DE102019126527A1 - Method for detecting an electric arc in a power supply network - Google Patents

Abstract

The invention relates to a method for detecting an electric arc in a power supply path of an on-board network, comprising the following method steps: determining (S10) a total resistance (RG, T) of a monitoring section (10) at a first point in time (T), the monitoring section is designed as a power supply path with a starting point (20) and an end point (30); measuring (S20) an input current intensity (It) at the starting point (20) of the monitoring section (10) at a second point in time (t); measuring (S30 ) a first voltage (V1, t) at the starting point (20) of the monitoring section (10) and a second voltage (V2, t) at the end point (30) of the monitoring path (10) at the second point in time (t); - determining (S40) a deviation (ΔVt) between an expected voltage drop (ΔVE, t) and an actual voltage drop (ΔVR, t) over the monitoring section (10) at the second point in time (t), the expected voltage drop (ΔVE, t) is calculated from the product of the total resistance (RG, T) and the measured current strength (It) according to ΔVE, t = RG, T It, and the actual voltage drop (ΔVR, t) is calculated from the difference between the measured first voltage (V1 , t) and the measured second voltage (V2, t) calculated according to ΔVR, t = V1, t-V2, t; - Determination (S50) of a residual (rt) as a deviation (ΔVt) according to the formula: rt = ΔVt = RG, T⋅It− (V1, t − V2, t) - Evaluate (S60) the residual (rt) whether it exceeds a previously defined limit value (rth); - Detect (S70) an arc if the residual (rn ) exceeds the previously defined limit value (rth) according to rt> rth

Description

The invention relates to a method for detecting an arc in an energy supply network, preferably in a vehicle, where the energy supply network is also referred to as an on-board network. Photovoltaics with high DC voltages is also a typical field of application for the present invention.

An on-board network is understood to mean the entirety of all electrical components in vehicles, such as automobiles, airplanes, ships, etc. The on-board network is responsible for the power supply and the flow of information between individual components and control units. If electrical circuits are opened in an on-board network by means of switches, plug connections or fuses, or if defects occur in current-carrying lines, arcing can occur in the on-board network. An arc is created by a high electrical voltage (potential difference) and current intensity by impact ionization. The gas discharge forms a plasma in which atoms and molecules are at least partially ionized. The result of the free charge carriers is that the gas is electrically conductive. In electrical power engineering, arcs that occur during switching operations are also referred to as switching arcs.

In particular, when using on-board electrical systems that are operated with higher DC voltages, arcs can occur, as these arise above 18 V and can be maintained at a current of 1 A. The formation also depends on other parameters such as the distance over which the arc occurs, the humidity and the materials of the current-carrying conductors. Due to the high power of the resulting plasma, an arc can lead to high temperatures and thus a fire if it does not go out again immediately. Detection of arcs in an on-board network is therefore of considerable importance for safety. This applies in particular to the automotive sector, where the 48 V voltage is increasingly used. Reliable arc detection is also necessary for high-voltage applications in electric vehicles with voltages of up to 1000 V.

Based on this, the object of the invention is to provide a method and a device with which a reliable and inexpensive detection of arcs in an on-board network is possible.

This object is achieved by the subject matter of claim 1 and the subject matter of claim 6. Preferred developments can be found in the subclaims.

• - Ermitteln eines Gesamtwiderstand eines Überwachungsabschnitts zu einem ersten Zeitpunkt, wobei der Überwachungsabschnitt als Stromversorgungspfad mit einem Anfangspunkt und einem Endpunkt ausgebildet ist;
• - Messen einer Eingangsstromstärke an dem Anfangspunkt des Überwachungsabschnitts zu einem zweiten Zeitpunkt;
• - Messen einer ersten Spannung an dem Anfangspunkt des Überwachungsabschnitts und einer zweiten Spannung an dem Endpunkt des Überwachungspfades zu dem zweiten Zeitpunkt;
• - Bestimmen einer Abweichung zwischen einem erwarteten Spannungsabfall und einem tatsächlichen Spannungsabfall über dem Überwachungsabschnitt zu dem zweiten Zeitpunkt (t), wobei der erwartete Spannungsabfall sich aus dem Produkt des Gesamtwiderstands und der gemessenen Stromstärke berechnet gemäß ΔV_E,t = R_G,T · I_t, und der tatsächliche Spannungsabfall sich aus der Differenz zwischen der gemessenen ersten Spannung und der gemessenen zweiten Spannung berechnet gemäß ΔV_R,t = V_1,t - V_2,t;
• - Bestimmen eines Residuums als Abweichung gemäß der Formel: $$r_t=\Delta V_t=R_{G,T}\cdot I_t-\left(V_{\mathrm{1,}t}-V_{\mathrm{2,}t}\right)$$
  
• - Bewerten des Residuums, ob es einen zuvor definierten Grenzwert überschreitet;
• - Feststellen eines Lichtbogens, falls das Residuum den zuvor festgelegten Grenzwert überschreitet gemäß r_t > rt_h·

According to a first aspect, the invention relates to a method for detecting an arc in a power supply path of an on-board network. The procedure comprises the following procedural steps:

• Determining a total resistance of a monitoring section at a first point in time, the monitoring section being designed as a power supply path with a starting point and an end point;
• Measuring an input current strength at the starting point of the monitoring section at a second point in time;
• Measuring a first voltage at the starting point of the monitoring section and a second voltage at the end point of the monitoring path at the second point in time;
• - Determination of a deviation between an expected voltage drop and an actual voltage drop across the monitoring section at the second point in time (t), the expected voltage drop being calculated from the product of the total resistance and the measured current intensity according to ΔV _{E, t} = R _{G, T} · I _t , and the actual voltage drop is calculated from the difference between the measured first voltage and the measured second voltage according to ΔV _{R, t} = V _{1, t} − V _{2, t} ;
• - Determine a residual as a deviation according to the formula: $$r_t=\Delta V_t={\mathrm{R.}}_{G,T}\cdot {\mathrm{I.}}_t-\left(V_{\mathrm{1,}t}-{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="DE102019126527A1\_0011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{2,}t}\right)$$
  
• Evaluating the residual as to whether it exceeds a previously defined limit value;
• - Detection of an arc if the residue exceeds the previously defined limit value according to r _t > rt _h

A voltage measuring device at the starting point and a second voltage measuring device at the end point of the monitoring section make it possible to carry out a voltage measurement only for the monitoring section, so that the rest of the vehicle electrical system and the electronic load are decoupled from the monitoring section. The voltage V ₁ at the starting point of the monitoring section is measured by the first _{voltage measuring device and the voltage V 2} at the end point of the monitoring section is measured by the second voltage measuring device.

In the event of a fault, an arc current flows at an unknown point in the monitoring section to earth or to another Power supply path from, or there is an additional voltage drop along an arc. By comparing the expected voltage drop and the actual voltage drop across the monitoring section, it can be determined according to the invention whether a fault current is flowing to ground at an unknown point in the monitoring section or a voltage is falling due to an arc.

In a further embodiment it is provided that the arc is a parallel arc. Parallel arcs arise between two conductors, in particular between two power supply paths in which the insulation is defective, as can occur due to environmental influences or aging phenomena, or between a defective power supply path and, for example, a vehicle body used as a ground.

In an advantageous further development it is provided that the limit value is greater than the value of 0V. Measurement errors can create a tolerance range so that it cannot be determined with certainty whether the difference between the expected and the actual voltage drop at a point in time t actually deviates from 0 V. This is ruled out by selecting a limit value greater than 0 V.

wobei x zwischen 0 und 1 liegt: x = 0, ... , 1The difference between the actual voltage drop and the expected voltage drop depending on different arc locations on the monitoring section and the amperage of the arc current is preferably calculated according to: $$\Delta \left(\Delta V_{\mathrm{E.}}-\Delta V_{\mathrm{R.}}\right)\left(x,{\mathrm{I.}}_{arc}\right)={\mathrm{I.}}_{arc}\cdot {\mathrm{R.}}_{G,T}\cdot \left(1-x\right)$$

where x is between 0 and 1: x = 0, ..., 1

This makes it possible to specify a quality of the method according to the invention for recognizing parallel arcs.

In a further development of the invention, it is provided that the current strength (I _arc ) of the arc is in the range from 50 A to 350 A. This range is typical for consumer flows.

zu bestimmen und zu bewerten, ob das Residuums einen zuvor definierten Grenzwert überschreitet, und falls das Residuum den zuvor festgelegten Grenzwert überschreitet gemäß r_n > r_th einen Lichtbogen feststellt.According to a second aspect, the invention relates to an arc monitoring device for detecting an arc in a power supply path of an on-board network, with a monitoring section with a starting point and an end point designed as a power supply path, the total resistance of which was determined at a first point in time and is known. A current measuring device is provided which is designed to measure an input current strength at the starting point of the monitoring section at a second point in time. Furthermore, a first voltage measuring device is provided which is designed to measure a first voltage at the starting point of the monitoring section, and a second voltage measuring device is provided which is designed to measure a second voltage at the end point of the monitoring section at the second point in time. A processor is provided which is designed to determine a deviation between an expected voltage drop and an actual voltage drop across the monitoring section at the second point in time, the expected voltage drop being calculated from the product of the total resistance and the measured current intensity, and the actual voltage drop being calculated calculated from the difference between the measured first voltage and the measured second voltage according to V _{1, t} − V _{2, t} ; and wherein the processor is designed to generate a residual as a deviation according to the formula: $$r_t=\Delta V_t={\mathrm{R.}}_{G,T}\cdot {\mathrm{I.}}_t-\left(V_{\mathrm{1,}t}-{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="DE102019126527A1\_0011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{2,}t}\right)$$

to determine and assess whether the residual exceeds a previously defined limit value, and if the residual exceeds the previously defined limit value according to r _n > r _th detects an arc.

A voltage measuring device at the starting point and a second voltage measuring device at the end point of the monitoring section make it possible to carry out a voltage measurement only for the monitoring section, so that the rest of the vehicle electrical system and the electronic load are decoupled from the monitoring section. The voltage V ₁ at the starting point of the monitoring section is measured by the first _{voltage measuring device and the voltage V 2} at the end point of the monitoring section is measured by the second voltage measuring device. However, a separate measuring device for measuring the voltages V ₁ and V ₂ can also be provided in each case.

In the event of a fault, an arc current flows off to ground or another power supply path at an unknown point in the monitoring section. By comparing the expected voltage drop and the actual voltage drop across the monitoring section, it can be determined according to the invention whether a fault current is flowing to ground at an unknown point in the monitoring section.

In a further embodiment, the arc monitoring device has a transmission device in order to send a detection signal from the processor to a central control device.

The measured value of the total resistance is advantageously stored in a memory device and / or in the processor.

In a further development of the invention it is provided that the arc monitoring device is designed to detect a parallel arc. Parallel arcs arise between two conductors, in particular between two power supply paths in which the insulation is defective, as can occur due to environmental influences or aging phenomena, or between a defective power supply path and, for example, a vehicle body used as a ground.

According to a third aspect, the invention relates to an on-board network of a vehicle, comprising an arc monitoring device according to the second aspect of the invention.

The invention is explained in more detail below using a preferred exemplary embodiment with reference to the drawings.

• 1 schematisch ein Ausführungsbeispiel eines Ersatzschaltbildes zur Überwachung eines Überwachungsabschnitts;
• 2 ein Flussdiagramm eines erfindungsgemäßen Verfahrens zum Erkennen eines Lichtbogens in einem Stromversorgungspfad;
• 3 schematisch ein Ausführungsbeispiel einer Lichtbogenüberwachungseinrichtung.

Show in the drawings

• 1 schematically, an embodiment of an equivalent circuit diagram for monitoring a monitoring section;
• 2 a flow diagram of a method according to the invention for detecting an arc in a power supply path;
• 3 schematically an embodiment of an arc monitoring device.

In 1 is a schematic equivalent circuit diagram for the monitoring of a monitoring section 10 an on-board network shown. The monitoring section 10 has a starting point 20th and an endpoint 30th on. At the monitoring section 10 it is a power supply path in a vehicle electrical system (not shown here), preferably a motor vehicle. An on-board network is understood to mean the entirety of all electrical components in vehicles such as automobiles, airplanes, ships, etc. The on-board network is responsible for the power supply and the flow of information between individual components and control units. Different electrical and electronic components can be connected to the power supply path, such as a battery, an alternator, a sensor, a ventilation component, a navigation device, etc. Various power supply paths can be provided in an on-board network, which can also differ in terms of current strength and voltage.

In principle, two basic types of arcs can occur in the vehicle electrical system, which are referred to as serial arcs and parallel arcs. A serial arc occurs, for example, when the power supply path is interrupted. A serial arc can then form over the break point between the line ends of the break point. A serial arc typically occurs in front of an electrical component, since after the electrical component the voltage usually drops to ground potential and the voltage is thus below the critical value of approximately 18 V.

Parallel arcs arise between two conductors, in particular between two power supply paths in which the insulation is defective, as can occur due to environmental influences or aging phenomena, or between a defective power supply path and, for example, a vehicle body used as a ground.

According to the present invention, a current measurement is at the starting point 20th of the monitoring section 10 and a voltage measurement at both the starting point 20th as well as at the end point 30th of the monitoring section 10 intended.

R₁ ist der Widerstand vor dem Auftreten eines Lichtbogens und R₂ ist der Widerstand des Überwachungsabschnitts 10 nach dem Lichtbogen.The individual resistors R ₁ and R ₂ represent the ohmic resistance of the monitoring section 10 where the total resistance R _{G of} the monitoring section 10 the sum of the individual resistances is: $${\mathrm{R.}}_G={\mathrm{R.}}_1+{\mathrm{R.}}_2$$

R ₁ is the resistance before an arc occurs and R ₂ is the resistance of the monitoring section 10 after the arc.

By a first tension measuring device 22nd at the starting point 20th and a second tension measuring device 32 at the end point 30th of the monitoring section 10 the possibility is created of a voltage measurement only for the monitoring section 10 undertake, so that the rest of the on-board network and the electronic load are decoupled from the monitoring section. The voltage V ₁ at the starting point 20th of the monitoring section 10 is from the voltage source 22nd and the voltage V ₂ at the end point 30th of the monitoring section 10 is from the voltage source 32 measured. However, a separate measuring device for measuring the voltages V ₁ and V ₂ can also be provided in each case.

In the event of a fault, an arc current I _{arc flows} at an unknown point in the monitoring section 10 to ground or another power supply path. For this, in 1 a power source 40 indicated with a voltage V _arc.

By comparing the expected voltage drop ΔV _E and the actual voltage drop ΔV _R over the monitoring section 10 According to the invention, it can be determined whether at an unknown point in the monitoring section 10 a fault current flows to ground.

• In einem Schritt S10 wird der Gesamtwiderstand R_G des Überwachungsabschnitts 10 zu einem Zeitpunkt T ermittelt, da er für das erfindungsgemäße Verfahren bekannt sein muss. Dafür können unterschiedliche Messverfahren oder Berechnungen eingesetzt werden. Es ist jedoch im Rahmen der Erfindung erforderlich, dass der Gesamtwiderstand R_G keinen Änderungen unterliegt, sondern als Konstante des erfindungsgemäßen Messverfahrens angesehen wird.

As in 2 In particular, the following steps are necessary for the method according to the invention:

• In a step S10, the total resistance R _{G of} the monitoring section becomes 10 determined at a point in time T, since it must be known for the method according to the invention. Different measurement methods or calculations can be used for this. However, within the scope of the invention it is necessary that the total resistance R _{G is} not subject to any changes, but rather is viewed as a constant of the measuring method according to the invention.

In a step S20, an input current I _t becomes at the starting point 20th of the monitoring section 10 measured at a second point in time t.

In a step S30, a first voltage V _{1, t} becomes at the starting point 20th of the monitoring section 10 and a second voltage V _{2, t} at the end point 30th of the monitoring path 10 measured at the second point in time t.

In a step S40, the deviation Δ between the expected and the actual voltage drop at the point in time t is determined. The expected voltage drop ΔV _{E, t is} calculated from the product of the total resistance R _{G, T} , which was determined at an earlier point in time T, and the measured current intensity I _t . The actual voltage drop ΔV _{R, t} results from the difference between the measured first voltage V _{1, t} and the measured second voltage V _{2, t} according to the formula: ΔV _{R, t} = (V _{1, t} - V _{2, t} )

This deviation is called the residual r _t and is determined as follows: $$r_t=\Delta V_t={\mathrm{R.}}_{G,T}\cdot {\mathrm{I.}}_t-\left(V_{\mathrm{1,}t}-{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="DE102019126527A1\_0011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{2,}t}\right)$$

In a step S60, the residual r _{t is} evaluated in order to infer a parallel arc or an arc-free state of the monitoring section. A limit value rth is defined for this purpose.

In a step S70, it is determined whether an arc is present if the residue r _n exceeds the previously established limit value rth according to r _t > r _th .

In order to take measurement errors into account, it is provided that the limit value rth cannot be at a value of 0 V. Measurement errors can create a tolerance range so that it cannot be determined with certainty whether the difference between the expected and the actual voltage drop actually deviates from 0 V. This is ruled out.

In order to specify a quality criterion for the quality of the method according to the invention of recognizing parallel arcs, it can theoretically be calculated how large the difference Δ (ΔV _E - ΔV _R ) between the actual voltage drop ΔV _R and the expected voltage drop ΔV _E must be. This difference Δ (ΔV _E - ΔV _R ) as a function of different arc locations x on the monitoring section 10 and the amperage of the arc current is calculated as follows, where x is between 0 and 1 (x = 0, 1): $$\Delta \left(\Delta V_{\mathrm{E.}}-\Delta V_{\mathrm{R.}}\right)\left(x,{\mathrm{I.}}_{arc}\right)={\mathrm{I.}}_{arc}\cdot {\mathrm{R.}}_{G,T}\cdot \left(1-x\right)$$

The size of the deviation of the voltage drops Δ (ΔV _E - ΔV _R ) therefore depends on the total resistance R _{G, T of} the monitoring section 10 from. The unknown quantities of the arc are the current I _{arc of} the arc current and the location x of the arc on the monitoring section 10 .

The method according to the invention is particularly suitable for arc currents in the range of consumer currents at currents from 50 A to 350 A.

In 3 is an arc monitoring device 100 shown, which uses the method according to the invention to prevent the occurrence of arcs in the monitoring section 10 to detect.

The light monitoring device 100 comprises the first tension measuring device 22nd at the starting point 20th and the second tension measuring device 32 at the end point 30th of the monitoring section 10 . However, it can also be provided that the voltage measuring devices are designed separately. This creates the possibility of a voltage measurement only for the monitoring section 10 make, so that the rest of the electrical system and the load from the monitoring section 10 are decoupled. There is also a current measuring device 50 at the starting point 20th of the monitoring section 10 provided in order to measure the input current I _t at a point in time t. There is also a processor 60 provided in which the measurement results of the measuring devices 22nd , 32 , 50 and the residual r _{t is} calculated. A transmitting device is preferred 70 provided with which a detection _{signal containing the calculated residual r t} can be sent to a central control device of the vehicle. However, within the scope of the invention it can also be provided that the measurement results are sent directly to the control device and the residual r _t is calculated there. If the value of the residual r _{t shows} that an arc is present, a corresponding alarm signal is preferably output, in particular from the processor 60 or from the central control device.

The method according to the invention can thus be based on the voltage drop across a monitoring section 10 an arc can be detected reliably and precisely. Since the monitoring section 10 through the separate voltage sources 22nd , 32 is decoupled from the on-board network and the electronic loads, corruption caused by interfering signals is minimized. In the event of a fault, an arc current I _{arc flows} at an unknown point in the monitoring section 10 to ground or another power supply path and this is recognized immediately, since a continuous measurement of the input current I _t and the voltages V _{1, t} and V _2, t takes place at each point in time t.

The invention on which this patent application is based was created in a project that was funded under the funding code / PSP element D-99-42618-001-081082 / D-99-42618-002-081082, title: "48V on-board electrical system arc analysis".

List of reference symbols

10

Monitoring section

20th

Starting point of the monitoring section

22nd

first voltage source

30th

End point of the monitoring section

32

second voltage source

40

Power source

50

Current measuring device

60

processor

70

Sending facility

100

Arc monitoring device

Claims (10)

A method for detecting an arc in a power supply path of an on-board network, comprising the following method steps: determining (S10) a total resistance (R _{G, T} ) of a monitoring section (10) at a first point in time (T), the monitoring section being a power supply path with a starting point (20) and an end point (30) is formed; - measuring (S20) an input current strength (I _t ) at the starting point (20) of the monitoring section (10) at a second point in time (t); - Measuring (S30) a first voltage (V _{1, t} ) at the starting point (20) of the monitoring section (10) and a second voltage (V _{2, t} ) at the end point (30) of the monitoring path (10) at the second point in time (t); - Determination (S40) of a deviation (ΔV _t ) between an expected voltage drop (ΔV _{E, t} ) and an actual voltage drop (ΔV _{R, t} ) across the monitoring section (10) at the second point in time (t), the expected voltage drop ( ΔV _{E, t} ) is calculated from the product of the total resistance (R _{G, T} ) and the measured current strength (I _t ) according to ΔV _{E, t} = R _{G, T} · I _t , and the actual voltage drop (ΔV _{R, t} ) calculated from the difference between the measured first voltage (V _{1, t} ) and the measured second voltage (V _{2, t} ) according to ΔV _{R, t} = V _{1, t} − V _{2, t} ; - Determination (S50) of a residual (r _t ) as a deviation (ΔV _t ) according to the formula: $$r_t=\Delta V_t={\mathrm{R.}}_{G,T}\cdot {\mathrm{I.}}_t-\left(V_{\mathrm{1,}t}-V_{\mathrm{2,}t}\right)$$

- Assess (S60) the residual (r _t ) whether it exceeds a previously defined limit value (rth); - Establishing (S70) an arc if the residue (r _n ) exceeds the previously defined limit value (rth) according to r _t > r _th . Procedure according to Claim 1 , the arc being a parallel arc. Procedure according to Claim 1 or 2 , where the limit value (rth) is greater than the value of 0 V. Method according to one or more of the Claims 1 to 3 , the difference (Δ) between the actual voltage drop (ΔV _R ) and the expected voltage drop (ΔV _E ) as a function of different arc locations (x) on the monitoring section (10) and the Amperage (I _arc ) of the arc current is calculated according to: $$\Delta \left(\Delta V_{\mathrm{E.}}-\Delta V_{\mathrm{R.}}\right)\left(x,{\mathrm{I.}}_{arc}\right)={\mathrm{I.}}_{arc}\cdot {\mathrm{R.}}_{G,T}\cdot \left(1-x\right)$$

where x is between 0 and 1: x = 0, ..., 1 Method according to one or more of the Claims 1 to 4th , where the current intensity (I _arc ) of the arc is in the range of 50 A to 350 A. Arc monitoring device (100) for detecting an arc in a power supply path of an on-board network, with a monitoring section (10) with a starting point (20) and an end point (30) designed as a power supply path, the total resistance (R _{G, T} ) of which at a first point in time (T ) was determined and is known, wherein a current measuring device (50) is provided which is designed _{to measure an input current strength (I t} ) at the starting point (20) of the monitoring section (10) at a second point in time (t), and wherein a First voltage measuring device (22) is provided, which is designed _{to measure a first voltage (V 1, t} ) at the starting point (20) of the monitoring section (10), and a second voltage measuring device (32) is provided, which is designed to have a second To measure voltage (V _{2, t} ) at the end point (30) of the monitoring section (10) at the second point in time (t), and wherein a processor (60) is provided which is designed to perform a Deviation (Δ) between an expected voltage drop (ΔV _{E, t} ) and an actual voltage drop (ΔV _{R, t} ) across the monitoring section (10) at the second point in time (t), the expected voltage drop (ΔV _{E, t} ) is calculated from the product of the total resistance (R _{G, T} ) and the measured current strength (I _t ), and the actual voltage drop (ΔV _{R, t} ) is calculated from the difference between the measured first voltage (V _{1, t} ) and the measured second voltage (V _{2, t} ) calculated according to V _{1, t} − V _{2, t} ; and wherein the processor is designed to generate a residual (r _t ) as a deviation (ΔV _t ) according to the formula: $$r_t=\Delta V_t={\mathrm{R.}}_{G,T}\cdot {\mathrm{I.}}_t-\left(V_{\mathrm{1,}t}-V_{\mathrm{2,}t}\right)$$

to determine and assess whether the residual (r _t ) exceeds a previously defined limit value (r _th ), and if the residual (r _n ) exceeds the previously defined limit value (rth), it detects an arc _{according to r t> rth.} Arc monitoring device (100) according to Claim 6 , wherein a transmitting device is provided to send a detection signal of the processor (60) to a central control device. Arc monitoring device (100) according to Claim 6 or 7th , wherein the measured value of the total resistance R _{G, T} is stored in a memory device and / or in the processor (60). Arc monitoring device (100) according to one or more of the Claims 6 to 8th , wherein the arc monitoring device (100) is designed to detect a parallel arc. On-board network of a vehicle, comprising an arc monitoring device (100) according to one of the Claims 6 to 9 .

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