IEC/IEEE 61007-389 Ed. 1.0 en:2026

IEC/IEEE 61007-389:2026 describes a number of tests for use in determining the significant parameters and performance characteristics of transformers and inductors for use in electronics and telecommunication equipment. These test methods are designed primarily for transformers and inductors used in all types of electronics applications that can be involved in any specification for such components.

Even though these tests could be applied supplementally for other types of transformers, such as those with larger power ratings used in the utility power industry, the tests discussed in this document are not intended to replace the tests in standards for those other transformers.

Some of the tests described are intended for qualifying a product for a specific application, while others are test practices used for manufacturing and customer acceptance testing. The test methods described here include those parameters most commonly used in the electronics transformer and inductor industry: electric strength, resistance, power loss, inductance, impedance, balance, transformation ratio and many others used less frequently.

This first edition of IEC/IEEE 61007-389 cancels and replaces IEC 61007:2020 and IEEE 389:2020, which has been technically revised.

This edition includes the following significant technical changes with respect to the previous edition:

• Added the following new test items:
  • transformer capacitance (in 4.5.6.1);
  • voltage transformation (VT) ratio (in 4.5.7.3);
  • thermo-couple method (in 4.5.15.3);
  • bridge circuit measurement (in 4.5.16.3);
  • dynamic CM capacitance of a transformer (in 4.5.20);
  • tests of the parameter in transformer equivalent circuit (in 4.5.21);
• Updated the following test items:
  • added test purpose: AC resistance (in 4.5.1.2); dielectric withstand voltage test (in 4.5.2.1); effective inductance (in 4.5.4.1); capacitance unbalance (in 4.5.5.1); total harmonic distortion (in 4.5.13);
  • testing fundamentals and equipment modification: DC winding resistance (in 4.5.1.1); AC resistance (in 4.5.1.2); winding continuity (in 4.5.1.3); excitation apparent-power measurements (in 4.5.3.4); capacitance unbalance (in 4.5.5.1); self-capacitance (distributed capacitance) (in 4.5.6.2); inter-winding capacitance (in 4.5.6.3); inherent self-resonance (in 4.5.8.1); resonant assemblies (in 4.5.8.2); insertion loss (in 4.5.9.1); return loss (in 4.5.9.2); crosstalk (in 4.5.10); pulse characteristics (in 4.5.11.1); transformer response measurements (in 4.5.11.2); total harmonic distortion (in 4.5.13); method utilizing the change in DC resistance of a winding (in 4.5.15.1); method using an additional series-opposing bifilar winding (in 4.5.15.2); safety screens (in 4.5.17.2); magnetic radiation (in 4.5.17.4); acoustic noise (in 4.5.18.1);
  • procedure modification: dielectric withstand voltage test (in 4.5.2.1); induced voltage test (in 4.5.2.2); capacitance unbalance (in 4.5.5.1);
  • Information to be stated modification: insulation resistance (in 4.5.2.4); excitation apparent-power measurements (in 4.5.3.4); stray-load losses (in 4.5.3.5); power factor (in 4.5.3.8); inherent self-resonance (in 4.5.8.1); parallel resonance and series resonance (in 4.5.8.3); transformer pulse response (in 4.5.11.3);
• Removed Annex D and Annex F in IEC 61007:2020.