BS EN 60664-4:2006 - Page 3

Insulation coordination for equipment within low-voltage systems. Consideration of high-frequency voltage stress | Status: Current

1 Scope and object This part of IEC 60664 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.

NOTE 1 Dimensioning values for frequencies above 10 MHz are under consideration.

NOTE 2 This standard does not consider the high-frequency emission to the mains. In normal use of equipment, it is assumed that the interference of high-frequency voltages emitted to the mains is negligible with respect to insulation stress. Therefore it is not necessary to take it into account.

It applies to equipment for use up to 2 000 m above sea level having a rated voltage up to a.c. 1 000 V. It 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.

NOTE 3 Higher voltages may exist in internal circuits of the equipment.

NOTE 4 Requirements for altitudes exceeding 2 000 m can be derived from Table A.2 of Annex A of Part 1.

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.