In an aspect, the method including the steps: of the controller inhibiting the overwriting of a previous display until the latching relay is reset.

[0042] In an aspect, the device further includes under voltage trip inputs associated with the trip relays, the method including the steps of: the controller undertaking a monitoring routine in which the under voltage trip inputs are monitored for an under voltage trip signal; and when an under voltage trip input signal is received, the controller enables the trip output. [0043] In an aspect, the method including the step of the controller undertaking a comparison routine in which the trip inputs and the under voltage trip inputs are compared to one other to determine which of the under voltage trip inputs received the under voltage trip signal, the controller providing the trip information based on the determination.

[0044] In an aspect, the method including the steps of: the controller undertaking a comparison between a voltage of the under voltage trip signal and a pre-determined threshold value, the controller enabling the trip output when the under voltage trip signal is less than a pre-determined threshold value.

[0045] In an aspect, the threshold value is 50% below a supply voltage to the electrical protection system.

[0046] hi an aspect, the method including the step of: the controller undertaking a comparison between a voltage of the trip signal and a pre-determined threshold voltage, the controller enabling the output trip signal when the voltage of the trip signal is greater than the pre-determined threshold value.

[0047] hi an aspect, the threshold value is 50% above a supply voltage to the electrical protection system.

[0048] In an aspect, the method including the step of: resetting the mechanical latch relay by a least one of manually moving a reset switch and the controller activating the reset switch.

[0049] In an aspect, the method including the step of: the controller undertaking at least one of storing the trip information on a memory device and transmitting the trip information by a communication device.

[0050] In accordance with a fifth main aspect there is provided, a device for tin electrical protection system including trip relays, the trip relays being moveable between a normal state and tripped state in which a trip signal is provided, the device including: trip inputs which are each configured to receive the trip signal from one of the trip relays; a latching relay in electrical communication with each of the trip inputs, the latching relay being moveable between a latched state and an unlatched state in response to the receipt of the trip input signal received at one or more of the trip inputs; and a controller in electrical communication with the trip inputs, wherein the controller is configured to detect which of the trip relays generated the trip input signal thereby enabling identification of which of the trip relays has moved between the normal state and tripped state.

Brief Description of the Figures

[0051 ] The invention is described, by way of non-limiting example only, by reference to the accompanying figures, in which;

[0052] Figure 1 is a simplified electrical schematic diagram illustrating a system of a flag relay device including the electrical components and connections within the flag relay device;

[0053 ] Figure 2 is a more detailed electrical schematic diagram illustrating another example of a flag relay device connected to trip relays and a circuit breaker;

[0054] Figure 3 is another diagram illustrating another example of a flag relay device located within an electrical protection system; and

[0055] Figure 4 is flow diagram illustrating an example method of the operation of the flag relay device.

Detailed Description

[0056] Referring to Figure 1, there is shown an electrical protection system 1 1 including an electronic flag relay system or sub-system 9. The electrical protection system 11 including trip relays 12 and a circuit breaker 14, and the electronic flag relay sub-system 9 is preferably provided in the form of an electronic flag relay device 10 including the components of the sub-system system 9. [0057] The electrical protection system 1 1 includes a shunt trip (non-fail safe) circuit 1 1 a, a fail safe (under voltage) circuit 1 1 b and a protection power supply 15. The protection power supply 15 provides a shunt trip power supply 15a to the shunt trip circuit 1 l a and an under voltage power supply 15b to the under voltage circuit 1 1 b. The protection power supply 15 may provide, for example, 48 or 110 volts depending on the application. Other voltage values may also be used.

[0058] The trip relays 12 include shunt trip contacts or switches 12a connected to a non-failsafe (shunt trip) circuit 1 1 a of the electrical protection and under voltage contacts or switches 12b connected to the under voltage circuit 1 lb.

[0059] The trip relays 12 may be in the form of a plurality of trip relays, in this example, the relays 12 include an over-current relay 16 and an earth leakage relay 18. Each of the over-current relay 16 and the earth leakage relay 18 are configured to monitor the current and/or voltage in an external system 21 which is shown and further described in relation to Figure 3.

[0060] When the relays 16, 18 detect a trip condition, for example, a large surge in current or sudden drop in voltage, the respective relay will trip and move between a normal state and a tripped state. The tripped relay generates a trip signal which is received by the apparatus 10.

[0061] The circuit breaker 14 includes a shunt trip 17 and an under voltage coil 19 which are respectively in electrical communication with the shunt trip circuit 11a, the over voltage circuit 1 l b and the device 10. When the device 10 receives the trip signal from one of the relays 12, the device 10 relays or communicates this signal to the circuit breaker 14 thereby tripping or opening the circuit breaker 14 which reduces or stops power to or from the external system 21.

[0062] Turning now to the electronic flag relay device 10 which in this example preferably includes the components of the electronic flag relay sub-system 11, the device 10 includes shunt trip inputs 20 and under- voltage inputs 22 which are electrically connected in use to each of the relays 12, in this example, the over-current relay 16 and the earth leakage relay 18. Each of the shunt trip inputs 20 and under- voltage inputs 22 are in electrical communication with a controller 40 which is configured to detect which of tine trip relays 12 generated the trip input signal thereby enabling identification of which of the trip relays 12 has moved between the normal state and tripped state.

[0063] The device 10 further includes a mechanical latching relay 50 in electrical communication with each of the trip inputs 20 and the controller 40. The latching relay 50 is moveable between a latched state and an unlatched state in response to the receipt of the trip input signal received at one or more of the trip inputs 20.

[0064] It is noted that the device 10 includes a number of components such as the mechanical latching relay 50 and controller 40 which may be provided as part of a single unit or as separate multiple units located remotely to one another. In this respect, the term "device " herein is intended to include single and/or multiple parts or components, located together or remotely located relative to one another.

[0065] hi this example, the controller 40 is in electrical communication with the latching relay 50 and the controller 40 is configured detect the latching relay 50 being in at least one of the latched state and an unlatched state.

[0066] The device 10 further includes a trip output 34 in electrical coinmunication with the trip inputs 20, the latching relay 50 and the controller 40.

[0067] The controller 40 includes a flag output 36 electrically connected to the latching relay 50 and the trip output 34. The controller 40 is configured to detect when at least one of the trip relays 12 is in the tripped state and communicate the output trip signal to the latching 50 via the flag output 36 thereby causing the latching relay 50 to move between the unlatched state and the latched state. In addition to the flag trip output 36, the controller 40 includes a flag trip a flag reset output 38.

[0068] The flag trip output 36 is directly electrically connected to the trip output 34 and to the mechanical flag relay 50. Accordingly, when the trip signal is outputted from the controller 40 at the flag trip output 36, the mechanical flag relay 50 is tripped and the shunt trip 17 of the circuit breaker 13 is tripped. [0069] The mechanical flag relay 50 is also electrically connected to the flag reset output 38 and may be reset on receipt of a reset signal outputted from the controller 40 at the flag reset output 38.

[0070] The controller 40 includes controller shunt trip inputs 42 and controller under voltage inputs 44. The controller shunt trip inputs 42 and controller under voltage inputs 44 are electrically connected to the shunt trip inputs 20 and under voltage inputs 22, respectively, via input buffer opto-isolators 46.

[0071 ] In this example, the controller 40 includes two controller shunt trip inputs 42 and controller under voltage inputs 44. However, the controller 40 may include any number of controller shunt trip inputs 42 and controller under voltage inputs 44 depending on the number of relays 12.

[0072] The separate inputs 42 for the controller shunt trip inputs 42 and controller under voltage inputs 44 allow the controller 40 to determine which of the relays 12 have tripped and perform various information processing, recording and display tasks as are further detailed below.

[0073] The trip inputs 20 each include two connections. The first connections 25 directly electrically connect the trip inputs 20 to the controller trip inputs 42 via the opto-isolators 46. The second connections 27 branch off the first connections 25 and each include a directional current control device in the form of diodes 29 between the trip inputs 20 and a common connection 35.

[0074] The common connection 35 directly electrically connects the output of the diodes 29 of the second connections 27 to the main trip output 34, the mechanical flag relay 50 and the controller flag trip output 36 via the opto-isolators 46.

[0075] Accordingly, the common connection 35 provides a simple single path connection between the each of the trip inputs 20 and the main trip output 34, the mechanical flag relay 50 and the controller flag trip output 36. [0076] Furthermore, the output from each of the diodes 29 are connected to the common connection 35 so as to allow a single direction of current flow from the trip inputs 20 into the common connection 35. The arrangement of the diodes 29 is important to electrically isolate each of the trip inputs 20 from one another. This ensures that the controller trip inputs 42 are electrically independent from of one another and allows the controller 40 to determine which of the relays 12 have tripped.

[0077] The device 10 includes a trip power input 31 and trip ground input 32 which are connected in use to the trip power supply 15a. The device 10 also includes a controller power unit 41 connected between the trip power input 31 and the controller 40. The power unit 41 is configured to convert the trip power supply 15a voltage to a voltage suitable for a controller 40 typically, 5 volts. The device 10 also includes an under voltage supply input 33 and an under voltage ground 23.

[0078] The controller 40 also includes a shunt trip power supply input 30 and an under voltage power supply input 28 which are respectively electrically connected the trip power input 31 and the under voltage supply input 33 and hence the shunt trip power supply 15a and the under voltage power supply 15b. Again, opto-isolators are located between the controller inputs 28, 30 and the device inputs 31 , 33.

[0079] To determine when to output a trip signal from the controller 40, the controller 40 performs a comparison between voltage of the shunt trip power supply input 15a and the controller shunt trip input 42. When the controller shunt trip input 42 voltage is above a threshold value, in this example it is 50% above the voltage of the controller shunt trip power supply input 15a, then the controller 40 outputs a flag trip output 36.

[0080] Similarly, in relation to the under voltage circuit 1 lb, to determine when to output a trip signal from the controller 40, the controller performs a comparison between voltage of the controller under voltage power supply 28 and the controller shunt trip input 42. When the shunt trip input voltage is above a threshold value, in this example it is 50% above the voltage of the controller under voltage power supply input 28, then the controller 40 outputs the llag trip output 36. [0081] In more detail, the mechanical flag relay 50 includes a mechanical latch or switch 52, a visible flag 54 and the reset button 56. The switch 52 and the flag 54 are electrically connected between the trip output 34 and the flag trip output 36 of the controller 40. The flag reset 56 is electrically connected to the flag reset output 38. The flag reset 56 may be manually reset or reset is response on receipt of a reset signal outputted from the controller 40 at the flag reset output 38. The mechanical flag relay 50 is configured to remain in a tripped state in the event of a power failure.

[0082] Advantageously, because the mechanical latch relay 50 is electrically connected to the trip inputs 20 and the flag trip output 36 of the controller 40, the mechanical latch relay 50 may be tripped by either the input trip signal at the trip input 20 or by the output trip signal provided at the flag trip output 36 of the controller 40.

[0083] For example, when one of the relays 12 trips, the mechanical latch relay 50 is directly tripped from the trip inputs 20. However, if the mechanical latching relay 50 is not tripped and the controller 40 receives the trip signal at one the controller trip inputs 42, the control ler 40 will output the trip signal at the flag trip output 36 to the mechanical latch relay 50 thereby tripping the mechanical latch relay 50.

[0084] The main trip output 34 is electrically connected to the circuit breaker 14. The main trip output 34 is also directly electrically connected to the trip inputs 20, the flag trip output 36 and the mechanical trip relay 50. Accordingly, any trip signals are directly relayed or communicated to the circuit breaker 14 and as such when one of the relays 12 trips, the circuit breaker 14 is directly tripped and the mechanical latching relay 50 is tripped, either directly or via the controller 40.

[0085] In the light of the above, it may be appreciated that, advantageously, the configuration of the apparatus 10 provides redundancy whereby the circuit breaker 14 may be directly tripped from the trip inputs 20, tripped by the controller 40 and also maintained in a tripped state by the mechanical latching relay 50 in the event of a power failure. [0086] The apparatus 10 also includes a display 60 in electrical communication with the controller 40. The display 10 is configured to indicate the state of the trip relays 20 based on receipt of a display signal outputted from a display output 62 of the controller 40.

[0087] In this example, the display 60 is a liquid crystal display (LCD) adapted to maintain a displayed image, in particular the most recent displayed image, in the event of a power loss where there is not electrical power present. One such commercially available display that may be utilised as the display 60 is an E-ink display. In this example, the E-Ink display is preferably used as or as part of the display 60. However, other liquid crystal displays (LCD) with similar functionality may also be used. . This is particularly, advantageous in situations where it may take operators some time to reach the device 10 and provides operators with information in relation to which relay 12 has tripped and the status of the device 10, for example, being tripped or normal.

[0088] In this example, the controller 40 may be any suitable a microcontroller which typically includes a memory module 45 for storing information such as computer executable codes and/or trip information in relation the state the flag relays 12. The microcontroller may also include a processor 55 for undertaking calculation steps such as the voltage comparisons as described above. Microcontrollers are well known and are not described in further detailed herein.

[0089] The operation of the controller 40, in particular, the information processing, storage and display functions of the controller are further described in relation to Figure 4 below. However, before describing the operation of the device 10, further examples of the device 10 and uses of the device 10 are described with reference to Figures 2 and 3.

[0090] Referring to Figure 2, there is shown another example of the device 10 which is substantially similar in configuration to the example of the device 10 as shown in relation to Figure 1. Accordingly, like numerals denote like parts.

[0091] In this example, the device 10 is shown as being configured for use with ten trip relays 12 being connected with trip outputs 20 and under voltage outputs 22. Accordingly, the device 10 includes ten trip relay inputs 20, ten controller trip inputs 42 at the controller 40, ten under voltage inputs 22 and ten under voltage controller inputs 44 at the controller 40. There are also ten opto-isolators 46 associated with each of the trip inputs 20 and ten opto-isolators 46 associated with each under voltage inputs 22. There are also opto-isolators arranged to detect the trip power supply and the under voltage power supply. The electrical configuration of the opto-isolators is shown in the Figure and will be understood by a person skilled in the art without further explanation.

[0092] In use, each of the ten relays 12 may be configured to perform a different function or monitor a different electrical component. For example, beginning with the trip relay closest to the trip power supply 15a, these may be "Relay 1: Overload Relay", "Relay 2: Short Circuit Relay", Relay 3: Earth Leakage Relay", "Relay 4: Temperature Relay", "Relay 5: Oil Level Relay", "Relay 6: Interlock Relays" and Relays 7 to 10: Spare relays for future expansion.

[0093] Each of these ten relays 12 would then be connected to a separate one of the ten trip relay inputs 20 and would be indicated or labelled as, for example, "Trip Input 1", "Trip Input 2"...."Trip Input 10". Similarly, the controller 40 will have corresponding controller trip inputs 42 indicated or labelled as, for example, " Controller Trip Input 1", "Controller Trip Input 2".... "Controller Trip Input 10". Similar, indicating or labelling is to be used for the under voltage inputs 22 and the under-voltage controller inputs 44.

[0094] In this configuration, there are now ten trip inputs 20 electrically connected to the common connection 35 via the diodes 29. If any one of the ten relays 12 are tripped then the common connection 35 receives the trip signal and the trip signal is communicated to the mechanical flag relay 50 and the shunt trip 17 of the circuit breaker 13. This will cause the circuit breaker 13 and the mechanical flag relay 50 to trip. The controller 40 will then receive the trip signal via the controller trip input 42 associated with the tripped relay 12. The controller 40 will then determine whether to send a trip output via the flag trip output 36 as has been described in relation to Figure 1. [0095] As will be further described below in relation to Figure 4, the controller 40 is configured to determine and/or record which of the relays 12 (for example Relay 2: Short Circuit Relay ) has tripped. This information may then be displayed on the E-Ink display 60, a conventional LCD display 64 or communicated via a communication module 66 to an external device such as a receiving device. The controller 40 is also electrically connected to an indictor light, in this example, an LED light 68 to provide another visual means to assess the status of the relays 12.

[0096] The remaining configuration of the device 10 illustrated in Figure 2 is similar to that described in relation to Figure 1 and is not repeated here. However, it should be appreciated that the above described device 10 is advantageously configured to display or flag the status of one or more of tipped relays 12 whilst only using only a single mechanical latch relay 50.

[0097] Referring now to Figure 3, there is shown an example of the device 10 being used within an electrical protection system 1 1 including a power supply 15, a circuit breaker 14 and relays 12 in communication with an external electrical system 21 to be protected. This example is similar to that shown in Figure 1. Accordingly like numerals are used to denote like parts. However, in this example device 10 is illustrated as being contained or supported within a housing 70 and the illustration relates to the physical location of components rather than the detailed electrical configuration.

[0098] The housing 70 includes a face 72 which displays the E-Ink display 60, the LCD display 64 and the indicator LCD lights 88. The housing 70 includes a number on inputs and outputs, such as the shunt trip inputs 20 and the under voltage inputs 22 which are connected to the relays 12 which are located extemally of the housing 70 and the device 10.

[0099] The housing 70 supports the under voltage ground input 23, the shunt trip ground input 32: the under voltage supply input 33 and the shunt trip supply input 30. The voltage ground input 23 and the under voltage ground input 32 are electrically connected to the ground of the power supply 15. The under voltage supply input 33 and the shunt trip supply input 30 are electrically connected to the active side of the protection power supply 15.

[00100] In this example, the device 10 includes an under voltage output 37 and a shunt trip output 34 which are respectively connected to the under voltage coil 19 and the shunt trip 17 of the circuit breaker 14.

[00101] Similarly to the examples of the device 10 described in relation to

Figures 1 and 2, the device 10 shown in this example is configured to monitor and receive input signals from the relays 12 via the shunt trip inputs 20 and under voltage inputs 22. When the one of the relays 12 trips thereby moving between a normal state and a tripped state, the device 10 relays this tripped signal to the circuit breaker 14 via one the shunt trip output 34, as appropriate. Accordingly, when the one of the relays 12 trips the circuit breaker 14 is tripped. The status or other information regarding the relays 12 may then be recorded, communicated by the controller 40 or displayed by one or more of the E-Ink display 60, the LCD display 64 and the indicator LCD lights 68.

[00102] The E-Ink display 60 will be configured to include a series of indication segments or panels, for example, 60a and 60b, which are associated with one of the trip relays 12, in this example, over current relay 16 and earth leakage relay 18. In use, when a trip signal is received by the device 10, the E-Ink display 60 will colour the panels, for example, grey or black in indicate which of the trip relays 12 have been tripped.

[00103] The device 10 also includes a reset button 86 for manually resetting the mechanical latch relay 50.

[00104] The functionality of the device 10 and the internal electrical control and processing components associated with the controller 40 are now described below in further detail with reference to Figure 4.

[00105] Referring now to Figure 4, a typical method or process of operation of the device 10, in particular, the controller 40 is now described. The steps below may be performed by a computer programme, computer readable medium or the like stored on a memory module 45 of the controller 40 and executed by a processing module 55 of the controller 40.

[00106] A method 100 to operate the device 10 may include an initialisation sequence or routine 103 whereby the microprocessor 40 and LCD 64 are initialised and a main sequence or routine 109 which is carried out when the device 10 has been initialised.

[00107] In the initialisation sequence 103, the steps may he as follows: on power up 101 , the microprocessor 40 will undertake a routine at step 102 that sets up all I/O (Input/Output) pins and other configuration parameters. The controller 40 may then initialises the LCD 64 screen at step 104 with a blank screen ready for text display.

[00108] The initialisation sequence 103 may further include an initial start up routine to determine if the mechanical flag relay 50 is tripped. The steps are as follows: the controller 40 undertake step 106 in which the controller 40 interrogates or scans the mechanical flag 50, for example, by determining the voltage at trip flag output 36. If the mechanical flag 50 is determined by the controller 40 to be in the tripped state then the controller 40 performs an interrogation step 1 10 to check the reset status of the mechanical flag relay 50, for example, by determining the voltage at flag reset output 38

[00109] If the controller 40 determines that the mechanical flag relay 50 has not been reset, then the controller 40 initiates a wait for reset routine at step 112 whereby the controller 40 will wait for the reset to be activated.

[001 10] The wait for reset step 1 12 is important because when the mechanical flag 50 is tripped the memory E-Tnk LCD display 60 should not be written to so as to retain a visual trip status of the device 10 until reset. This is because once the device 10 has been reset (and all the trip inputs are healthy), the memory E-Tnk LCD 60 is cleared to a blank screen and the main program routine 109 within the controller 40 is run. [001 1 1 ] If the device 10 is powered up and the mechanical flag 50 is determined as not to be tripped at step 106, the device 10 assumes everything connected to the device leading up to the power loss remained healthy. Because inputs from devices (particularly electronic devices) can take a few seconds to "boot up" and electrically change to the normal (healthy) state, the controller 40 initiates 5 wait sequence at step 108 whereby inputs are ignored for 5 seconds on start-up.

[001 12] After the initialisation routine 103, the device 10 then enters a main operating routine 109 which includes a scanning routine 111. In the scanning routine 1 1 1 , the controller 40 undertakes a shunt trip scanning step 1 16 in which the controller 40 scans all of the controller shunt trip inputs 42 (non-failsafe inputs) for any active (high) conditions.

[00113] The controller 40 also undertakes an under voltage scanning step 118 in which the controller scans each of the controller under voltage inputs 44 (failsafe inputs) for any active (low) conditions. The state of each of the controller shunt trip inputs 42 and controller under voltage inputs 44 may be temporarily or permanently stored in the memory module 45 of the controller 40.

[001 14] The controller 40 then undertakes a shunt trip determination step 120 to determine whether or not to output a trip signal from the controller 40. In this step the controller 40, more specifically the processor 55, performs a comparison between voltage of the shunt trip power supply input 30 and the controller shunt trip input 42. When the controller shunt trip input 42 voltage is above a threshold value, in this example it is 50% above the voltage of the controller shunt trip power supply input 30, then the controller 40 undertakes an enabling step 126 whereby the flag trip output 36 is enabled.

[001 15] In respect to the under voltage inputs, the controller 40 undertakes an under voltage determination step 122 to determine whether or not to output a trip signal from the controller 40 relation to the under voltage circuit. To determine when to output a trip signal from the controller 40, the controller 40 performs a comparison between voltage of the controller under voltage power supply 28 and controller under voltage input 44.

[001 16] When the input voltage is below a threshold value, in this example it is

50% below the voltage of the controller under voltage power supply input 28, then the controller 40 undertakes an additional step 124 to determine which trip device 12 has tripped from the status of the controller shunt trip inputs 42. For example, if an under voltage input 44 is low, there may be other inputs low if these other inputs are wired after the first tripped contact. If, say, the seventh trip relay in an under voltage loop becomes unhealthy (open circuit), the seventh trip input will become low as well as the eighth, ninth and tenth input.

[00117 J It is noted that there is also an under voltage power input 33, so that if the power supply 15 fails and all controller under voltage inputs 44 go low, the device 10 will be able to distinguish between an input trigger (i.e. an trip event on the relays 12) and a power supply fault. The power supply fault may be alarmed on the display and signalled remotely via the communication module 66, by for example, serial communications.

[00118] Then, if the controller 40, more specifically the processor 55, has determined there is a trip activated, it will trigger or enable the trip output 36 at step

126. The trip output 36 is electrically connected to the internal mechanical latch relay 50. If the mechanical latch relay 50 is not already tripped, the trip output 36 will trip the mechanical latch relay 50. The mechanical latch relay 50 is also electrically connected to the circuit breaker 14 so that the circuit breaker 14 trips in response to the tripping of the trip output 36. The mechanical latch relay 50 maintains the tripped state until reset.

[001 19] The controller 40 then writes to the E-ink or memory LCD's 60 at step

127, by activating the wires associated with the segment associated with the trip input. This takes approximately 500ms to get a contrasting colour change on the LCD so the residual power for the controller 40 and the LCD needs to remain active for at least this time, this can be achieved from the capacitors in the input power supply regulation (not shown). [00120] If power is still present to the controller 40 it can then be used to provide "smart" information such as circuit breaker opening times. For example, option timing step 128 may be under taken in which the time between when the controller 40 detected an input trigger and the time it took for the circuit breaker or switching device to open through an auxiliary switch on the circuit breaker or switching device which is wired into the relay (not shown).

[00121 ] If power is still present, the conventional LCD display 64 is then written to at step 130 with the following information: Trip Input ( with indication whether the shunt trip and/or under voltage was detected); circuit breaker opening time; and prompt for a reset if all inputs are healthy.

[00122] After a trip event has occurred, the controller 40 then undertakes a reset monitoring step 132 whereby the controller monitors if a reset action, such as the manual pressing of the reset 56, has been performed on the mechanical flag relay 50. If the reset 56 is activated, the controller 40 then undertakes a further scanning sequence at step 134 whereby the controller 40 again interrogates or scans all of the controller shunt trip inputs 42 (non-failsafe inputs) for any active (high) conditions and scans each of the controller under voltage inputs 44 (failsafe inputs) for any active (low) conditions.

[00123] If there are trips still active, the controller 40 will not allow the reset and the trip output 36 will be maintained and hence the mechanical latch 50 will remain tripped. The controller 40 will then continue to monitor the reset at step 132.

[00124] If there are no trips still active at scanning sequence step 134, the controller 40 undertakes a reset sequence step 136 whereby the flag trip output 36 is disabled and the mechanical flag relay 50 is permitted to reset. The controller 40 then clears the LCD screens.

[00125] The controller then jumps to the top of the main routine 109 to step

116 and performs the scanning functions and determination at steps 116, 118, 120 and 122 until the next trip input is provided. [00126] The above described device and method of operating the device have a number of advantages aspects. For example, the device provides an electronic flag relay which may be utilised with a plurality of trip relays whilst only requiring a single mechanical flag latching relay to ensure the device remains tripped in the event of a power failure. Accordingly, the device generally requires less moving parts and wiring in comparison to a convention trip relay thereby saving time, costs and increasing reliability.

[00127] Furthermore, the device includes a display, more specifically a

"memory" E-lnk display which displays the state of the trip relays. In particular, in the event of a power failure, the device, more specifically the controller, is configured to retain or maintain the E-Ink display such that an operator or user may visually determine which of the trip relays tripped.

[00128] Another advantage is that the mechanical flag latching relay is wired directly to the trip relays so as to rapidly trip when a trip input is received. This provides a safety advantage over known flag relays. In addition, the mechanical flag latching relay may also be tripped by controller if not already tripped thereby providing the device with further safety and reliability via redundancy. Furthermore, the controller is configured to maintain the mechanical flag latching in the tripped state whilst any of the trip inputs are in the tripped state.

[00129] Yet another advantage is that the device, more specifically the controller, monitors the under voltage inputs (fail safe inputs). This enables the device, more specifically the controller, to output a trip signal to the mechanical latch relay and circuit breaker in the event of wiring or trip relay failures. The controller is also configured to determine in which segment of the circuit the malfunction occurred.

[00130] The reference in this specification to any known matter or any prior publication is not, and should not be taken to be, an acknowledgment or admission or suggestion that the known matter or prior art publication forms part of the common general knowledge in the field to which this specification relates. [00131 ] While specific examples of the invention have been described, it will be understood that the invention extends to alternative combinations of the features disclosed or evident from the disclosure provided herein.

[00132] Many and various modifications will be apparent to those skilled in the ait without departing from the scope of the invention disclosed or evident from the disclosure provided herein.