GB2079065A - Linear differential transformer - Google Patents
Linear differential transformer Download PDFInfo
- Publication number
- GB2079065A GB2079065A GB8021212A GB8021212A GB2079065A GB 2079065 A GB2079065 A GB 2079065A GB 8021212 A GB8021212 A GB 8021212A GB 8021212 A GB8021212 A GB 8021212A GB 2079065 A GB2079065 A GB 2079065A
- Authority
- GB
- United Kingdom
- Prior art keywords
- alloy
- core
- iron
- yttrium
- chromium
- 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.)
- Granted
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 52
- 238000004804 winding Methods 0.000 claims abstract description 46
- 239000000956 alloy Substances 0.000 claims abstract description 32
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 32
- 229910052742 iron Inorganic materials 0.000 claims abstract description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 23
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 23
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 23
- 239000004411 aluminium Substances 0.000 claims abstract description 23
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 23
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 23
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 23
- 239000011651 chromium Substances 0.000 claims abstract description 23
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 23
- 239000010703 silicon Substances 0.000 claims abstract description 23
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 23
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims abstract description 23
- 230000005284 excitation Effects 0.000 claims abstract description 13
- 230000035699 permeability Effects 0.000 claims abstract description 12
- 238000006073 displacement reaction Methods 0.000 claims abstract description 5
- 239000000203 mixture Substances 0.000 claims description 13
- 239000012535 impurity Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- QHGVXILFMXYDRS-UHFFFAOYSA-N pyraclofos Chemical compound C1=C(OP(=O)(OCC)SCCC)C=NN1C1=CC=C(Cl)C=C1 QHGVXILFMXYDRS-UHFFFAOYSA-N 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
- 230000002889 sympathetic effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F21/00—Variable inductances or transformers of the signal type
- H01F21/02—Variable inductances or transformers of the signal type continuously variable, e.g. variometers
- H01F21/06—Variable inductances or transformers of the signal type continuously variable, e.g. variometers by movement of core or part of core relative to the windings as a whole
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
- G01D5/22—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature differentially influencing two coils
- G01D5/2291—Linear or rotary variable differential transformers (LVDTs/RVDTs) having a single primary coil and two secondary coils
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/16—Receiving elements for seismic signals; Arrangements or adaptations of receiving elements
- G01V1/18—Receiving elements, e.g. seismometer, geophone or torque detectors, for localised single point measurements
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Remote Sensing (AREA)
- Life Sciences & Earth Sciences (AREA)
- Acoustics & Sound (AREA)
- Environmental & Geological Engineering (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geophysics (AREA)
- Transmission And Conversion Of Sensor Element Output (AREA)
- Soft Magnetic Materials (AREA)
Abstract
A linear differential transformer is disclosed. The transformer has a primary, excitation winding (1), first and secondary windings (3, 4) connected in series opposition, and a displaceable core (6) for the windings. The core (6) is made of an alloy which comprises carbon, silicon, chromium, aluminium, yttrium and iron. The alloy has a permeability which does not vary, or varies in direct or substantially direct proportion to temperature, over the temperature range from 0 DEG C to 400 DEG C. Such a linear differential transformer could be used for a displacement transducer, which transducer could provide accurate results up to temperatures of approximately 400 DEG C. <IMAGE>
Description
SPECIFICATION
A linear differential transformer
This invention relates to a linear differential transformer.
Linear differential transformers comprise a primary winding, two identical secondary windings, the two secondary windings being connected in series opposition, and a displaceable core . In use, an excitation voltage is applied to the primary windings and an output voltage is obtained from the secondary windings because of voltages induced therein. The output voltage is linearly dependent upon the position of the core with respect to the two secondary windings because the coupling with each of the secondary windings alters as the core is displaced. This output voltage is zero when the core is at a central position with respect to the two secondaries, because the respective voltages induced in the two.secondaries cancel.
Linear differential transformers are thus useful as displacement transducers and, with appropriate auxiliary mechanisms, can also be used to measure velocity, acceleration, force.
pressure, liquid level, or rate of flow. However, known differential transformers, in which the cores are made of iron, are subject to significant errors when used over wide temperature ranges extending to 500"C. These errors are caused by:
1) large changes in the magnetic permea
bility of the iron cores at elevated tem
peratures;
2) progressive oxidisation of the iron cores
at elevated temperatures; and
3) changes in excitation currents produced
in the cores because of the inherent
temperatue coefficient of the windings.
According to the present invention there is provided a linear differential transformer comprising a primary, excitation winding, first and second secondary windings connected in series opposition, and a displaceable core for the windings, the core being made of an alloy which comprises carbon, silicon, chromium, aluminium, yttrium and iron, which alloy has a permeability which does not vary, or varies in direct or substantially direct proportion to temperature, over the temperature range from 0 C to 400"C.
The alloy may have the following composition: carbon 0.015 to 0.045%, silicon 0.15 to 0.45%, chromium 7.9 to 23.7%, aluminium 2.4 to 7.2%. yttrium 0.15 to 0.45%, and the balance being iron, excluding any incidental impurities.
Conveniently the alloy may have the following composition: carbon 0.0195 to 0.0405%, silicon 0.195 to 0.405%, chromium 10.27 to 21.33%, aluminium 3.12 to 6.48% yttrium 0.195 to 0.405%, and the balance beig iron, excluding any incidental impurities.
Conveniently, the alloy has the following composition: carbon 0.024 to 0.036%, silicon 0.24 to 0.36%, chromium 12.64 to 18.96%, aluminium 3.84 to 5.76%, yttrium 0.24 to 0.36%, and the balance being iron, excluding any incidental impurities.
Conveniently the alloy has the following composition: carbon 0.027 to 0.033%, silicon 0.27 to 0.33%, chromium 14.22 to 17.38%, aluminium 4.32 to 5.28%, yttrium 0.27 to 0.33%, and the balance being iron, excluding any incidental impurities.
Conveniently the alloy has the following composition: carbon 0.0285 to 0.0315%, silicon 0.285 to 0.315%, chromium 15.01 to 16.59%, aluminium 4.56 to 5.04%, yttrium 0.285 to 0.315%, and the balance being iron, excluding any incidental impurities.
The alloy may have the following composition: carbon 0.03%, silicon 0.3%, chromium 15.8%, aluminium 4.8%, yttrium 0.3%, and the balance being iron, excluding any incidental impurities.
The core is preferably segmented radially. A displacement transducer could be provided with such a linear differential transformer.
The present invention will now be described, by way of example, with reference to the single figure of the accompanying drawing which shows a side, sectional view of a linear differential transformer according to the invention.
Referring to the figure, the linear differential transformer includes a primary winding 1 which is wound on a former 2. Two identical secondary windings 3 and 4 are wound over the primary winding 1 and are located at respective positions along the length of the latter. The secondary windings 3 and 4 are connected in series opposition. Connections to the primary winding 1 and secondary windings 3 and 4 are made via leads 5.
A core 6 is located inside the former 2 and may be displaced along the length of the former 2 by means of an actuating rod 7, as indicated by the arrow 8.
The core 6 is segmented radially and is made of an alloy comprising carbon, silicon, chromium, aluminium, yttrium and iron. Such an alloy is available commercially under the name "Fecralloy" ("Fecralloy" being a registered trade mark of the United Kingdom
Atomic Energy Authority) and is manufactured by Resistalloy Limited, of Woodside Works,
Rutland Road, Sheffield, S3 9PN. The typical composition of "Fecralloy" is: carbon 0.03%, silicon 0.3%, chromium 15.8%, aluminium 4.8%, yttrium 0.3%, and the balance being iron.
In use of the linear differential transformer, the primary winding 1 is supplied, via the leads 5, with an excitation signal from a constant current a.c. source (not shown) at 25
KHZ. Energisation of the primary winding 1
produces a local magnetic field which induces
sympathetic voltages in the secondary wind
ings 3 and 4. With the core 6 centrally
disposed with respect to the secondary wind
ings 2 and 3, the induced voltage therein are
of equal magnitude and-because the sec
ondary windings 3 and 4 are connected in
series opposition-the resultant output volt
age therefrom is zero. Axial displacement of
the core 6 from this central position, by
means of the actuating rod 7, produces an
imbalance of the induced voltages of the
secondary windings 3 and 4 and thus an
output voltage therefrom.This output voltage
varies linearly in dependence upon the posi
tion of the core 6. The radial segmentation of the core 6 reduces unwanted eddy currents therein, which currents give rise to errors.
The use of "Fecralloy" as the material for the core 6 enables the linear differential transformer to be used to provide accurate results
over the temperature range from - 40"C to 500"C. Comparative tests with two known
linear differential transformers having cores
made of "Permendur' and "Fl-EN 56" respectively have shown that these known transformers are capable of providing reasonably
linear outputs only up to a temperature of approximately 300"C. The improved results obtained using "Fecralloy" as the material for the core 6 at high temperatures are attributable to that fact that "Fecralloy has a magnetic permeability which is substantially constant at temperatures up to approximately 300"C, whereas the magnetic permeability of iron, for example, is not. Also, "Fecralloy" has a long term stability because of its resistance to oxidation at high temperatures.
Although a frequency of 25 KHz is used, in the embodiment described above, for the excitation signal applied to the primary winding 1, in practice any desired frequency could be used-for example, a frequency in the range fron 500 Hzto 100 KHz.
Claims (10)
1. A linear differential transformer comprising a primary, excitation winding, first and second secondary windings connected in series opposition, and a displaceable core for the windings, the core being made of an alloy which comprises carbon, silicon, chromium, aluminium, yttrium and iron, which alloy has a permeability which does not vary, or varies in direct or substantially the direct proportion to temperature, over the temperature range from 0 C to 400"C.
2. A linear differential transformer comprising a primary, excitation winding, first and second secondary windings connected in series opposition, and a displaceable core for the windings, the core being made of an alloy which comprises carbon, silicon, chromium, aluminium, yttrium and iron, which alloy has a permeability which does not vary, or varies
in direct or substantially direct proportion to
temperature, over the temperature range from 0 C to 400"C, the alloy having the following
composition: carbon 0.015 to 0.045%, sili
con 0.15 to 0.45%, chromium 7.9 to
23.7%, aluminium 2.4 to 7.2%, yttrium
0.15 to 0.45%, and the balance being iron,
excluding any incidental impurities.
3. A linear differential transformer com
prising a primary, excitation winding, first and
second secondary windings connected in se
ries opposition, and a displaceable core for the windings, the core being made of an alloy
whch comprises carbon, silicon, chromium,
aluminium, yttrium and iron, which alloy has
a permeability which does not vary, or varies
in direct or substantially direct proportion to temperature, over the temperature range from 0 C to 400"C, the alloy having the following
composition: carbon 0.0195 to 0.0405%,
silicon 0.195 to 0.405:, chromium 10.27 to
21.33%, aluminium 3.12 to 6.48%, yttrium
0.195 to 0.405%, and the balance being
iron, excluding any incidental impurities.
4. A linear differential transformer com
prising a primary, excitation winding, first and second secondary windings connected in se
ries opposition, and a displaceable core for the winding, the core being made of an alloy which comprises carbon, silicon, chromium, aluminium, yttrium and iron, which alloy has a permeability which does not vary, or varies
in direct or substantially direct proportion to temperature, over the temperature range from 0 C to 400"C, the alloy having the following composition: carbon 0.024 to 0.036%, silicon 0.24 to 0.36%, chromium 12.64 to
18.96%, aluminium 3.84 to 5.76%, yttrium 0.24 to 0.36%, and the balance being iron, excluding any incidental impurities.
5. A linear differential transformer comprising a primary, excitation winding, first and second secondary windings connected in series opposition, and a displaceable core for the winding, the core being made of an alloy which comprises carbon, silicon, chromium, aluminium, yttrium and iron, which alloy has a permeability which does not vary, or varies in direct or substantially direct proportion to temperature, over the temperature range from 0 C to 400"C, the alloy having the following composition: carbon 0.027 to 0.033%, silicon 0.27 to 0.33%, chromium 14.22 to
17.38%, aluminium 4.32 to 5.28%, yttrium 0.27 to 0.33%, and the balance being iron, excluding any incidental impurities.
6. A linear differential transformer comprising a primary, excitation winding, first and second secondary windings connected in se- ries opposition, and a displaceable core for the winding, the core being made of an alloy which comprises carbon, silicon, chromium, aluminium, yttrium and iron, which alloy has a permeability which does not vary, or varies in direct or substantially direct proportion to temperature, over the temperature range from 0 C to 400"C, the alloy having the following composition: carbon 0.0285 to 0.0315%, silicon 0.285 to 0.315%, chromium 15.01 to 16.59%, aluminium 4.56 to 5.04%, yttrium 0.285 to 0.315%, and the balance being iron, excluding any incidental impurities.
7. A linear differential transformer comprising a primary, excitation winding, first and second secondary windings connected in series opposition, and a displaceable core for the winding, the core being made of an alloy which comprises carbon, silicon, chromium, aluminium, yttrium and iron, which alloy has a permeability which does not vary, or varies in direct or substantially direct proportion to temperature, over the temperature range from 0 C to 400"C, the alloy having substantially the following composition: carbon 0.03%, silicon 0.3%, chromium 15.8%, aluminium 4.8%, yttrium 0.3, and the balance being iron, excluding any incidental impurities.
8. A linear differential transformer according to any preceding claim, wherein the core is segmented radially.
9. A linear differential transformer substantially has herein described with reference to the accompanying drawing.
10. A displacement transducer comprising a linear differential transformer according to any preceding claim.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8021212A GB2079065B (en) | 1980-06-27 | 1980-06-27 | Linear differential transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8021212A GB2079065B (en) | 1980-06-27 | 1980-06-27 | Linear differential transformer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2079065A true GB2079065A (en) | 1982-01-13 |
| GB2079065B GB2079065B (en) | 1983-09-07 |
Family
ID=10514391
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8021212A Expired GB2079065B (en) | 1980-06-27 | 1980-06-27 | Linear differential transformer |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2079065B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2147742A (en) * | 1983-10-03 | 1985-05-15 | Itt | Reduced inductance windings for solenoids |
| EP0171690A1 (en) * | 1984-08-16 | 1986-02-19 | TELEFUNKEN Fernseh und Rundfunk GmbH | Coil-configuration with magnetizable pin core |
| EP0480461A1 (en) * | 1990-10-11 | 1992-04-15 | Nisshin Steel Co., Ltd. | Aluminum-containing ferritic stainless steel having excellent high temperature oxidation resistance and toughness |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110480064A (en) * | 2019-08-28 | 2019-11-22 | 付梓豪 | A kind of wireless induction drilling equipment |
-
1980
- 1980-06-27 GB GB8021212A patent/GB2079065B/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2147742A (en) * | 1983-10-03 | 1985-05-15 | Itt | Reduced inductance windings for solenoids |
| EP0171690A1 (en) * | 1984-08-16 | 1986-02-19 | TELEFUNKEN Fernseh und Rundfunk GmbH | Coil-configuration with magnetizable pin core |
| EP0480461A1 (en) * | 1990-10-11 | 1992-04-15 | Nisshin Steel Co., Ltd. | Aluminum-containing ferritic stainless steel having excellent high temperature oxidation resistance and toughness |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2079065B (en) | 1983-09-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0137347A1 (en) | A detector circuit for current measurements | |
| US4503714A (en) | Arrangement for non-contacting measurement of static and dynamic torques | |
| US2688253A (en) | Pressure differential responsive device | |
| EP0309979B1 (en) | Magnetoelastic torque transducer | |
| US1778795A (en) | Electrical measuring instrument | |
| US2481345A (en) | Device for magnetically determining thickness of coatings | |
| GB2079065A (en) | Linear differential transformer | |
| US2196809A (en) | Telemetric system | |
| US2558184A (en) | Electrical equipment for remote measuring and controlling | |
| US3017621A (en) | Proximity limit position detector | |
| US1945378A (en) | Temperature indicating device | |
| US3229524A (en) | Pressure measuring transducer | |
| US2137878A (en) | Direct-current measuring means | |
| GB963965A (en) | Improvements in or relating to pressure transducers | |
| US2731624A (en) | Electromagnetic rod-position indicator | |
| US1565504A (en) | Measuring device | |
| US1680216A (en) | Electromagnetic instrument | |
| Wilkins et al. | Automatic measurement of local power losses in grain-oriented silicon iron | |
| US2034019A (en) | Electrical frequency responsive device | |
| Blundell et al. | An ac force transducer using amorphous ribbon cores | |
| SU855378A1 (en) | Transformer converter of linear displacements | |
| SU802819A1 (en) | Magnetoelastic transformer-type transducer | |
| US2023228A (en) | Magnetic flux generation and magnetic testing | |
| SU567090A1 (en) | Electric transducer of displacement | |
| JPH0743105A (en) | Position detector |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |