The present invention relates to electrically connecting to main conductors of a main cable and determining position and nature of main conductors of a main cable. Specific embodiments relate to a device for determining position and nature of main conductors of a main cable, a device for determining a nature of main conductors of a main cable, a system for determining position and nature of main conductors of a main cable, the use of such a device or system for determining position and nature, or a nature, of main conductors of a main cable, and a device for electrically connecting such a main conductor.

For certain purposes, such as constructing a house branch socket, i.e. a socket that branches off a branch cable from a main electrical cable for supplying electrical supply to a building, such as a house or commercial premises, it is useful to determine position and nature of the main conductors in the main cable. This is because there are typically four different main conductors in such a main cable, but sometimes more, e.g. 6, or less, and the branch line should connect properly to each main conductor. In particular, it is important that the contact with each main conductor of the main cable is sufficiently centred in that main conductor, to avoid failing contact, and in addition, the branch must match the nature, or colour, of the main conductor, to obtain the correct mutual voltages between the main conductors of the branch cable.

The common approach for determining position and nature of main conductors of a conductor involves stripping the main cable, to expose the main conductors; mounting a clamp on the main conductors; wrapping the clamp and padding the exposed part of the main cable (typically with resin) to restore that exposed part.

This common approach has at least the following drawbacks:

- It is labour-intensive, as it requires the main cable to be stripped and, after branching, sheathed and filled with, for example, resin.

- It does not provide sufficient safety as several conductors are exposed during the operation, especially during the stripping of the main cable. - It does not provide a sufficient guarantee of quality, because quality depends very much on how well a technician applies the branch socket, and moreover, stripping the main cable makes its structure and the precise position of the main conductors in the main cable less stable.

Analogous drawbacks apply to electrically connecting to main conductors of a main cable.

It is an object of the present invention to solve at least one or more of these drawbacks.

To this end, the present invention provides a device for electrically connecting to at least one main conductor of main conductors of a main cable, comprising:

- an at least on its inner side substantially annular bracket provided with a recess for accommodating the main cable in a state of use;

- at least one electrically conductive contact pin extending radially away from an imaginary centre of the recess, wherein the or each contact pin is provided with a sharp end directed towards the imaginary centre of the recess, which sharp end is arranged to cut plastic once the cutting pressure exceeds a threshold; and

- at least one sheath that sheaths the at least one contact pin, respectively, formed of an electrically insulating material, preferably plastic, and provided with a pointed end directed towards the imaginary centre of the recess, wherein the at least one sheath is arranged to be pierced in the state of use by the or each sharp end of the at least one contact pin, in particular at its or their pointed end.

In this way, the electrically conductive contact pin, encased in its sheath, can pierce due to sufficient pressure an outer sheath of the main cable and an outer sheath of the main conductor, wherein the wires of the ground shield in the outer sheath can also be pushed aside. Next, its own sheath will be pierced due to the cutting pressure so that an electrical connection - electrically insulated from the rest of the surroundings - due to the sheath - can be established between the electrically conductive contact pin and the main conductor. Conduction with the main conductor can then be obtained via the contact pin. This device can be referred to as a house branch socket in this context.

In one embodiment, the bracket comprises at least two complementary parts, which parts are arranged to be connected to each other to form the bracket in a form-fitting manner.

In one embodiment, the device comprises at least one injection organ arranged to inject a filler, such as resin, into the main vein.

The present invention also provides for the use of such a device for electrically connecting to at least one main conductor of main conductors of a main cable.

The present invention also provides a device for determining position and nature of main conductors of a main cable, wherein the device in a state of use is rotatable around the main cable, comprising:

- at least one conductor electrically insulated from the main conductors, wherein the or each conductor is arranged to be in the state of use at an outer wall of the main cable, wherein the or each conductor extends, preferably predominantly, along a longitudinal direction that shares at least a longitudinal component with a longitudinal direction of the main cable;

- a voltmeter equipped for measuring a voltage or voltages between the or each conductor and a predetermined reference point, which voltage or voltages are generated by electrostatic influence of charge carriers in the main conductors when the or each conductor is in the state of use at the outer wall of the main cable; and

- a microcontroller arranged for detecting a maximum amplitude or minimum amplitude of the measured voltage or voltages when the device in the state of use is rotated around the main cable, and arranged for determining the locations of the main conductors based on the detected maximum amplitude or minimum amplitude.

This device solves the disadvantages described above, as it no longer requires the main cable to be stripped, sheathed and filled with resin, because none of the conductive elements inside the main cable are exposed, and because the stability of the structure of the main cable is maintained. Moreover, this device is convenient and quick to apply, with a minimum of training for an operator, making the deployment possibilities very numerous.

Note that the nature of a main conductor of a main cable typically corresponds to the colour of that main conductor, but that the nature is, in a strict sense, actually determined by the ratio of the alternating electrical voltage to that in the other main conductors. The person skilled in the art will have no difficulty in making this distinction, which is why "nature" will suffice in the present text.

Note also that it is implicitly assumed that a power source is available to the microcontroller. This may simply be its own battery, or a connection may be provided for connection to an external power source. In another embodiment, even a parasitic power system may be provided, arranged to drive the microcontroller based on energy harvested from the environment, preferably from the electrical energy present in the main cable.

In practical embodiments, the predetermined reference point may be, for example, an internal ground of the device itself, or, for example, the ground shield of the main cable, or, for example, an earth pin embedded in the ground, etc.

In an embodiment, the at least one conductor comprises at least two conductors, arranged to be, in the state of use, on opposite sides of the outer wall.

This makes it possible to suffice with rotating only 180 degrees.

In an embodiment, the at least one conductor comprises three conductors, arranged to be, in the state of use, on three sides of the outer wall, which three sides are mutually either substantially perpendicular to each other or substantially at 120° to each other.

In one embodiment, the at least one conductor comprises four conductors, arranged to be, in the state of use, on four sides of the outer wall, which four sides are substantially perpendicular to each other. In an embodiment, the at least one conductor comprises six conductors, arranged to be, in the state of use, on six sides of the outer wall, which six sides are substantially 60° apart from each other.

In one embodiment, the or each conductor extends along a longitudinal direction that corresponds to an estimated conventional winding pitch of the main conductors.

The person skilled in the art will appreciate that the conventional winding pitch can be determined on the basis of applicable norms and standards, such as, for example, standard NEN 3616:2001 nl in the Netherlands for the definition of this type of main cables. Even if in practice a main cable should deviate from the conventions defined in such norms and standards, the estimated conventional winding pitch provides a suitable approximation, at least to start with.

In this way, the most efficient electrostatic influence can be obtained.

In one embodiment, the device comprises a substantially annular recess arranged to receive the main cable. Alternatively, the device may comprise a differently shaped, for example substantially quadrangular, recess, for example formed by attaching four angled components to the cable, also arranged to accommodate the main cable.

In this way, the device can closely connect to the main cable.

In a further developed embodiment, the device comprises two complementary shaped jaw portions that, in the use state, form the recess for accommodating the main cable.

In this way, the operator can suffice with access from only one direction; he does not need to be able to reach the "back" or "bottom" of the main cable.

In a further developed embodiment, the two jaw portions are coupled together, preferably by means of a clamping spring; or wherein the two jaw portions are independent with respect to each other and each of the two jaw portions comprises a complementary shaped connection mechanism arranged for decoupling the two jaw portions from each other.

In this way, the device offers increased ease of use, because the clamping spring ensures that the jaw portions close automatically to accommodate the main cable.

In one embodiment, the microcontroller is arranged to determine, under the assumption that the main cable exhibits a known right-handed field:

- that a detected minimum amplitude indicates that an underlying main conductor is a neutral conductor;

- that phase 2 lies opposite the neutral conductor;

- that phase 1 has a phase lead compared to phase 2; and

- that phase 3 has a phase lag compared to phase 2.

In an alternative or additional embodiment, the microcontroller is arranged to determine, under the assumption that the main cable exhibits a known left-handed field:

- that a detected minimum amplitude indicates that an underlying main conductor is a neutral conductor;

- that phase 2 lies opposite the neutral conductor;

- that phase 1 has a phase lag compared to phase 2; and

- that phase 3 has a phase lead compared to phase 2.

Note that this determination can be made under the assumption of a known conventional right-turning or left-turning electric field. In case the direction of rotation of the electric field would not be known, it is possible to determine it conveniently by other means, as will be described below with reference to the use of another device.

In one embodiment, the device comprises an indicator, preferably a buzzer or an optical indicator, wherein the microcontroller is arranged for controlling the indicator such that the indicator provides an indication when the maximum amplitude or minimum amplitude is detected. This allows the operator to smoothly rotate the device to a suitable rotation angle.

In an embodiment, the microcontroller is arranged for converting the measured voltage or voltages from a time domain to a frequency domain by means of a Fourier transform; and the microcontroller is arranged for determining the locations of the main conductors, based on at least one frequency peak corresponding to the maximum amplitude or minimum amplitude when the device is rotated around the main cable.

In this way, it is possible to exclude higher and lower frequencies than the mains voltage frequency, and the interpretation of maximum amplitude and minimum amplitude is easier, namely as simple height of the peak around the mains voltage frequency in the frequency domain.

In one embodiment, the device comprises a gyroscope arranged for determining a rotation angle made by the device relative to a conventional vertical direction, preferably the direction of gravity, wherein the microcontroller is arranged to take into account the rotation angle determined by the gyroscope when determining the locations of the main conductors.

This allows the microcontroller to determine the locations of the main conductors independently of the current rotation angle of the device, as the microcontroller can compensate for the current rotation angle of the device.

In an embodiment, the device comprises at least one indicator means, wherein the microcontroller is arranged for controlling the at least one indicator means based on the determined locations of the main conductors, such that the at least one indicator means provides an indication of an underlying main conductor or respective underlying main conductors.

In this way, there is increased ease of use, greater accuracy, and better precision in indicating the zone for the operator. In a specific embodiment, the at least one indication means comprises at least one of the following: an indicator zone, preferably an LED strip; and a preferably cylindrical display.

In an embodiment, wherein the at least one indicator zone comprises a first, second, third and fourth indicator zone, wherein the microcontroller is arranged to display the respective colours of the main conductors, preferably by:

- illuminating the first indicator zone with a first colour, preferably green, to indicate that an underlying main conductor is a neutral conductor;

- illuminating the second indicator zone with a second colour, preferably yellow, to indicate that the underlying main conductor is phase 2, lying opposite the neutral conductor; and in case the main cable shows a right-handed field:

- illuminating the third indicator zone with a third colour, preferably red, to indicate that the underlying main conductor is phase 1 , with a phase lead compared to phase 2; and

- illuminating the fourth indicator zone with a fourth colour, preferably blue, to indicate that the underlying main conductor is phase 3, with a phase lag compared to phase 2; or in case the main cable shows a left-handed field:

- illuminating the third indicator zone with a third colour, preferably red, to indicate that the underlying main conductor is phase 1 , with a phase lag compared to phase 2; and

- illuminating the fourth indicator zone with a fourth colour, preferably blue, to indicate that the underlying main conductor is phase 3, with a phase lead compared to phase 2.

Alternatively or additionally, the device comprises a communication module, preferably a Bluetooth module, arranged to communicate with a user device, preferably a smartphone, of an installer, and to indicate by means of that communication which main conductor is located where in the main cable.

In an embodiment, the device comprises a module for determining data related to branches, such as data on a location of the or each branch, preferably a GNSS, in particular GPS, module, and a communication module, which allows the device to send the data to a central database. In this way, an operator can better keep abreast of which branches are located where on the main cable or cables.

The present invention also provides for the use of a device according to one of the embodiments described above, for determining position and nature of main conductors of a main cable.

In an embodiment of the use, the use moreover comprises:

- connecting a house branch socket comprising at least one contact pin;

- inserting by means of a mechanism the at least one contact pin into respective main conductors of the main cable, which mechanism is arranged to insert each contact pin of the at least one contact pin with a guaranteed tightening torque or at a guaranteed depth into the main conductor.

Such a mechanism may operate, for example, by means of a pre-imposed spring force of a spring that is automatically released, or by means of a pre-set motor, or by means of a pre-set pressure that can be built up by means of a pneumatic reservoir, or by means of a contact pin with a well-selected shear bolt that is arranged to break at a pre-set torque, or by means of a bolt with a fixed setting depth, etc.

The present invention also provides a device for determining a nature of main conductors of a main cable, comprising:

- an at least on its inner side substantially annular bracket provided with a recess for accommodating the main cable in a state of use;

- at least one hollow pipe extending radially away from an imaginary centre of the recess, wherein the or each hollow pipe is provided with a sharp end directed towards the imaginary centre of the recess, which sharp end is arranged to cut plastic once the cutting pressure exceeds a threshold; and

- at least one plastic arrowhead, arranged to be clamped, in the state of use, between the or each sharp end and the main cable, with the tip of the or each plastic arrowhead directed towards the imaginary centre of the recess. This device allows to see the insulation colour and thus the nature of the main conductors, in order to determine which main conductor is involved.

The hollow pipe can be pushed through an outer jacket of the main cable and an outer jacket of the main conductor, itself pushing aside the wires of the ground shield in the outer jacket due to the plastic arrowhead. Next, the plastic arrowhead will touch the aluminium of the main conductor, which will increase the pressure such that the sharp end of the hollow pipe cuts through the plastic arrowhead, as well as through the (typically coloured) insulation layer of the main conductor, leaving a particle of the insulation layer in the cavity of the hollow pipe that can be easily extracted if required.

In one embodiment, the bracket comprises at least two complementary parts, which parts are arranged to be connected to each other to form the bracket in a form-fitting manner. Note that a "bracket" in this context may refer to a "ring for closing an object" - the closure may thereby be fixed or spring-loaded or hinged.

In this way, the device can be applied anywhere along the main cable.

In one embodiment, the device comprises at least one injection organ arranged to inject a filler, such as resin, into the main conductor.

In this way, the main cable can be made locally watertight or at least more water- resistant. This can be exploited both against local water intrusion and also against capillary water intrusion along the length of the main cable from water that has entered the main cable from more distant water contact points.

The present invention also provides for the use of a device for determining a nature of main conductors of a main cable according to one of the embodiments described above.

The present invention also provides a system for determining position and nature of main conductors of a main cable, comprising a device for determining position and nature of main conductors of a main cable according to one of the embodiments described above and a device for determining a nature of main conductors of a main cable according to one of the embodiments described above.

The present invention also provides for the use of such a system for determining position and nature of main conductors of a main cable, wherein the device for determining the nature of the main conductors - i.e. the device comprising at least one hollow pipe - is employed for determining the nature of the main conductors if the rotational field of the main cable is unknown beforehand, wherein by means of the at least one hollow pipe a particle of a coloured insulation wall of at least one selected main conductor is cut and detached from the main cable, so that by visual inspection of the particle it becomes apparent which nature the at least one selected main conductor has.

The person skilled in the art will be able to understand even more fully the abovedescribed embodiments of the present invention with the help of the description that follows and the accompanying drawings, wherein:

Figure 1 schematically shows an example of an embodiment of a device according to the present invention;

Figure 2 schematically shows another example of an embodiment of a device according to the present invention;

Figure 3 schematically shows yet another example of an embodiment of a device according to the present invention;

Figure 4 shows four graphs showing an example of signals that can be detected or used by a device according to the present invention;

Figure 5 schematically shows an example of a hollow pipe that can form part of a device according to the present invention;

Figure 6 schematically shows an example of an embodiment of a second device according to the present invention;

Figure 7 schematically shows an example of an embodiment of a third device according to the present invention; and

Figure 8 schematically shows an example of a use for a device according to the present invention. Figure 1 schematically shows an example of an embodiment of a device according to the present invention. The device is for determining position and nature of main conductors of a main cable 100, wherein the device, in a state of use, is rotatable around the main cable 100. The device comprises at least one conductor 101A-C, which is electrically insulated from the main conductors 106B, 106G, 106R, 106Y, preferably through existing insulation walls such as outer wall 105 and/or insulation wall 109 of the main cable. The or each conductor 101A-C is arranged to be, in the state of use, at an outer wall 105 of the main cable 100, wherein the or each conductor 101A-C extends along a longitudinal direction that shares at least a longitudinal component with a longitudinal direction of the main cable 100. Note that the exemplary embodiment shown in this figure has the preferred feature of conductors 101A-C extending predominantly along the longitudinal direction sharing at least a longitudinal component with a longitudinal direction of the main cable 100, i.e. the conductors extend relatively more along the length of the main cable 100 than along the circumference of the main cable 100.

The device further comprises a voltage meter 103 arranged for measuring a voltage or voltages between the or each conductor 101A-C and a predetermined reference point 104, which voltage is or which voltages are generated by electrostatic influence of charge carriers in the main conductors 106Y, 106R, 106G, 106B (collectively named as 106) when the or each conductor 101 A-C is in the state of use at the outer wall 105 of the main cable 100. To this end, the voltage meter 103 may be coupled 102 with the respective conductor or conductors 101 A-C. In this example, one such coupling 102 is shown, but the person skilled in the art will appreciate that such coupling is possible with multiple conductors 101A-C. The device further includes a microcontroller (not shown) arranged for detecting a maximum amplitude or minimum amplitude of the measured voltage or voltages when the device in the state of use is rotated around the main cable 100, and arranged for determining the locations of the main conductors 106 based on the detected maximum amplitude or minimum amplitude.

The figure also shows some auxiliary conductors 107, in particular 107Y, 107R, 107G, 107B, which are less relevant to the device, as well as a ground shield 108. The operation of the device will be described more clearly with reference to the embodiment of Figure 3, which can be seen as a further development of the embodiment of Figure 1.

Figure 2 schematically shows another example of an embodiment of a device 200 according to the present invention. The device 200 is shown abstractly in this figure, but may correspond in form to, for example, the embodiment of Figure 1 and/or Figure 3. Like the embodiment of Figure 1 , the device 200 comprises at least one conductor 201 , coupled to a voltage meter 202, and a microcontroller 203. The voltage or voltages read by the voltage meter 202 may be presented to the microcontroller 203, based on which the locations of the main conductors can be determined, as explained above.

The device 200 may also include an optional buzzer 204 acting as an indicator, where the microcontroller 203 is arranged to control the buzzer 204 to provide an indication when maximum amplitude or minimum amplitude is detected. An alternative indicator may for example be an LED which then emits maximum or minimum light respectively, or a clicker which indicates amplitude at a click frequency, or any other serviceable indicator.

The device 200 may also comprise at least one optional indicator means 205, wherein the microcontroller 203 is arranged to control the at least one indicator means 205 based on the determined locations of the main conductors, such that the at least one indicator means 205 provides an indication of an underlying main conductor or respective underlying main conductors. For example, a convenient indicator means 205 is an indicator zone such as an LED strip, but a full-fledged display, preferably a cylindrical one so that it fits well with the shape of the main cable 100, may also be used. The LED strip may be controlled by the microcontroller 203 to indicate by means of a well-chosen colour the nature of an underlying main conductor. If the LED strip comprises a sufficiently large number of separate LEDs, it is possible to determine the position with sufficient certainty and precision. Figure 3 schematically shows another example of an embodiment of a device 300 according to the present invention, applied to a main cable 100 as described with reference to Figure 1. The device 300 may comprise an annular recess 302 arranged to receive the main cable 100. This recess 302 is substantially annular because it does not need to be closed around the main cable 100 to still work properly (as is the case in the example shown here), although it may of course be closed around it. In this example, the device 300 comprises two complementary shaped jaw portions 301A-B that in the state of use form the recess 302 for accommodating the main cable 100. It is advantageous to couple the jaw portions 301 A-B together as in this example, by, for example, a clamping spring, with corresponding operating points 304A-B, to allow the device 300 to be easily opened and closed around a main cable 100.

The figure also shows the optional indicator, here a buzzer 306, as described in the context of Figure 2, and the optional indicator zone, here an LED strip 303, also as described in the context of Figure 2. In addition, as in this example, the device 300 may include a battery 305, to power other components of the device 300.

The figure also shows recesses 307 in the device 300 for accommodating the conductors, such that in the state of use they are located near the outer wall 105 of the main cable 100.

Figure 4 shows four graphs exemplifying signals that can be detected or used by a device according to the present invention. Graph 401 shows a voltage in mV measured over time, as detected by the voltage meter on one of the conductors of the device. In practice, this voltage may be noisy, as shown in graph 401. Nevertheless, it is possible to observe a dominant frequency 405 in the measured voltage, as shown in graph 402. A convenient and apt way to isolate this dominant frequency 405 is shown in graph 403, where the measured voltage has been converted from the time domain to the frequency domain in Hz, by means of a Fourier transform, where a peak 406 is clearly observable around 50 Hz, indicating that AC voltage has been applied to the main conductor above which the conductor is located at the mains frequency 50 Hz. By rotating the device, it becomes possible to detect when this peak 406 reaches a maximum 408 or a minimum 407 in terms of amplitude, as shown in graph 404. By comparing these extrema, it is possible to determine the nature of the underlying main conductor, as indicated in graph 404 by references 1 , 2, 3, Nul (i.e. neutral), for the different phases and the neutral conductor. In doing so, it is advantageous if the device also includes a gyroscope arranged to determine a rotation angle made by the device relative to a conventional vertical direction, preferably the gravity direction, with the microcontroller arranged to take into account the rotation angle determined by the gyroscope when determining the locations of the main conductors. In this way, the rotation angle at which maximum 408 and/or minimum 407 occur can be accurately determined.

Figure 5 schematically shows an example of a hollow pipe 501 that may form part of a device according to the present invention. The hollow pipe 501 is provided with a sharp end 502 arranged to cut plastic once the cutting pressure applied to the sharp end 502 exceeds a threshold. The figure also shows a plastic arrowhead 503 which will be described below. Hollow pipe 501 will be further illustrated with reference to Figure 6.

Figure 6 schematically shows an example of an embodiment of a second device 600 according to the present invention, seen in perspective. The device 600 is for determining a nature of main conductors of a main cable, such as main cable 100 shown in Figure 1. The device 600 comprises an at least on its inner side substantially annular bracket 601 provided with a recess 602 for accommodating the main cable 100 in a state of use. The device 600 additionally includes at least one hollow pipe 603, such as, for example, hollow pipe 501 of Figure 5, extending radially away from an imaginary centre of the recess 602, wherein the or each hollow pipe 603 is provided with a sharp end 502 directed towards the imaginary centre of the recess 602, which sharp end 502 is arranged to cut plastic once the cutting pressure exceeds a threshold. The device 600 also includes at least one plastic arrowhead 503, arranged to be clamped, in the state of use, between the or each sharp end 502 and the main cable, with the tip of the or each plastic arrowhead 503 directed towards the imaginary centre of the recess 602. Figure 7 schematically shows an example of an embodiment of a third device 700 according to the present invention, seen in cross-section. The device 700 is for electrically connecting to at least one main conductor of main conductors of a main cable, such as main cable 100 shown in Figure 1. The device 700 includes an at least on its inner side substantially annular bracket 701 provided with a recess 702 for accommodating the main cable 100 in a state of use. The device 700 additionally includes at least one electrically conductive contact pin 703 extending radially away from an imaginary centre of the recess 702, wherein the or each contact pin 703 is provided with a sharp end directed towards the imaginary centre of the recess 702, which sharp end is arranged to cut plastic once the cutting pressure exceeds a threshold. The device 700 also comprises at least one sheath that sheaths the at least one contact pin 703, respectively, formed of an electrically insulating material, preferably plastic, and provided with a pointed end directed towards the imaginary centre of the recess 702, wherein the at least one sheath is arranged to be pierced in the state of use by the or each sharp end of the at least one contact pin 703, in particular at its or their pointed end.

Each contact pin 703 is contained in a preferably plastic sheath, which sheath serves to electrically isolate the contact pins 703 from the ground shield. The sheath also has a pointed end to penetrate the main cable 100 up to the main conductors 106B-G-R- Y. The contact pin 703, when penetrating the main conductor 106B-G-R-Y, will split the plastic sheath once the pressure applied to it exceeds a certain threshold value, and will then further penetrate the main conductor 106B-G-R-Y and make electrical contact with it.

Figure 8 schematically shows an example of a use of a device according to the present invention. In an example situation, a house 805 (or another type of building) is to be connected to a main cable 801-802, by means of a house branch socket. In such situations, it is not always clear from which main cable should be tapped, for example if several main cables are present. A common solution in such cases is to place a current train from a power plant 803, for example from a transformer house, on two main conductors in the main cable 801 - one main conductor carries the current train in one direction, the other main conductor in the other - so that an installer can use a known clamp meter or simple coil to determine which main cable is the correct one. This is because the clamp meter will show the current train running over the two main cores of the correct main cable, and will not show an identifiable result (e.g. just noise) if the clamp meter is connected to the wrong main cable. However, a common problem is that a house 805 (or any other type of building) should be connected to an end 802 of the main cable, which is beyond the last closure 804 of the circuit of the main cable, as seen from the plant. In that case, it is impossible to detect such a current train with the known clamp meter or coil, since the main cable does not form a closed circuit in that end 802 of the main cable.

The device according to the present invention solves this problem by being able to detect the voltage train induced by such a current train, even in that end 802 of the main cable, because voltage can be detected on the main conductors even if the circuit is not closed.