FI89635C - Current transformer for a static electricity meter - Google Patents

Description

8 9 6 5 S

CURRENT TRANSFORMER FOR STATIC ELECTRIC METER - STRÖMTRANS-FORMATOR FOR STATISTIC METER

The invention relates to a current transformer device according to the main feature of claim 1.

Measuring large currents to determine energy consumption with a static electricity meter 1a requires the use of current transformers, the output signals of which must be suitable for re-use in electronic measuring devices. The currents to be measured are greater than 100 amps, which must be determined with a minimum line arithmetic deviation in the measurement range of 1 amp. Such devices must be quite insensitive to the DC portions of the current being measured. In addition, the consumption of auxiliary energy required to operate the device must be kept to a minimum.

Furthermore, the provisions of IEC publication 521, in particular galvanic isolation with high insulation resistance, short-circuit resistance, insensitivity to external magnetic interference fields: · *: and frequency interference suppression must be met.

; ·. According to DE-AS 1 079 192, a device designed as a magnetic voltmeter consists of two secondary coils connected in series and surrounding a busbar. The secondary sub-windings are short-circuited at their ends by a magnetic material. Thus, a closed magnetic circuit (Rogowski-ke 1a) is obtained, which behaves statically towards foreign fields if the winding density of the sub-windings is sufficiently high and the winding distribution is uniform. At high current densities in the primary line, the secondary fault 1 oi 1la must have a predetermined distance therein in order to allow proper integration of the unevenly distributed windings of the sub-voltages.

The known current transformer device is provided with an electronic integration step, the inverse of which is inversely proportional to the output signal of the input signal 1 and compensates for a phase angle of 90 ° with respect to the measured current of the output signal. The integration of the measurement signal at the phase output is an effect-independent measurement of the frequency and is located in the opposite phase of the measured current in a direct relationship between the amplitudes.

It is detrimental in the known current transformer device that the requirement of strong insensitivity to external magnetic interference fields cannot be fully met due to the use of ferromagnetic material. In addition, the known device produces very small output signals because there is only a small connection between the fields of the primary conductor and the secondary coil. Thus, this method is not suitable for measuring currents of about 1 kiloampere downwards.

It is an object of the invention to further develop such a current transformer device as mentioned at the outset in such a way that insensitivity to external magnetic interference fields and a large secondary output signal with a small-space structure and at the same time using cheap structural elements are possible.

The features of the solution according to the invention are given in claim 1. In this device, the coil holder has a permeability almost independent of the magnetic field of the primary conductor. The secondary winding is formed by two coils connected in series, the center lines of which are parallel. The purpose of winding the coils corresponds to one solenoid locally 180 ° folded in the middle. This astatic arrangement of the coils results in a secondary winding that is independent of external homogeneous magnetic interference fields because in both coils the partial voltages induced by the interference fields cancel each other out. In the known coils of sub-coils, when the sub-coils are always assembled as a closed integration path corresponding to the Rogowski coil, the secondary coils in the invention only extend by a partial length of less than 50% due to so that no closed integration path is formed. The second secondary coil then acts primarily to compensate for the effect of foreign fields. In order to achieve the best possible compensation, both of the secondary coils 11a have small volume dimensions and are placed as close to each other as possible.

The secondary coil 1 at may be parallel to each other in the cylindrical or non-coil coil 11a, whereby at least one of the two coils is located where the primary current generates the highest possible field strength. the secondary high-side device uiosmenosignaa1 required in the high field intensity is achieved by shaping the primary wire loop. Thus, the secondary particles reach the magnetic field of the primary line only locally at points, the sum of the voltages induced in both secondary ke 1 o i s sa being proportional to the detected primary current.

A power transformer to the peculiar feature is a strong magnetic coupling between the primary line and the secondary coil so that a large secondary side ulosmenosignaale and which allows the device using · - measuring misen streams linear virranvoimakkuuk- public all the way down to a few mi 11 i in amperes I in to the . This is achieved by using a ferromagnetic material. In this way, a small-volume construction method is obtained, which makes it possible to manufacture cost-effectively.

In a preferred embodiment, the loop-shaped primary wire surrounds the secondary coil in its circumferential direction as tightly and completely as possible. Since the secondary coil is then placed inside the primary line shaped as an eye, an optimal magnetic coupling and correspondingly large output signals are generated.

In a preferred embodiment, the primary wire surrounds both secondary coils with two windings connected in series. But 8 9 6 35 4 it is also possible that the primary conductor consists of sub-conductors connected in parallel with each other, the windings of which in each case surround one of the coils. In this case, the primary current to be measured is divided into two windings, so that corrugations in the cruises of the line sections can be avoided, usually with a primary wire stamped from copper and with rectangular cross-sections.

A very suitable embodiment is defined by the features of claim 5. Here, the flat-shaped primary cable is crimped at an angle of 180 ° about the transverse axis so that the supply and return lines overlap a small distance from each other. This distance may be at least partially shaped so that the resulting space is suitable for accommodating the secondary winding. In this embodiment, the effect of the magnetic interference field on the measurement result becomes practically switched off even without magnetic raw materials. The shape and small dimensions of the device make it possible to manufacture fully automatically in a simple manner.

It is advantageous if the openings push slightly from the center line of the primary cable towards the edge in opposite directions. Thus, the electric current flowing in the longitudinal direction of the flat primary line becomes reversed in the center of the primary line so that the current path becomes loop-shaped.

In another embodiment, it is provided that the opposite conductor portions of the primary conductor each have two openings directed opposite each other and arranged in parallel, and thus form two longitudinally adjacent windings of the primary conductor, the magnetic flux of each coil passing substantially through each other. In this case, the coils of the secondary winding are suitably between the conductor parts of the primary conductor. Since the design of the primary wire results in two adjacent windings, the axes of which in each case are formed by the ends of the openings bent towards each other, each coil of the secondary winding 5 8 965b can in each case be placed on the primary winding so as to create an optimal flow chain.

Another preferred embodiment is obtained when the coils of the secondary winding are arranged in a single-layer or multilayer construction in the planar technique, possibly also in spirals on both sides on a single substrate. This 1-shaped base can be pushed between the spaced-apart guide parts. The base with both coils of the secondary winding can also be placed above the effective winding surfaces of the primary conductor outside the space between the conductor parts.

In addition, it is possible that the base has electronic components for the electricity meter. These can be, for example, integration phase and multiplier phase electronic structural elements.

Another embodiment is obtained in such a way that one conductor part has two openings facing each other, extending to the edge of the primary conductor on a common longitudinal axis, in which a central opening in the other ..... conductor part is arranged in parallel. With this arrangement of the openings, the current paths are controlled in such a way that two coils connected in parallel are formed, which in each case are in a chain with the magnetic flux of the secondary winding coil.

The invention is described in more detail below with the aid of an embodiment shown in the drawing. The presentation of a known integration circuit has been abandoned.

The pictures show:

Figure 1 is an end view of two statically constructed secondary coils, one of which is the primary wire - ''. surround i mä.

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Figure 2 is an end view of two statically constructed coils surrounded by primary line windings connected in series.

Fig. 3 is, however, the arrangement of the secondary faults according to Fig. 2 with the windings of the primary conductor connected in parallel.

Figure 4 is a perspective view of a primary wire formed as a flat wire, with one statically constructed secondary coil interposed between opposite wire portions of the flat wire and the other secondary coil outside the flat wire.

Figure 5 is a perspective view of an embodiment of the primary line modified from Figure 4.

Figure 6 is a perspective view of the statically constructed secondary winding coils with base plates that can be inserted into the primary wire of Figure 5.

Fig. 7 is a cross-sectional view of the device of Figs. 5 and 6 in a ready-to-use position in a reduced view.

Figure 8 is a perspective view of an embodiment of the primary line modified from Figures 4 and 5.

Fig. 9 is a perspective view of the statically constructed wires 1i as a secondary winding with a base 1 evy 11 which can be inserted into the primary wire according to Fig. 8.

Fig. 10 is a perspective view of a primary wire comparable to Fig. 8 with secondary winding coils disposed therein.

Figure 11 is a top view of a primary wire formed as a flat wire.

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Fig. 12 is a top view of the primary wire of Fig. 11 in a collapsed state.

Fig. 13 is a top view of a base plate having an astatically constructed Flat Coil that is structurally comparable to Fig. 9.

Fig. 14 is a top view of the assembled primary conductor of Fig. 11 from the side opposite to Fig. 12, and

Figure 15 is a cross-sectional view of the device of Figure 14.

Fig. 1 shows two spaced apart astatically constructed sy1 interim secondary coil 3 coils 1 and 2. The coils 1 and 2 supported by the distance denotor 4 are geometrically and electrically identical and their cylindrical centerlines are parallel to each other. The coils 1 and 2 are arranged in the insulating cylinders 5 and 6. The coil 1 is surrounded by a winding 7a of the primary line 7, through which the current to be measured is a signal proportional to 1. With the induction of homogeneous external interference switching fields, the voltages have different signs due to the astatic arrangement of coils 1 and 2 and they equalize in sum. This measure attenuates the effect of external magnetic alternating fields on the correct operation of the current transformer device considerably. With the magnetic shield surrounding the coils, the effect of the foreign field can be further reduced.

: In Fig. 2, coils 8 and 9 correspond to those shown in Fig. 1: coils. The secondary coils 8 and 9 are successively surrounded by a common primary line 10. This series connection of the primary windings 10a and 10b results in a larger measurement signal compared to the device of Figure 1.

In Fig. 3, the coils 11 and 12 correspond to the coils 8 and 9 in Fig. 2. The primary wire 13 is branched into two sub-wires, each of which is formed as a winding 13a or 13b 8a 6 ά 5 6 surrounding one coil 11 or 12. The current 1 ^ branches into the sub-lines of the windings 13a and 13b, whereby the sum of the voltages induced in the coils 11 and 12 is proportional to the measured current I. The advantage of the device according to Fig. 3 compared to the embodiment according to Fig. 2 is that corrugations in the primary conductors 13, which are mainly stamped from copper and have a rectangular cross-section (flat conductor), can be avoided in cruises of the conductor parts.

In the embodiment of Figure 4, the primary conductor 14 is formed as a flat conductor having a rectangular cross-section corrugated so that opposing conductor portions 14a and 14b form a rectangular hollow space 15. Outside the hollow space 15 are opposed portions of the primary conductor 14 separated from each other by an insulating layer 16. The conduit portion 14 is provided with a slit-like opening 17 extending from the center to the edge. Apertures 17 and 18 affect the geometric position of the current path of the current to be measured, shown by arrows 19 and 20, so that a primary current 1e becomes formed in the winding. A dashed secondary coil 21 is placed in the magnetic field of this coil. The second secondary coil 22 is located outside the primary wire to compensate for the magnetic foreign fields.

The primary conduit 23 shown in Fig. 5 differs from the embodiment of Fig. 4 in that the opposing conduit portions 23a and 23b each have two opposed slit-like openings 24 and 25 or 26 and 27. The side openings 24-27 each extend approximately to the conductor portions 23a. and 23b to the middle. The openings 24 and 26 are in the same plane perpendicular to the primary wire 23 when it is folded into the ready-to-use position 180 °, i.e. the wire parts 23a and 23b are parallel. Similarly, the openings 25 and 27 are in a common plane perpendicular to the primary wire 23.

3 9 6 55 9

With the above design of the openings 24-27, the primary flow paths marked by arrows 29a-29g run through. Thus, in the planes of the conductor parts 23a and 23b, primary windings are connected in series, in the magnetic field of which the secondary windings can be placed.

The base plate 30 shown in Fig. 6 has two statically arranged secondary coils 31 and 32. In the ready-to-use state, the base plate 30 with the coils 31 and 32 is between the primary conductor portions 23a and 23b of Fig. 5. The position of the coil 31 in Fig. 6 is marked on the lead portion 23b in Fig. 5 by the dashed circle 33. In the corresponding manner, the coil 32 is in the area shown by the dashed circle 60 in Fig. 6.

Figure 7 shows a power converter apparatus of Figure 5, the pri-määripuolen parts, and the secondary side of Figure 6 in accordance with its components in ready mode. In this case, the upper and lower parts of the primary conductor 23 are separated by an insulating layer 61.

The primary conductor 34 in Fig. 8 is comparable to the primary conductor 23 in Fig. 5. However, the distance between the upper conductor portion 34a and the lower conductor portion 34b is smaller and corresponds to the thickness of the insulating layer 35.

The base plate 36 shown in Fig. 9 with the secondary coils 38 and 39 placed thereon is in the ready-to-use state of the current transformer device between the lead portions 34a and 34b of the primary lead 34 of Fig. 8. The coils 38 and 39 in Fig. 9 are constructed in a helical shape and manufactured in a planar technique 1a so that the small space between the conductor portions 34a and 34b in Fig. 8 is sufficient. Ready to use, the center of the spool 38 is approximately at the center end of the slit-like opening 40 in Figure 8. Correspondingly, the coil 39 and the end in the middle of the opening 41 are arranged to cover each other.

Fig. 10 shows a primary conduit 42 substantially corresponding to the primary conduit 34 in Fig. 8. However, the openings 44 and 45 at the center ends of their primary conduit 42 89655 are formed as holes in which the astatically constructed secondary coils 46 and 47 are mounted.

In the embodiment of Figure 11, the primary line 48 is shown open, i.e. before folding around the line 49. The folded state has a lead portion 48a on top of the lead portion 48b. The guide portion 48b has openings 50 and 51 facing each other and along the same longitudinal axis parallel to the fold line 49. The lead portion 48a has an opening 52 located only in the center region of the lead portion 48 and spaced the same distance as the apertures 50 and 51. The locations of the secondary defects 1 are given by the dotted circles 53 and 54. Reflectively to the fold line 49 with respect to the respective bottom surfaces 55 and 56 for the secondary coils.

Fig. 12 shows the primary wire of Fig. 11 in a collapsed state so that the wire portions 48a and 48b overlap. Respectively, there are only openings 50 and 51 with their locations for the secondary coils, which are marked with circles 53 and 54.

Fig. 13 shows secondary coils 56 and 57 mounted on the base plate 55 in an astatic manner. This device, which corresponds in principle to the device of Fig. 9, differs substantially in that the coils 56 and 57 in Fig. 13 are equidistant from the folding line 49. The coils 56 and 57 can likewise be manufactured technique 11a. In order to place both coils in the corresponding primary magnetic flux, they can also be placed outside the conductor portions 48a and 48b folded according to Fig. 11, if the magnetic coupling is sufficient for a large output signal. Also in this case, the circles shown in Figs. 11 and 12 are the corresponding places for the reel coils.

Fig. 14 shows the primary wire 48 of Fig. 11 in a folded state on the opposite side compared to Fig. 12. Correspondingly, only the opening 52 in the middle is visible.

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Also shown in Figure 15 is the primary conduit 48 in the collapsed state, with the distance between the upper conduit portion 48a and the lower conduit portion 48b determined by the insulating layer 57. The direction of the primary current to be measured is indicated by arrows 58 and 59. The base plate 55 of Figure 13 is inserted.

Claims (11)

12 89655 A current transformer device, in particular for a static electricity meter, with primary wires carrying the current to be measured and secondary windings consisting of at least two coils connected in series, the input voltage of which is applied to an electronic integration phase to produce a frequency-independent measurement signal. 23,34,42,48) is formed into a loop that the secondary winding is statically constructed from electrically identical coils (1,8,11,12,21,22,31, 32,38,39,46,47,56,57), that at least one of the secondary coils achieves as fully as possible the current in the primary line to generate maximum magnetic coupling of the magnetic flux on the primary line without the use of ferromagnetics, and that this secondary line 1a extends in the axial direction to the shortest possible primary line current generated by the magnetic field1 over the injections. Current transformer device according to Claim 1, characterized in that the primary line formed as a loop surrounds the secondary break 1a in the circumferential direction as closely and completely as possible. Current transformer device 1 according to Claim 1 or 2, characterized in that the primary conductor (10) surrounds both coils (8, 9) by means of primary windings (10a, 10b) connected in series. Current transformer device according to Claim 1 or 2, characterized in that the primary conductor is formed by two sub-conductors connected in parallel, the windings (13a, 13b) of which each surround the coils (11, 12). Current transformer and device according to one of the preceding claims, characterized in that the primary conductor (14,23,34,42,48) formed as a flat conductor and formed as a current loop has opposing conductor parts (14a), 14b, 23a, 23b, 34a, 34b, 48a, 48b), which always have. one opening (17,18,25-28,50-52) for forming one or more winding portions in the plane of the primary conductor, the openings facing the conducting portions forming a primary winding having winding surfaces approximately parallel to the surface of the flat conductor, and that the secondary winding the coils are arranged on their winding surfaces approximately parallel to the flat wire and are at least partially permeated by a primary magnetic flux substantially perpendicular to the surface of the flat wire. A current transformer device according to claim 5, characterized in that the openings (17, 18, 22-28) extend in opposite directions approximately up to the edge of the primary conductor. Current transformer device according to Claim 6, characterized in that the opposite conductor parts of the primary conductor each have two opposite and parallel openings (25-28) and thus form two longitudinally adjacent windings of the primary conductor (23) and that the magnetic flux of each winding substantially one secondary winding coil (31,32). Current transformer device according to one of Claims 5 to 7, characterized in that the coils of the secondary winding are arranged between the conductor parts of the primary conductor. Current transformer device 1 according to Claim 7 or 8, characterized in that the coils (38, 39) of the secondary winding in the plan construction method are arranged in single or multilayer spirals on a substrate. A current transformer device according to claim 9, characterized in that the base includes other electronic devices of the electricity meter. 14 H 9 6 3 5 II. Current transformer device according to Claims 5 and 8 to 10, characterized in that one conductor part (48b) has two openings (50, 51) extending opposite one another and extending to the edge of the primary conductor (48) on a common longitudinal axis, with which parallel! is a central opening located on the second lead portion (48a). i is 39635