Method for monitoring electrical insulations of a mining vehicle

Abstract

A computer-implemented method (500) for monitoring electric insulations of a mining vehicle (100) by means of a plurality of insulation monitoring devices (440), IMDs, the mining vehicle (100) being arranged to travel in a mining environment, the mining environment comprising infrastructure for energy transmission to mining vehicle during transport, the mining vehicle (100) comprising an electric drive line comprising at least one traction motor, an energy transmission system comprising a converter (120) and a current collector (110), for connection of the mining vehicle (100) to the infrastructure for energy transmission and for transmitting electric energy to the electric drive line, and an arrangement (400) comprising the plurality of IMDs (440), comprising at least one energy transmission system IMD (442; 443; 444) arranged to monitor a respective electric insulation of the energy transmission system, the method (500) comprising: initiating a predetermined monitoring sequence comprising, for each of the plurality of IMDs (440), transmitting a monitoring signal and subsequently receiving a monitoring response, the monitoring sequence defining the order in which each of the plurality of IMDs (440) transmits the monitoring signal, wherein, an IMD is triggered to transmit a monitoring signal when a preceding IMD in the monitoring sequence receives the monitoring response

Description

METHOD FOR MONITORING ELECTRICAL INSULATIONS OF A MINING VEHICLETechnical field

[0001] The present invention relates generally to electrically powered vehicles. More specifically it relates to monitoring electrical insulations of electrically powered vehicles.Background art

[0002] In electrically power vehicles, electric insulation is required in different forms to electrically isolate circuitry and electric devices from each other and from their surroundings. Furthermore, in unearthed networks, also known as IT networks (lat. Isolation Terra), an electric installation is isolated from earth. Electric insulation comes in many forms such as insulation on wires or an insulating board of a printed circuit board. In high voltage systems the electric insulation may be in the form of a liquid, such as oil, in spaces where arcs may form. In some systems, vacuum is used instead of a liquid. Monitoring that the electric insulations of an electrically powered vehicle are intact, and not damaged or malfunctioning, is crucial to ensure the function of the vehicle, but also to ensure the safety of humans in its vicinity.

[0003] In a mining environment, electric insulations of the vehicle are additionally prone to insulation faults, due to the harsh environment. For example, an insulation arranged on the outside of the vehicle is exposed to falling rocks, and the uneven road quality increases the risk of vibration damages. In a mining environment it is additionally important to avoid damages in the vehicle which may bring the vehicle out of use, for example because service is not always readily available and because a suddenly malfunctioning vehicle may block an only way in or out of the mine.

[0004] An advantage of IT networks is that, in the event of a first insulation fault, the network can commonly continue to operate without interruption due to the fact that it is floating. The safety risk appears if a second fault occurs, affecting adifferent insulation than that of the first fault. Therefore, insulation monitoring devices, IMDs, are used to detect insulation faults and locate where the fault has appeared. An IMD may monitor direct current (DC) networks, alternating current (AC) networks or mixed AC / DC networks, and may function in various ways depending on the type of network. Generally, an IMD monitors the insulation by injecting measurement signal with known voltage to the monitored IT network. In case of an insulation fault, the fault impedance closes the measurement loop and determines the measurement current. At the IMD, this measurement current alters a voltage drop over the known measurement resistors. The voltage drop is measured and used to determine the insulation resistance of the monitored system.

[0005] In electrically power vehicles which only draw energy from a battery in the vehicle, a single IMD is sufficient to monitor the whole vehicle. It is commonly arranged in the battery and monitors insulation of battery terminals and the driveline against the vehicle chassis. A different IMD set up is required in vehicles drawing energy from an external high voltage power source during transport, such as overhead contact lines. More than one IMD is then needed to monitor the increased number of electrically isolated parts which are provided in vehicles connected to a high voltage power source. However, there are problems associated with running multiple IMDs at the same time. The monitoring signal transmitted by one IMD may interfere with the monitoring signal of another IMD. This renders the results from the monitoring useless, as it is not known which of the several IMDs interfere and to what extent. Having unreliable monitoring results is a safety risk and may lead to damage of the vehicle.Summary of invention

[0006] An object of the present disclosure is to overcome at least some of the problems outlined above. This is provided in a first aspect of the invention by a computer-implemented method for monitoring electric insulations of a mining vehicle by means of a plurality of insulation monitoring devices, IMDs. The mining vehicle is arranged to travel in a mining environment comprising infrastructure for energy transmission to mining vehicles during transport. The mining vehiclecomprises an electric drive line comprising at least one traction motor, an energy transmission system comprising a converter and a current collector, for connection of the mining vehicle to the infrastructure for energy transmission and for transmitting electric energy to the electric drive line, and an arrangement comprising the plurality of IMDs, comprising at least one energy transmission system IMD arranged to monitor a respective electric insulation of the energy transmission system. The method comprises initiating a predetermined monitoring sequence comprising, for each of the plurality of IMDs, transmitting a monitoring signal and subsequently receiving a monitoring response, the monitoring sequence defining the order in which each of the plurality of IMDs transmits the monitoring signal, wherein, an IMD is triggered to transmit a monitoring signal when a preceding IMD in the monitoring sequence receives the monitoring response.

[0007] The present disclosure allows operation of multiple IMDs without interference therebetween in an externally powered mining vehicle. When the mining vehicle is connected to an external power source during transport, an IMD of the external power source may interfere with the operation of IMDs of the mining vehicle. The disclosure thus provides that the safe operation of electric insulations of the vehicle may be confirmed, before the IMD of the external power source is able to interfere. It furthermore provides that the safe operation of electric insulations of the vehicle may be confirmed, before electricity from external power source is led to the vehicle, which, if an insulation fault were present, could cause damage.

[0008] In an exemplary embodiment, the disclosure comprises, when at least one of the received monitoring responses during at least one monitoring sequence indicates an insulation fault: preventing connection of the mining vehicle to the infrastructure for energy transmission, and when each of the received monitoring responses during at least one monitoring sequence indicates no insulation fault: allowing connection of the mining vehicle to the infrastructure for energy transmission.

[0009] In an exemplary embodiment, the disclosure comprises, when at least one of the received monitoring responses during at least one monitoring sequence indicates an insulation fault: initiating the predetermined monitoring sequence. In an exemplary embodiment, the disclosure comprises repeating the monitoring sequence as long as the mining vehicle is not connected to the infrastructure for energy transmission. The monitoring sequence may thus be run until safe connection is possible.

[0010] In an exemplary embodiment, the mining vehicle comprises an electric energy storage comprising at least one drive line IMD arranged to monitor a respective insulation of the electric drive line, the method further comprising, when starting the vehicle: transmitting, by the at least one drive line IMD, a monitoring signal and subsequently receiving a monitoring response, when the monitoring response indicates an insulation fault: preventing connection between the electric energy storage and the electric drive line, when the monitoring response indicates no insulation fault: connecting the electric energy storage to the electric drive line and initiating the predetermined monitoring sequence. In an exemplary embodiment, the at least one drive line IMD is one of the plurality of IMDs.

[0011] In some embodiments, the vehicle may comprise two alternative energy sources for propulsion: the external power source and the electric energy storage. For example, the electric energy storage may be used to transport the vehicle to and from the external power source. The disclosure provides that the safe operation of the electric energy storage is ensured before starting the monitoring sequence. The disclosure furthermore provides that the IMD of the electric energy storage is part of the monitoring sequence, such that if a fault is detected, the electric energy storage may be disconnected and the vehicle prevented from travelling.

[0012] In an exemplary embodiment, the disclosure comprises: when a monitoring response received by an IMD of the plurality of IMDs is below a predetermined threshold, indicating an insulation fault of the respective monitored electric insulation, when the monitoring response is above the predeterminedthreshold, indicating no insulation fault of the respective monitored electric insulation.

[0013] In an exemplary embodiment, transmitting a monitoring signal comprises injecting a current into a circuit containing the insulation to be monitored, and receiving a monitoring response comprises detecting the injected current.

[0014] In an exemplary embodiment, the at least one energy transmission system IMD is one of: a first current collector IMD monitoring an insulation between the current collector and a chassis of the vehicle, a second current collector IMD monitoring an insulation between the current collector and a converter primary side, a converter IMD monitoring an insulation between a chassis of the vehicle and the converter primary side.

[0015] According to a second aspect of the disclosure there is provided a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to the disclosure.

[0016] According to a third aspect of the disclosure there is provided a computer-readable medium comprising instructions which, when executed by a computer, cause a computer to carry out the method according to according to the disclosure.

[0017] According to a third aspect of the disclosure there is provided an arrangement for monitoring electric insulations of a mining vehicle by means of a plurality of insulation monitoring devices, IMDs, the mining vehicle being arranged to travel in a mining environment, the mining environment comprising infrastructure for energy transmission to mining vehicles during transport. The mining vehicle comprises an electric drive line comprising at least one traction motor, and an energy transmission system comprising a converter and a current collector, for connection of the mining vehicle to the infrastructure for energy transmission and for transmitting electric energy to the electric drive line. The arrangement comprises processing circuitry, means for communication, amemory, and the plurality of IMDs, comprising at least one energy transmission system IMD arranged to monitor a respective electric insulation of the energy transmission system. The arrangement is operative for initiating a predetermined monitoring sequence comprising, for each of the plurality of IMDs, transmitting a monitoring signal and subsequently receiving a monitoring response, the monitoring sequence defining the order in which each of the plurality of IMDs transmits the monitoring signal, wherein, an IMD is triggered to transmit a monitoring signal when a preceding IMD in the monitoring sequence receives the monitoring response.

[0018] In an exemplary embodiment, the mining vehicle comprises an electric energy storage comprising at least one drive line IMD arranged to monitor a respective insulation of the electric drive line.

[0019] In an exemplary embodiment, the at least one drive line IMD is one of the plurality of IMDs.

[0020] In an exemplary embodiment, the mining vehicle does not comprise an electric energy storage as an energy source for forward drive.

[0021] In an exemplary embodiment, the at least one energy transmission system IMD is one of: a first current collector IMD monitoring an insulation between the current collector and a chassis of the vehicle, a second current collector IMD monitoring an insulation between the current collector and a converter primary side, a converter IMD monitoring an insulation between a chassis of the vehicle and the converter primary side.

[0022] According to a third aspect of the disclosure there is provided a mining vehicle arranged to travel in a mining environment, the mining environment comprising infrastructure for energy transmission to mining vehicles during transport. The mining vehicle comprises an electric drive line comprising at least one traction motor, an energy transmission system comprising a converter and a current collector, for connection of the mining vehicle to the infrastructure for energy transmission and for transmitting electric energy to the electric drive line,and an arrangement comprising a plurality of IMDs for monitoring electric insulations of the mining vehicle, comprising at least one energy transmission system IMD arranged to monitor a respective electric insulation of the energy transmission system.

[0023] In an exemplary embodiment, the electric drive line comprises an electric energy storage comprising at least one drive line IMD arranged to monitor a respective insulation of the electric drive line.

[0024] In an exemplary embodiment, the at least one drive line IMD is one of the plurality of IMDs.

[0025] In an exemplary embodiment, the at least one energy transmission system IMD is one of: a first current collector IMD monitoring an insulation between the current collector and a chassis of the vehicle, a second current collector IMD monitoring an insulation between the current collector and a converter primary side, a converter IMD monitoring an insulation between a chassis of the vehicle and the converter primary side.Brief description of drawings

[0026] The invention is now described, by way of example, with reference to the accompanying drawings, in which:Fig. 1 displays a mining vehicle according to the disclosure,Fig. 2 displays a mining vehicle according to the disclosure,Fig. 3 displays an electric network of a mining vehicle according to the disclosure,Fig. 4 displays an arrangement according to the disclosure,Fig. 5 displays a method according to the disclosure,Fig. 6 displays a method according to the disclosure,Fig. 7 displays an embodiment of a monitoring scheme according to the disclosure,Fig. 8 displays an embodiment of a monitoring scheme according to the disclosure.Description of embodiments

[0027] In the following, a detailed description of a computer-implemented method, an arrangement and a mining vehicle is provided. In the figures, like reference numerals designate identical or corresponding elements throughout the figures. It will be appreciated that these figures are for illustration only and do not in any way restrict the scope of the present disclosure.

[0028] With reference to Fig. 1 and Fig. 2 there is displayed a vehicle 10. The vehicle 10 is a mining vehicle 10 arranged for travelling in a mining environment. The mining environment may be, but is not limited to, an underground mine, a surface mine, an open-pit mine. The mining environment may be an area adjacent to or in connection to a mine. As such, the mining environment could be seen as any area where the mining vehicle 10 may normally travel during operation. The mining vehicle 10 seen in Fig. 1 is exemplified as a truck. The truck is arranged for transporting blasted rock in the mining environment. During normal operation, a loader loads blasted rock into the truck at a blasting site, which then transports the blasted rock away from the blasting site. It will be understood that the exemplary mining vehicle 10 is not limiting to the scope of the disclosure, and that other types of mining vehicles are encompassed by the present disclosure. Examples of mining vehicles include loaders, dumpers, trucks, excavators, drill rigs, haulers. The vehicle 10 may be operated by an operator sitting inside the vehicle 10, operated by a remote operator or autonomously operated.

[0029] Fig. 3 displays an embodiment of a network 200 comprising electrical connections in the vehicle.

[0030] The vehicle 10 comprises an electrical driveline to propel the vehicle. The electrical driveline comprises a motor drive, comprising at least one traction motorand at least one inverter. In an alternative embodiment, the vehicle 10 comprises more than one traction motor. The driveline is connected to, and receives electrical power from, a power source in order to propel the vehicle 10.

[0031] The power source may be a traction battery 130. The traction battery 130 may comprise a battery insulation monitoring device 441 , IMD (seen in Fig. 3). The battery IMD 441 monitors an electric insulation of the traction battery 130. The battery IMD 441 may determine, based on a monitoring response, if it is safe to connect the traction battery 130 to the driveline of the vehicle 10. When the battery IMD 441 is connected to the motor drive it may determine, based on a monitoring response, if there is an insulation fault in the driveline of the vehicle 10. The vehicle 10 may comprise one or more traction batteries. The traction battery 130 may for example be a Voltage Class B (VCB) battery.

[0032] The power source may be an external high voltage power source 300 from which the vehicle 10 may receive electrical power during transport. To this end, the vehicle 10 furthermore comprises a current collector 110 such that the vehicle 10 may be connected to the external power source 300. In Fig. 1 , the vehicle 10 is connected to the external power source 300 and in Fig. 2, the vehicle 10 is disconnected from the external power source 300. The current collector 110 generally comprises a contacting means 111 for connecting to the external power source 300. The contacting means 111 comprises electric components for transmitting electricity from the external power source 300 to the vehicle 10. The current collector 110 may furthermore comprise a housing 112. In Fig. 1 and Fig.2, the current collector 110 is arranged on the roof of the vehicle 10. The current collector 110 displayed in the figures collects electrical power through contact with overhead contact lines. In one embodiment the current collector 110 is a pantograph which collects electrical power through contact with high voltage overhead contact lines. In an alternative embodiment the current collector 110 is arranged at a bottom part of the vehicle 10 and is exemplified as a contact shoe, or sliding shoe, arranged to collect power from a power source located in or close to the ground, such as a high voltage rail in the ground. It will be understood that the exemplary current collector 110 is not limiting to the scope of the disclosure,and that other types of current collectors are encompassed by the present disclosure.

[0033] In one embodiment, the vehicle 10 comprises both the traction battery 130 and the current collector 110 for connecting to the external power source 300.

[0034] The vehicle 10 further comprises a converter 120. The converter 120 is arranged to receive power from the external power source 300, via the current collector 110, and convert the voltage level before the current is fed to the drive line. In one embodiment the converter 120 is an isolating converter 120. The converter 120 may be an insulated DC / DC converter. An isolating converter is divided into a primary side (input side) and a secondary side (output side), wherein the primary and secondary side are galvanically isolated from each other, that is, there is no direct conduction path between them.

[0035] The vehicle 10 may also be provided with an internal battery for running internal processes of the vehicle 10, such as controls, lights, cooling pumps, or processes related to start-up of the vehicle 10. The internal battery may for example transmit power to control systems for controlling the current collector or the converter. The internal battery may for example transmit power to IMDs of the vehicle 10 or to control systems for controlling IMDs of the vehicle 10. The internal battery may for example be Voltage Class A (VCA) battery.

[0036] The disclosure furthermore relates to an arrangement 400 seen in Fig. 4 for monitoring electric insulations of the vehicle 10. The arrangement 400 is preferably comprised in the vehicle 10. The arrangement 400 generally comprises processing circuitry 410, means for communication 420, a memory 430 and a plurality of insulation monitoring devices 440, IMDs, to provide safe operation of the vehicle 10. The processing circuitry 410 is arranged to execute a method 500 according to the disclosure. The means for communicating is arranged to communicate with the plurality of IMDs 440. The means for communicating may furthermore be arranged to communicate with a control system of the vehicle 10, for example a control system for connecting and disconnecting the current collector 110 to the external power source 300. In one embodiment, thearrangement 400 is comprised in and / or integrated with the control system of the vehicle 10. The means for communicating may furthermore be arranged to communicate with a remote control system 450 of the mining environment.

[0037] The plurality of IMDs 440 may be arranged to monitor DC-networks, AC- networks, or mixed AC / DC-networks. Each of the plurality of IMDs 440 is arranged to monitor an insulation of a circuit in the network 200 of the vehicle 10. The network 200 is preferably an IT-network. Each of the plurality of IMDs 440 comprises a transmitter arranged to transmit a monitoring signal, a detector arranged to detect a monitoring response and a control unit arranged to interpret the monitoring response and optionally communicate the monitoring response, or communicate information based on the monitoring response. Communication may for example be with the processing circuitry 410, or with another IMD of the plurality of IMDs 440.

[0038] In one embodiment, transmitting the monitoring signal comprises injecting a monitoring signal with a known voltage into a circuit which it is measuring. In case of an insulation fault, the fault impedance closes the measurement loop. An insulation fault in the circuit appears as a change in resistance over the circuit, such that the circuit has a fault resistance other than a normal operations resistance. The fault resistance causes a fault current to be induced which alters a voltage drop. The detector detects the voltage drop over the circuit and may therethrough detect an insulation fault.

[0039] In one embodiment, at least one of the plurality of IMDs 440 is arranged to monitor an electric insulation of the current collector 110. The insulation of the current collector 110 may for example be an insulation between the current collector 110 and a chassis of the vehicle 10. The insulation of the current collector 110 may for example be an insulation between the housing 112 of the current collector 110 and a chassis of the vehicle 10. The insulation of the current collector 110 may for example be an insulation between the current collector 110 and the converter primary side. The insulation of the current collector 110 may for examplebe an insulation between the housing 112 of the current collector 110 and a converter primary side.

[0040] In one embodiment, at least one of the plurality of IMDs 440 is arranged to monitor an electric insulation of the converter 120. The insulation of the converter 120 may for example be an insulation between the converter primary side and a chassis of the vehicle 10.

[0041] In one embodiment, at least one of the plurality of IMDs 440 is the battery IMD 441.

[0042] Exemplary embodiments of the method 500 according to the disclosure will now be described with reference to Fig. 5, Fig. 6, and Fig. 7.

[0043] The method 500 generally comprises running the plurality of IMDs 440 to monitor respective electric insulations of the vehicle 10. The method 500 further comprises determining if at least one of the electric insulations is malfunctioning. When it is determined that at least one of the monitored electric insulations is malfunctioning, the method 500 comprises preventing the vehicle 10 from connecting to the external power source 300. The method 500 furthermore comprises, when it is determined that all of the monitored electric insulations are functioning, allowing connection of the vehicle 10 to the external power source 300. Connecting to the external power source 300 is preferably performed by means of the current collector 110.

[0044] The method 500 comprises a monitoring phase. The method 500 may comprise start-up phase preceding the monitoring phase. The method 500 may comprise a connected phase following the monitoring phase.

[0045] The start-up phase displayed in Fig. 5 generally comprises start-up of the vehicle 10. The start-up phase may for example be initiated when an operator starts the vehicle 10. The start-up phase comprises running S510 the battery IMD 441. Running S510 the battery IMD 441 comprises transmitting S511 a monitoring signal and subsequently detecting S512 a monitoring response. The monitoring response may indicate that the battery insulation is malfunctioning, that is, thatthere is an insulation fault, or the monitoring response may indicate that the battery insulation is functioning, that is, that there is no insulation fault. The startup phase is completed when the battery IMD 441 indicates no insulation fault. The start-up phase comprises communicating S513, to the processing circuitry 410 of the arrangement 400, an indication that there is an insulation fault, that there is no insulation fault or that it cannot be determined if there is an insulation fault.

[0046] In one embodiment, the battery IMD 441 is arranged to monitor an insulation of the traction battery 130. When the monitoring response indicates an insulation fault, the traction battery is prevented from connecting (or is disconnected if previously connected) to the drive line and propulsion of the vehicle 10 is prevented.

[0047] The monitoring phase generally comprises initiating S520 a predetermined monitoring sequence for running the plurality of IMDs 440 in a predetermined order defined by the predetermined monitoring sequence, to avoid interference between the monitoring signals transmitted by the plurality of IMDs 440. The plurality of IMDs 440 is arranged to be operated, during the monitoring sequence, such that no one IMD is running at the same time as another IMD in the monitoring sequence. Running an IMD should be understood as transmitting a monitoring signal and detecting a monitoring response, as will be described in detail below. Running an IMD should not be seen as relating to if the IMD is electrically connected to the network 200 or not. It will thus be understood that the plurality of IMDs 440 may or may not be electrically connected at the same time, regardless if they are running.

[0048] As mentioned, the method 500 comprises initiating S520 the predetermined monitoring sequence. Initiating the predetermined monitoring sequence comprises, as a first step of the monitoring sequence, running a first IMD of the plurality of IMDs 440. Running the first IMD comprises transmitting5521 a monitoring signal to a circuit comprising a first electric insulation which the first IMD is monitoring. Running the first IMD subsequently comprises detecting5522 a monitoring response. In one embodiment, the method 500 compriseselectrically disconnecting the first IMD from the network 200 when the monitoring response is detected.

[0049] Running the first IMD furthermore comprises determining S523 if the monitoring response indicates an insulation fault in the first insulation. The monitoring response may indicate: that there is an insulation fault, that there is no insulation fault, or that it cannot be determined if there is an insulation fault. The method 500 comprises determining that there is an insulation fault in the first insulation when the monitoring response indicates that there is an insulation fault or when the monitoring response indicates that it cannot be determined if there is an insulation fault.

[0050] Determining if the monitoring response indicates an insulation fault may comprise comparing the monitoring response to a threshold value. In one embodiment, the monitoring response is a voltage, and the monitoring response indicates an insulation fault when the voltage is below the threshold value. In one embodiment, the monitoring response is a voltage, and the monitoring response indicates an insulation fault when a difference between the voltage and the threshold value is greater than a predetermined difference.

[0051] In one embodiment, determining if the monitoring response indicates an insulation fault may comprise comparing the monitoring response to a first threshold value and a second threshold value. In this embodiment the first threshold value relates to an increased risk of an insulation fault. As such, when the monitoring response is below the first threshold value, a warning may be communicated to an operator or to a control system that there is a risk of an emerging insulation fault. The second threshold value relates to an actual insulation fault. As such, when the monitoring response is below the second threshold value, it is determined that the monitoring response indicates an insulation fault.

[0052] When the first IMD detects a monitoring response, a second IMD in the monitoring sequence is triggered to start running, as a second step of the monitoring sequence. As such, the first and second IMD do not run at the sametime. Running the second IMD works in an equivalent manner as running the first IMD. That is, running the second IMD comprises transmitting S524 a monitoring signal and detecting S525 a monitoring response and, when the second IMD detects a monitoring response, a subsequent IMD of the plurality of IMDs 440 is triggered to start running. Running the second IMD thus also comprises determining S526 if the detected monitoring response indicates an insulation fault. Running the plurality of IMDs 440 continues until each of the plurality of IMDs 440 in the monitoring sequence has been run at least one time. How many times and in which order the plurality of IMDs 440 are run is defined by the monitoring sequence.

[0053] The method 500 comprises determining S527 if any one of the plurality of IMDs 440 has indicated an insulation fault during the monitoring sequence. In one embodiment, this is determined S527 when the monitoring sequence has been completed. In one embodiment, this is determined S527 during the monitoring sequence. In one embodiment, this is determined S527 at regular intervals during the monitoring sequence, for example after an IMD of the plurality of IMDs 440 has received a monitoring response. When it is determined that each of the plurality of IMDs 440 indicates no insulation fault, the method 500 comprises allowing S528a the vehicle 10 to connect to the external power source 300. This may comprise communicating to an operator or a control system that it is safe to connect. When it is determined that at least one of the plurality of IMDs 440 indicates an insulation fault, the method 500 comprises preventing S528b the vehicle 10 from connecting to the external power source 300. This may comprise communicating to an operator or a control system that it is not safe to connect.

[0054] The method 500 may furthermore comprise re-initiating S529 the predetermined monitoring sequence. The predetermined monitoring sequence may be re-initiated when the last IMD of the plurality of IMDs 440 in the sequence has received a monitoring response. The predetermined monitoring sequence may be re-initiated when it is determined that at least one of the plurality of IMDs 440 has indicated an insulation fault. In one embodiment, the monitoring sequence is re-run until each of the plurality of IMDs 440 indicates no insulation fault during thesame monitoring sequence. In one embodiment, the monitoring sequence is re-run until the vehicle 10 is connected to the external power source 300.

[0055] The connected phase of the method 500 is initiated S530 when the vehicle 10 is connected, through the current collector 110, to the external power source 300. During the connected phase, the predetermined monitoring sequence is not initiated. The external power source 300 may comprise an external IMD 310 which is running during the connected phase. The external IMD 310 is, in the connected phase, connected to the same network 200 as the plurality of IMDs 440 of the vehicle 10. During the connected phase, each of the plurality of IMDs 440 may or may not be running. The predetermined monitoring sequence is preferably initiated again when the vehicle 10 is disconnected from the external power source 300.Example 1

[0056] An exemplary embodiment of the disclosure will now be described with reference to a monitoring sequence schedule seen in Fig. 7. The monitoring sequence schedule displays in which phase and in what order the respective IMDs are run. Each row relates to a step and an “x” indicates if the IMD is running in said step.

[0057] In the exemplary embodiment, the plurality of IMDs 440 comprises three IMDs: a first current collector IMD 442 monitoring an insulation between the housing 112 of the current collector 110 and the chassis of the vehicle 10, a second current collector IMD 443 monitoring an insulation between the housing 112 of the current collector 110 and the converter primary side, and a converter IMD monitoring an insulation between the chassis of the vehicle 10 and the converter primary side.

[0058] In the sequence schedule in Fig. 7 there is displayed the start-up phase comprising running the battery IMD 441 and determining if there is an insulation fault in the battery insulation. When it is determined there is no insulation fault inthe battery insulation, the method 500 comprises initiating the predetermined monitoring sequence.

[0059] The sequence schedule displays the predetermined monitoring sequence defining the order of running the plurality of IMDs 440 in the monitoring phase. The monitoring sequence comprises: firstly running the first current collector IMD 442, secondly running the second current collector IMD 443, and thirdly running the converter IMD, thus completing the monitoring sequence. Running each of the IMDs is described above. Each time the monitoring sequence is completed, it is determined if an insulation fault has been detected by at least one of the plurality of IMDs 440. When it is determined that no one of the plurality of IMDs 440 indicated an insulation fault, the current collector 110 may be connected to the external power source 300.

[0060] In the monitoring phase, the vehicle 10 may travel in the mining environment by drawing electricity from the battery.

[0061] In the sequence schedule in Fig. 7 there is displayed the connected phase. In this embodiment, the external IMD 310 and the battery IMD 441 is running during the connected phase.Example 2

[0062] The embodiment according to Example 2 is essentially equal to embodiment according to Example 1 , if not stated otherwise.

[0063] In the embodiment according to Example 2, the plurality of IMDs 440 comprises four IMDs: the first current collector IMD monitoring the insulation between the housing 112 of the current collector 110 and the chassis of the vehicle 10, the second current collector IMD monitoring the insulation between the housing 112 of the current collector 110 and the converter primary side, the converter IMD monitoring the insulation between the chassis of the vehicle 10 and the converter primary side, and the battery IMD.

[0064] During the monitoring phase, the battery IMD is running as part of the predetermined monitoring sequence. When the monitoring sequence is completed, and if it is determined that the battery IMD indicated an insulation fault, the method 500 further comprises disconnecting the battery from the drive line, thus returning to the start-up phase of the method 500.

[0065] Preferred embodiments of a computer-implemented method, an arrangement and a mining vehicle have been described. However, a person skilled in the art realizes that this can be varied within the scope of the appended claims without departing from the inventive idea.

[0066] All the described alternative embodiments above or parts of an embodiment can be freely combined or employed separately from each other without departing from the inventive idea as long as the combination is not contradictory.

Claims

CLAIMS1 . A computer-implemented method (500) for monitoring electric insulations of a mining vehicle (100) by means of a plurality of insulation monitoring devices (440), IMDs, the mining vehicle (100) being arranged to travel in a mining environment, the mining environment comprising infrastructure for energy transmission to mining vehicle during transport, the mining vehicle (100) comprising: an electric drive line comprising at least one traction motor, an energy transmission system comprising a converter (120) and a current collector (110), for connection of the mining vehicle (100) to the infrastructure for energy transmission and for transmitting electric energy to the electric drive line, and an arrangement (400) comprising the plurality of IMDs (440), comprising at least one energy transmission system IMD (442; 443; 444) arranged to monitor a respective electric insulation of the energy transmission system, the method (500) comprising: initiating a predetermined monitoring sequence comprising, for each of the plurality of IMDs (440), transmitting a monitoring signal and subsequently receiving a monitoring response, the monitoring sequence defining the order in which each of the plurality of IMDs (440) transmits the monitoring signal, wherein, an IMD is triggered to transmit a monitoring signal when a preceding IMD in the monitoring sequence receives the monitoring response.

2. The method (500) according to claim 1 , further comprising, when at least one of the received monitoring responses during at least one monitoring sequence indicates an insulation fault: preventing connection of the mining vehicle (100) to the infrastructure for energy transmission, and when each of the received monitoring responses during at least one monitoring sequence indicates no insulation fault: allowing connection of the mining vehicle (100) to the infrastructure for energy transmission.

3. The method (500) according to claim 1 or 2, further comprising when at least one of the received monitoring responses during at least one monitoring sequence indicates an insulation fault: initiating the predetermined monitoring sequence.

4. The method (500) according to any one of the preceding claims, further comprising repeating the monitoring sequence as long as the mining vehicle (100) is not connected to the infrastructure for energy transmission.

5. The method (500) according to any one of the preceding claims, wherein the mining vehicle (100) comprises an electric energy storage (130) comprising at least one drive line IMD (441 ) arranged to monitor a respective insulation of the electric drive line, the method (500) further comprising, when starting the vehicle (100): transmitting, by the at least one drive line IMD (441 ), a monitoring signal and subsequently receiving a monitoring response, when the monitoring response indicates an insulation fault: preventing connection between the electric energy storage (130) and the electric drive line, when the monitoring response indicates no insulation fault: connecting the electric energy storage (130) to the electric drive line and initiating the predetermined monitoring sequence.

6. The method (500) according to claim 5, wherein the at least one drive line IMD (441 ) is one of the plurality of IMDs (440).

7. The method (500) according to any one of the preceding claims, further comprising: when a monitoring response received by an IMD of the plurality of IMDs (440) is below a predetermined threshold, indicating an insulation fault of the respective monitored electric insulation, when the monitoring response is above the predetermined threshold, indicating no insulation fault of the respective monitored electric insulation.

8. The method (500) according to any one of the preceding claims, wherein the at least one energy transmission system IMD is one of: a first current collector IMD (442) monitoring an insulation between the current collector (110) and a chassis of the vehicle (100), a second current collector IMD (443) monitoring an insulation between the current collector (110) and a converter primary side, a converter IMD (444) monitoring an insulation between a chassis of the vehicle (100) and the converter primary side.

9. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method (500) according to any one of the preceding claims.

10. Computer-readable medium comprising instructions which, when executed by a computer, cause a computer to carry out the method (500) according to any one of the claims 1-8.11 . Arrangement (400) for monitoring electric insulations of a mining vehicle (100) by means of a plurality of insulation monitoring devices (440), IMDs, the mining vehicle (100) being arranged to travel in a mining environment, the mining environment comprising infrastructure for energy transmission to mining vehicle (100)s during transport, the mining vehicle (100) comprising: an electric drive line comprising at least one traction motor, and an energy transmission system comprising a converter (120) and a current collector (110), for connection of the mining vehicle (100) to the infrastructure for energy transmission and for transmitting electric energy to the electric drive line, the arrangement (400) comprising: processing circuitry (410), means for communication (420), a memory (430), and the plurality of IMDs (440), comprising at least one energy transmission system IMD arranged to monitor a respective electric insulation of the energy transmission system,the arrangement (400) being operative for: initiating a predetermined monitoring sequence comprising, for each of the plurality of IMDs (440), transmitting a monitoring signal and subsequently receiving a monitoring response, the monitoring sequence defining the order in which each of the plurality of IMDs (440) transmits the monitoring signal, wherein, an IMD is triggered to transmit a monitoring signal when a preceding IMD in the monitoring sequence receives the monitoring response.

12. The arrangement (400) according to claim 11 , wherein the mining vehicle (100) comprises an electric energy storage (130) comprising at least one drive line IMD (441 ) arranged to monitor a respective insulation of the electric drive line.

13. The arrangement (400) according to claim 11 or 12, wherein the at least one drive line IMD (441 ) is one of the plurality of IMDs (440).

14. The arrangement (400) according to any one of claims 11 - 13, wherein the at least one energy transmission system IMD is one of: a first current collector IMD (442) monitoring an insulation between the current collector (110) and a chassis of the vehicle (100), a first current collector IMD (443) monitoring an insulation between the current collector (110) and a converter primary side, a converter IMD (444) monitoring an insulation between a chassis of the vehicle (100) and the converter primary side.

15. A mining vehicle (100) arranged to travel in a mining environment, the mining environment comprising infrastructure for energy transmission to mining vehicle (100)s during transport, the mining vehicle (100) comprising: an electric drive line comprising at least one traction motor, an energy transmission system comprising a converter (120) and a current collector (110), for connection of the mining vehicle (100) to the infrastructure for energy transmission and for transmitting electric energy to the electric drive line, and an arrangement (400) comprising a plurality of IMDs (440) for monitoring electric insulations of the mining vehicle (100), comprising at least one energytransmission system IMD arranged to monitor a respective electric insulation of the energy transmission system.

16. The mining vehicle (100) according to claim 15, wherein the electric drive line comprises an electric energy storage (130) comprising at least one drive line IMD (441 ) arranged to monitor a respective insulation of the electric drive line.

17. The mining vehicle (100) according to claim 15 or 16, wherein the at least one drive line IMD (441 ) is one of the plurality of IMDs (440).

18. The mining vehicle (100) according to any one of claims 15-17, wherein the at least one energy transmission system IMD is one of: a first current collector IMD (442) monitoring an insulation between the current collector (110) and a chassis of the vehicle (100), a first current collector IMD (443) monitoring an insulation between the current collector (110) and a converter primary side, a converter IMD (444) monitoring an insulation between a chassis of the vehicle (100) and the converter primary side.

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