TECHNICAL FIELD OF THE INVENTION
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The invention is in the field of DC supplied lighting tracks. More specifically, the invention relates to an electrical module for such a lighting track and to a lighting track system.
BACKGROUND OF THE INVENTION
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A lighting track system provides tracks (sometimes referred to as power tracks) to which luminaires can be mounted in a simple and intuitive way. The mounted luminaires are supplied by electrical power and sometimes also control signals via the tracks.
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Typically, the tracks provide numerous mechanical mounting options for the luminaires and, at the same time, provide electrical energy and control signals to the mounted luminaires via their entire length. The electrical and/or mechanical contacting between the luminaires and the tracks is often carried out via one or two adapter elements (e.g., plug/socket pairs for the electrical connection of luminaires to tracks). The electrical connections are often designed so that a layperson and not just a qualified electrician can open and close the connection.
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Most conventional tracks provide an AC supply voltage in a low-voltage range (e.g., 230VAC in Europe or 110VAC in North America). The properties of the AC mains supply are well known and interactions with the lighting system are specified and included in corresponding standards.
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For many applications, it would be advantageous to have lighting tracks which provide DC instead of AC power. However, transitioning from an AC to a DC power supply via tracks can lead to specific problems, particularly when switching on and off or contacting/de-contacting DC conductors.
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In particular, a lighting track system should guarantee electrical safety not only during operation, but also when mounting/dismounting luminaires. As it cannot be assumed that a layperson will only carry out such actions when an external power supply is switched off, these activities should be safe to carry out at all times. For instance, there should be no risk that a user could receive an electrical shock or that the track, the luminaire or the adapter could be damaged during such actions (e.g., by current, heating or other effects when opening/closing electrical contacts).
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A conventional lighting track system might not fulfill these safety requirements when it is supplied by DC power, because the physical properties and expected effects of a DC voltage network are not considered in conventional lighting track systems.
SUMMARY OF THE INVENTION
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Thus, it is an objective of the invention to provide an improved lighting track system which provides DC power and which avoids the above-mentioned disadvantages.
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The object of the present invention is achieved by the solution provided in the enclosed independent claims. Advantageous implementations of the present invention are further defined in the dependent claims.
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According to a first aspect, the invention relates to an electrical module for a lighting track. The electrical module is designed to be mounted in the lighting track and comprises: a first electrical connection which is arranged for being directly or indirectly connected to a building-side DC power supply; a second electrical connection which is arranged for being connected to an electrical conductor arrangement of the lighting track; wherein the electrical module is configured to electrically connect the DC power supply with the electrical conductor arrangement to provide DC power to the electrical conductor arrangement. The electrical module further comprises a sensing element which is configured to monitor at least one first electrical characteristic of the DC power supply and/or at least one second electrical characteristic of the electrical conductor arrangement; wherein the sensing element is configured to detect at least one fault condition based on the at least one first electrical characteristic and/or the at least one second electrical characteristic.
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This achieves the advantage that electrical faults or other unwanted effects that occur at the side of the DC power supply (e.g., voltage/current surges) can be efficiently detected. At the same time, electrical faults or other unwanted effects that occur at the tracks (e.g., at the luminaires or their contacting adapters) can be efficiently detected as well. Upon detecting such unwanted effects, the electrical module can initiate further measures (e.g., issue a warning or interrupt the power connection between track and power supply).
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The first electrical connection can comprise a number of terminals which are connected to the building-side DC power supply. This connection can be indirect, e.g. via a further connector module in the lighting track which is, in turn, connected to the building-side DC power supply.
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The DC power supply can provide DC power with voltages above 120VDC, i.e., above the extra-low voltage range.
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The second electrical connection can comprise contact pads which are electrically connected to the electrical conductor arrangement if the electrical module is mounted in the lighting track.
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The electrical conductor arrangement can comprise a plurality of electrical lines or conductors which are arranged to run along the length of the track.
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The electrical module being designed to be mounted in the lighting track may refer to the electrical module being shaped such that it can be inserted in the lighting track which, e.g., has a U-shaped cross section. For instance, the electrical module can be mounted in the lighting track with a positive fit.
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The lighting track can be a DC power track. The lighting track can supply devices (e.g., luminaires) mounted in or to the track with (DC) electrical power.
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The electrical module can be configured to transmit a DC supply signal from the building-side DC power supply to the electrical conductor arrangement of the lighting track. As a result, a DC voltage can be present between the conductors (e.g., electrical lines) of the electrical conductor arrangement. Luminaires that are mounted in the lighting track and are thus in contact with the conductors can receive their electrical supply from said voltage.
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The sensing element can comprise one or more voltage and/or current sensors. The electrical module or more particular the sensing element may further comprise a processor or a control logic configured to analyze the measured first and/or second electrical characteristic to detect the at least one fault condition.
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In an embodiment, the at least one first electrical characteristic comprises a voltage and/or a current provided by the DC power supply. This provides the advantage that voltage and/or current anomalies at the DC supply side can be detected.
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In an embodiment, the at least one second electrical characteristic comprises: a current flowing through at least one conductor of the electrical conductor arrangement, a differential current between at least two conductors of the electrical conductor arrangement and/or a voltage between at least two conductors of the electrical conductor arrangement. This provides the advantage that voltage and/or current anomalies at the lighting track side can be detected.
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In an embodiment, the at least one fault conduction comprises: an inrush current surge (e.g., from the DC power supply), an overvoltage surge from the DC power supply, a residual current at the electrical conductor arrangement, and/or an electrical discharge at the electrical conductor arrangement. For instance, the inrush current surge can be caused by an impedance change on the track (e.g. due to charging of a luminaire driver capacitor).
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For example, the sensing element can be configured to detect the inrush current surge when a monitored current supplied by the DC power supply sharply increases from zero, e.g., above a first threshold value.
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The sensing element can be configured to detect the overvoltage surge when a monitored voltage provided by the DC power supply exceeds a second threshold value. For instance, the overvoltage can be a common mode overvoltage from the DC supply (e.g., due to inductive effects when disconnecting devices) or a differential mode overvoltage from the DC supply (e.g., in case of a lightning strike in a line). The sensing element can detect both common mode and differential mode overvoltages.
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Furthermore, the sensing element can be configured to detect the residual current if it detects a differential current between different conductors of the electrical conductor arrangement.
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Moreover, the sensing element can be configured to detect the electrical discharge (e.g., an arc-discharge, a corona-discharge or a glow discharge) when the monitored voltage between two conductors and/or the current flowing through a conductor show a characteristic behavior, e.g. exceed above a third threshold value or have a certain shape in time or frequency domain.
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The sensing element may further detect slowly changing and/or increasing effects such as tracking due to dirt in the conductor arrangement.
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In an embodiment, the electrical module further comprises an interface which is configured to issue a warning signal if the sensing element detects the at least one fault condition. For instance, the warning signal can comprise additional information, e.g., which fault condition is reached. The interface can be a communication interface.
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In an embodiment, the electrical module further comprises a switching element and/or a DC fuse; wherein the switching element and/or the DC fuse are configured to interrupt the electrical connection between the DC power supply and the electrical conductor arrangement if the sensing element detects the at least one fault condition.
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For instance, the switching element and/or a DC fuse can be configured to interrupt the electrical connection if the fault condition is an overvoltage surge or a residual current.
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In an embodiment, the electrical module further comprises a current and/or voltage limiting element which is configured to limit a current and/or a voltage of a DC supply signal which is transmitted by the electrical module from the DC power supply to the electrical conductor arrangement if the sensing element detects the at least one fault condition.
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For instance, the current and/or voltage limiting element can be configured to limit the current if the fault condition is an inrush current surge. Furthermore, the current and/or voltage limiting element can be configured to limit the voltage if the fault is an overvoltage surge.
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In an embodiment, the sensing element is configured to sense the at least one first electrical characteristic of the DC power supply at the first electrical connection.
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In an embodiment, the sensing element is configured to sense the at least one second electrical characteristic of the DC power supply at the second electrical connection.
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In an embodiment, the electrical module comprises a housing with at least one side wall which is complementary shaped to a profile of at least one side wall and/or base of the lighting track. This achieves the advantage that the electrical module can be mounted in the lighting track in a simple and intuitive manner.
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In an embodiment, the second electrical connection comprises a number of electrical contact pads which electrically contact the conductor arrangement if the electrical module is mounted in the lighting track. For instance, the electrical contact pads are arranged on the at least one side wall of the electrical module.
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According to a second aspect, the invention relates to a lighting track system comprising: a lighting track which comprising an electrical conductor arrangement; and the electrical module according to the first aspect of the invention which is mounted in the lighting track.
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The lighting track can have a U-shaped cross-section. The inner side walls and/or the inner base of the U-shaped track can comprise a profile which allows mounting the electrical module or other components (e.g., luminaire adapters). The conductors of the conductor arrangement can be arranged to run along the profiled inner side walls and/or base. Two or more side walls of the electrical module can have a complementary profile to the lighting track profile. In this way, the electrical module can be mounted in the lighting track in a simple and secure way.
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In an embodiment, the lighting track comprises a DC connector module which is connected to a building-side DC power supply; wherein the first electrical connection of the electrical module is electrically connected to the connector module.
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For instance, the DC connector module can be mounted in the lighting track and can comprise connection terminals, e.g. clamp connectors, for connecting electrical lines from the DC power supply.
BRIEF DESCRIPTION OF THE DRAWINGS
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The invention will be explained in the followings together with the figures.
- Fig. 1
- shows a schematic diagram of an electrical module according to an embodiment;
- Fig. 2
- shows a schematic diagram of a lighting track system according to an embodiment;
- Fig. 3
- shows a schematic diagram of a lighting track system according to an embodiment; and
- Fig. 4
- shows a schematic diagram of a lighting track system according to an embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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Fig. 1 shows a schematic diagram of an electrical module 10 for a lighting track 21 according to an embodiment. The electrical module 10 is designed to be mounted in the lighting track 21.
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The electrical module 10 comprises: a first electrical connection 11 which is arranged for being directly or indirectly connected to a building-side DC power supply 30; a second electrical connection 12 which is arranged for being connected to an electrical conductor arrangement 22 of the lighting track 21; wherein the electrical module 10 is configured to electrically connect the DC power supply 30 with the electrical conductor arrangement 22 to provide DC power to the electrical conductor arrangement 22. The electrical module 10 further comprises a sensing element 13 which is configured to monitor at least one first electrical characteristic of the DC power supply 30 and/or at least one second electrical characteristic of the electrical conductor arrangement 22; wherein the sensing element 13 is configured to detect at least one fault condition based on the at least one first electrical characteristic and/or the at least one second electrical characteristic.
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The first electrical connection 11 can comprise a number of terminals which are connected to the building-side DC power supply 30. This connection can be direct, as shown in Fig. 1, or indirect, e.g. via a further connector module mounted in the lighting track 21 which is, in turn, connected to the building-side DC power supply 30.
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The building-side DC power supply 30 can be a DC power source or a DC supply network which is adapted for electrically supplying one or more devices, e.g. multiple lighting tracks, luminaires, and/or sensors, in a building with DC power.
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The DC power supply can provide DC power with voltages above 120VDC, i.e., above the extra-low voltage range.
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The second electrical connection 12 can comprise contact pads which are electrically connected to the electrical conductor arrangement 22 if the electrical module 10 is mounted in the lighting track 21.
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The electrical conductor arrangement 22 can comprise a plurality of conductors (e.g., electrical lines) which are arranged to run along the length of the track 21.
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The electrical module 10 being designed to be mounted in the lighting track 21 may refer to the electrical module being shaped such that it can be inserted in the lighting track 21 which, e.g., has a U-shaped cross section. For instance, the electrical module can be mounted in the lighting track with a positive fit. The electrical module 10 can be detachably attached to the lighting track 21 in this way.
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The electrical module 10 can be configured to transmit and/or feed a DC supply signal from the building-side DC power supply 30 to the electrical conductor arrangement 22. As a result, a DC voltage can be present between the conductors of the electrical conductor arrangement 22. Luminaires that are mounted in the lighting track 21 (e.g., via an adapter) and are thus in contact with the electrical conductors can receive their electrical supply from said DC voltage.
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Thereby, the voltage between the conductors of the track 21 and/or a current passing through individual conductors may depend on the DC supply signal that is forwarded to the conductors and/or on a state of devices connected to the track (e.g., luminaires). For instance, mounting or dismounting luminaires to or from the track can cause instantaneous changes in said voltage or current.
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The sensing element 13 can comprise one or more voltage and/or current sensors. The electrical module 10 or more particular the sensing element 13 may further comprise a processor or a control logic configured to analyze the measured at least one first and/or second electrical characteristic and, as a result of this analysis, detect the at least one fault condition.
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The first and/or second electrical characteristics can be electrical parameters, e.g., of a current and/or voltage from the DC power supply respectively on the conductor arrangement.
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For example, the at least one first electrical characteristic comprises a voltage and/or a current provided by the DC power supply 30.
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The at least one second electrical characteristic may comprise a current flowing through at least one conductor of the electrical conductor arrangement 22, a differential current between at least two conductors of the electrical conductor arrangement 22 and/or a voltage between at least two conductors of the electrical conductor arrangement 22.
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For example, the sensing element 13 can be configured to sense the at least one first electrical characteristic of the DC power supply 30 at the first electrical connection 11 and/or to sense the at least one second electrical characteristic of the electrical conductor arrangement at the second electrical connection 12. Therefore, the sensing element 13 can be electrically connected to the first and/or second electrical connection 11, 12.
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By monitoring the at least one first and/or second electrical characteristic, the electrical module 10 can detect faults which emerge from the DC power supply and/or faults which emerge from the lighting track (e.g., at the luminaires or their contacting adapters). Upon detecting such unwanted effects, the electrical module 10 can initiate further measures (e.g., issue a warning or interrupt the power connection between track and power supply), as will be discussed in the following.
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The electrical module 10 can comprise an optional interface 14, e.g. a communication interface, which is configured to issue a warning signal if the sensing element detects the at least one fault condition. For example, the warning signal can comprise additional information, e.g., which fault condition is reached. This communication may especially be carried out in case of fault conditions caused on the lighting track side of the electrical module 10 (e.g., at the conductor arrangement 22 or the connected luminaires).
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In another example, the interface 14 is connected to a return channel for feeding back a portion of a received DC signal in case a fault condition (e.g., an overcurrent / overvoltage) is detected.
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The electrical module 10 can further comprise an optional switching element and/or DC fuse 15. The switching element and/or the DC fuse 15 can be configured to interrupt the electrical connection between the DC power supply 30 and the electrical conductor arrangement 22 if the sensing element 13 detects the at least one fault condition. The switching element can be a DC circuit breaker.
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In this way it can be prevented that faults which occur at the building-side DC power supply (e.g., voltage/current surges) are transferred to the conductor arrangement 22 and the connected luminaires. At the same time, it can be prevented that faults at the conductor arrangement 22 are transferred back to the DC power supply 30.
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In addition or alternatively, the electrical module 10 can comprise a current and/or voltage limiting element 16. The current and/or voltage limiting element 16 can be configured to limit a current and/or a voltage of a DC supply signal which is transmitted by the electrical module 10 from the DC power supply 30 to the electrical conductor arrangement 22 if the sensing element detects the at least one fault condition (e.g., an overvoltage surge or an inrush current surge surge).
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The current and/or voltage limiting element 16 can be specifically adapted for limiting DC currents and/or voltages.
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Figs. 2-4 show exemplary embodiments of a lighting track system 20 which comprise the electrical module 10 and the lighting track 21, wherein the electrical module 10 is mounted in the lighting track 21.
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In the system 20 shown in Fig. 2, the first electrical connection 11 of the electrical module 10 is connected to a connector module 23 of the system 20 which is in-turn connected to the building-side DC power supply (not shown). Thus, the electrical module 10 is indirectly connected to the DC power supply. However, a direct connection between electrical module 10 and DC supply might also be possible.
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In the exemplary system 20 shown in Fig. 2, the first electrical connection 11 of the electrical module 10 comprises two connectors for connecting to L+ and L- (positive and negative line) of the DC power supply and the second electrical connection 12 comprises two connectors (e.g., formed as contact pads) for connecting to two different conductors DCIL+, DCIL- (i.e., positive and negative line conductors) of the electrical conductor arrangement. In this way, the electrical module 10 can form a power feeder for the lighting track 21 which forwards a DC supply signal to the conductor arrangement 22 and at the same time monitors the DC supply and the conductors of the conductor arrangement 22.
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In an example, the electrical module 10 can detect a fault condition in the form of a discharge (e.g., an arc-discharge, a corona-discharge or a glow discharge) on the electrical conductor arrangement 22.
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For instance, in case a device, such as a luminaire, on the lighting track 21 does not contact the conductors DCIL+ und DCIL-properly, e.g. when mounting / dismounting a luminaire, an electric arc can occur between the conductor and the incomplete contact to the device. Furthermore, a glow discharge can occur if an electrically connection is not fully closed. The discharge detection, e.g. the sensing element 13, can be directly connected with the conductors DCIL+, DCIL- and can electrically detect such discharge events, e.g., via detection of a high frequency component of the current or voltage, which is caused by a discharge)
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This arc-detection can be communicated directly or via the connector module 23 to an external monitoring system or fuse (e.g., a DC sector smart breaker) via the interface 14.
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The electrical module 10 can comprise an active element which can be formed by the switching element and/or the DC fuse 15 or by the current and/or voltage limiting element 16. In case the active element is formed by the switching element and/or the DC fuse 15 it can terminate a detected discharge, e.g., by completely separating DCIL+ and DCIL- from L+ and L-. In case the active element is formed by the current and/or voltage limiting element 16, it can disrupt a discharge by limiting the current. Furthermore, the active element 16 could change its impedance, e.g., by switching on a stronger impedance to prevent resonant re-ignition of the discharge.
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In addition or alternatively, the electrical module 10 can be configured to detect and reduce an inrush current, e.g., when switching on the DC power supply 30. In this way, the electrical module 10 can limit the current flowing through the conductors DCIL+/DCIL+ which is.
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For instance, the inrush current can be detected when the current which is supplied by the DC power supply and forwarded to the conductor arrangement 22 sharply increases from zero, e.g., due to pre-loading of luminaires with sudden load changes. However, the switch-on of the L+, L- could also be communicated to the electrical module 10 in other ways.
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The current limitation in case of an inrush current surge can be carried out by the current and/or voltage limiting element 16 of the electrical module 10. This element 16 can be specifically adapted to the typically switch-on currents of the luminaires connected to the lighting track 21 and can reduce the current that flows through the conductors 22 in case L+/L- is switched-on and all connected luminaires have a high power demand simultaneously for a short time. This current limitation can be adapted to typical luminaire conditions and the capacitive start-up behavior of the luminaires.
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Fig. 3 shows the electrical module 10 being further connected to a protective earth PE line on the DC power supply 30 side and a corresponding conductor 22 for PE on the lighting track 21 side.
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For example, the electrical module 10 is configured to detect a fault condition in the form of a residual current at the electrical conductor arrangement 22. For instance, the sensing element 13 detects residual currents by monitoring currents flowing between the conductors of the conductor arrangement 22.
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Normally, devices (e.g., luminaires) connected to the lighting track are supplied from the conductors DCIL+ and DCIL- and no current flows through the protective earth PE. For residual current detection, the sensing element 13 can monitor currents flowing through DCIL+, DCIL- and PE. In case of a differential current between DCIL+ and DCIL- or in case of a current through DCIL+/DCIL- flows through PE, this detected "fault condition" can be signaled (e.g., via the interface 14) and/or DCIL-/DCIL+ can be disconnected from L+/L- (e.g., via the switching element and/or the DC fuse 15).
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In addition or alternatively, the electrical module 10 can be configured to detect and reduce overvoltage surges or spikes from the DC power supply. For instance, the sensing element 13 can detect such overvoltage surges or spikes if a DC supply voltage provided by the DC power supply exceeds a threshold value.
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For instance, the current and/or voltage limiting element 16 of the electrical module 10 can divert or limit the temporary overvoltage events in L+/L-, such that only small overvoltages occur on DCIL+/DCIL-. Thereby, the current and/or voltage limiting element 16 can specifically be adapted for the requirements of the lighting track 21 and the connected devices (e.g., luminaires), e.g., with regards to voltages, powers and possible reference points.
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For instance, the overvoltage between L+ and PE, between L- and PE, and between L+ and L- can be diverted respectively reduced separately by the element 16. Thereby, the overvoltages can be reduced in such a way that the conductor arrangement 22 only carries voltages which can be tolerated by the connected luminaries, in particular with respect to their lighting requirements (e.g., to ensure suppression of light flickering).
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Fig. 4 shows a perspective view of the lighting track system 20, wherein the electrical module 10 is mounted in the lighting track 21.
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The lighting track 21 can be a profiled track (or rail), e.g. made of a metal, which can accommodate adapters for electrically and mechanically contacting various devices and modules (e.g., luminaire adapters).
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As shown in Fig. 4, the lighting track 21 can have a U-shaped cross section with a profile on one or two inner side walls 25 and/or on the inner base. The conductors of the conductor arrangement 22 can be electrical lines which are arranged to run along the profiled inner side walls 25 and/or along the base of the track 21.
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For instance, the conductor arrangement 22 comprises conductor lines for electrically supplying connected luminaires and conductors lines for carrying control information to and/or from the luminaires.
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The electrical module 10 can comprise a housing with at least one side wall which is complementary shaped to the profile of the inner side wall 25 of the lighting track. In this way, the electrical module 10 can be mounted in the U-shaped track in a form-fitting manner. For instance, the electrical module does not recess from the U-shaped track if it is mounted in the track.
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For example, the second electrical connection 12 comprises a number of electrical contact pads which are arranged on the side walls of the electrical module 10 and which electrically contact the conductor arrangement 22 along the profiled side wall 25 if the electrical module 10 is mounted in the lighting track 21. In this way, both an electrical and a mechanical contacting between the electrical module 10 and the tracks can be realized in a simple and intuitive way.
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As shown in Fig. 4, the DC connector module 23 can be mounted in the lighting track and can comprise connection terminals, e.g. clamp connectors, for connecting electrical lines from the DC power supply. The DC connector module 23 can be interposed between the first electrical connection 11 of the electrical module 10 and the DC power supply.
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The electrical module 10 (in particular, together with the connector module 23) can be a barrier module and/or a power monitoring module. The electrical module 10 can form a power feeder or a feed-track for feeding DC power to the lighting track 21. For instance, the electrical module 10 can designed as an adapter, e.g. a DC supply quality infeed adapter, which can be mounted in the track 21.
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For instance, one or more luminaries can be connected to the lighting track 21 via adapters which are mounted in the track 21. The luminaire adapter(s) can receive electrical power and control information from the electrical conductor arrangement in the track and forward said power and control information to the luminaire. The luminaire adapter(s) can be mechanically fixated in the track 21 in the same way as the electrical module 10 (e.g., via a form-fitting connection). The luminaire adapter(s) can comprise adapter elements (e.g., plug/socket pairs for the electrical connection of luminaires to tracks).
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In summary, the electrical module 10 can establish an electrical connection between the lighting track and the DC power supply (e.g., a DC supply network). The electrical module 10 can thereby monitor electrical parameters of the DC power supply side and of the lighting track conductors, e.g., to ensure that no DC specific fault conditions occur on the lighting track.
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For instance, the electrical module 10 can have any combination of the following functions:
- An arc detection which detects discharge events on the luminaire side (e.g., at the electrical conductor arrangement 22) and which can switch off the DC power supply in response ("super-fuse");
- A residual current protective switch (DC capable) which can, e.g., detect common mode and differential mode currents.
- A DC fuse for voltage surges on DC supply side (e.g., a melting fuse or a switching element for DC).
- A return channel ("DC branch-off") for reporting fault conditions (discharge, load change, residual current, etc.).
- An overcurrent protection, e.g., for avoiding negative feedback when connecting a new luminaire.
- An overvoltage protection for avoiding damage to connected luminaires via reduction of voltage surges and spikes on the lighting track side of the electrical module 10.
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Although the invention has been illustrated and described with respect to one or more implementations, equivalent alternations and modifications will occur to those skilled in the art upon the reading of the understanding of the specification and the annexed drawings. In addition, while a particular feature of the invention may have been disclosed with respect to only of the several implementations, such features may be combined with one or more other features of the other implementations as may be desired and advantage for any given or particular application.