Surge protection device, corresponding apparatus and method

Abstract

Surge protection devices, corresponding apparatus and methods are disclosed. A surge protection apparatus (10, 12) for providing a power supply to an electrical device, such as an outdoor lighting device affected by possible overvoltage phenomena caused by a lightning stroke, comprises: surge protection circuitry (103, 104) configured to provide a surge discharge path between lines (L, N) in a power supply; a fault detection network (101, 102) coupled to the surge protection circuitry (103, 104) and configured to generate a detection signal that switches between a first value and a second value in response to a fault in the surge protection network (103, 104); and a driver (12) coupled (D4i / LSI) to the fault detection network (101, 102) to receive a detection signal from the fault detection network, the driver (12) configured (200, 201, 204) to issue a warning signal in response to the detection signal switching between a first value and a second value.

Description

Technical Field

[0001] This instruction manual relates to surge protection devices.

[0002] The solution disclosed herein may be used, for example, in outdoor lighting devices (eg, using LEDs as light generator sources) that are affected by possible overvoltage phenomena. Background Art

[0003] Outdoor lighting equipment can be subject to overvoltage conditions caused by lightning strikes to the wiring within the equipment.

[0004] Different solutions can be employed in order to protect the driver circuitry of a light source in a lighting device.

[0005] Outdoor lighting (e.g. street lighting), such as Figure 1 As shown, one or more (eg pole-mounted) lighting sources L (eg using LEDs as light generators) may be included, which are powered by a power cabinet C which in turn is powered by the mains distribution network.

[0006] For example, considering the case of L to N mode surge, protection widely used in such equipment includes a surge protection device (SPD) 10 housed in a cabinet C and including a varistor such as, for example, a metal oxide varistor (MOV).

[0007] This is a component that exhibits non-linear behavior and is configured to essentially behave like a Zener diode for voltages above the rated voltage of the component.

[0008] For example, for voltages above 230V RMS or 320V peak, the MOV starts clamping any (high) overvoltages coming from the mains distribution network (typically up to 10KV).

[0009] A problem associated with such a solution is that each surge (or "shot") may have a large amount of energy associated with it: therefore, even after a limited number of overvoltage events, the protection circuit may fail and short-circuit.

[0010] A short circuit to the mains may be counteracted via a fuse, but the fuse may eventually blow so that after a period of time the driver circuitry will no longer be protected.

[0011] Different solutions have been proposed to provide information about the status of a protection circuit (generally speaking, “feedback”). These may include an indicator 10A associated with a surge protection device (SPD) 10.

[0012] In an installation comprising a limited number of luminaires L, the protection may be located in the cabinet C of the installation (e.g. Figure 1 ), so that the indicator 10A will be easy to check.

[0013] For installations in long streets with many luminaires (e.g., mounted on poles), the SPD is connected directly next to the driver in the pole head to be more efficient.

[0014] This means that having an indicator is useless because it is difficult for the operator to see it.

[0015] In the case where the system is not equipped with an indicator, when the SPD fails, a fuse connected in series with the driver may cause the driver to shut down, which means that the lighting source will also be shut down (ie turned off).

[0016] Documents US2023 / 223749A1, US10004123B1 and US2022 / 159808A1 are examples of the prior art. Summary of the Invention

[0017] One or more embodiments are directed to helping address the various issues discussed above.

[0018] According to one or more embodiments, such objects are achieved by a surge protection device (SPD) having the features set out in the appended claims.

[0019] One or more embodiments relate to corresponding devices.A street lighting device comprising one or more (eg pole-mounted) lighting sources (eg using LEDs as light generators) may be an example of such a device.

[0020] One or more embodiments are directed to corresponding methods.

[0021] The claims are an integral part of the technical teaching regarding the embodiments provided herein.

[0022] The solution as described herein facilitates building a "smart" SPD, where information about possible failures of the SPD is provided to the driver.

[0023] In response to recognizing an SPD fault, the driver may provide the desired information (also referred to herein as "external" feedback) via a wireless / wired network and / or through the intensity of light emitted by the luminaire, through the ability to store relevant information, or through other feedback channels.

[0024] The solution as described herein provides one or more of the following advantages:

[0025] Continuously provides surge protection while providing feedback when damage occurs;

[0026] Reduce costs, because existing interfaces in the system can be used to detect faults and send corresponding feedback;

[0027] Reliability due to direct connection to the SPD. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] One or more embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0029] Figure 1 The related technologies and the shortcomings experienced by them have been discussed above;

[0030] Figure 2 is a block diagram illustrating the principles behind the solution described in this article;

[0031] Figure 3 and Figure 4 a circuit diagram that is part of the solution described herein; and

[0032] Figure 5 is an exemplary overall circuit diagram of the solution described herein. DETAILED DESCRIPTION

[0033] In the following description, one or more specific details are provided to provide a deeper understanding of examples of embodiments of the present specification. Embodiments may be obtained without one or more of the specific details or with other methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not described or illustrated in detail so that certain aspects of the embodiments are not obscured.

[0034] References to "an embodiment" or "one embodiment" in the framework of this specification are intended to indicate that a specific configuration, structure, or characteristic described with respect to the embodiment is included in at least one embodiment. Therefore, phrases such as "in an embodiment" or "in one embodiment" that may appear in one or more points of this specification do not necessarily refer to the same embodiment. Furthermore, specific configurations, structures, or characteristics may be combined in any appropriate manner in one or more embodiments.

[0035] The headings / reference numbers used herein are provided for convenience only and do not limit the scope of protection or the scope of the embodiments.

[0036] In all drawings attached herein, similar parts or elements are indicated by similar reference numerals / numbers unless the context indicates otherwise, and the corresponding description will not be repeated for the sake of brevity.

[0037] Furthermore, for simplicity and ease of explanation, the same reference numerals may be applied throughout the specification to indicate:

[0038] A node or line and a signal appearing on that node or line (this may be the case of the signal / line FB mentioned below), and / or

[0039] Components (such as capacitors or resistors) and their electrical parameters.

[0040] When it is mentioned herein that an element is “connected to” or “coupled to” another element, it should be understood that yet another element may be interposed between the elements, and the element may be directly connected or coupled to another element.

[0041] On the contrary, when it may be mentioned that an element is “directly connected to” or “directly coupled to” another element, it should be understood that there is no further element interposed between the elements.

[0042] Figure 2 is a block diagram illustrating the principles behind the solution described in this article.

[0043] exist Figure 2 In FIG. 1 , reference numeral 10 denotes a surge protection device (SPD) which is configured to be coupled (and thus activated) between a “line” terminal L and a “neutral” (ground) terminal N.

[0044] Such lines / terminals may exist in, for example, already combined Figure 1 The device in question is a street lighting comprising one or more (e.g. pole-mounted) lighting sources or luminaires L (e.g. using LEDs as light generators), which are powered by a power supply cabinet C which in turn is supplied with power from the mains distribution network.

[0045] Here again, by way of example, the case of a so-called surge protection device (SPD) 10 housed in a cabinet C between the differential line and the neutral point (between L and N) is considered.

[0046] In the solution described herein, the SPD 10 is made into a “smart” type of SPD (SPDS) with the capability of providing (external) feedback information about the status of the SPD 10 .

[0047] As shown herein, this information may be provided via connection or channel FB towards driver unit 12 (e.g., as signal SPDfb discussed below), which is configured to receive from SPD 10:

[0048] As is conventional in the art, power is supplied via lines L and N, and

[0049] Feedback information FB from the SPD 10.

[0050] In the solution described herein, the driver 12, and more generally the SPDS assembly (SPD 10 plus driver 12), is configured to be able to provide "external" feedback even in the absence of an indicator (such as Figure 1 In the case of indicator 10A).

[0051] As illustrated herein, such "external" feedback may be provided through channels including a wired connection WN (eg, a wired network) and / or through a wireless link WL (eg, via an antenna A).

[0052] Figure 3 is an exemplary circuit diagram of a "smart" SPD 10 configured to provide feedback in the form of a (advantageously) isolated signal FB.

[0053] exist Figure 3 In the circuit shown, a series connection of the emitter side of an optocoupler 101 (eg, a light emitting diode) and a resistor network 102 comprising two cascaded resistors RS1 and RS2 has been coupled between lines L and N.

[0054] exist Figure 3 In the exemplary circuit of , the series connection of the fuse 103 and the varistor 104 is likewise arranged between the lines L and N.

[0055] A varistor is a voltage-sensitive resistor. The resistance of a varistor is variable and depends on the applied voltage. When the voltage increases, the resistance decreases.

[0056] The varistor 104 may be of any type known to those skilled in the art. Advantageously, the varistor 104 may be a metal oxide varistor (MOV).

[0057] Such a varistor 104 (hereinafter referred to as MOV as an example of a varistor for simplicity) can provide appropriate surge protection, while the fuse 103 provides supplementary protection in the event of damage (end of life) of the MOV 104 .

[0058] The middle node between fuse 103 and MOV 104 is connected to the middle node between resistors RS1 and RS2 in resistor network (essentially a voltage divider) 102 .

[0059] MOV 104 is the active portion that provides protection for driver 12. Fuse 103 may operate to disconnect MOV 104 from the circuit when MOV 104 fails, which may occur after a certain number of surges (overload events).

[0060] In fact, even after a limited number of overvoltage events, the fuses 103 and / or the varistors 104 in the surge protection network may be damaged in different ways:

[0061] Fuse 103 "burns" or blows, thereby becoming an open circuit;

[0062] The varistor 104 becomes a short circuit (which almost always causes the fuse 103 to burn or blow immediately); and / or

[0063] The varistor 104 is set to a very high impedance, effectively becoming an open circuit (which may eventually cause the fuse 103 to burn out or blow).

[0064] Resistors RS1 and RS2 (collectively 102 ) plus optocoupler 101 provide the “intelligence” of smart SPD 10 .

[0065] In such Figure 3 In the exemplary circuit shown, the optocoupler 101 can be turned on (activated) in response to the fuse 103 opening (burning, thereby becoming non-conductive), which causes the (electrically isolated) feedback signal FB to become available at the output side of the optocoupler 101 (e.g., the phototransistor).

[0066] When fuse 103 blows, the emitter side (LED) in optocoupler 101 is activated by a current that may depend on whether MOV 104 also blows or whether MOV 104 is shorted.

[0067] In fact, the occurrence of damage in MOV 104 may be difficult to predict, such that:

[0068] In the case of a short circuit of the MOV, only the resistor RS2 in the resistor network 102 will limit the current through the optocoupler 101;

[0069] With the MOV 104 open circuit (having high impedance, essentially non-conductive), the optocoupler 101 will be powered through RS1 and RS2.

[0070] The resistors RS1 and RS2 may be sized so that the output transistor of the optocoupler 101 will close (become conductive), and the level of the feedback signal FB will change to indicate the occurrence of a fault condition.

[0071] In the apparatus illustrated herein, a surge discharge path between lines L and N is provided via surge protection circuitry, the surge discharge path including at least one of a fuse 103 and a varistor 104 having terminals coupled to a fault detection network consisting of elements 101 and 102 .

[0072] In summary, in the arrangement as described herein, a surge discharge path in the surge protection circuitry includes a series connection of a fuse 103 and a varistor 104 having a common terminal coupled to the fault detection networks 101 , 102 .

[0073] In an arrangement as described herein, such a fault detection network 101, 102 comprises:

[0074] a first resistor RS1 connected in parallel with the varistor 104 such that the first resistor RS1 is coupled to a common terminal of the fuse 103 (arranged between the line L and the varistor 104 ) and the varistor 104 (arranged between the fuse 103 and the line N);

[0075] A second resistor RS2 has a first end coupled to a common terminal of the fuse 103 and the varistor 104 and a second end coupled to an input of a signal transmission element (optionally an optocoupler) 101, such that such a signal transmission element has an output (e.g., an output transistor) configured to provide a detection signal FB / SPDfb that switches between a first value and a second value in response to a fault in the surge protection network 103, 104.

[0076] Optocoupler 101 facilitates isolation, which may be primary or dual.

[0077] A driver 12 associated with a “smart” SPD as described herein is configured to sense a feedback signal FB and process the feedback signal to know whether the output (transistor) of the optocoupler 101 is open or shorted.

[0078] like Figure 4 The exemplary driver 12 shown includes:

[0079] a port for receiving a feedback signal FB (eg, in the form of data SPDfb);

[0080] L / N input line or port 1 to the bridge rectifier 12;

[0081] a power factor controller (PFC) 122 coupled to the output of the bridge rectifier 121;

[0082] The DC / DC converter 123 is configured (in a manner known per se to a person skilled in the art) to supply power to the lighting source ( Figure 1 The lamp L) supplies DC voltage;

[0083] an auxiliary power supply 124 also controlled by the PFC 122; and

[0084] The interface 125 is supplied with voltages V− and V+ by the power supply 124 . The interface 125 is configured to collect data, mainly a feedback signal FB (eg, referred to as voltage V−) provided by the circuit 10 and a power supply voltage provided by the converter 123 .

[0085] The interface 125 is configured to emit signals corresponding to / derived from the collected data and communicate them as "external" feedback provided over a wired connection WN (eg, a wired network) and / or over a wireless link WL (eg, via antenna A).

[0086] exist Figure 4 In FIG. 1 , reference Rp denotes a pull-up resistor, via which a voltage V+ can be applied to one of the conductors of the line carrying the feedback signal FB, the other conductor being at a voltage V−.

[0087] The solution as described herein is suitable for being implemented as a universal driver.

[0088] However, advantageous implementations of the driver 12 illustrated herein may be based on a “D4i” (“IoT for Devices”) configuration that facilitates interoperability between devices within a lighting system.

[0089] As illustrated herein, the signal SPDfb is read at the input port of the feedback signal FB.

[0090] Advantageously, this is the input port of the driver 12, with a pull-up resistor Rp, the connection of which to the output of the optocoupler 100 of the SPD refers to the use of a (advantageous but not mandatory) "D4i type" driver in Figure 5 It is clearly stated in.

[0091] Figure 5 The circuit diagram of further details a possible advantageous implementation of a "smart" SPD as discussed herein.

[0092] exist Figure 5 In the embodiment, the various parts or components (such as the bridge rectifier 121, the power factor control circuit system 122 or the auxiliary power supply 124 described in conjunction with the previous figures) are represented by the same reference numerals / numbers: for the sake of brevity, they will not be combined again. Figure 5 The corresponding descriptions of these elements are repeated.

[0093] Furthermore, some parts or elements described in conjunction with the previous figures may be assumed to be incorporated into Figure 5 , so that certain aspects of the implementation will not be obscured: for example, Figure 4 The converter 123 may be assumed to be included in Figure 5 The power supply unit 201 and Figure 4The interface 125 may be assumed to be included in Figure 5 In the controller 200.

[0094] When the output of the "intelligent" SPD 10 is as Figure 5 When connected as shown, resistor Rp sinks current into the output (transistor) of optocoupler 101 to prevent damage to MOV 104.

[0095] The associated D4i ports are advantageously supplied via an auxiliary power supply 124 (voltages V+ and V- equal to 24V and DA-) so that these can advantageously be isolated with respect to the mains power supply ( Figure 1 ), even though this does not amount to a mandatory feature.

[0096] Figure 5 The circuit diagram shows a controller 200 cooperating with a power supply unit (PSU) 201.

[0097] Advantageously, associated with the controller 200 is an isolation block 202 that facilitates the collection of signals used by the controller 200 to cooperate with the power supply unit 201 to power lighting sources (eg, LEDs) generally designated 203 .

[0098] The isolation block 202 transmits (e.g., differentially, via the DA- pin of the D4i port plus a pin / line LSI added to that port) a feedback signal SPDfb from the surge protection device (SPD) 10 toward the controller 200: this is essentially the feedback signal / information also previously referred to as FB.

[0099] Therefore, the device 10, 12 as disclosed herein comprises at least one galvanic isolator located in the path of the detection signal FB; SPDfb through the fault detection network 101, 102 and the driver 12, namely:

[0100] An optical coupler 101 in the fault detection network, configured to apply a detection signal FB; SPDfb to the D4i / LSI port; and / or

[0101] The isolator block 202 located in the driver 12 is configured to receive the detection signal FB; SPDfb from the coupling port D4i / LSI.

[0102] The controller 200 is configured to identify whether the signal SPDfb is high or low and transmit a corresponding signal through an output line such as WN (wired network) and / or WL (wireless network). For the latter effect, the wireless module 204 can be coupled to the D4i / LSI port.

[0103] Advantageously, in an apparatus 10, 12 as described herein, the driver 12 may be configured to emit a warning signal ("external feedback") as:

[0104] an electrical warning signal on the wired link WN; and / or

[0105] RF warning signal on wireless link WL,A.

[0106] Advantageously, the controller 200 may be configured (in a manner known per se to those skilled in the art) to modify the DC / DC behavior of the PSU 201 and effect some changes in the parameters controlling the LED load as shown in block 203 .

[0107] That is, in the devices 10, 12 proposed herein, the driver 12 is configured to drive (via the PSU 201) an electrical load 203 based on a set of drive parameters and to modify the set of drive parameters by switching between a first value and a second value in response to a detection signal SPDfb from the optical isolator 101.

[0108] As mentioned above, although this does not represent a mandatory option, a "smart" SPD as discussed herein benefits from the driver 12 being based on an otherwise conventional D4i driver configuration modified as discussed herein.

[0109] Drives called D4i drives are "intelligent" drives that collect and transmit data to a central data management system. These drives can potentially use associated data interfaces to reveal when protection is no longer available (expired) or damaged: this facilitates the correct scheduling (synchronization) of services to possibly replace damaged components.

[0110] In short, for this reason, Figure 5 The driver 12 illustrated in FIG. 1 may advantageously include:

[0111] Bridge rectifier 121;

[0112] Power factor correction (PFC) circuitry 122;

[0113] Auxiliary (isolated) power circuitry 124 configured to provide dedicated low voltage power to the power factor correction (PFC) circuitry 122 and the power supply unit 201 of the LED source 203;

[0114] an isolation block 202 for isolating the D4i / LSI port with respect to the control unit 200;

[0115] D4i / LSI input / output ports, ie D4i ports supplemented with LSI pins in the solution as described herein.

[0116] As discussed, the LSI pin is configured to detect a fault / damage condition affecting the MOV 104, the fuse protection 103 of the MOV 104, the supply to the optocoupler 101 when the MOV 104 is damaged, or the optocoupler 101 based on the feedback FB (signal SPDfb) provided at the output of the optocoupler 101.

[0117] In summary, the "smart" SPDs 10, 12 disclosed herein include surge protection circuitry 103, 104 configured to provide a surge discharge path between lines L, N in a power source, and a fault detection network 101, 102 coupled to the surge protection circuitry 103, 104 and configured to generate a detection signal FB that switches between a first value and a second value in response to a fault in the surge protection network 103, 104. A driver 12 coupled to the fault detection network 101, 102 (via a D4i / LSI port) receives the detection signal FB; SPDfb from the fault detection network and issues a warning signal in response to the detection signal FB; SPDfb switching between the first value and the second value.

[0118] In the devices 10, 12 as shown herein, the fault detection network 101, 102 includes a signal transmission element (optocoupler 101) having an output (e.g., an output transistor) coupled to a pull-up resistor Rp, which facilitates the signal transmission element 101 to cause the detection signal FB; SPDfb to switch between a first (logical) value and a second (logical) value in response to a fault in the surge protection network 103, 104.

[0119] It should be noted that the pull-up resistor Rp is shown as included in Figure 4 The driver 12 and included in Figure 5 In SPD 10.

[0120] This is to emphasize that the pull-up resistor Rp does not necessarily need to be included in the driver 12 .

[0121] The name D4i / LSI is also intended to emphasize that the port may advantageously comply with the D4i standard, with a 24V pin configured to connect to the intelligent SPD 10 and an additional LSI input.

[0122] Providing a pull-up resistor Rp in the smart SPD 10 facilitates preparing the component for direct connection to a 24V voltage.

[0123] Furthermore, the controller 200 can read the LSI signal passing through the isolation block 202 and can also transmit “external feedback” data for wireless communication through the module 204 configured as a communication module conforming to the Digital Addressable Lighting Interface (DALI) dedicated protocol for digital lighting control.

[0124] It will be understood that although the differential LN surge mode has been discussed herein by way of example, the solution as proposed herein may also be applied to other surge modes, such as the common L / N-to-ground surge mode.

[0125] Thus, a solution as proposed herein may facilitate the adoption of (e.g., MOV-based) SPD devices (for both common-mode surge protection and differential-mode surge protection) wherein a feedback signal is provided in the event of damage to the protection circuitry, advantageously as an (isolated) feedback signal as provided, for example, via an optical isolator.

[0126] Without prejudice to the underlying principle, the details and embodiments may vary even significantly with respect to what is described purely by way of example, without departing from the scope of protection.

[0127] The scope of protection is determined by the appended claims.

[0128] Reference Signs List

[0129] Lighting source (lamp) L

[0130] Cabinet C

[0131] Surge protective device (SPD) 10

[0132] SPD indicator 10A

[0133] Drive 12

[0134] Line L, N

[0135] Feedback FB

[0136] Wired Network WN

[0137] Wireless Network WL

[0138] Antenna A

[0139] Optocoupler 101

[0140] Resistor network RS1, RS2 102

[0141] Fuse 103

[0142] Metal Oxide Varistor (MOV) 104

[0143] Pull-up resistor Rp

[0144] Bridge rectifier 121

[0145] Power Factor Control (PFC) 122

[0146] DC / DC converter 123

[0147] LED power supply 123A

[0148] Auxiliary power supply unit 124

[0149] Interface 125

[0150] Input / output port D4i / LSI

[0151] Controller 200

[0152] LED Power Supply Unit (PSU) 201

[0153] Isolator block 202

[0154] LED lighting source 203

[0155] Wireless module 204

Claims

1. A surge protection device (10, 12), comprising: Surge protection circuitry (103, 104) configured to provide a surge discharge path between lines (L, N) in a power supply, a fault detection network (101, 102) coupled to the surge protection circuitry (103, 104) and configured to generate a detection signal (FB) that switches between a first value and a second value in response to a fault in the surge protection network (103, 104), and A driver (12) is coupled (D4i / LSI) to the fault detection network (101, 102) to receive the detection signal (FB) from the fault detection network, and the driver (12) is configured (125, WN, WL, A; 200, 201, 204) to issue a warning signal in response to the detection signal (FB) switching between the first value and the second value.

2. The device (10, 12) according to claim 1, wherein The driver (12) is configured to issue the warning signal as: an electrical warning signal on the wired link (WN); and / or RF warning signal on wireless link (WL, A).

3. The device (10, 12) according to claim 1 or claim 2, wherein The driver (12) is configured to drive (201) an electric load (203) based on a set of driving parameters and to modify the set of driving parameters by switching between the first value and the second value in response to the detection signal (FB).

4. The device (10, 12) according to any one of claims 1 to 3, comprising at least one galvanic isolator (101, 202) located in the path of the detection signal (FB) through the fault detection network (101, 102) and the driver (12).

5. The device (10, 12) according to claim 4, comprising the fault detection network (101, 102) to the coupling port (D4i / LSI) of the driver (12), wherein The at least one electrical isolator (101, 202) comprises: an optical coupler (101) located in the fault detection network (101, 102), configured to apply the detection signal (FB; SPDfb) to the coupling port (D4i / LSI); and / or An isolator block (202) located in the driver (12) is configured to receive the detection signal (FB) from the coupling port (D4i / LSI).

6. The device (10, 12) according to any one of the preceding claims, wherein The fault detection network (101, 102) comprises a signal transmission element (101) having an output coupled to a pull-up resistor (Rp), wherein the signal transmission element (101) is configured to provide the detection signal (FB) which switches between a first value and a second value in response to a fault in the surge protection network (103, 104).

7. The device (10, 12) according to any one of the preceding claims, wherein The surge discharge path in the surge protection circuitry includes at least one of a fuse (103) and a varistor (104) having terminals coupled to the fault detection network (101, 102).

8. The device (10, 12) according to claim 7, wherein The surge discharge path in the surge protection circuitry includes a series connection of a fuse (103) and a varistor (104) having a common terminal coupled to the fault detection network (101, 102).

9. The device (10, 12) according to claim 8, wherein The fault detection network (101, 102) comprises: a first resistor (RS1) connected in parallel with the varistor (104), wherein the first resistor (RS1) is coupled to the common terminal of the fuse (103) and the varistor (104); A second resistor (RS2) has a first end coupled to the common terminal of the fuse (103) and the varistor (104) and a second end coupled to an input of the signal transmission element (101).

10. The device (10, 12) according to claim 9, wherein The signal transmission element (101) is an optocoupler and has an output configured to provide the detection signal (FB), which switches between a first value and a second value in response to a fault in the surge protection network (103, 104).

11. A surge protection device comprising: The electrical load, supplied via the lines (L, N) in the power supply, and The apparatus (10, 12) according to any one of claims 1 to 9, arranged with the protection circuitry (103, 104) coupled to the lines (L, N) in the power supply and configured to provide a surge discharge path between the lines (L, N) in the power supply.

12. The apparatus according to claim 11, wherein The electrical load is a set of lighting sources (L).

13. A method of operating a device comprising an electrical load provided via lines (L, N) in a power supply, in, The method comprises: The device is provided with an apparatus (10, 12) according to any one of claims 1 to 9, the apparatus being arranged with the protection circuitry (103, 104) coupled to the lines (L, N) in the power supply and being configured to provide a surge discharge path between the lines (L, N) in the power supply.

14. The method according to claim 13, wherein The electrical load is a set of lighting sources (L).

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