JPH03201412A - Magnetic material for earth leakage breaker consisting of crystallite base alloy - Google Patents

Abstract

PURPOSE: To provide a core material for an earth leakage breaker having high saturation magnetic flux density and magnetic characteristics of low temperature dependency by employing a microcrystal iron based alloy of specified composition. CONSTITUTION: An iron based alloy containing iron by 60atm.% or more where 50% or more of the entire texture is composed of microcrystal having a grain size smaller than 100nm and having saturation flux density of 1.1T or above and remanence ratio Br/Bs smaller than 0.7 is employed as a core material. A microcrystal core thus produced has very good soft magnetic characteristics of low temperature dependency. It is true for a core having a circular hysteresis loop, i.e., a remanence ratio in the range of 0.4-0.7. Furthermore, an annular core exhibits very good stability for not only pulse level control but also a small superposed DC field.

Description

DETAILED DESCRIPTION OF THE INVENTION [Top Field of Application] This invention relates to a magnet material for earth leakage circuit breakers comprising a microcrystalline iron-based alloy.

[Prior Art] Earth leakage circuit breakers have been used for many years to protect humans and machinery. The key component of the earth leakage circuit breaker is a soft magnetic core that acts as a differential current transformer.The tripping current for a machine protection earth leakage circuit breaker is in the range of about 300-500 mA. On the other hand, in the case of earth leakage circuit breakers for personal protection, the tripping current is only 30 mA.
7) Paper “Crystalline and Amorphous Soft Magnetic Metals (Weichm
agnetischekristalline und
amorphe Metalle) J, x Elektronik, Volume 22, 1
987 describes the requirements for magnetic cores and the materials used for them. ? In addition to a high maximum magnetic permeability or a sufficient magnetic flux density at low magnetic field strengths, the a1 core material must also have a low temperature dependence of the magnetic properties over the entire range of use, especially for 30 mA ground fault circuit breakers. A crystalline nickel-iron alloy (permalloy type) containing approximately 77% nickel is used. The saturation value of this material is approximately 0.8T. However, in order to reduce the temperature dependence of the magnetic properties of the material, additional and expensive annealing is necessary in the case of permalloy alloys. This makes the production of earth fault circuit breaker cores expensive and expensive. The need for annealing is due to fire
er) and Pol (Rol1), IEEE Transacti
ons), Magnetic Handbook, Vol. MAG-5, No. 3, 19
It is described in detail in September 1969, pages 365-370.

In addition to crystalline materials, amorphous materials for earth leakage circuit breakers have already been proposed. 30mA because a small magnetizing force is required
For commercial 1 m disconnectors, only cobalt-rich alloys are a problem, and their saturation (i is in the range 0.55 to 0.7 T). , problems arise when using amorphous materials with high demands regarding temperature dependence.

[Problems to be Solved by the Invention] An object of the present invention is to provide a magnetic core material for an earth leakage circuit breaker that has a high saturation magnetic flux density and at the same time has a small temperature dependence of magnetic properties.

[Means for Solving the Problem] This problem is based on the present invention, and has an iron base grain content of 60 atomic % or more, 50% or more of its structure consists of microcrystalline grains with a grain size of less than 1100 nm, and t , t”r or more and a remanence ratio B r /B s less than 0.7, as the magnetic core material, where B is the remanence; BS is the saturation magnetic flux density.

This kind of microcrystalline iron-based alloy is available in European Patent Application Publication FJ2
It is known from Publication No. 71B57. In particular, in addition to iron, it mainly contains 0.1-3 at.% copper, 0.1-30 at.% Nb, W, Ta, Zr, Hf, Ti, N.
another metal such as o, up to 30 atom % silicon and 25
It is an alloy containing less than atomic percent of boron.

At that time, the total content of boron and silicon is 5 to 30 at%
within the range of Iron can be partially replaced by cobalt and/or nickel. This material has been proposed for use in high frequency transformers, chokes and magnets due to its good magnetic high frequency properties. From European Patent Application No. 299,498 a magnetic core is known consisting of a microcrystalline iron-based alloy, which magnetic core exhibits a very low time-dependent change in magnetic permeability. For the use of magnetic cores in chokes, filters and high frequency transformers as described in the above publication, 0
．． A magnetic core having a remanence ratio of 3 or less or 0.7 or more is used. Furthermore, papers by Yoshizawa, Yamauchi, Nakaki, and Sugihara, Journal of Applied Physics (Journal
al of Applied Physics),?
Volume 564, No. 10, 1988, Nos. 6047-604
From page 9, CH3. - Cores made of microcrystalline iron-based alloys for use in coils are known. This paper includes measurements of the temperature dependence of saturation magnetic flux density,
The magnetic permeability at temperatures above the freezing point is described.

[Operation and Effect] Surprisingly, it has been discovered that the temperature dependence of the magnetic properties of microcrystalline iron-based alloys is extremely small even at sub-zero temperatures of -25°C, which is the range of temperatures in which earth leakage circuit breakers are used. Ta. The small temperature dependence of the magnetic properties above the freezing point is not sufficient for use as core material in earth leakage circuit breakers, and furthermore, as is known from the materials conventionally used for earth leakage circuit breakers. (see Figure 4), does not provide evidence for a small temperature dependence in the case of sub-zero temperatures.As already mentioned in the paper by Pfeiffer and Pol, the nickel-iron alloys based on the prior art are also At low temperatures, the decrease in magnetic permeability is relatively small; on the other hand, at low temperatures, the decrease in magnetic permeability is significant.

The microcrystalline magnetic core according to the invention for earth leakage circuit breakers has very good soft magnetic properties and the temperature dependence of these properties is small, which means that it has a round hysteresis loop, i.e. This holds especially true for magnetic cores with a remanence ratio of less than .7. The production of this alloy is economical. This is because no special supplementary annealing is required to reduce the temperature dependence of the magnetic properties.

The toroidal core exhibits very good stability not only to pulse level control but also to small superimposed DC magnetic fields.

[Examples] Next, the present invention will be explained in detail using graphs showing the characteristics of a plurality of examples of magnetic materials based on the present invention.

An annular tape core with a round hysteresis loop as well as an annular tape core with a round hysteresis loop were made. For use in 30mA earth leakage circuit breakers,
Materials with a remanence ratio in the range from 0.4 to 0.7 have proven particularly advantageous. The microcrystalline tape was fabricated by crystallizing the originally amorphous tape by - heat treatment steps followed by cooling with a cooling rate of 0.4 to 7 minutes or more.

A method for producing microcrystalline tapes is known in principle from the aforementioned European Patent Application Publication No. 2003-210002. The grain size of the microcrystalline particles was always less than 25 nm in all examples. In addition to 73.5 atom % of iron, the magnetic core of the example also contains 1 atom % of copper,
It contained 3 at.% niobium, 13.5 at.% silicon and 9 at.% boron. The completed annular tape core had dimensions of φ19×φ15×5 mm. f4 (50Hz) and static magnetic flux density deviation Δ13stat and dynamic magnetic flux density deviation ΔBdV, respectively, for the annular tape core.
Hysteresis loops and magnetization curves of n were measured at room temperature for sinusoidal, half-wave rectified and full-wave rectified currents. Furthermore, the static and dynamic magnetic flux density excursions and the temperature dependence of L4 at 50 Hz were measured.

Example 1: A magnetic core subjected to a heat treatment without a magnetic field had a remanence ratio of 0.65 (round hysteresis loop). FIG. 1 shows the nearly static hysteresis loop of this core.

FIG. 2 shows the relationship between ΔBstat, ΔBdyn, and magnetic field strength. The magnetic flux density B of the magnetic core according to the invention with a round hysteresis loop is already 10 mA/cm.
For a magnetic field strength of , a value of 0.5 T is reached, thus exceeding the value of magnet materials for earth leakage circuit breakers according to the prior art. The magnetic core according to the invention also exhibits high values for static and dynamic flux density excursions. FIGS. 3a) to 3c) show the temperature dependence of the magnetic properties of the magnetic core according to the invention. This temperature dependence has very high constancy with small variations over the entire temperature range required for practical applications from -258C to +80'C.

For comparison, FIG. 4 shows the temperature dependence of magnetic properties for alloys based on the prior art. This alloy is a high nickel goldstone alloy sold for earth leakage circuit breakers under the trade name Ultrapalm F80(7). This alloy also has a very good constancy of the magnetic value to temperatures above the freezing point. However, large fluctuations occur for temperatures below freezing.

Example 2: A remanence ratio of 0.1 was measured for a core heat treated in a transverse magnetic field (flat hysteresis loop). This magnetic core likewise has a good constancy of the magnetic properties upon temperature changes, as shown in FIGS. 5a) to 5c). However, this variation was larger than in the case of the magnetic core with round hysteresis loop.

[Brief explanation of drawings]

The first VgJ is B of an embodiment of the magnet material based on this invention.
-H curve, Figure 2 is the fl of the same material as Figure 1.
(50Hz), Δ13stat, ΔBdyn -H characteristics as a graph, FIG. 3 a) to C) are μa (50H2), Δ13 stat shown in FIG. Figure 4 is a graph showing the temperature dependence of ΔB d, n. Figure 4 is a graph showing the same temperature dependence as Figure 3 for a conventional example. Figure 5 a) to C) is a graph for another example. Figure 3 a) to C of the example
) is a diagram illustrating the same temperature dependence as a graph. Fiber bundle release ITJ Senwa LIT noμ4~ (l ICXλfuno200 20406080 t rocno00

Claims (1)

[Scope of Claims] 1) Having an iron content of 60 atomic % or more, and having an iron content of 50 atomic % or more,
% or more consists of microcrystalline particles with a particle size of less than 100 nm,
A magnet material for an earth leakage circuit breaker, characterized in that it is made of a microcrystalline iron-based alloy having a saturation magnetic flux density of 1.1 T or more and a remanence ratio Br/Bs of less than 0.7. 2) The magnetic material according to claim 1, having a remanence ratio of 0.4 or more. 3) The temperature-dependent change in magnetic flux density deviation at the operating point is -2
The magnetic material according to claim 1, characterized in that the magnetic material exhibits a temperature difference of less than ±10% with respect to room temperature in a temperature range of 5°C to +800°C. 4) Magnet material according to claim 1, characterized in that the microcrystalline particles have a particle size of less than 25 nm.