Convertor Transformers - Part 1: Transformers for Industrial Applications
|Publication Date:||1 September 1997|
|ICS Code (Transformers. Reactors):||29.180|
This International Standard deals with the specification, design and testing of power transformers and reactors which are intended for integration within semiconductor convertor plants; it is not applicable to transformers designed for industrial or public distribution of a.c. power in general.
The scope of this standard is limited to applications of power convertors, of any power rating, for local distribution, at moderate rated convertor voltage, generally for industrial applications and typically with a highest voltage for equipment not exceeding 36 kV.
This standard is not applicable to transformers for HVDC power transmission. These are highvoltage transformers, and they are subjected to d.c. voltage tests.
The standards for the complete convertor plant (IEC 60146, or other publications dedicated to particular fields of application) may contain requirements of guarantees and tests (such as insulation, power loss) for the whole plant, including the convertor transformer and possibly auxiliary transformers and reactor equipment. This does not relieve the application of the requirements of this standard concerning the guarantees and tests applicable to the convertor transformer itself as a separate component before being assembled with the remainder of the convertor plant.
The guarantees, service and type tests defined in this standard apply equally to transformers supplied as part of an overall convertor package, or to those transformers ordered separately but for use with convertor equipment. Any supplementary guarantee or special verification has to be specifically agreed in the transformer contract.
The convertor transformers covered by this standard may be of the oil-immersed or dry-type design. Unless specific exceptions are stated in this standard, the transformers are required to comply with IEC 60076 for oil-immersed transformers, and with IEC 60726 for dry-type transformers.
1 For some convertor applications, it is possible to use common distribution transformers of standard design. The use of such standard transformers in the special convertor applications may require a certain derating. This matter is not specifically covered in this standard, which deals with the requirements to be placed on specially designed units. It is possible to estimate this derating from the formulae given in 5.1, and also from clause 9 of IEC 60076-8.
2 Where dry-type transformers are used, special care should be taken in considering the short time constants applicable and the increased eddy currents flowing in the larger cross-section conductors or foil windings.
This standard only deals with transformers with one active part and one interphase transformer. For several active parts in the same tank, an agreement between the purchaser and manufacturer is necessary regarding the determination and the measurement of the total losses.
This standard deals only with transformer star Y and delta Δ connections. For other connections an agreement between purchaser and manufacturer is necessary.