Current transformer

Abstract

Current transformer (3) with an insulating housing (11, 27) having a conductor entry opening (5) and a current tap winding (4) arranged adjacent to the conductor entry opening (5) and current tap winding connection contacts electrically connected to the current tap winding (4), wherein the current transformer (3) is configured to detect the electric current flowing through an electrical conductor (6) passing through the conductor entry opening (5), and wherein the current transformer (3) is configured to tap the voltage potential applied to the electrical conductor (6) passing through the conductor entry opening (5), wherein a contact tongue (12) projects from the insulating housing (11, 27) for tapping the voltage potential.wherein the contact tongue (12) is aligned parallel to the electrical conductor (6) passing through the conductor feedthrough opening (5) and is designed for connection to a conductor terminal (1), and wherein the contact tongue (12) has a contact surface (15) arranged adjacent to the current tap winding (4) and has a fuse (14), wherein the fuse (14) is supported on the contact surface (15) and electrically connects the contact surface (15) to a voltage tap terminal contact (17).

Description

[0001] The invention relates to a current transformer with an insulating housing, which has a conductor opening and a current tap winding arranged adjacent to the conductor opening and current tap connection contacts electrically connected to the current tap winding.

[0002] DE 10 2011 102 978 A1 discloses a current transmitter for measuring a current flowing through an electrical cable with a probe ring. The probe ring is divided into a base ring section and at least one movable ring section, so that it can be opened to insert an electrical cable.

[0003] US 3,208,021 A describes a short-circuiting mechanism for a current transformer. The windings are connected to terminals on the outside of the current transformer (current transmitter) and can be short-circuited there using a short-circuiting bridge.

[0004] US 7,955,102 B2 discloses a current transformer with a plug-in terminal and a short-circuit switch integrated into the plug-in terminal. A connector can be attached to the plug-in terminal, which relocates the short-circuit switch with a protruding lug and eliminates the short circuit between the current tap terminals. When the connector is not attached, the current tap terminals are electrically connected to each other to prevent the current tap windings from running unplugged.

[0005] DE 10 2012 107 279 A1 discloses a current transformer with a short-circuit winding that is integrated into a housing surrounding the current transformer.

[0006] A conventional current transformer is known from US patent 2007 / 0136010 A1. A micromechanical pressure sensor device and corresponding measuring arrangement are known from German patent DE 102 31 727 A1. An electrical quick-connect and disconnect system with integrated short-circuit function is known from US patent 2009 / 0186504 A1.

[0007] US 8,476,895 B2 describes a measuring unit with which the current flowing through a conductor can be measured using an inductive current sensor and the voltage by means of a contact tap on the conductor. The measuring unit can be placed directly in front of the line output of a current limiter.

[0008] Based on this, the object of the present invention is to create an improved current transformer in which the voltage potential applied to the electrical conductor can also be tapped.

[0009] The problem is solved by the current transformer having the features of claim 1. Advantageous embodiments are described in the dependent claims.

[0010] It is proposed that the current transformer has a contact tongue projecting from the insulating housing. The contact tongue is aligned parallel to an electrical conductor passing through a conductor entry opening, i.e., parallel to the axis of the conductor entry opening, and is intended for connection to a conductor terminal.

[0011] This allows the current transformer to be connected to a conductor terminal, so that the electrical conductor passed through the conductor feedthrough opening is electrically connected in parallel via the conductor terminal to the contact tongue and the associated voltage tap connection contact.

[0012] The contact tongue can be electrically connected to a voltage tap terminal contact of the current transformer, via which the voltage potential of the electrical conductor can be tapped.

[0013] The conductor connection terminal can be, for example, a terminal block that can be mounted on a DIN rail. The current transformer is then attached to the conductor connection terminal by inserting its contact tongue into an opening in the terminal that leads to a terminal. The contact tongue is then electrically connected via the terminal to a conductor clamp of the terminal, which is used to clamp an electrical conductor. For this purpose, the electrical conductor to be tested is passed through the conductor entry opening and clamped to the designated clamping point of the terminal. The current transformer thus forms a unit with the associated conductor connection terminal, with the conductor entry opening being positioned relative to the terminal by means of the contact tongue inserted into the terminal.The distance of the contact tongue to the center of the conductor entry opening of the current transformer essentially corresponds to the distance of the opening for receiving the contact tongue in the conductor terminal to the center of the conductor entry opening of the conductor terminal.

[0014] It is also conceivable that the current transformer is first slid over an electrical conductor or attached to an electrical conductor that is already connected to the terminal block. In this case, the electrical conductor is inserted into a corresponding conductor entry opening in the terminal block and connected to the terminal block before the current transformer is attached.

[0015] The contact tongue of the current transformer can be positioned adjacent to the current tap winding. This allows for a very compact design, in which the contact tongue is positioned next to the conductor entry axis defined by the conductor entry opening of the current tap winding.

[0016] The contact tongue has a contact surface located adjacent to the current tap winding. According to the invention, a fuse is mounted on this contact surface, which electrically connects the contact surface to the voltage tap terminal contact. In this way, the voltage tap and the electrical components connected to or downstream of the voltage tap are protected from overload due to excessive current flow. Such a fuse can, for example, be a cartridge fuse with a cylindrical glass or ceramic body and metal caps at opposite ends. This fuse can then be placed on the contact surface with a metal cap.

[0017] In this context, a fuse cover may be provided. The voltage tap connection contact can be electrically connected to the fuse cover. The fuse cover is placed on the fuse opposite the contact surface of the contact tongue. It has an electrical conductor leading from a first contact area of ​​the fuse cover, which connects to the fuse, to a second contact area of ​​the fuse cover, which connects to the voltage tap connection contact. This electrical conductor can be a wire, a sheet metal part, or a vapor-deposited conductor.

[0018] In such a current transformer, the voltage tap terminal contact can have a feed-through opening for receiving the fuse. The second contact area of ​​the fuse holder then rests against the area bordering the feed-through opening for electrical contact. This feed-through opening of the voltage tap terminal contact provides a holder for the fuse, allowing the fuse to be inserted into the opening and resting on the contact surface of the contact tongue.

[0019] The current tap connection contacts and the voltage tap connection contact can be integrated into a common terminal block on the current transformer. This has the advantage that connecting a measuring instrument via the common terminal block is very quick and easy.

[0020] The terminal block can be designed as a socket for accepting a connector. Alternatively, the terminal block can have a connector with contact points for clamping electrical conductors. Such a connector could, for example, have spring-loaded terminals to which test leads are attached. The test leads are inserted into conductor entry openings in the connector and routed to the corresponding spring-loaded terminals.

[0021] The current tap terminals can be connected to a short-circuit bridge. The short-circuit bridge has a movable switching contact designed to disconnect the short-circuit bridge from the current tap terminals when mating contacts are connected to the current tap terminals. By integrating a short-circuit bridge into the current tap terminal area, a protective mechanism is provided that protects the current tap winding from damaging open-circuiting with open winding ends and current flow through the measured electrical conductor.

[0022] The current tap winding can have windings that completely surround the conductor entry opening. However, it is also conceivable that the current tap winding is designed as a Rogowski coil, i.e., a toroidal air coil. A Rogowski coil consists of a conductor wire wound around a rod bent at least partially circularly, made of a non-conductive and non-ferromagnetic material. The conductor wire of the air coil is wound around the ring of the coil body in such a way that the terminal ends of the conductor wire lie next to each other. With such a toroidal air coil, it is possible for the electrical conductor to be only partially surrounded by the coil, allowing the conductor to be inserted into an opening of the Rogowski coil.

[0023] The invention is described in more detail below with reference to an exemplary embodiment and the accompanying drawings. These show: Fig. 1 - Perspective view of a conductor terminal block with a current transformer mounted on it; Fig. 2 - Side view of the current transformer made of Fig. 1; Fig. 3 - Perspective partial section view of the conductor terminal block with current transformer mounted on it; Fig. 4 - Side partial sectional view of the current transformer from Fig. 1 to 3; Fig. 5 - Side view of the current transformer; Fig. 6 - View of the current transformer from Fig. 5 from the bottom; Fig. 7 - Perspective front view of the current transformer; Fig. 8 - Perspective rear view of the current transformer; Fig. 9 - Side view of the conductor terminal block with current transformer mounted on it and the inserted and clamped electrical conductor.

[0024] Fig. Figure 1 shows a perspective view of a conductor terminal block 1 in the form of a terminal block mounted on a mounting rail 2. A current transformer 3 is mounted on one of the narrow sides of this conductor terminal block 1. This current transformer 3 is shown in partial section. The conductor terminal block 1 is shown partially transparent for clarity.

[0025] The current transformer 3 has a current tap winding 4 which defines a conductor entry opening 5 over at least part of its circumference. An electrical conductor 6 can thus be passed through the conductor entry opening 5 and connected to the conductor terminal 1 at a clamping point. When current flows through the electrical conductor 6, a current is induced in the current tap winding 4, which can then be measured. In this way, a non-contact measurement of the electric current flowing in the electrical conductor 6 is possible. Such current transformers 3 are well known per se.

[0026] The current tap winding 4 is connected to the plug contacts of a connector 7. The connector 7 is designed as a pin header with an insulating base and solder pins integrated within it as plug contacts. A mating connector 8, e.g., in the form of a spring-loaded terminal block with spring-clamp terminals for connecting electrical conductors inserted into corresponding conductor entry openings 9 of the mating connector 8, can be mounted on this connector 7. In the illustrated embodiment, the mating connector 8 has a grip 10, which can also serve as a conductor holder.

[0027] The connector 7 is integrated into an insulating housing 11 of the current transformer 3.

[0028] The current transformer 3 has a contact tongue 12 that projects from the insulating housing 11 and is inserted into a corresponding opening, such as a bridge opening 13 of the conductor terminal 1. There, the contact tongue 12 is electrically connected, for example by means of a spring-loaded clamp, to the terminal of the conductor terminal 1 for clamping the electrical conductor 6. Thus, the electrical voltage potential present on the electrical conductor 6 is applied to the contact tongue 12. This potential is conducted via the contact tongue to a plug contact in the connector 7 by means of an electrical connection between the contact tongue 12 and the corresponding plug contact of the connector 7.

[0029] The electrically conductive connection is made by means of a fuse 14. In the illustrated embodiment, a cylindrical fuse is provided, which rests on a contact surface 15 of the contact tongue 12 located adjacent to the current tap winding 4. The opposite side of the fuse 14 is electrically connected to the voltage tap terminal 17 via a fuse cover 16. For this purpose, the fuse cover 16 rests on a platform-like area which has a through-hole for receiving the fuse 14 and, together with the area adjacent to the through-hole, provides a contact surface for the fuse cover 16.

[0030] Fig. 2 omits the arrangement Fig. Figure 1 shows the side view. Here it becomes even clearer that the contact tongue 12 is guided into the interior of the conductor terminal 1 and lies adjacent to the stripped end of the electrical conductor 6. An electrically conductive connection between the contact tongue 12 and the electrical conductor 6 can then be made there by means of a spring-loaded clamp connection in a manner known per se. The contact tongue 12 is preferably inserted into a bridge opening 13 of the conductor terminal 1 and electrically connected to a busbar of the conductor terminal 1. The electrical conductor 6 is connected on the opposite side of the conductor terminal 1 to another electrical conductor that can be inserted there for current / voltage transmission. This is known per se and is not shown.

[0031] This illustration clearly shows that the plug contact (solder pin) of connector 7 transitions into a voltage tap connection contact 17, and the fuse 14 passes through the platform of the voltage tap connection contact 17. The fuse cover 16 is placed on the fuse 14 and is in electrically conductive contact with the voltage tap connection contact 17. Thus, the fuse 14, which extends into the interior of the fuse cover 16, is electrically connected to the voltage tap connection contact 17 via a conductive trace present in the fuse cover 16.

[0032] Fig. Figure 3 omits a perspective view of the arrangement. Fig. 1 and Fig. 2. Here, the plug contacts 18 of the connector 7 are visible; these are designed as solder pins and are installed in the insulating frame of the spring strip. A pair of these plug contacts 18 are electrically connected to the two winding ends of the current tap winding 4. In this way, by plugging in the mating connector 8, a measuring instrument can be connected to the current tap winding 4 via a measuring lead connected to a mating connector 8, and the current flowing through the electrical conductor 6 can be measured.

[0033] The contact tongue 12 is inserted into a bridge opening 13 of the conductor terminal 1. The bridge opening 13 is located adjacent to a conductor entry opening 19 of the conductor terminal for inserting an electrical conductor 6. In this way, the contact tongue 12 and the stripped electrical end of the inserted electrical conductor 6 are positioned adjacent to each other in the conductor terminal 1 and can be electrically connected to each other via a spring-loaded clamping connection of the conductor terminal 1. The electrical voltage potential of the electrical conductor applied to the contact tongue 12 is then conducted to a further plug contact 18 of the connector 7. As described in this embodiment, this is done via a fuse 14, such as a glass fuse.

[0034] Fig. Figure 4 shows a partial side view of the current transformer 3. Here it becomes clear again that the contact tongue 12 protrudes from the current transformer 3. The fuse 14 rests on a contact surface 15 located adjacent to the current tap winding 4. In the illustrated embodiment, the contact tongue 12 has tongue sections 20 that extend downwards from the plane of the contact surface 15 on both sides, in the direction of the conductor entry opening 5 or the electrical conductor. These are adapted to the clamping contact in the bridge opening 13 of the conductor connection terminal 1.

[0035] It is also evident that the voltage tap terminal 17 has a collar 21 projecting towards the contact tongue 12. This collar 21 provides an internal thread for screwing on the fuse cover 16. The collar 21 defines a feed-through opening into which the fuse 14 is inserted.

[0036] It becomes clear that the fuse 14 has a metal contact 22a, 22b at each of its opposite ends and an intermediate fuse body, for example made of glass or ceramic. Such a construction of fuses is well known.

[0037] Furthermore, it can be seen that the conductor entry opening 5 is limited by a guide sleeve 23, which is surrounded by the current winding 4 and extends parallel to the contact tongue 12 in the same direction. The contour of this guide sleeve 23 is adapted to the front contour of the associated conductor terminal 1, so that the current transformer 3 can be fitted precisely onto the conductor terminal 1.

[0038] Fig. Figure 5 shows a side view of the current transformer 3 in partial section without the insulating housing. The current transformer 3 has a printed circuit board 24 as its central element. The plug contacts 18 (solder pins) of the connector 7 are inserted into this printed circuit board 24 and soldered to it. In this way, the connector 7, which is designed as a pin header, is permanently connected to the printed circuit board 24. The winding ends of the current tap winding 4 are then electrically connected (soldered) to the corresponding plug contacts 18 of the connector 7 via the printed circuit board 24.

[0039] Similarly, the voltage tap connection contact 17 is soldered to the circuit board 24 and connected to the associated plug contact 18. The circuit board 24 with the other components soldered to it is then installed in an insulating housing (not shown in this illustration).

[0040] Fig. Figure 6 shows a top view of the current transformer 3. It is evident that the voltage tap terminal 17 has, for example, a rectangular base plate with a through-hole 25 for receiving a fuse. The voltage tap terminal 17 is electrically connected to an associated plug contact 18 (solder pin) of the connector 7.

[0041] Fig. Figure 7 shows a perspective front view of the current transformer 3. The connector 7 has four plug contacts 18 (solder pins), of which only three are used. Two of these plug contacts 18 are connected to the winding ends of the current tap winding 4. A plug contact 18, preferably located on the outside and furthest from the two current tap contacts, is electrically connected to the contact tongue 12.

[0042] Fig. Figure 8 shows a perspective rear view of the current transformer 3. It is evident that the winding ends 26 of the current tap winding 4 are soldered to the circuit board 24 and electrically connected to a corresponding plug contact 18 of the connector 7. The voltage tap connection contact 17 is also routed to the circuit board 24 and electrically connected to the adjacent plug contact 18 (solder pin) of the connector 7.

[0043] It is further evident that the fuse 14 rests on the contact surface 15 of the contact tongue 12. It becomes even clearer that contact planes 20 are bent laterally and frontally from the contact tongue 12 out of the plane of the contact surface 15 (e.g., by deep drawing or stamping).

[0044] Fig.Figure 9 shows a side view of the conductor terminal 1 with a current transformer 3 mounted on it. The conductor terminal 1 is snapped onto a mounting rail 2 in a manner known per se. The contour of the current transformer 3's insulating housing 27 is adapted to the front contour of the insulating housing of the conductor terminal 1. It can be seen that the plug contacts of the connector 7 are provided for easy connection of a measuring instrument. For this purpose, a mating connector 8 can simply be inserted into the connector 7, and the measuring leads connected to the mating connector 8 (not shown) can be routed to a measuring instrument (also not shown).

Claims

[1] Current transformer (3) with an insulating housing (11, 27) having a conductor entry opening (5) and a current tap winding (4) arranged adjacent to the conductor entry opening (5) and current tap winding connection contacts electrically connected to the current tap winding (4), wherein the current transformer (3) is configured to detect the electric current flowing through an electrical conductor (6) passing through the conductor entry opening (5), and wherein the current transformer (3) is configured to tap the voltage potential applied to the electrical conductor (6) passing through the conductor entry opening (5), wherein a contact tongue (12) projects from the insulating housing (11, 27) for tapping the voltage potential.wherein the contact tongue (12) is aligned parallel to the electrical conductor (6) passing through the conductor feedthrough opening (5) and is designed for connection to a conductor terminal (1), and wherein the contact tongue (12) has a contact surface (15) arranged adjacent to the current tap winding (4) and has a fuse (14), wherein the fuse (14) is supported on the contact surface (15) and electrically connects the contact surface (15) to a voltage tap terminal contact (17). [2] Current transformer (3) according to claim 1, characterized by , that the contact tongue (12) is arranged adjacent to the current tap winding (4). [3] Current transformer (3) according to one of claims 1 to 2, characterized by, that the voltage tap connection contact (17) can be electrically connected to a fuse cover (16) which can be placed on the fuse (14) opposite the contact surface (15) of the contact tongue (12) and has an electrical conductor leading from a first contact area of ​​the fuse cover (16) for contacting the fuse (14) to a second contact area of ​​the fuse cover (16) for contacting the voltage tap connection contact (17). [4] Current transformer (3) according to claim 3, characterized by , that the voltage tap connection contact (17) has a feedthrough opening (25) for receiving the fuse (14), and that the second contact area of ​​the fuse cover (16) is located on the area limiting the feedthrough opening (25) for electrical contact. [5] Current transformer (3) according to any one of the preceding claims, characterized by, that the current tap connection contacts and the voltage tap connection contact (17) are integrated into a common conductor terminal on the current transformer (3). [6] Current transformer (3) according to claim 5, characterized by , that the conductor terminal is a socket for receiving a connector or a connector with connection contacts for connecting electrical conductors. [7] Current transformer (3) according to any one of the preceding claims, characterized by that the current tap connection contacts can be connected to a short-circuit bridge and the short-circuit bridge has a movable switching contact designed to disconnect the connection of the short-circuit bridge to the current tap connection contacts when mating contacts are connected to the current tap connection contacts. [8] Current transformer (3) according to any one of the preceding claims, characterized bythat the current tap winding (4) has windings completely surrounding the conductor feedthrough opening (5) or is designed as a Rogowski coil. [9] Current transformer (3) according to any one of the preceding claims, characterized by , that the current transformer (3) is adapted to a terminal block that can be mounted on a mounting rail (2), in particular adapted to the contour of the insulating housing, wherein the terminal block has a conductor entry opening (19) and adjacent to this a bridge opening (13), and the contact tongue (12) is provided for insertion into the bridge opening (13) and an electrical conductor (6) passed through the conductor entry opening (5) is provided for insertion into the conductor entry opening (19).

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