IEC TS 63493-1:2025

Transformer bushings dimensional standardization - Part 1: Medium voltage bushings with <em>U</em>_m from 12 kV up to and including 52 kV and <em>I</em>_r from 630 A up to and including 3 150 A

IEC TS 63493-1:2025 specifies the main parameters to facilitate interchangeability or at least to define some frame conditions of MV bushings:
- with Um from 12 kV up to and including 52 kV;
- Ir from 630 A up to and including 3 150 A.
This document deals with non-capacitance graded bushings for Power Transformers, according to the IEC 60076 series (usually for transformer with conservator).
In this document only liquid to air bushings are considered. Bushings of liquid-to-liquid and air-to-air type and bushings for transformers with air-cushion in tank are not considered.
MV is considered up to 52 kV; this value is used to cover specific insulation levels or for high pollution levels, even if the field of application is very restricted.
Both solutions with external insulation in porcelain and polymeric can be used and need to enable interchangeability (in terms of mechanical and electrical performance).

General Information

• Status: Published
• Publication Date: 10-Dec-2025
• ICS: 29.080.20 - Bushings
• Technical Committee: SC 36A - Insulated bushings
• Drafting Committee: JWG 7 - TC 36/SC 36A/JWG 7
• Current Stage: PPUB - Publication issued
• Start Date: 11-Dec-2025
• Completion Date: 26-Dec-2025

Standards Content (Sample)

IEC TS 63493-1 ®
Edition 1.0 2025-12
TECHNICAL
SPECIFICATION
Transformer bushings dimensional standardization -
Part 1: Medium voltage bushings with U from 12 kV up to and including 52 kV
m
and I from 630 A up to and including 3 150 A
r
ICS 29.080.20  ISBN 978-2-8327-0895-8

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CONTENTS
FOREWORD . 2
INTRODUCTION . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Designations, main characteristics and dimensions . 6

Figure 1 – Bushing general overall drawing . 6
Figure 2 – Mounting flange interface drawing . 11

Table 1 – Ceramic bushings with hollow core porcelain insulator . 7
Table 2 – Composite bushings with hollow core composite insulator . 9
Table 3 – Combined insulation bushings with solid core combined insulator . 10
Table 4 – Mounting flange interface dimensions . 11

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Transformer bushings dimensional standardization -
Part 1: Medium voltage bushings with U from 12 kV up to and including
m
52 kV and I from 630 A up to and including 3 150 A
r
FOREWORD
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IEC TS 63493-1 has been prepared by subcommittee SC 36A: Insulated bushings, of IEC
technical committee TC 36: Insulators. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
36A/270/DTS 36A/273/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
A list of all parts in the IEC 63493 series, published under the general title Transformer bushings
dimensional standardization, can be found on the IEC website.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
INTRODUCTION
The scope of this part of IEC 63493 is to facilitate interchangeability or at least to define some
frame conditions (this is not intended to be a mandatory document).
Standardization of bushings would bring several benefits, among which:
– decreasing the number of products to be developed, tested and maintained;
– leveraging economy of scale with an overall positive effect on product cost and quality;
– reducing inventories and lead times;
– simplifying the purchasing process;
– enabling the interchangeability of bushings produced by different manufacturers;
– facilitating retrofitting of old products with new ones based on more advanced technologies;
– etc.
This document deals with a specific typology of medium voltage bushings.

1 Scope
This part of IEC 63493, which is a Technical Specification, specifies the main parameters to
facilitate interchangeability or at least to define some frame conditions of MV bushings:
– with U from 12 kV up to and including 52 kV;
m
– I from 630 A up to and including 3 150 A.
r
This document deals with non-capacitance graded bushings for Power Transformers, according
to the IEC 60076 series (usually for transformer with conservator).
In this document only liquid to air bushings are considered. Bushings of liquid-to-liquid and air-
to-air type and bushings for transformers with air-cushion in tank are not considered.
MV is considered up to 52 kV; this value is used to cover specific insulation levels or for high
pollution le
...