WG 3 - TC 112/WG 3

IEC 61251:2015 describes many of the factors involved in voltage endurance tests on electrical insulating materials and systems. It describes the voltage endurance graph, lists test methods illustrating their limitations and gives guidance for evaluating the sinusoidal a.c. voltage endurance of insulating materials and systems from the results of the tests. This International Standard is applicable over the voltage frequency range 20 Hz to 1 000 Hz. The general principles can also be applicable to other voltage shapes, including impulse voltages. The terminology to be used in voltage endurance is defined and explained. This first edition of IEC 61251 cancels and replaces the second edition of IEC TS 61251, published in 2008. This edition constitutes a technical revision and includes the following significant technical changes with respect to the second edition of IEC TS 61251:
a) upgrade from Technical Specification to an International Standard;
b) clarification of issues raised since publication of IEC TS 61251.

IEC 60243-3:2013 gives requirements additional to those in IEC 60243-1 for the determination of the electric strength of solid insulating materials under 1,2/50 µs impulse voltage stress. This third edition cancels and replaces the second edition, published in 2001, and constitutes an editorial revision.
This publication is to be read in conjunction with IEC 60243-1:2013.

IEC 60243-2:2013 gives requirements additional to those in IEC 60243-1 for the determination of the electric strength of solid insulating materials under direct voltage stress. This third edition cancels and replaces the second edition published in 2001, and constitutes an editorial revision.
This publication is to be read in conjunction with IEC 60243-1:2013.

IEC 60243-1:2013 provides test methods for the determination of short-time electric strength of solid insulating materials at power frequencies between 48 Hz and 62 Hz. This standard does not cover the testing of liquids and gases, although these are specified and used as impregnates or surrounding media for the solid insulating materials being tested. NOTE: Methods for the determination of breakdown voltages along the surfaces of solid insulating materials are included.

IEC 62068:2013 applies to electrical equipment, regardless of voltage, containing an insulation system, which is:
- connected to an electronic power supply, and
- requires an evaluation of insulation endurance under repetitive voltage impulses. This standard proposes a general test procedure to facilitate screening of electrical insulating materials (EIM) and systems (EIS) and to achieve a relative evaluation of insulation endurance under conditions of repetitive impulses. This first edition of IEC 62068 replaces IEC 62068-1:2003. It has been re-numbered as IEC 62068, as decided at the Plenary Meeting of TC 112 in Prague 2011. The main changes with regard to IEC 62068-1:2003 concern the terms and definitions which are now aligned, in part, on IEC/TS 61934 and IEC/TS 60034-18-42.

IEC/TS 61934:2011(E) is applicable to the off-line electrical measurement of partial discharges (PD) that occur in electrical insulation systems (EIS) when stressed by repetitive voltage impulses generated from electronic power devices. Typical applications are EIS belonging to apparatus driven by power electronics, such as motors, inductive reactors and windmill generators. Excluded from the scope of this technical specification are:
- methods based on optical or ultrasonic PD detection,
- fields of application for PD measurements when stressed by non-repetitive impulse voltages such as lightning impulse or switching impulses from switchgear.
The principal changes with regard to the previous edition concern the addition of:
- an Introduction that provides some background information on the progress being made in the field of power electronics;
- impulse generators;
- PD detection methods;
- a new informative Annex C covering practical experience obtained from round-robin testing (RRT);
- example of noise levels, as shown in new informative Annex D.

Presents the important material properties for polymeric materials used in outdoor insulation and, where applicable, lists the standardised test methods including the minimum requirements. If no standardised tests are available, then test methods reported in literature are summarised. This report is valid for insulating materials used in outdoor high voltage electrical applications with a system voltage greater than 1000 V a.c. having polymeric insulation including also such applications where the housing is an integral part of the devices e.g. in surge arrestors and cable terminations. The scope of this report is limited to the materials only. The performance of insulators in service depends on several factors such as the type of material, the design, environmental conditions etc. Consequently, the choice of materials that fulfil the requirements listed below is a necessary condition but does not guarantee satisfactory performance when used in outdoor insulation