TEVKO
Overhead crane lifting a transformer cover inside the workshop bay, with technicians guiding the lift from a ladder

Service

Shell-type (acorazado) transformer repair

Repair and rehabilitation of shell-type power transformers and their tap changers, subject to workshop feasibility by weight, dimensions and process — scope confirmed for each asset.

Overhead crane lifting a transformer cover inside the workshop bay, with technicians guiding the lift from a ladder
What the photo showsOverhead crane lifting a transformer cover inside the workshop bay, with technicians guiding the lift from a ladder.

TEVKO repairs and rehabilitates shell-type (acorazado) power transformers subject to workshop feasibility by weight, dimensions and process — including rewinding, core and insulation work and tap-changer repair. The shell-type construction is harder to service than column-type, so scope and handling resources must be confirmed for each asset.

In a shell-type (acorazado) transformer the magnetic core surrounds the windings, rather than the windings surrounding the core as in column-type units. That geometry gives excellent mechanical strength against short-circuit forces — which is why it is common in large, heavily-stressed transformers — but it also makes the active part far more demanding to access and repair. Disassembling, rewinding and reassembling a shell-type unit correctly requires specific experience that most service shops simply do not have.

TEVKO repairs shell-type transformers subject to workshop feasibility by weight, dimensions and process across the full scope: total or partial rewinding of high- and low-voltage windings with conductor and insulation to the design specification, magnetic core repair, insulation restoration, and repair of the tap changer. As an independent, multi-brand service provider, TEVKO works on shell-type units of any manufacturer — the repair is driven by the asset's condition and design, not by an OEM tie.

Every shell-type repair is executed under the applicable standards (IEEE C57, IEC 60076) and validated with the full electrical test protocol — turns ratio, winding resistance, power factor, SFRA — with Omicron and Megger instrumentation, in TEVKO's 5,600 m² plant equipped with 60-ton cranes, drying ovens and a test bench. TEVKO does not manufacture transformers: it returns your shell-type unit to the performance the manufacturer specified, with real electrical data and a documented protocol.

Scope of shell-type repair

Rewinding

Total or partial rewinding of HV/LV windings with conductor and insulation to design specification.

When it applies: Shorted turns, winding failure or insulation end of life.

Core & insulation

Magnetic core repair and insulation restoration of the shell-type active part.

When it applies: Core defects, contamination or post-fault damage.

Tap-changer repair

Repair of the tap changer of shell-type units (contacts, mechanism, oil).

When it applies: Tap-changer faults found in diagnostics.

How we execute the repair

Diagnosis

Full electrical and oil diagnosis to locate and size the damage before disassembly.

Disassembly

Controlled disassembly of the shell-type active part in the plant, with the unit documented at every step.

Repair

Rewinding, core/insulation work and tap-changer repair to design specification, with drying.

Acceptance testing

Full electrical protocol (TTR, winding resistance, power factor, SFRA) before returning to service.

Frequently asked questions — shell-type (acorazado) transformer repair

What is a shell-type (acorazado) transformer?

One in which the magnetic core surrounds the windings, rather than the windings surrounding the core (column-type). The geometry gives strong resistance to short-circuit forces, common in large transformers, but makes the active part much harder to access and repair.

Why are shell-type transformers harder to repair?

Because the core surrounds the windings, disassembling, rewinding and reassembling the active part correctly requires specific experience and equipment that most shops lack. Few shops in Mexico and Latin America can execute a shell-type repair.

Up to what size does TEVKO repair shell-type transformers?

The scope is confirmed by weight, dimensions, handling and process. It may include rewinding, core, insulation and tap-changer work, with agreed acceptance tests.

Does TEVKO manufacture transformers?

No. TEVKO is an independent, multi-brand service provider: it repairs, rehabilitates, diagnoses and tests transformers and substations — including shell-type units — but does not manufacture them.

Shell-type (acorazado) transformer repair in images

Workshop interior with transformers and overhead cranes.
Workshop interior with transformers and overhead cranes.
Core-and-coil assembly lifted by crane inside the workshop bay, in black and white
Core-and-coil assembly lifted by crane inside the workshop bay, in black and white
Power transformer with its conservator tank and radiators, with technicians working on the cover and at the base
Power transformer with its conservator tank and radiators, with technicians working on the cover and at the base

Related services and articles

Talk to a transformer specialist

Tell us about your asset so we can define the assessment scope and prepare a tailored quote.

Get a quoteEmergency