Inductor devices – Coils of special configuration – Toroidal
Patent
1998-02-12
1999-11-09
Donovan, Lincoln
Inductor devices
Coils of special configuration
Toroidal
336174, 336200, 336225, H01F 2728
Patent
active
059822651
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention is directed to a current-detection coil for a current transformer operating according to the Rogowski principle.
BACKGROUND INFORMATION
A previously proposed current-detection coil is discussed in the British EPE Journal, vol. 3, No. 1, March 1993, pp. 51-59, where simple solid toroids or flexible cut-open coil bodies are proposed as annular body shapes. Furthermore, the use of circular cut-open plastic rings with a rectangular cross section, which can be bent for placement on a conductor and then return to their annular shape, is discussed therein. Each of the various annular bodies used in the current-detection coils discussed in the EPE Journal are used to form a Rogowski current transformer.
Although all of the current-detection coil embodiments of the EPE Journal can be made to exhibit good transfer characteristics, when they are mass-produced, however, virtually each unit will exhibit different transfer characteristics and therefore individual adjustments or electronic correction circuits must be used to achieve uniform results. The effect of small deviations of the geometry of Rogowski current transformer coils from the ideal shape on their transfer characteristics is known. One solution proposed is to use polished straight ceramic rods as winding supports. See German Journal Technische Mitteilungen AEG-Telefunken 60 (1970) 7, pp. 444-448. Because, however, a current-detection coil operating according to the Rogowski principle must surround a conductor on a closed path, the use of straight ceramic rods requires that a closed current-detection coil be made of four partial coils. In this case, the rectangular junction of the component parts causes considerable interference in the electromagnetic field. In order to remove this influence, the junction points are made field-free through the use of a shielding. The desired accuracy of the Rogowski current transformer is therefore associated with considerable expense for the manufacture of the current-detection coils.
SUMMARY OF THE INVENTION
The present invention is directed to a current-detection coil with an electrically insulating annular body as a support for a winding, the shape of the annular body cross section having flattened regions on the outer periphery and on the inner periphery.
An object of the present invention is to provide a current-detection coil of a Rogowski current transformer that exhibits a minimum spread of its characteristics and is suitable for both regular current measurement and triggering.
This object is achieved according to the present invention by designing the remaining regions of the cross section shape in an approximately semicircular shape. The annular body is made from a fiber-reinforced thermosetting plastic material as a solid single-piece body in a divisible mold, with the annular body being made without burrs and having no undercuts, and the winding is applied with a toroidal core winding machine.
The annular body provided according to the present invention is a very stable component having high heat resistance and a low thermal expansion factor. These characteristics result in minimum changes in the winding shape when, for example, the current-detection coil is applied to the main current paths of a low-voltage power switch, which can exhibit strong mechanical shocks and temperatures up to more than 100.degree. C. The flattened cross section shape on the inner and outer periphery of the annular body contributes to this stability of the annular body by increasing the resisting moment against mechanical deformation. The burr-free manufacture of the annular body contributes to the desired uniformity and quality of the winding by the fact that the winding wire is in tight contact with the entire periphery of the annular body and therefore cannot be displaced or deformed.
An annular body having an outer diameter of approximately 80 to 100 mm, and wound with a single layer of lacquered copper wire that is approximately 0.05 to 0.1 mm thick is particularly well suited f
REFERENCES:
patent: 3611230 (1971-10-01), Maake
patent: 4268810 (1981-05-01), Iwasa et al.
patent: 4706020 (1987-11-01), Viertl et al.
patent: 5012218 (1991-04-01), Haug et al.
patent: 5066904 (1991-11-01), Bullock
patent: 5329229 (1994-07-01), Chiba et al.
W.F. Ray et al., "Wide Bandwidth Rogowski Current Transducers Part I: The Rogowski Coil", EPE Journal, vol. 3, No. 1, Mar. 1993, pp. 51-59.
K. Heumann, "Messung und Oszillographische Aufzeichnung von Hohen Wechsel-und schnell veranderlichen Impulsstromen", Techn. Mitt. AEG-Telefunken 60 7, pp. 444-448.** No Date.
Moncke Hartmut
von Skarczinski Albrecht
Donovan Lincoln
Lee Richard K.
Siemens Aktiengesellschaft
LandOfFree
Current-detection coil for a current transformer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Current-detection coil for a current transformer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Current-detection coil for a current transformer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1461947