IEC 61007:2020 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 can be useful to the other types of transformers used in power distribution applications in utilities, industry, and others, the tests discussed in this document can supplement or complement the tests but are not intended to replace the tests in standards for 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 edition includes the following significant technical changes with respect to the previous edition:a) scope: the application of the scope of IEC 61007 was extended;b) Clause 2: added new references and updated the references;c) Clause 3: new definitions were added in 3.3, and in 3.7 the voltage-time product was redefined;d) test procedures were updated;e) environmental test procedures: new references were added;f) Annexes A to G were added.