| Products: magnetizers &... |
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 Magnetic Material Analysis
 SOFT MAGNETIC MATERIAL
AC-DC Permeameter - The measure of magnetically soft materials
Introduction
The characterization of soft magnetic materials is done in closed circuit. This condition can be obtained in two ways:
– On ring-shape specimen, which are naturally closed on their self;
– On samples having shape of bar or strips, which are closed at their ends through poles made of high-permeability materials. |
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The DC measure is done in quasi-static conditions, i.e. using an excitation field H that changes in a very low way. The measure is in agreement with International standard IEC 60404-4. The main results are the hysteresis loop and the normal magnetization curve, from which it is obtained the permeability vs. H- field curve.
The DC measure gives the intrinsic magnetic characteristic of the material. |
| The AC measure can be performed on ring-shape specimens, generally in two main conditions: magnetizing the sample with a sinusoidal H field, or with a field such that the resulting magnetic induction B is sinusoidal (generally, this is the most often used condition). The measure is described by the International Standard IEC 60404-6. The main results are the AC hysteresis loop, the AC normal magnetization curve and the specific losses (in W/kg) on the material. |
DC-AC Permeameter (up to 20 kHz)
DC-AC permeameter, customizable, permits the DC and AC measure of ring-shape specimens, in agreement with Standard IEC 60404-4 and 60404-6.
The system can be expanded for the measure of bars and strips.
The complete system includes
> Main cabinet with instruments (see below)
> PC + printer
> Software Soft-2005
> Reference sample |
The signal acquisition is performed through an
ADC board mounted directly on PC (for frequency
up to 1 kHz), or by a fast board or an oscilloscope
(for frequency up to 20 kHz). |
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- Fluxmeter Digital Flux
To measure the flux in DC conditions
- Arbitrary function generator
To generate requested waveforms (sinH or sinB)
- Power amplifier
To amplify the output signals from the arbitrary function generator. Customizable depending on requirements.
- Slide box with ring connections
Ring connections with fan grid |
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- Main electrical unit
220 VAC ( ± 10 %); 50-60 Hz |
The measure of bars and strips with yoke
The measure of bars and strips is done in an electromagnetic yoke (Sanford-Bennet yoke) realized with high-permeability strips. The magnetic flux produced by two excitation coils is driven by the yoke in an air-gap with adjustable amplitude, in which the specimen is inserted.
The circuit is perfectly closed on the samples due to two couples of shaped poles, which have a cavity that matches the cross section of the sample.
The measure of H is done by a Hall probe positioned close to the central cross-section of the bar. The measure of the induction B is done through a flux measurement with a pick-up coil in which the sample is inserted. |
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DC-AC permeameter is immediately ready for the connection to Sanford-Bennet yoke and to the measure of samples having shape of bars and strips.
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| Combo unit for the measure of hard and soft magnetic materials |
The ‘Combo’ unit joins the AC-DC permeameter for soft with hysteresisgraph IS-300 for hard, permitting the measure of all types of magnetic materials in a unique solution!
The two systems have some instruments and part of the electrical services in common, so, it is not only a compact solution, but also a saving-cost solution. |
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System composition:
> 2 fluxmeters Digital Flux
> Arbitrary function generator
> Power amplifier
> Slide box for ring connections
> Heating unit for LPT poles
> DC power supply
> Acquisition unit
> Electromagnet (yoke)
> Main electrical unit
> Compensated measuring coil
> PC + printer
> Software Hyst-2004
> Software Soft-2005
> Soft and hard reference samples |
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Software SOFT-2005 - For DC-AC Permeameter
Main characteristics
> Measure of hysteresis cycle, normal magnetization curve and permeability, in DC and AC conditions;
> Choice of measuring conditions (sinusoidal H or B) and of form factor;
> Manual or automatic selection of acquisition conditions;
> Automatic feedback with visualization of resulting waveforms;
Results
> Br, Hc, vertex and saturation values, m(H), mmax,m initial, mdifferential, loop area, specific losses, losses separation, Steinmetz coefficients, etc.;
> Curve comparison and possibility of grouping more curves in sets (with same frequency, with same amplitude, etc.);
> Losses separation (hysteresis, eddy currents and ‘excess’ losses);
> Linear and logarithmic scales;
> Comparison with reference curves;
> All characteristics of software Hyst-2004 are included in Soft-2005. |
Losses separation:
> Hysteresis losses
> Eddy current losses
> Excess (or anomalous) losses |
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Permeameter PFMM - Measure of permeability of feebly magnetic materials
Some materials, like austenitic stainless steels, are generally considered non-magnetic. But how much are they really non-magnetic?
Permeameter PFMM (Feebly Magnetic Materials) permits to quantify the magnetic ‘weakness’ of a material measuring its magnetization and its permeability. |
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When these materials are used in application for which it is necessary a very weak or null interaction with magnetic fields, it is fundamental to control that quantities like magnetization and permeability are weak enough.
There are a lot of applications that make use of feebly magnetic materials: big electric machines, turbo generators, NMR instruments, devices for ionic or electronic beams, precision weight, etc. |
PFMM permeameter was developed in accordance with reference standard ASTM A342.
The measuring range for relative permeability is generally between 1.001 and 4.
To better understand the sensibility of the instrument, we can focus that a material with a permeability of 1.001, when under a magnetic field of 1 tesla (10 kOe) has a magnetization of 10 gauss!
On the other side, remember that ferromagnetic materials such as Fe-Ni alloys, have permeability up to 105 ¸ 106.
In spite of the difficulty of the measure, the typical total accuracy of the system is better than 2 %.
The specimen should have a shape of bar with a uniform cross-section, with length bigger than 100 mm and cross section not lower than 20 mm2. Typical diameter of the solenoid is 50 mm, but custom dimensions are available. |
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