Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With coupling means
Patent
1987-06-12
1990-01-16
Eisenzopf, Reinhard J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With coupling means
324117R, 336181, G01R 1102
Patent
active
048946109
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a current-transformer arrangement for a static electricity meter, including a primary conductor carrying the alternating current to be measured and a secondary winding consisting of at least two coils connected in series, the output voltage from which is passed to an electronic integrating stage in order to produce a measuring signal which is independent of frequency.
The measuring of large currents for the determination of energy consumption by means of static electricity meters requires the use of current-transformers, the output signals from which must be suitable for further processing in electronic measuring instruments. The currents to be measured amount to more than 100 amperes which must be picked up in the milliampere range with little deviation in linearity. Arrangements of this kind must be largely insensitive to direct current components of the current being measured. In addition, as little auxiliary power as possible should be needed to operate the arrangement.
Furthermore, the requirements set forth in IEC Publication 521 must be met, more particularly galvanic separation with high insulating strength, resistance to short-circuiting, insensitivity to external magnetic interference fields and retention of frequency effects.
The arrangements according to German Auslegunsschrift No. 1,079,192, which is in the form of a magnetic volt-meter, consists of two secondary coils connected in series and surrounding a busbar. The ends of the secondary part-windings are short-circuited with a magnetic material. This provides a closed magnetic circuit (a Rogowski coil) which behaves astatically towards interfering fields if the winding density of the part-windings is sufficiently high and the distribution of the windings is uniform. In the case of high current densities in the primary conductor, the secondary coils must be at a certain distance therefrom in order to ensure satisfactory integration of the part-voltages of the irregularly distributed winding.
Known current-transformer arrangements are equipped with an electronic integrating stage, the frequency response of which, regarding its input signal to output signal, compensates for the proportional frequency-dependency of the voltage induced into the secondary winding of the current being measured, and which rotates the input signal, in relation to the opposite phase position of its output signal, through a 90.degree. phase angle. As a result, the measuring signal at the output from the integrating stage is independent of the measuring frequency and is in opposing phase to the measuring current, with direct proportionality between the amplitudes.
One disadvantage of such a current-transformer arrangement is that the requirement for substantial insensitivity to external magnetic interference fields is not completely met by the use of ferromagnetic materials. Furthermore, the arrangement delivers very weak output signals since only very slight coupling exists between the fields of the primary conductor and of the secondary coils. This arrangement is therefore unsuitable for measuring current intensities of less than about 1 kiloampere.
It is therefore an object of the invention to provide a current-transformer arrangement of the type mentioned hereinabove featuring high insensitivity to external magnetic interference fields, and a high secondary side output signal, combined with a compact design and simultaneous use of inexpensive structural elements.
In accordance with the present invention, there is thus provided a current-transformer arrangement for a static electricity meter, including a primary conductor carrying the alternating current to be measured and a secondary winding consisting of at least two coils connected in series, the output voltage from which is passed to an electronic integrating stage to produce a measuring signal independent of frequency, characterized in that the primary conductor is formed into a loop to produce maximal field strength, the secondary winding is designed astatically with electrical
REFERENCES:
patent: 4182982 (1980-01-01), Wolf et al.
patent: 4385273 (1983-05-01), Lienhard et al.
patent: 4464625 (1984-08-01), Lienhard et al.
patent: 4492919 (1985-01-01), Milkovic
patent: 4496932 (1985-01-01), Halder
patent: 4513273 (1985-04-01), Friedl
patent: 4513274 (1985-04-01), Halder
patent: 4559495 (1985-12-01), Lienhard
patent: 4596950 (1986-06-01), Lienhard et al.
patent: 4616176 (1986-10-01), Mercure et al.
patent: 4626778 (1986-12-01), Friedl
patent: 4629974 (1986-12-01), Friedl
patent: 4706017 (1987-11-01), Wilson
Burns W.
Eisenzopf Reinhard J.
LOZ Landis & Gyr Zug AG
LandOfFree
Current-transformer arrangement for an electrostatic meter 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-transformer arrangement for an electrostatic meter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Current-transformer arrangement for an electrostatic meter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1337177