GB2030373A - Current Transformers - Google Patents
Current Transformers Download PDFInfo
- Publication number
- GB2030373A GB2030373A GB7932038A GB7932038A GB2030373A GB 2030373 A GB2030373 A GB 2030373A GB 7932038 A GB7932038 A GB 7932038A GB 7932038 A GB7932038 A GB 7932038A GB 2030373 A GB2030373 A GB 2030373A
- Authority
- GB
- United Kingdom
- Prior art keywords
- current transformer
- air gaps
- core
- secondary windings
- measuring instrument
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/22—Instruments transformers for single phase ac
- H01F38/28—Current transformers
- H01F38/30—Constructions
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transformers For Measuring Instruments (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
Abstract
A current transformer for an electrical measuring instrument comprises an iron or ferrite core 1, 2 having two symmetrically disposed air gaps (3) and two secondary windings (4) which are associated with the air gaps (3) and are so connected that voltages induced in them add together. A primary winding 7 is placed symmetrically relative to the air gaps (3). Extraneous field errors thus tend to be cancelled out. <IMAGE>
Description
SPECIFICATION
Current Transformer for an Electrical
Measuring Instrument
The invention relates to a current transformer for an electric measuring instrument.
A current transformer which employs an iron or ferrite core having a large air gap has been disclosed in German Offenlegungsschrift 26 27 031. This known current transformer has the advantage that it is not only suitable for a large measuring range, but is also of simple construction and therefore cheap to produce. The large measuring range is achieved by the linearisation of the magnetisation curve owing to the large air gap. Also, due to the large air gap, the primary and secondary windings can readily be pushed on to the core. However, this known current transformer has the disadvantage that it has a relatively high extraneous field error due to non-symmetrical construction.
The present invention aims to provide an improved current transformer.
According to the present invention, there is provided a current transformer for an electrical measuring instrument, the transformer comprising an iron or ferrite core having two symmetrically disposed air gaps and two secondary windings which are associated respectively with the air gaps and which are so connected that voltages induced therein add together Advantageously, a primary winding is also distributed on the core symmetrically in relation to the air gaps.
An embodiment of the invention will now be more particularly described by way of example, with reference to the accompanying diagrammatic drawing, which illustrates a current transformer for an electrical measuring instrument.
The illustrated transformer comprises two Ushaped core parts 1 and 2, of which legs 1 a and 2a are directed towards one another and are separated from one another by non-magnetic shims for producing two symmetrical working air gaps 3. The two secondary windings 4 are disposed around the legs 1 a and 2a symmetrically in relation to the air gaps 3. They are so connected that the voltages induced in them add together. There are denoted by 5 and 6 corresponding terminal connecting members. A primary winding 7 with two terminal connecting members 8 and 9 is mounted on the yoke of the core part 1, symmetrically in relation to the air gaps 3.
When an extraneous magnetic filed passes through the two core parts 1 and 2, the voltages induced in the secondary windings 4 by this field tend to cancel one another out. In this way, the extraneous field error can be kept optimally low.
It may be appreciated that the illustrated embodiment may be modified to provide a plurality of pairs of symmetrical air gaps such as 3 with respective secondary windings, such that extraneous field errors tend to be cancelled out.
Claims
1. A current transformer for an electrical measuring instrument, the transformer comprising an iron or ferrite core having two symmetrically disposed air gaps and two secondary windings which are associated respectively with the air gaps and which are so connected that voltages induced therein add together.
2. A current transformer according to Claim 1, having a primary winding which is distributed on the core symmetrically in relation to the air gaps.
3. A current transformer substantially as hereinbefore described with reference to the accompanying drawing.
4. An electrical measuring instrument having a current transformer according to any preceding claim.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (4)
1. A current transformer for an electrical measuring instrument, the transformer comprising an iron or ferrite core having two symmetrically disposed air gaps and two secondary windings which are associated respectively with the air gaps and which are so connected that voltages induced therein add together.
2. A current transformer according to Claim 1, having a primary winding which is distributed on the core symmetrically in relation to the air gaps.
3. A current transformer substantially as hereinbefore described with reference to the accompanying drawing.
4. An electrical measuring instrument having a current transformer according to any preceding claim.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19782840550 DE2840550A1 (en) | 1978-09-18 | 1978-09-18 | CURRENT TRANSFORMER FOR ELECTRICAL MEASURING DEVICES |
Publications (1)
Publication Number | Publication Date |
---|---|
GB2030373A true GB2030373A (en) | 1980-04-02 |
Family
ID=6049742
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB7932038A Withdrawn GB2030373A (en) | 1978-09-18 | 1979-09-14 | Current Transformers |
Country Status (2)
Country | Link |
---|---|
DE (1) | DE2840550A1 (en) |
GB (1) | GB2030373A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE9406290U1 (en) * | 1993-12-09 | 1994-06-16 | Siemens Ag | Electronic counter |
EP1372166A1 (en) * | 2002-06-10 | 2003-12-17 | ABB Schweiz AG | Instrument transformer for low voltage devices |
CN110085408A (en) * | 2019-05-20 | 2019-08-02 | 广州汉光电气股份有限公司 | A kind of novel current transformer of small-sized wide input range |
CN110389254A (en) * | 2019-07-16 | 2019-10-29 | 广州汉光电气股份有限公司 | A kind of metering device and end metering device of single-phase electrical parameter |
CN110389253A (en) * | 2019-07-16 | 2019-10-29 | 广州汉光电气股份有限公司 | A kind of metering device and end metering device of three phase electrical parameters |
-
1978
- 1978-09-18 DE DE19782840550 patent/DE2840550A1/en active Pending
-
1979
- 1979-09-14 GB GB7932038A patent/GB2030373A/en not_active Withdrawn
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE9406290U1 (en) * | 1993-12-09 | 1994-06-16 | Siemens Ag | Electronic counter |
EP1372166A1 (en) * | 2002-06-10 | 2003-12-17 | ABB Schweiz AG | Instrument transformer for low voltage devices |
CN110085408A (en) * | 2019-05-20 | 2019-08-02 | 广州汉光电气股份有限公司 | A kind of novel current transformer of small-sized wide input range |
CN110085408B (en) * | 2019-05-20 | 2024-04-30 | 广州汉光电气股份有限公司 | Novel current transformer with small-sized wide input range |
CN110389254A (en) * | 2019-07-16 | 2019-10-29 | 广州汉光电气股份有限公司 | A kind of metering device and end metering device of single-phase electrical parameter |
CN110389253A (en) * | 2019-07-16 | 2019-10-29 | 广州汉光电气股份有限公司 | A kind of metering device and end metering device of three phase electrical parameters |
Also Published As
Publication number | Publication date |
---|---|
DE2840550A1 (en) | 1980-03-20 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |