Hysteresisgraphs

Since introducing the first hysteresisgraphs in the 1960's, Walker Scientific has been leading the development of automatic hysteresisgraphs for magnetic material analysis that meet or exceed ASTM and other international magnetic standards. The ease of use of the Walker Scientific AMH Series Hysteresigraphs renders them ideal for both R&D and production line testing of magnetic materials. AMH Series hysteresisgraphs measure 2^nd quadrant demagnetizing curves, major and minor hysteresis loops, recoil hysteresis loops, initial magnetization curves from DC to 1 MHz. All types of magnetic materials can be characterized from very hard rare earth magnets to very soft magnetic materials.

SPECIAL FEATURES

• Windows NT Software with user configurable script language interface
• Frequencies from DC to 1 mHz
• Excitation fields >3 tesla to measure very hard magnetic materials
• Standard Power Supplies to >4 kW

AMH Series Hysteresisgraphs comply with the following international standards: ASTM A977-97, A773/A773M-96, A343, A348, A804/A804M, A912, A927/A927M-94, A932/A932M-95, A927, NFC 28-911, DIN 50-470 and IEC404-2 & 5. In some cases special tooling and fixtures may be required.

The following articles are related to the use of hysteresisgraphs and magnetic measurements:

• Magnetic Domains
• How is Magnetism Expressed?
• AMH Speeds Accurate Analysis of Soft Magnetic Materials
• How a Hysteresisgraph Measures the BH-Curve of Soft Magnetic Materials
• Core Loss Measurements Using a Hysteresisgraph as Compared to a Wattmeter
• Measurement of Different Soft Magnetic Material Geometries with a Hysteresisgraph
• Losses in Electrical Steels in AC Applications
• The Initial and Four-Quadrant BH-Curve of Soft Magnetic Materials

Series AMH (Automatic Magnetic Hysteresisgraph)

The latest generation of the AMH Series precision hysteresisgraph systems, which have set an industry standards for magnetic properties analysis through the years, are available in a line of computer-controlled instrumentation designed to analyze a broad range of magnetic material, from very soft magnetic material to very high energy rare earth permanent magnets such as neodymium-iron-boron magnets.

AMH-25 Automatic Magnetic Hysteresisgraph

• Measurement of hard and soft magnetic materials from DC to >50 kHz
• Over 4 kilowatts of peak power (75.6 volts rms @ 37.8 amps rms)
• Magnetic excitation fields >3 tesla (30,000 oe) for very hard rare earth magnet materials
• Windows NT software with a script language user interface

AMH-15 Automatic Magnetic Hysteresisgraph

• Measurement of hard and soft magnetic materials from DC to >1000 Hz
• 1700 watts of peak power (83.3 volts rms @ 21.5 amps rms)
• Magnetic excitation fields >2.5 tesla for very hard rare earth magnet materials
• Windows NT software with a script language user interface

AMH-5 Automatic Magnetic Hysteresisgraph

• Measurement of hard and soft magnetic materials
• Over 216 watts of peak power (36 volts @ 6 amps)
• Windows NT software with a script language user interface

AMH-401 Automatic Magnetic Hysteresisgraph

• Measurement of soft magnetic materials from 50 Hz to 100 kHz
• Measures core loss and hysteresis loop parameters
• Displays current and secondary voltage waveforms

AMH-401A Automatic Magnetic Hysteresisgraph

• Measurement of soft magnetic materials from 50 Hz to 1 mHz
• Measures core loss and hysteresis loop parameters
• Displays current and secondary voltage waveforms

AMH Series Hysteresisgraphs comply with the following international standards: ASTM A977-97, A773/A773M-96, A343, A348, A804/A804M, A912, A927/A927M-94, A932/A932M-95, A927, NFC 28-911, DIN 50-470 and IEC404-2 & 5. In some cases special tooling and fixtures may be required.


OPTIONS

Electromagnets

Walker Scientific electromagnets can produce maximum fields greater than 30 kOe. The maximum magnetic field depends upon the air gap and pole face diameter.  For example, with the HV-7V electromagnet, up to 35 kOe is possible with 1.5 inch diameter pole face and 0.25 inch air gap. Other pole face diameters and air gap openings will yield less magnetizing force but more exposure area for larger samples. Curves are available from Walker Scientific which show magnetizing force as a function of gap opening and pole face diameter.

Model	HV-4V	HV-7V	HV-10V
Pole Diameter: inches (mm)	4” (101)	7” (178)	10” (254)
Maximum Field: 1 inch (25 mm) air gap	15 kOe	20 kOe	25 kOe
Air Gap	0 to 3.25"	0 to 4.25"	0 to 5.5"
Shipping Weight	425 lbs	1200 lbs	3000 lbs

Power Supplies

AMH Hysteresigraphs can be used with several different power amplifiers. The power amplifier required depends on the frequency of the measurement, the size of the sample and the magnetic field required. See How to Choose the Correct Hysteresigraph.

Power Amplifier Options

Model 36/6 72/6 5050 7780 4014A Peak Power (Watts) 200 400 1750 >4000 160 Voltage (Volts Max) 36 72 118 107 75 Current (Amps Max) 6 6 30 71 4 Frequency (kHz) 13 10 to 70 kHz >20 kHz 1 mHz Slew Rate Volts/Micro-sec) 3 9 >30 46 400

Epstein Test Frames

Used to characterize electrical steel samples cut in strips, as called out in ASTM-A343 and A348.

Single Strip Test Fixture

Used to characterize electrical steel samples cut in strips, as called out in ASTM-A804. Custom Test Frames available upon request.

ACCESSORIES

Embedded Pole Caps

Embedded pole caps are a convenient way to measure the magnetic properties of many hard magnetic materials.  Walker Scientific offers a variety of models to meet specific measurement requirements.

TCSC-2 Temperature Measurement System

• Temperature range: -40°C to +300°C
• Fits most standard Walker LDJ electromagnets.

Sample Coil Sets

Walker Scientific offers a range of sample coil sets for B, Bi and H field measurements. These coil sets are specifically designed for use with AMH series Automatic Magnetic Hysteresisgraphs and allow all measurements to be made using the two AMH fluxmeters or a Hall probe and AMH gaussmeter.

MTC-1 Volt Second Calibrator

The MTC-1 Volt-Second Generator is a precision traceable standard with 11 impulse outputs from 0.0001 V-S to 10 V-S, which corresponds to a range of 10⁴ to 10⁹ maxwell-turns, and has an overall instrument accuracy which is better than ±0.05%.

Used as a primary standard to calibrate fluxmeters, electronic integrators and ballistic galvonometers without recourse to standard search coils or reference magnets, the MTC-1 will calibrate a fluxmeter to allow the fluxmeter to be used as a secondary standard for calibration of search coils, reference magnets, Hall probes and gaussmeters.

Hysteresigraph Sample Testing

Walker Scientific’s Magnetic Measurement Service is capable of measuring both hard and soft magnetic materials. Magnetic hysteresis curves as well as various magnetic parameters can be measured and analized on a contract basis. For pricing, please complete and submit this Sample Testing Form detailing your test sample specifications.

To help choose the correct hysteresigraph for your application go to How to Choose  the Correct Hysteresisgraph. Also to better understand hysteresigraph measurement principles the above technical articles may be of interest.

AMH System Specifications

Ask an Applications Expert about this product

(800) 962-4638
Contact our Webmaster. © Copyright 2002 Walker Scientific. All rights reserved.