处理低压设备中承受高频电压应力的基本、补充和加强绝缘。尺寸值直接适用于基本绝缘；对于加强绝缘，根据第1部分，附加要求适用。它适用于基频高于30 kHz且高达10 MHz的任何类型的周期性电压下的间隙、爬电距离和固体绝缘的尺寸标注。 IEC 60664的本部分只能与IEC 60664-1或IEC 60664-5（在本标准中称为第1部分或第5部分）一起使用。通过将第1部分或第5部分与本部分一起使用，第1部分或第5部分的频率限制扩展到高于30 kHz的频率。 本部分也适用于第3部分，适用于大于30 kHz的频率和1型保护。对于2类保护，这个问题正在考虑中。 适用于额定电压高达交流1000 V、海拔2000米以下的设备。 根据设备的性能标准，规定设备的间隙、爬电距离和固体绝缘要求。它包括与绝缘配合有关的电气测试方法。 本部分规定的最小间隙不适用于出现电离气体的情况。此类情况的特殊要求可由相关技术委员会自行决定。 本部分不涉及距离 -通过液体绝缘， -通过空气以外的气体， -通过压缩空气。 本标准的目的是指导负责不同设备的技术委员会合理化其要求，以便在规定设备的空气间隙、爬电距离和固体绝缘时实现绝缘协调。 IEC 60664-4修订期间的主要变化如下: -包括高频电压应力下绝缘耐受特性的最新信息（见附录A、B和C）； -包括高频电压应力下间隙尺寸的要求（见第4条）； -包括高频电压应力下爬电距离的尺寸要求（见第5条）； -包括高频电压应力下固体绝缘的尺寸要求（见第6条）； -包括图表，为高频电压应力的尺寸标注提供指导（见附录F）； 关于高频电压应力的试验规范（见第7条）。 -包括高频耐压试验和局部放电试验的试验电路（见附录D。 1和D.2.1）； -包括高频电压下局部放电试验电路的设计标准（见附录D.2.2）； -包括处理非正弦电压应力的标准（见第8条和附录E）。 具有符合IEC指南104的基本安全出版物的状态。

Deals with basic, supplementary and reinforced insulation subjected to high-frequency voltage stress within low-voltage equipment. The dimensioning values directly apply for basic insulation; for reinforced insulation additional requirements apply according to Part 1. It is applicable for the dimensioning of clearances, creepage distances and solid insulation stressed by any type of periodic voltages with a fundamental frequency above 30 kHz and up to 10 MHz. This part of IEC 60664 can only be used together with IEC 60664-1 or with IEC 60664-5 (in this standard called Part 1 or Part 5). By using Part 1 or Part 5 together with this part the frequency limit of Part 1 or Part 5 is extended to frequencies higher than 30 kHz. This part also applies to Part 3 for frequencies greater than 30 kHz and protection of type 1. For type 2 protection this question is under consideration. Applies to equipment for use up to 2 000 m above sea level having a rated voltage up to a.c. 1 000 V. Specifies the requirements for clearances, creepage distances and solid insulation for equipment based upon their performance criteria. lt includes methods of electric testing with respect to insulation coordination. The minimum clearances specified in this part do not apply where ionized gases occur. Special requirements for such situations may be specified at the discretion of the relevant technical committee. This part does not deal with distances - through liquid insulation, - through gases other than air, - through compressed air. The object of this standard is to guide technical committees responsible for different equipment in order to rationalise their requirements so that insulation coordination is achieved when specifying clearances in air, creepage distances and solid insulation for equipment. The major changes made during the revision of IEC 60664-4 were the following: - inclusion of more recent information about the withstand characteristics of insulation at high-frequency voltage stress (see Annexes A, B and C); - inclusion of requirements for the dimensioning of clearances at high-frequency voltage stress (see Clause 4); - inclusion of requirements for the dimensioning of creepage distances at high-frequency voltage stress (see Clause 5); - inclusion of requirements for the dimensioning of solid insulation at high-frequency voltage stress (see Clause 6); - inclusion of diagrams to provide guidance on dimensioning with respect to high-frequency voltage stress (see Annex F); specification of tests with respect to high-frequency voltage stress (see Clause 7). - inclusion of test circuits for high-frequency voltage withstand testing and partial discharge testing (see Annex D.1 and D.2.1); - inclusion of design criteria for partial discharge test circuits at high-frequency voltage (see Annex D.2.2); - inclusion of criteria for dealing with non sinusoidal voltage stress (see Clause 8 and Annex E). Has the status of a basic safety publication in accordance with IEC Guide 104.