EP2839497B1 - Overcurrent protection device - Google Patents

Description

The invention relates to an overcurrent protection device, comprising a conductor, an evaluation unit, a temperature sensor, wherein the conductor is configured such that a current is conducted from a source along a defined path of the conductor to a consumer.

From the WO 2007/082775 A1 Such an overcurrent protection device is already known. A disadvantage of the known overcurrent protection device is that it works with a bimetallic release, in which only a limited adjustment range of the overcurrent protection switch is given.

The publication EP 1 912 238 A1 shows a miniature overcurrent limiter with a mix of current measurement and temperature measurement to match a trip point to an ambient temperature.

The adjustment range is the range in which monitoring of an operating current of an electrical consumer can take place. It is limited by an operating current _upper limit I ₀ and an operating current _lower limit I _U. By means of an adjusting means (eg an adjusting screw) on the device, a thermal overload release (bimetal) can be set to the respective system current, so that a targeted monitoring of the downstream consumer to be monitored can take place.

To the adjustment range for the overcurrent protection of the WO 2007/082775 A1 To expand, elaborate additional adjustment means and methods are provided.

It is an object of the present invention to provide an overcurrent protection device in which an extended Setting range in a simpler manner than is given in the prior art, is possible.

The object is achieved by an overcurrent protection device, comprising a conductor, an evaluation unit, a temperature sensor, wherein the conductor is configured such that a current is conducted from a source along a defined path of the conductor to a consumer and arranged the temperature sensor to the conductor is that a temperature of the conductor can be measured as a temperature measured value, wherein the temperature sensor is connected to the evaluation unit, while the evaluation unit is configured to compare the temperature measured value with a temperature limit stored in the evaluation unit, wherein the temperature Limit value is selected such that it represents a prevailing in the conductor distribution of a maximum allowable electric current, wherein a resulting current density is counted as an overcurrent in the conductor, the evaluation unit is further configured so that when the temperature reading the temperature ur limit value has been reached, a control signal is output via a control output of the evaluation unit, which indicates the overcurrent in the conductor.

Higher accuracy and extension of the adjustment range is achieved in that the overcurrent protection device has a first temperature sensor, a second temperature sensor and a third temperature sensor arranged distributed along the path of the conductor and the temperature sensors are arranged to the conductor, that a first temperature of the conductor to a first location, a second temperature at a second location and a third temperature at a third location of the conductor as a first, second and third temperature measurement is measurable.

ΔT_n:

Temperaturdifferenzwert

T_n1:

Ermittelte Temperatur des ersten Temperatursensors am ersten Ort

T_n2:

Ermittelte Temperatur des zweiten Temperatursensors am zweiten Ort

T_n3:

Ermittelte Temperatur des dritten Temperatursensors am dritten Ort

n:

Betrachtetes Messelement bzw. betrachteter Leiter.

To determine a temperature difference value (ΔT _n ), for example, the following formula can be used: $${\mathrm{.DELTA.T}}_{\mathrm{n}}=\frac{\left(T_{n2}-T_{n1}\right)+\left(T_{n2}-T_{n3}\right)}{2}=T_{n2}-\left(\frac{T_{n1}-T_{n3}}{2}\right)$$

ΔT _n :

Temperature difference value

_Tn1 :

Determined temperature of the first temperature sensor at the first location

T _n2 :

Determined temperature of the second temperature sensor at the second location

T _n3 :

Determined temperature of the third temperature sensor at the third location

n:

Viewed measuring element or considered conductor.

The temperature difference value can be determined by the evaluation unit, for example, during a simultaneous determination of the individual temperatures of the temperature sensors. By a corresponding evaluation of the temperature difference value in the evaluation unit can finally be recognized whether a proper operation of the consumer is present or whether an overload on the consumer is pending or already exists.

The current density characterizes the distribution of the electric current in a conductor and serves as a measure of its electrical load capacity. It is defined as the ratio of the current intensity to the current cross-sectional area through which the current passes. The larger the current density, the more the conductor heats up and the better the temperature sensor can detect a temperature reading. Depending on the choice of the temperature limit value, an adjustment range for the overcurrent protection device can now be selected.

When monitoring by means of a bimetallic release, as is the case in the prior art, a current to be monitored is coupled to a bimetallic actuator in such a way that the increase in current leads to heating of the bimetallic release and finally to a spatial deflection of a part of the bimetallic release , A typical setting range of a bimetallic release is approx. 1 to 1.6. A typical value for a necessary temperature in a bimetal trip, for example, 16 Kelvin overtemperature. By contrast, in the case of a solution by means of a conductor with a temperature sensor, a current-related heating of approximately 1 Kelvin can already be determined. This adjustment ranges can be greater than 1 to 4, in particular greater than 1 to 6 realize.

In a further embodiment of the overcurrent protection device, the conductor is formed as a sequence of loops, while a conductor length of the conductor is accommodated by the loop sequence on a measuring section, wherein the length dimension of the measuring section is smaller than the conductor length. Due to the sequence of loops, the conductor in an overcurrent protection device requires less installation space than is known in the prior art.

In one embodiment variant of the overcurrent protection device, the conductor has a meander-shaped configuration and thus essentially has a rectangular area for an installation space. The rectangular area is advantageous if the temperature sensors are arranged between the rectangular area and, for example, a printed circuit board.

Another alternative embodiment provides that the conductor has a meandering, circular configuration and thereby a circular area is given for an installation space, wherein the loops of the conductor are arranged bifilar. A bifilar arrangement of the loops has the particular advantage that, in a circular arrangement, a magnetic field produced by the conductor cancels itself out. In the case of a circular meander-shaped configuration, for example in the case of a bifilar spiral, it is advantageous that an installation space is minimized. A temperature reading can be taken in particular in the middle of the circular area, since centralized here a heating power. A three-point temperature measurement could be here at a start, in the center and at one end of the meandering, circular conductor are performed.

A further embodiment of the overcurrent protection device provides that the conductor is designed as a flat strip extended in the longitudinal direction and in one Loop is arranged a cross-sectional reduction in the strip, which leads to increase the current density in the vicinity of the cross-sectional reduction. A cross-sectional reduction could, for example, be realized by a hole, a recess or a lateral recess in the flat strip. In the case of a bore or a lateral narrowing of the strip or of the conductor, the current density increases at these points, since here the cross-section is reduced. An increase in the current density at the reduced cross section results in a temperature increase at this point. Accordingly, a measuring point can be arranged by means of a temperature sensor at this point, a query of a temperature is thus facilitated.

A further preferred embodiment provides that the conductor is designed as a flat strip by a layered composition of several loops as a cuboidal element.

Furthermore, it is advantageous if an insulating material is arranged between the layers arranged loops of the cuboidal element.

A further embodiment of the cuboidal element provides that an initial section of the conductor and an end section of the conductor are arranged substantially at right angles to the cuboid element and a partial region of the initial and final sections is reinforced in each case with a further electrically conductive, surface-shaped material. A reinforcement, for example, with a copper plate, makes installation on a printed circuit board easier and forms a contact surface for a switch mechanism arranged in the overcurrent protection device.

The material of the conductor advantageously has a chromium-nickel alloy, in particular a copper-nickel alloy, in particular a steel-nickel alloy, in particular a chromium-aluminum alloy. Such alloys have the advantage that the resistance remains constant as possible despite heating, which favors an additional strength of the conductor, based on an overload current or short-circuit current at which the overcurrent protection device is not yet to react directly. Because with a suitable choice of material and a sufficient cross-section of the conductor is not destroyed in a short-term overcurrent ("burn-through danger").

Advantageously, a resistance of the conductor relative to the path will be in the range of 1 milliohm to 100 milliohms.

For use, such as a motor circuit breaker, the overcurrent protection device is configured as comprising an electrical switch assembly, an input clamping region for connecting source lines, an output clamping region for connecting consumer leads, and in addition to the first conductor, a second conductor, a third conductor a first switching means, a second switching means, a third switching means, wherein the conductors are respectively arranged in series with the switching means between an associated first, second and third input terminal of the input terminal and a first, second and third output terminal of the output terminal.

The overcurrent protection device has for each a conductor each cooperating with the respective switching means switching mechanism for switching off the current flowing through the conductor, wherein the force of a spring is used, with a manual switching tensioned and upon reaching the excess temperature limit via a with the control output connected triggering device is relaxed.

FIG 1

eine Überstromschutzeinrichtung 1 für einen dreiphasigen Schutz zwischen einer Quelle und einen Verbraucher,

FIG 2

eine erste Ausgestaltungsvariante eines Leiters,

FIG 3

eine zweite Ausgestaltungsvariante eines Leiters,

FIG 4

eine Querschnittsverkleinerung in einem Leiter,

FIG 5

eine weitere Querschnittsverkleinerung in einem Leiter,

FIG 6

eine dritte Ausgestaltungsvariante eines Leiters,

FIG 7

eine vierte Ausgestaltungsvariante eines Leiters,

FIG 8

eine Überstromschutzeinrichtung ausgestaltet als eine Schaltbaugruppe und

FIG 9

eine Leiterplatte der Schaltbaugruppe.

The drawing shows several embodiments of the embodiment of a conductor of an overcurrent protection device. Show it:

FIG. 1

an overcurrent protection device 1 for a three-phase protection between a source and a consumer,

FIG. 2

a first embodiment variant of a conductor,

FIG. 3

a second embodiment variant of a conductor,

FIG. 4

a cross-sectional reduction in a conductor,

FIG. 5

another cross-sectional reduction in a ladder,

FIG. 6

a third embodiment variant of a leader,

FIG. 7

a fourth embodiment variant of a conductor,

FIG. 8

an overcurrent protection device designed as a switch assembly and

FIG. 9

a circuit board of the switch assembly.

According to FIG. 1 an overcurrent protection device 1 for the protection of a consumer 201 is shown. Under consumer here, for example, an electric motor is considered. The load 201 receives its power via a three-phase source 101. For a connection of the source 101 and the load 201, the overcurrent protection device 1 provides an input clamping region 100 and an output clamping region 200.

For the three-phase protection of the load 201, a first conductor 10, a second conductor 20 and a third conductor 30 are arranged in the overcurrent protection device 1. The conductors 10, 20, 30 are designed such that a current I ₁ , I ₂ , I _{3 is conducted} from the source 101 along a defined path of the conductors 10, 20, 30 to the consumer 201.

In order to determine a temperature distribution in the conductors 10, 20, 30, each conductor has a first temperature sensor 11, 21, 31, a second temperature sensor 12, 22, 32 and a third temperature sensor 13, 23, 33. The structure of the first conductor 10 is explained in more detail. The first conductor 10 has the first temperature sensor 11, the second temperature sensor 12 and the third temperature sensor 13 distributed along the path of the conductor 10 arranged on. The temperature sensors 11,12,13 are arranged to the conductor 10, that a first temperature of the conductor 10 at a first location X1 (see FIG. 3 and FIG. 7 ), a second temperature at a second location X2, and a third temperature at a third location X3 of the conductor 10 as a first, second, and third temperature measurements.

The temperature sensors 11, 12, 13 are each connected to an evaluation unit 4, in which case the evaluation unit 4 is configured to compare a temperature measurement value with a temperature limit value stored in the evaluation unit 4 or to determine a temperature difference value and by an evaluation a rise rate of the temperature difference value to close an overcurrent in the conductor 10.

ΔT_n:

Ist der Temperaturdifferenzwert des entsprechenden Leiters "n" 10,20,30 zum jeweiligen Auswertezeitpunkt, in welchem durch die entsprechenden Temperatursensoren gleichzeitig die Temperaturen erfasst werden.

n:

Betrachteter Leiter 10,20,30

x:

Auswertezeitpunkt (aktueller Zeitpunkt einer Messauswertung)

An evaluation of the temperature difference value ΔT _n can be made by the following formula. $${\left(\frac{{d\mathrm{\Delta }T}_n}{\mathit{dt}}\right)}_x=\frac{{\mathrm{\Delta }\mathit{T}}_{\mathit{nx}}-{\mathrm{\Delta }\mathit{T}}_{n\left(x-1\right)}}{t_x-t_{x-1}}$$

ΔT _n :

If the temperature difference value of the corresponding conductor "n" is 10, 20, 30 at the respective evaluation time in which the temperatures are simultaneously detected by the corresponding temperature sensors.

n:

Considered ladder 10,20,30

x:

Evaluation time (current time of a measurement evaluation)

Furthermore, the evaluation unit 4 is configured such that when the temperature measured value has reached the temperature limit value or the temperature difference value reaches the temperature difference limit value, a control signal 4a which indicates an overcurrent in the conductor 10 via a control output 4a of the evaluation unit 4 to spend.

The control output 4a is connected to a trip unit 5 in connection. The trip unit 5 is in turn configured to operate a first switching means 105, a second switching means 205 and a third switching means 305 and thus to interrupt the circuit from the source 101 to the load 201 as a protective measure. The temperature sensors 11, 12, 13; 21, 22, 23 and 31, 32, 33 of each conductor 10, 20, 30 are each separated by a first insulation layer 51, a second insulation layer 52 and a third insulation layer 53 from the conductors.

A first embodiment of a conductor 10 is according to FIG. 2 shown. Between a first copper rail 73 and a second copper rail 74, a planar, meander-shaped conductor is arranged. As a special feature in this embodiment variant, the planar, meander-shaped configuration of the conductor has a first recess 71 and a second recess 72. A current emanating from the first copper bus 73 may be distributed into a first and a second branch until it is recombined at a surface 75 for a temperature sensor. This merger has a cross-sectional enlargement result so that decreases a current density at this point again. The decrease in the current density at the surface 75 has the advantage that a temperature sensor can be placed here which measures a temperature which does not necessarily have to coincide with the temperature prevailing at another location of the conductor 10. This ensures that in the case of a short-time overcurrent, for example inrush current of an engine, the measured temperature does not immediately reach the range of the temperature limit value.

According to FIG. 3 another embodiment of the conductor 10 is shown. The conductor 10 is in each case arranged between a copper plate 23. The conductor 10 is arranged as a flat, metallic strip meandering between the two copper plates 23. Thus, the conductor 10 is formed as a succession of loops S1, ..., S6. A conductor length of the conductor 10, which is to be equated with a path W of the conductor 10 is accommodated by the loop sequence on a measuring path MS, wherein the length dimension of the measuring path MS is smaller than the conductor length of the conductor 10, that is smaller than the path W. As advantageous has been found, for example, when the conductor 10 is an approximately 8 mm wide and 1 mm thick flat metal alloy, such as a chromium-aluminum alloy. The ratio of width to thickness of the conductor should therefore in particular be 1 to 10.

For later installation of the conductor 10 in a switch assembly as an overcurrent protection device, it is advisable if the conductor 10 is arranged on a first insulating layer 51. The conductor 10 and the insulating layer 51 are in turn arranged on a printed circuit board 60 (see also FIG FIG. 9 ).

Below the circuit board 60 is in the FIG. 3 schematically indicated the measuring section MS by a route mark. The route description has a first location X1, a second location X2, and a third location X3. At these three locations X1, X2, X3, three different temperature sensors are arranged distributed.

According to 4 and FIG. 5 is in each case a side view of the conductor 10 from FIG. 3 shown. With FIG. 4 For example, a first type of cross-sectional reduction in a loop of the conductor 10 is illustrated. These are lateral recesses 21. In FIG. 5 a second type of cross-sectional reduction is shown. This is a bore 22.

A further embodiment variant of a conductor 10 is according to FIG. 6 displayed. In this case, the conductor 10 has a meandering, circular configuration, it is characterized given a circular area for an installation space that is special in this case, the loops of the conductor 10 are arranged bifilar, whereby a magnetic field cancels. The meandering, circular configuration of the conductor 10 could also be considered as a spiral, wherein a first temperature sensor is arranged at the left input of the spiral and a third temperature sensor is arranged at the right exit of the spiral, the second temperature sensor is thus arranged in the center of the spiral, because there is a concentration of heat here.

A particular preferred embodiment variant of the conductor 10 is according to the FIG. 7 given. By a layered composition of several loops S1, ..., S13 a flat strip of the conductor 10 is folded into a cuboidal element. Between the layers arranged loops S1, ..., S13, an insulating material 40 is arranged. An initial section A1 of the conductor 10 and an end section E1 of the conductor 10 is arranged substantially perpendicular to the cuboidal element, wherein in each case a reinforced copper plate can be applied in a partial area of the start and end sections.

As a result of the layered arrangement of the loops S1,..., S13, a considerably larger path W of the conductor 10 can be accommodated on a longitudinal extent of a measuring path MS.

At the locations X1, X2 and X3, temperature sensors can be attached via the conductor 10.

With FIG. 8 is a possible embodiment variant of an overcurrent protection device 1 shown as a switching assembly. Between the input clamping region 100 and the output clamping region 200 are the protective elements as they are symbolic With FIG. 1 were arranged. A printed circuit board 60 has a first conductor 10, a second conductor 20 and a third conductor 30, the conductors 10, 20, 30 being configured as a layered arrangement of a plurality of loops S1,..., S13 to form a parallelepiped element.

According to FIG. 9 is the circuit board 60 off FIG. 8 shown in a detailed view. In addition to the first conductor 10, the second conductor 20 and the third conductor 30, a first installation space 301, a second installation space 302 and a third installation space 303 can be seen here. The bays 301, ..., 303 serve to receive the first to third temperature sensor. The printed circuit board 60 is constructed, for example, as a multilayer, and has inside the printed circuit board 60 in the vicinity of the mounting locations 301,..., 303 the corresponding temperature sensors in semiconductor design in the interior of the printed circuit board 60. Corresponding conductor tracks are guided by the temperature sensors within the printed circuit board 60 to the evaluation unit 5. The evaluation unit 5 is designed to determine a temperature difference value and to compare with a corresponding limit and when the corresponding limit is exceeded, a corresponding switching mechanism, as is known in the prior art, trigger and thus safety to an overcurrent react.

Claims (12)

1. Overcurrent protection device (1) comprising
   a conductor (10),
   an evaluation unit (4),
   a first temperature sensor (11), wherein

   - the conductor (10) is embodied such that a current (I) is conducted from a source (101) along a defined path (W) of the conductor (10) to a load (201) and

   - the temperature sensor (11) is arranged relative to the conductor (10) such that a temperature of the conductor (10) can be measured as a temperature measured value, wherein

   - the first temperature sensor (11) is connected to the evaluation unit (4), here the evaluation unit (4) is embodied to compare the temperature measured value with a temperature limit value stored in the evaluation unit (4), wherein the temperature limit value is selected such that it represents a distribution of a maximum permissible electric current which prevails in the conductor (10), wherein a current density resulting therefrom is evaluated as an overcurrent in the conductor (10),

   the evaluation unit (4) is further embodied such that if the temperature measured value has reached the temperature limit value, a control signal is output via a control output (4a) of the evaluation unit (3), said control signal indicating the overcurrent in the conductor (10),
   characterised in that in addition to the first temperature sensor (11), a second temperature sensor (12) and a third temperature sensor (13) are arranged distributed along the path (W) of the conductor (10) and the temperature sensors (11, 12, 13) are arranged relative to the conductor (10) such that a first temperature of the conductor (10) at a first location (X1), a second temperature at a second location (X2) and a third temperature at a third location (X3) of the conductor (10) can be measured as a first, second and third temperature measured value in each case, wherein the evaluation unit (4) is connected to the first temperature sensor (11), the second temperature sensor (12) and the third temperature sensor (13) and is embodied to calculate a temperature difference value from the first, second and third temperature measured value.
2. Overcurrent protection device (1) according to claim 1, wherein the conductor (10) is embodied as a sequence of loops (S1,...,S13), here a conductor length of the conductor (10) is accommodated by the loop sequence on a measuring section (MS), wherein the linear extension of the measuring section (MS) is smaller than the conductor length.
3. Overcurrent protection device (1) according to one of claims 1 or 2, wherein the conductor (10) has a meander-shaped embodiment, and as a result an essentially rectangular surface is provided for an installation space.
4. Overcurrent protection device (1) according to one of claims 2 or 3, wherein the conductor (10) has a meander-shaped, circular embodiment, and as a result a circular area is provided for the installation space, wherein the loops of the conductor (10) are arranged in a bifilar manner.
5. Overcurrent protection device (1) according to one of claims 2 to 4, wherein the conductor (10) is embodied as a two-dimensional strip extended in the longitudinal direction and a cross-sectional reduction in the strip is arranged in a loop, which results in an increase in the current density in the surroundings of the cross-sectional reduction.
6. Overcurrent protection device (1) according to claim 3, wherein the conductor (10) as a two-dimensional strip is embodied as a box-shaped element by a composition of a number of loops (S1, ..., S13) in layers.
7. Overcurrent protection device (1) according to claim 6, wherein an insulation material (40) is arranged between the loops (S1, ..., S13) arranged in layers.
8. Overcurrent protection device (1) according to claim 6 or 7, wherein an initial section (A1) of the conductor (10) and a final section (E1) of the conductor (10) are essentially arranged at right angles to the box-shaped element and a subarea of the initial and final section (A1, E1) is strengthened in each case with a further electrically conducting, two-dimensional material.
9. Overcurrent protection device (1) according to one of claims 1 to 8, wherein the material of the conductor has

   - a chrome-nickel alloy, in particular

   - a copper-nickel alloy, in particular

   - a steel-nickel alloy, in particular

   - chrome-aluminium alloy.
10. Overcurrent protection device (1) according to one of claims 1 to 9, wherein a resistance of the conductor (10) in respect of the path (W) is in the range between 1 milliohm and 100 milliohms.
11. Overcurrent protection device (1) according to one of claims 1 to 10, embodied as an electrical switching module comprising
    an input terminal area (100) for connecting source lines,
    an output terminal area (200) for connecting load lines and in addition to the
    first conductor (10),
    a second conductor (20),
    a third conductor (30),
    a first switching means (105),
    a second switching means (205),
    a third switching means (305),
    wherein the conductors (10, 20, 30) are each arranged in series with the switching means (105, 205, 305) between an associated first, second or third input terminal of the input terminal area (100) and a first, second or third output terminal of the output terminal area (200).
12. Overcurrent protection device (1) according to claim 11 having, for each conductor (10, 20, 30), a latch which interacts with each respective switching means (105, 205, 305) for disconnecting the current (I ₁, I ₂, I ₃) flowing via the conductor (10, 20, 30), wherein the force of a spring is used, which is tensioned with a manual connection and is detensioned when the temperature limit value is reached via a trigger device (5) connected to the control output (4a).

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