International Electrotechnical Commission

Selection and dimensioning of high-voltage insulators intended for use in polluted conditions – Part 4: Insulators for d.c. systems - Edition 1.0
 N TS 60815-4

Annotation

This part of IEC 60815, which is a Technical Specification, is applicable as first approach for the determination of the required d.c. Unified Specific Creepage Distance for insulators with respect to pollution. To avoid excessive over or under design, existing operation experience should be compared and eventually additional appropriate tests may be performed by agreement between supplier and customer.

It is applicable to:

• Glass and porcelain insulators;

• Composite and hybrid insulators with an HTM or non-HTM housing.

This part of IEC 60815 gives specific guidelines and principles to arrive at an informed judgement on the probable behaviour of a given insulator in certain pollution environments.

The structure and approach of this part of IEC 60815 are similar to those explained in Part 1, but adapted for the specific issues encountered with polluted HV d.c. insulation.

The aim of this Technical Specification is to give the user simplified means to:

• Identify issues specific to d.c. applications that can affect the choice and design process;

• Determine the equivalent d.c. Site Pollution Severity (SPS) from measurements, correcting for electrostatic effects, diameter, pollution distribution and composition;

• Determine the reference USCD for different candidate insulating solutions, taking into account materials, dimensions and risk factors; • Evaluate the suitability of different insulator profiles;