ASTM A348 Alternating Current Magnetic Properties of Materials Using the Wattmeter-Ammeter-Voltmeter Method, 100 to 10,000 Hz and 25-cm Epstein Frame

ASTM A348 is primarily intended for evaluating laminated soft magnetic materials assembled in a standardized 25-cm Epstein frame to obtain consistent and reproducible AC magnetic property measurements. The test method is frequently used together with other ASTM magnetic standards when comprehensive evaluation of magnetic materials is required.

Get Certified ASTM A348 Testing for Reliable Magnetic Material Performance

Testing performed in accordance with ASTM A348 enables manufacturers to evaluate the AC magnetic performance of soft magnetic materials before they are used in electrical equipment. Standardized testing provides consistency in the product, minimizes losses in energy, includes an energy quality assurance program, and complies with customer and industrial requirements.

• Characterizing the soft magnetic material’s AC magnetic properties. 
• Measuring AC magnetic properties over the frequency range of 100 Hz to 10,000 Hz.
• Measuring and calculating core loss, exciting power, apparent power, permeability, and magnetic induction.
• Applying the standardized 25 cm Epstein frame testing method. 
• Safeguarding quality control, research, and production of electrical steel. 
• Applicability to soft magnetic materials used in electromagnetic equipment, including electrical steels and other soft magnetic alloys.

What are the Uses of ASTM A348 Testing?

ASTM A348 testing helps manufacturers and laboratories evaluate the AC magnetic performance of soft magnetic materials used in electrical and electromagnetic equipment. The test results support material selection, quality assurance, product certification, and research by providing accurate magnetic property data under alternating current conditions. Common applications include: 

• Evaluates the AC magnetic properties of electrical steel used in transformers, motors, and generators. 
• Measures core loss, magnetic permeability, exciting power, and magnetic induction for quality assurance. 
• Compares the performance of grain-oriented and non-grain-oriented electrical steels. 
• Supports material selection for transformers, inductors, reactors, relays, solenoids, and other electromagnetic components. 
• Helps verify compliance with applicable material specifications and customer requirements during manufacturing and quality control.
• Assists research and development of advanced soft magnetic alloys with improved efficiency and reduced energy losses. 
• Helps optimize the design of energy-efficient electrical machines and power distribution equipment. 
• Provides reliable magnetic property data for quality control, failure analysis, and material development. 

What Materials Can Be Tested Using ASTM A348?

ASTM A348 is primarily used to evaluate soft magnetic materials intended for alternating-current applications. Common materials are grain-oriented electrical steel, non-grain-oriented electrical steel, silicon steel, iron-cobalt alloys, nickel-iron alloys, amorphous metal ribbons, nanocrystalline magnetic alloys, and other laminated magnetic materials, including electrical machines and power equipment.

Why is AC Magnetic Property Testing Important?

In electrical equipment, alternating magnetic fields are continually switched back and forth, resulting in energy losses in the magnetic material. ASTM A348 is used throughout the design phase to help engineers assess these losses, reduce heat generation, and optimize transformer and motor performance and efficiency. 

Common Challenges and Troubleshooting

The accuracy of the measurement is affected by improper specimen assembly, burrs on the specimen edges, improper strip orientation, poor electrical connections, incorrect instrument calibration, magnetic saturation, and unstable frequency control. These problems are minimized through proper specimen preparation, routine instrument calibration, careful Epstein frame assembly, and strict adherence to ASTM A348 testing procedures. In the case of grain-oriented electrical steel, it is especially crucial to maintain the correct orientation of the strips in the Epstein frame, as the magnetic properties of the material depend on the rolling direction of the steel.

ASTM A348 Testing Process and Data Collection

Technicians prepare standardized magnetic strip specimens and assemble them in the Epstein frame. Alternating current is applied to the specimen at the test frequency, and the voltage, current, and power are monitored continuously. The measured values are used for the calculation of magnetic induction, core loss, exciting power, apparent power and permeability. The final report is a summary of all the magnetic properties measured and the testing conditions. The test frequency, magnetic induction level, specimen mass, calculated magnetic properties, testing conditions, and equipment identification are all included in test reports to ensure complete documentation.