EN 50209:1998

Test of insulation of bars and coils of high-voltage machines

This specification applies to rotating electrical machines with rated voltages (Un) from 5 kV to 24 kV inclusive and with rated output from 5 MVA upwards and from 5 MW upwards for motors Requirements for machines with rated voltage above 24 kV should remain the subject of individual agreement This specification is also applicable to machines with rated outputs between 1MVA( 1MW) and 5 MVA(5MW) and with rated voltages of 5 kV and above, provided its use has been agreed beforehand In the case of machines whose windings are cured in the stator, tests on the separate winding elements are not possible; for these machines the requirements in Part B apply. The test of the conductor lamination insulation must however be carried out in accordance with 23 of Part A of this standard

Prüfung der Isolierung von Stäben und Spulen von Hochspannungsmaschinen

Essai de l'isolation des barres et des bobines des machines à haute tension

Test of insulation of bars and coils of high-voltage machines

General Information

• Status: Published
• Publication Date: 24-Mar-1998
• Withdrawal Date: 24-Sep-1998
• ICS: 29.080 - Insulation
• ICS: 29.160.10 - Components for rotating machines
• Technical Committee: CLC/TC 2 - Rotating machinery
• Drafting Committee: IEC/TC 2 - IEC_TC_2
• Parallel Committee: IEC/TC 2 - IEC_TC_2
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 09-Nov-2022
• Completion Date: 23-Sep-2025
• Ref Project: SIST EN 50209:1999 - Test of insulation of bars and coils of high-voltage machines

Overview

EN 50209:1998 (adopted as SIST EN 50209:1999 in Slovenia) is a CLC specification for the electrical insulation tests of bars and coils used in high‑voltage rotating machines. The standard covers machines with rated voltages (Un) from 5 kV to 24 kV inclusive and generally applies to machines with rated outputs from 5 MVA (and motors from 5 MW) upward. It also permits use for machines with outputs between 1 MVA (1 MW) and 5 MVA (5 MW) at prior agreement.

Key scope notes included in the standard:

• Requirements for machines with rated voltage above 24 kV are subject to individual agreement.
• For machines whose windings are cured in the stator, tests on separate winding elements may not be possible; in such cases Part B of the specification applies.
• The test of conductor lamination insulation must be performed in accordance with clause 23 of Part A.

This standard supports manufacturers, test laboratories and end users who need consistent criteria for dielectric performance and safety of high‑voltage machine windings.

Key Topics

• Scope and applicability: voltage and power ranges, special cases for cured stator windings.
• Test coverage: insulation of bars, coils and conductor lamination (referenced clauses and parts).
• Interfaces between parts: how Part A and Part B apply depending on winding construction.
• Agreement conditions: guidance for machines with ratings outside the standard limits.

These topics ensure clarity about when and how the standard should be applied, and what agreements are required for exceptions.

Applications

EN 50209 is valuable for:

• Manufacturers of large rotating electrical machines preparing factory acceptance tests.
• Test laboratories validating dielectric integrity of stator and rotor windings.
• Utilities and plant operators verifying insulation performance for high‑voltage generators and motors.
• Specification authors and procurement teams requiring compliant test criteria for machines in the 5–24 kV range.

Practical benefits include improved safety, reduced risk of insulation failure in service, and harmonized test procedures that facilitate cross‑border acceptance and conformity assessment.

Related Standards

• Part A and Part B of EN 50209 (referenced for specific test clauses and cured‑winding procedures).
• National adoptions such as SIST EN 50209:1999.

For implementation, users should consult the full EN 50209 document and any referenced clauses to ensure correct application of tests and to confirm whether individual agreement is required for machines outside the standard's default ratings.

Standards Content (Sample)

SLOVENSKI STANDARD
01-april-1999
Test of insulation of bars and coils of high-voltage machines
Test of insulation of bars and coils of high-voltage machines
Prüfung der Isolierung von Stäben und Spulen von Hochspannungsmaschinen
Essai de l'isolation des barres et des bobines des machines à haute tension
Ta slovenski standard je istoveten z: EN 50209:1998
ICS:
29.080.01 (OHNWULþQDL]RODFLMDQD Electrical insulation in
VSORãQR general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
...