JPH0474677B2 - - Google Patents
Info
- Publication number
- JPH0474677B2 JPH0474677B2 JP10892790A JP10892790A JPH0474677B2 JP H0474677 B2 JPH0474677 B2 JP H0474677B2 JP 10892790 A JP10892790 A JP 10892790A JP 10892790 A JP10892790 A JP 10892790A JP H0474677 B2 JPH0474677 B2 JP H0474677B2
- Authority
- JP
- Japan
- Prior art keywords
- iron loss
- magnetic
- coil
- magnetic material
- voltage
- 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.)
- Expired
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 86
- 229910052742 iron Inorganic materials 0.000 claims description 38
- 230000005284 excitation Effects 0.000 claims description 14
- 238000001514 detection method Methods 0.000 claims description 12
- 239000000696 magnetic material Substances 0.000 description 45
- 230000004907 flux Effects 0.000 description 24
- 238000005259 measurement Methods 0.000 description 6
- 239000011800 void material Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
Landscapes
- Measuring Magnetic Variables (AREA)
Description
【発明の詳細な説明】
本発明は、磁性材料の鉄損測定装置に関するも
のである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring iron loss of magnetic materials.
従来から行われている磁性材料の鉄損測定装置
の一つに、第１図に示すような磁気センサ１を使
用する装置がある。ここにいう鉄損測定装置とは
絶対値ではなくある一定の磁界あるいは磁束等の
条件で較正された標準試料に対する比が測定でき
るものである。この磁気センサ１は、断面がほぼ
コの字形の鉄心２に、一次コイル（励磁コイル）
３及び二次コイル（出力二次電圧コイル）４を巻
いて構成され、一次コイル３は交流電源５及び増
幅器６を介して電計力７に接続され、二次コイル
４は増幅器８を介して電力計７に接続されてい
る。いま、磁性材料９の表面に磁気センサ１の、
鉄心２の開口端２ａ，２ｂを接触させて、交流電
源５により、一次コイル３を励磁すると、磁束は
鉄心２から磁性材料９の中を、矢印で示すように
流れ、再び鉄心２に戻る磁路を形成し、この磁束
により二次コイル４には電圧が誘起される。この
電圧を増幅器で増幅して、出力二次電圧として電
力計７に出力する。電力計７では、二次コイル４
からの出力二次電圧と、一次コイル３の励磁電流
を入力して、これ等を乗算して磁性材料９と鉄心
２の鉄損を表示する。この場合、鉄心２の鉄損
を、磁性材料９の鉄損に比べて十分に小さくして
おけば、電力計７に表示された鉄損は、ほぼ磁性
材料９の鉄損と考えてよい。 One of the conventional iron loss measuring devices for magnetic materials is a device using a magnetic sensor 1 as shown in FIG. The iron loss measuring device referred to herein is one that can measure not an absolute value but a ratio to a standard sample calibrated under certain conditions such as a certain magnetic field or magnetic flux. This magnetic sensor 1 has a primary coil (excitation coil) attached to an iron core 2 whose cross section is approximately U-shaped.
3 and a secondary coil (output secondary voltage coil) 4 are wound. It is connected to the power meter 7. Now, the magnetic sensor 1 is placed on the surface of the magnetic material 9.
When the open ends 2a and 2b of the iron core 2 are brought into contact and the primary coil 3 is excited by the AC power source 5, magnetic flux flows from the iron core 2 through the magnetic material 9 as shown by the arrow, and returns to the iron core 2 again. A voltage is induced in the secondary coil 4 by this magnetic flux. This voltage is amplified by an amplifier and output to the wattmeter 7 as an output secondary voltage. In the wattmeter 7, the secondary coil 4
The output secondary voltage and the excitation current of the primary coil 3 are input, and these are multiplied to display the iron loss of the magnetic material 9 and the iron core 2. In this case, if the iron loss of the iron core 2 is made sufficiently smaller than the iron loss of the magnetic material 9, the iron loss displayed on the wattmeter 7 can be considered to be almost the iron loss of the magnetic material 9.
しかし、この場合、磁性材料９の表面に凹凸が
あると、磁気センサ１の鉄心２の開口端２ａ，２
ｂを磁性材料９の表面に接触させた場合、磁気セ
ンサ１の鉄心２の端面２ａ，２ｂと、磁性材料９
の接触面の間に空隙を生じ、磁気抵抗が増加する
ので磁束が漏洩し、磁性材料９内を流れる磁束の
磁束密度が減少する。一実施例によると、0.01mm
の空隙があると、磁性材料９内の磁束密度は約21
％減少する。一般に、鉄損は磁束密度のほぼ２乗
に比例するから、漏れ磁束は鉄損の測定精度に大
きな影響を及ぼす。従つて、前記の従来の鉄損測
定装置では、磁性材料９と磁気センサ１の鉄心２
の端面２ａ，２ｂの間に空隙が生ずると、漏れ磁
束のために鉄損の測定精度が低下し、磁性材料９
の鉄損測定に大きな誤差を生ずるという欠点があ
つた。 However, in this case, if the surface of the magnetic material 9 is uneven, the open ends 2a, 2 of the iron core 2 of the magnetic sensor 1
b in contact with the surface of the magnetic material 9, the end surfaces 2a, 2b of the iron core 2 of the magnetic sensor 1 and the magnetic material 9
An air gap is created between the contact surfaces of the magnetic material 9 and the magnetic resistance increases, so that the magnetic flux leaks and the magnetic flux density of the magnetic flux flowing within the magnetic material 9 decreases. According to one embodiment, 0.01mm
With an air gap of , the magnetic flux density within the magnetic material 9 is approximately 21
%Decrease. Generally, since iron loss is approximately proportional to the square of the magnetic flux density, leakage magnetic flux has a large effect on the measurement accuracy of iron loss. Therefore, in the conventional iron loss measuring device described above, the magnetic material 9 and the iron core 2 of the magnetic sensor 1 are
If a gap is created between the end surfaces 2a and 2b of the magnetic material 9, the measurement accuracy of iron loss will decrease due to leakage magnetic flux, and the magnetic material 9
The drawback was that it caused large errors in iron loss measurements.
また、一般に、磁性材料に作用する応力と鉄損
の間には密接な関係があり、横軸に引張応力及び
圧縮応力を、縦軸に鉄損を取り、磁性材料に作用
する応力と鉄損の関係を示すと第２図のようにな
る。即ち、磁性材料に圧縮応力が作用する時は、
圧縮応力と鉄損はほぼ直線関係にあるので、この
関係を利用し、圧縮応力の作用している磁性材料
の鉄損を測定すれば、高精度でその圧縮応力を求
めることができる。いま、第２図において、磁性
材料に圧縮応力が作用していない時の鉄損を
Wo、圧縮応力σの作用した時の鉄損をWiとする
と、圧縮応力σは（Wi−Wo）に比例する。従つ
て、比例常数をαとすると、磁性材料に作用する
圧縮応力σは、
σ＝α（Wi−Wo） ……(1)
から求めることができる。ここに、比例常数α
は、磁束量、磁性材料の種類、鉄損測定に使用し
た磁気センサの種類等によつて決まるものであ
る。 Additionally, there is generally a close relationship between stress acting on magnetic materials and iron loss, with tensile stress and compressive stress on the horizontal axis and iron loss on the vertical axis. The relationship is shown in Figure 2. That is, when compressive stress acts on a magnetic material,
Since compressive stress and iron loss have a nearly linear relationship, by utilizing this relationship and measuring the iron loss of a magnetic material to which compressive stress is applied, the compressive stress can be determined with high accuracy. Now, in Figure 2, the iron loss when no compressive stress is acting on the magnetic material is
When Wo is the iron loss when compressive stress σ acts, then compressive stress σ is proportional to (Wi−Wo). Therefore, if the proportionality constant is α, the compressive stress σ acting on the magnetic material can be found from σ=α(Wi−Wo) (1). Here, the proportionality constant α
is determined by the amount of magnetic flux, the type of magnetic material, the type of magnetic sensor used to measure iron loss, etc.
従つて、磁性材料に圧縮応力が作用していない
時の鉄損Woと、圧縮応力が作用している時の鉄
損Wiを測定すれば、前記の(1)式から、その磁性
材料に作用している圧縮応力σを求めることがで
きる。しかし、第１図に示すような従来の鉄損測
定装置では、磁性材料９と磁気センサ１の鉄心２
の端面２ａ，２ｂとの間に空〓があると、前記の
ような理由により、鉄損測定精度が低下し、磁性
材料９に作用する圧縮応力の測定にも大きな誤差
を生ずるという欠点があつた。 Therefore, if we measure the iron loss Wo when no compressive stress is acting on the magnetic material and the iron loss Wi when compressive stress is acting, then from equation (1) above, we can calculate the effect on the magnetic material. The compressive stress σ can be determined. However, in the conventional iron loss measuring device as shown in FIG.
If there is an air space between the magnetic material 9 and the end surfaces 2a and 2b, the iron loss measurement accuracy will be lowered for the reasons mentioned above, and there will be a large error in the measurement of the compressive stress acting on the magnetic material 9. Ta.
本発明は、前記の欠点を除去するためになされ
たもので、磁気センサと磁性材料の接触面の間に
空〓があつても、高精度で鉄損を測定することが
できる鉄損測定装置を提供することを目的とする
ものである。 The present invention has been made to eliminate the above-mentioned drawbacks, and is an iron loss measuring device that can measure iron loss with high accuracy even if there is an air gap between the contact surface of the magnetic sensor and the magnetic material. The purpose is to provide the following.
以下、本発明の一実施例を図面について説明す
る。 An embodiment of the present invention will be described below with reference to the drawings.
第３図は本発明の鉄損測定装置の一実施例の説
明図である。 FIG. 3 is an explanatory diagram of an embodiment of the iron loss measuring device of the present invention.
なお、第１図、第３図において、同一番号は同
一部材を示す。 In addition, in FIG. 1 and FIG. 3, the same number indicates the same member.
第３図において、鉄損測定装置１０は、交流電
源５と、電力計７と、磁気センサ１２と、増幅器
１８より構成されている。 In FIG. 3, the iron loss measuring device 10 includes an AC power source 5, a wattmeter 7, a magnetic sensor 12, and an amplifier 18.
磁気センサ１２は、内側鉄心１３と、この内側
鉄心１３の背部に巻かれた電圧コイル１４及びそ
の脚部に巻かれた検出コイル１５と、内側鉄心１
３を覆うように、その外側に設けられた断面がほ
ぼコの字形の外側鉄心１６と、この外側鉄心１６
に巻かれた励磁コイル１７とから構成されてい
る。内側鉄心１３は、断面がほぼコの字形の形状
を有し、電圧コイル１４と検出コイル１５の間に
各脚部からそれぞれ内部に向けて突起１３′，１
３″が設けられ、この突起１３′，１３″の間には、
磁気抵抗を調整するための空〓が設けられてい
る。そして電圧コイル１４を交流電源５と、電力
計７の電圧端子に接続し、検出コイル１５を演算
増幅器１８（以下、増幅器１８と略記する。）の
入力側に接続し、また、励磁コイル１７の一端を
電力計２０を介して電力計７の電流端子に接続す
る。励磁コイル１７の他端は、増幅器１８の出力
側の一端に、増幅器１８の出力側の他端は電力計
７の電流端子に接続する。電圧コイル１４には、
電圧コイル１４の電圧を測定する電力計１９が並
列に接続されている。今、磁気センサ１２を磁性
材料９の表面に配置して、電圧コイル１４を交流
電源５により、一定電圧で励磁すると、磁束は内
側鉄心１３内を矢印の方向に流れ、一部分は突起
１３′から空〓を介して突起１３″を通り元に戻る
第１内側磁路Ａを形成し、他部分は内側鉄心１３
の一方の脚部から磁性材料９の中を、矢印の方向
に流れ、内側鉄心１３の他方の脚部に戻る第２内
側磁路Ｂを形成する。この第２内側磁路Ｂを流れ
る磁束により、検出コイル１５に電圧が誘起され
る。この検出コイル１５に誘起された電圧を、増
幅器１８で増幅して、電力計７及び電流計２０を
介して、この検出コイル１５に誘起された電圧を
打消す方向に励磁コイル１７に印加すると、励磁
コイル１７に電流が流れ、磁束は外部鉄心１６か
ら磁性材料９の中を流れ、その磁束の一部分は、
矢印で示すように、内側鉄心１３の一方の脚部か
ら入り、内側鉄心１３の中を流れ、内側鉄心１３
の他方の脚部から出て、再び磁性材料９の中を流
れて、外側鉄心１６に戻る外側磁路Ｃを形成す
る。この場合、増幅器１８の増幅率を極めて大き
くしておき、外側鉄心１６から、内側鉄心１３に
分流した磁束で、電圧コイル１４の励磁により発
生し、内側鉄心１３内を流れる磁束を打消させ、
検出コイル１５部の磁束が殆んど零になるように
すると、内側鉄心１３の各脚部の起磁力は殆んど
零となり、内側鉄心１３の各脚部の突起１３′，
１３″の近傍の２点Ｘ−Ｙ間の起磁力と、内側鉄
心１３の各脚部の端面と対向する磁性材料９内の
２点Ｕ−Ｖ間の起磁力が等しくなる。この時検出
コイル１５部の磁束は殆んど零となつて、電圧コ
イル１４の電圧は、Ｘ−Ｙ間の磁束に相当し一定
となる。またＵ−Ｖ間の起磁力も一定なのでその
起磁力に相当する磁束が流れる。すなわち電圧コ
イル１４の電圧は相対的にＵ−Ｖ間の磁束に対応
する値になる。従つて、この時の電圧コイル１４
の電圧と、励磁コイル１７の電流を電力計７で測
定すれば、磁性材料９のＵ−Ｖ間の起磁力を一定
とした鉄損に相当した値となる。このように、内
側鉄心１３の各脚部の磁束を殆ど零にすれば、内
側鉄心１３の端面と、磁性材料９の間の空〓の大
小に関係なく、常に高精度で磁性材料９のＵ−Ｖ
間の起磁力を一定とした鉄損に相当した値を測定
することができる。ここで絶対値が必要な場合
は、エプスタイン装置等により鉄損がわかつてい
る磁性材料により較正すればよい。 The magnetic sensor 12 includes an inner core 13 , a voltage coil 14 wound around the back of the inner core 13 , a detection coil 15 wound around its legs, and an inner core 13 .
3, an outer core 16 with a substantially U-shaped cross section is provided on the outside thereof, and this outer core 16
The excitation coil 17 is wound around the excitation coil 17. The inner core 13 has a substantially U-shaped cross section, and has protrusions 13', 1 extending inward from each leg between the voltage coil 14 and the detection coil 15.
3'' is provided, and between these protrusions 13', 13'',
A space is provided to adjust the magnetic resistance. Then, the voltage coil 14 is connected to the AC power supply 5 and the voltage terminal of the wattmeter 7, the detection coil 15 is connected to the input side of the operational amplifier 18 (hereinafter abbreviated as amplifier 18), and the excitation coil 17 is connected to the input side of the operational amplifier 18 (hereinafter abbreviated as amplifier 18). One end is connected to the current terminal of the wattmeter 7 via the wattmeter 20. The other end of the excitation coil 17 is connected to one end on the output side of an amplifier 18, and the other end on the output side of the amplifier 18 is connected to a current terminal of the wattmeter 7. The voltage coil 14 includes
A wattmeter 19 that measures the voltage of the voltage coil 14 is connected in parallel. Now, when the magnetic sensor 12 is placed on the surface of the magnetic material 9 and the voltage coil 14 is excited with a constant voltage by the AC power source 5, magnetic flux flows inside the inner core 13 in the direction of the arrow, and a part of the magnetic flux flows from the protrusion 13'. A first inner magnetic path A is formed which passes through the protrusion 13'' through the air and returns to the original position, and the other portions are connected to the inner core 13.
A second inner magnetic path B is formed which flows from one leg of the magnetic material 9 through the magnetic material 9 in the direction of the arrow and returns to the other leg of the inner core 13 . A voltage is induced in the detection coil 15 by the magnetic flux flowing through the second inner magnetic path B. When the voltage induced in the detection coil 15 is amplified by the amplifier 18 and applied to the excitation coil 17 via the wattmeter 7 and the ammeter 20 in a direction that cancels the voltage induced in the detection coil 15, Current flows through the excitation coil 17, magnetic flux flows from the outer core 16 through the magnetic material 9, and a portion of the magnetic flux is
As shown by the arrow, it enters from one leg of the inner core 13, flows through the inner core 13, and flows through the inner core 13.
exits from the other leg of the magnetic material 9 and flows through the magnetic material 9 again to form an outer magnetic path C that returns to the outer core 16 . In this case, the amplification factor of the amplifier 18 is made extremely large, and the magnetic flux shunted from the outer core 16 to the inner core 13 cancels out the magnetic flux generated by the excitation of the voltage coil 14 and flowing inside the inner core 13.
When the magnetic flux of the detection coil 15 becomes almost zero, the magnetomotive force of each leg of the inner core 13 becomes almost zero, and the protrusions 13', 13' of each leg of the inner core 13,
The magnetomotive force between the two points X-Y in the vicinity of the inner core 13'' becomes equal to the magnetomotive force between the two points U-V in the magnetic material 9 facing the end face of each leg of the inner core 13.At this time, the detection coil The magnetic flux at part 15 becomes almost zero, and the voltage of the voltage coil 14 corresponds to the magnetic flux between X and Y and becomes constant.Also, since the magnetomotive force between U and V is also constant, it corresponds to the magnetomotive force. Magnetic flux flows. That is, the voltage of the voltage coil 14 has a value corresponding to the magnetic flux between U and V. Therefore, the voltage of the voltage coil 14 at this time
If the voltage and the current of the excitation coil 17 are measured with the wattmeter 7, the value corresponds to the iron loss when the magnetomotive force between U and V of the magnetic material 9 is constant. In this way, if the magnetic flux of each leg of the inner core 13 is made almost zero, the U of the magnetic material 9 can be adjusted with high precision regardless of the size of the space between the end face of the inner core 13 and the magnetic material 9. -V
It is possible to measure a value equivalent to iron loss with a constant magnetomotive force between the two. If an absolute value is required here, it may be calibrated using a magnetic material whose iron loss is known using an Epstein apparatus or the like.
従つて、磁性材料９の表面と、磁気センサの内
側鉄心の端面の間に空〓があつても、その空〓の
大小に関係なく、常に高精度で磁性材料９に作用
する応力を前記の(1)式より求めることができる。
尚、前記実施例の検出コイル１５のかわりに、ホ
ール素子等のセンサを使用してもよいことは自明
である。以上のように、本発明の鉄損測定装置
は、磁性材料の表面と磁気センサの内側鉄心の端
面の間に空〓があつても、その空〓の大小に関係
なく、高精度で磁性材料の鉄損を測定することが
できる。従つて、前記の(1)式より空〓により測定
誤差を生ずることなく、常に高精度で磁性材料の
応力を求めることができる。 Therefore, even if there is a void between the surface of the magnetic material 9 and the end face of the inner core of the magnetic sensor, regardless of the size of the void, the stress acting on the magnetic material 9 can always be reduced with high precision as described above. It can be obtained from equation (1).
It is obvious that a sensor such as a Hall element may be used in place of the detection coil 15 of the above embodiment. As described above, the iron loss measuring device of the present invention can measure the magnetic material with high accuracy even if there is a void between the surface of the magnetic material and the end face of the inner core of the magnetic sensor, regardless of the size of the void. The iron loss can be measured. Therefore, the stress of the magnetic material can always be determined with high accuracy from the above equation (1) without causing measurement errors due to voids.
第１図は従来の鉄損測定装置の説明図、第２図
は磁性材料に作用する応力と鉄損の関係を示す特
性曲線図、第３図は本発明の鉄損測定装置の一実
施例の説明図である。
５…交流電源、７…電力計、９…磁性材料、１
０，１０′…鉄損測定装置、１２，２１…磁気セ
ンサ、１３，２２…内側鉄心、１３′，１３″…突
起、１４…電圧コイル、１５…検出コイル、１６
…外側鉄心、１７…励磁コイル、１８…増幅器、
１９…電力計、２０…電流計。
Fig. 1 is an explanatory diagram of a conventional iron loss measuring device, Fig. 2 is a characteristic curve diagram showing the relationship between stress acting on a magnetic material and iron loss, and Fig. 3 is an embodiment of the iron loss measuring device of the present invention. FIG. 5...AC power supply, 7...wattmeter, 9...magnetic material, 1
0, 10'... Iron loss measuring device, 12, 21... Magnetic sensor, 13, 22... Inner core, 13', 13''... Protrusion, 14... Voltage coil, 15... Detection coil, 16
...outer iron core, 17...excitation coil, 18...amplifier,
19... Wattmeter, 20... Ammeter.
Claims (1)
検出コイルを巻装するとともに前記脚部の間に磁
気抵抗の高いバイパスを形成した内側鉄心と、断
面略コの字形で開口端を前記内側鉄心の開口端と
同一平面同一方向に設け、背部に励磁コイルを巻
装した外側鉄心とからなる磁気センサと；前記電
圧コイルを励磁する交流電源と；入力側が前記検
出コイルに、出力側の一端が電力計の電流端子
に、他端が励磁コイルの一端に接続された増幅器
と；前記電圧コイルは電圧端子に、励磁コイルの
他端と増幅器の一端は電流端子に接続された電力
計とからなることを特徴とする鉄損測定装置。1. An inner core having a substantially U-shaped cross section and having a voltage coil wound around the back and a detection coil wound around the legs, and a bypass with high magnetic resistance formed between the legs; a magnetic sensor consisting of an outer core provided on the same plane and in the same direction as the open end of the inner core and having an excitation coil wound around its back; an AC power source that excites the voltage coil; an input side connected to the detection coil; an amplifier having one end connected to the current terminal of the wattmeter and the other end connected to one end of the excitation coil; said voltage coil being connected to the voltage terminal, and the other end of the excitation coil and one end of the amplifier being connected to the current terminal An iron loss measuring device comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10892790A JPH03115876A (en) | 1990-04-26 | 1990-04-26 | Measuring device of core loss |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10892790A JPH03115876A (en) | 1990-04-26 | 1990-04-26 | Measuring device of core loss |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2288582A Division JPS58140655A (en) | 1982-02-17 | 1982-02-17 | Iron loss measurement method and stress measurement device using the method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03115876A JPH03115876A (en) | 1991-05-16 |
| JPH0474677B2 true JPH0474677B2 (en) | 1992-11-26 |
Family
ID=14497187
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10892790A Granted JPH03115876A (en) | 1990-04-26 | 1990-04-26 | Measuring device of core loss |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03115876A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4789354B2 (en) * | 2001-06-26 | 2011-10-12 | 日本信号株式会社 | Power receiver |
| JP4916896B2 (en) * | 2007-01-12 | 2012-04-18 | 新日本製鐵株式会社 | Electromagnetic field analysis system |
| JP5157646B2 (en) * | 2008-05-28 | 2013-03-06 | 新日鐵住金株式会社 | Iron loss optimization system |
| JP5365304B2 (en) * | 2009-03-30 | 2013-12-11 | Ｊｆｅスチール株式会社 | Single-plate magnetic property tester for magnetic steel sheet and magnetic property measurement method |
| JP5885646B2 (en) * | 2012-12-05 | 2016-03-15 | 公立大学法人首都大学東京 | Single plate magnetic property measuring method and measuring apparatus |
| JP6575394B2 (en) * | 2016-02-23 | 2019-09-18 | 日本製鉄株式会社 | Apparatus and method for evaluating magnetic properties of iron core joints |
-
1990
- 1990-04-26 JP JP10892790A patent/JPH03115876A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03115876A (en) | 1991-05-16 |
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