Corefficient’s Electrical Steel and Transformer Core Testing Capabilities

transformer core testing

What sets an electrical transformer core company apart from the rest? Here at Corefficient, we believe that the difference lies in the ability to perform accurate transformer core testing by testing the capabilities of our cores through every stage of the manufacturing process. As a complete core solution provider, we produce and test our transformer cores in wound, DG (distributed gap), Duo Core and SLFM (step lap full mitre) construction.

Corefficient has a complete on-site quality control laboratory to verify the integrity of our raw materials. Here, we test the core loss, permeability, and dimensions of your electrical steel using techniques based on ATSM testing methods.

Electrical Steel Material Testing

  • Epstein Testing: We test our shipments of electrical steel routinely for core loss and permeability using a Brockhaus MPG 200 testing system- using both standard and custom Epstein frames, we test the steel using different Tesla and frequency inputs based on ATSM A717 test methods.
  • Single Sheet Testing: Each and every coil of electrical steel is measured for NLL (no load losses) and permeability using modern SST equipment and techniques. Measuring domain refined electrical steel is a complicated yet important process, so we’ve found the only equipment available to do it.
  • Franklin Testing: Utilizing specialized equipment, we test single strips of flat rolled electrical steel and observe their properties under preset pressure, voltage, and temperature conditions.
  • Dimensional Testing: Along with SST, we test each coil of electrical steel for variations in material thickness and width based upon ASTM A971 testing methods.

On the assembly line, the transformer core testing makes multiple stops at our testing stations, where we insure that the integrity of the core remains consistent throughout construction.

Finally, once manufacture is complete, we subject the core to a variety of tests.

Assembled Core Electrical Testing

  • To insure that our customers are satisfied with their product, all assembled SLFM and DG cores are tested to their limits on automatic Yokogawa precision power analyzers to guarantee that NNL (no load losses) are met.
  • Additionally, upon request, any assembled SLFM and DG core can be tested for insulation resistance and sound over a wide range of densities and frequencies. Customers are provided detailed test reports and curve graphs.
  • We also provide first piece and PPAP inspection to our customers, showinglayout inspection and/or functional verification to our customers blueprints and performance standards as specified, and we pass along this information to you.


To learn more about how you can make our testing capabilities work for you, give us a call at (81) 2088-4000, or toll free USA at 1 (844) 202-1226.

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