Distribution Transformer Technical Specification Guide
A good specification prevents misunderstandings between what the buyer expects and what the manufacturer builds. This guide lists the clauses that matter and the ones most often missing.
Use it as a checklist when writing or reviewing a transformer specification.
A good specification prevents misunderstandings between what the buyer expects and what the manufacturer builds. This guide lists the clauses that matter and the ones most often missing.
Use it as a checklist when writing or reviewing a transformer specification.
Scope and standards
State the applicable standard (IEC 60076 or IEEE C57.12), the type and number of units, and any national or utility requirements that override the base standard.
Electrical parameters
Rated power; primary and secondary voltage; frequency; phase; vector group; impedance; tapping range; insulation level; winding material; cooling class; and neutral arrangement.
Service conditions
Ambient temperature range, altitude, humidity, pollution degree, indoor or outdoor installation, enclosure IP rating and any corrosive or dusty conditions. These affect de-rating, creepage distances and finishes.
Losses and efficiency
Specify maximum guaranteed no-load and load loss values, or require compliance with a minimum energy performance standard. State the reference temperature and the applicable tolerances.
Construction and accessories
Oil immersed or dry type; cooling and fan arrangements; bushings and cable boxes with entry direction; monitoring devices; protection accessories; painting and corrosion protection; and the nameplate language.
Testing and inspection
Routine tests to be performed, type tests required, witness testing arrangements, and the format and language of test reports.
Documentation and delivery
Datasheets, GA drawings, wiring diagrams, test reports, manuals, certificates, spare parts list, packing and marking requirements, and Incoterms.
Clauses most often forgotten
Site access limits. Door widths, lift capacity, weight restrictions
Noise limit. Maximum dB(A) at a defined distance
Cable entry direction. Top or bottom, and gland plate details
Spare parts. Which spares are supplied and which are recommended
Training. Whether installation or maintenance training is required
Frequently Asked Questions
Related Products, Applications and Support
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