Service
Power transformer rewinding
Total or partial rewinding of high- and low-voltage windings, with conductor and insulation to the design specification, up to 230 MVA.
Rewinding replaces the windings of a power transformer — totally or partially — with conductor and insulation matched to the original design. It is the core of a major rehabilitation when windings have shorted turns, mechanical damage or end-of-life insulation, and TEVKO executes it up to 230 MVA on units of any manufacturer.
The windings are the heart of a transformer, and when they fail — shorted turns from insulation degradation, mechanical deformation after a through-fault, or simple end of life of the paper — a rewind restores the machine instead of scrapping it. The work is total when an entire winding is replaced, or partial when only the affected section is, always with conductor cross-section, number of turns and insulation matched to the original electrical design.
Done right, a rewind is precision work, not a patch. It requires reproducing the design exactly: the conductor type and dimensions, the turn count that sets the ratio, the insulation system and the clamping that withstands short-circuit forces. An incorrect rewind changes the transformer's behavior or fails again under stress, which is why the design data and the acceptance testing matter as much as the winding itself.
TEVKO rewinds power transformers up to 230 MVA, including the demanding shell-type (acorazado) construction, in its 5,600 m² plant with cranes, drying ovens and a test bench. Every rewind is dried, reassembled and validated with the full electrical protocol — turns ratio, winding resistance, power factor, SFRA — under IEEE C57 and IEC 60076, with Omicron and Megger instrumentation. TEVKO does not manufacture transformers; it returns the rewound unit to the performance the manufacturer specified, with a documented protocol.
Scope of rewinding
Total rewind
Full replacement of a winding with conductor, turns and insulation to design specification.
When it applies: Winding failure, widespread insulation end of life.
Partial rewind
Replacement of the affected section of a winding, preserving the sound part.
When it applies: Localized shorted turns or damage.
How we execute the rewind
Diagnosis & design data
Electrical diagnosis and recovery of the winding design (conductor, turns, insulation) before disassembly.
Winding
Total or partial rewind with conductor and insulation to specification, with controlled clamping.
Drying & reassembly
Drying of the active part and reassembly under controlled procedure.
Acceptance testing
Full electrical protocol (TTR, winding resistance, power factor, SFRA) before returning to service.
Frequently asked questions — power transformer rewinding
When does a transformer need rewinding?
When the windings have shorted turns from insulation degradation, mechanical deformation after a through-fault, or end-of-life paper insulation. A rewind restores the machine instead of replacing it, and is the core of a major rehabilitation.
What is the difference between a total and partial rewind?
A total rewind replaces an entire winding; a partial rewind replaces only the affected section. In both cases the conductor, turn count and insulation are matched to the original electrical design, and the result is validated by acceptance testing.
Up to what size does TEVKO rewind transformers?
Up to 230 MVA, including shell-type (acorazado) units, on transformers of any manufacturer. Each rewind is dried, reassembled and validated with the full electrical test protocol before returning to service.
How is a rewind validated?
With the full electrical protocol — turns ratio (TTR), winding resistance, power factor and SFRA — under IEEE C57 and IEC 60076, confirming the new winding has the correct ratio, connections and mechanical integrity before energizing.
Power transformer rewinding in images
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