Modernization and Repowering of Generators

Redesign for power increase of existing un

As insulation materials have been developed, with better dielectric properties, it has become possible to reduce the wall thickness of the insulation. Thus, in older generators to which it is desired to change windings, it is possible to increase the section of the copper conductor and achieve a power increase or a reduction of temperature.

Maintenance, Assembly of Windings and Repair in Factory or Site


Rehabilitation of winding fastening systems, including: cleaning; Change of wedges, spacers, moorings and retaining rings; Withdrawal, evaluation, substitution, rearrangement and assembly of coils in stator windings; Application of semiconductor material paints and tapes to rehabilitate electric field grading systems; Change of insulation and, if necessary, coils and field windings in rotors of smooth and protruding poles; Minor minor repairs on stator cores; And modification of insulation design to increase efficiency and, if possible, generator power.

Repair of cores and parts manufacturing

In the event of further damage to stator cores, GENERMEX offers the supply and installation of laminating packages or complete cores to replace packages or cores damaged by electrical or mechanical faults. This includes internal laminations, external laminations with welded “I” rods, pressing fingers, pressure plates and any other components that are necessary to recover or improve the clamping conditions, tightening and original magnetic characteristics of the core

Rehabilitation of Rotors

In smooth pole rotors, GENERMEX offers the removal and placement of retaining rings (bells), the cleaning and surface rehabilitation of coil heads, the change of separators, and in case the retaining rings are damaged or in case of GENERMEX offers the supply and installation of retaining rings, fans and fittings or special parts of the rotor.

In outgoing pole rotors, GENERMEX offers poles re-polishing and manufacturing and, if necessary, the supply of “V” blocks separating polar reels.

In both types of rotors, GENERMEX offers the execution of electrical, mechanical, non-destructive tests to the exposed parts of the rotor, as well as the execution of minor works such as polishing of slip rings and stumps, rectification of labyrinths of lubrication or seal, and The replacement of components such as slip rings, diodes, power supply lines to the field and dynamic balancing at low speed.

Stator Rewinding

The rewinding of generator stators consists of the removal of the exhausted or failed winding and the installation of a new winding. The design of the new coils includes the application of new materials in such a way that, if the original design allows, the generator has greater capacity or works cooler and thus extends its life expectancy. Before installing the new winding, the state of the interlaminar insulation of the stator core and the tightening torque of the lamination fastening systems is rated. It is not advisable to install a new winding, whose life expectancy exceeds 30 years, in a core whose life expectancy is lower. The rewinding includes the analysis and implantation, change of wedges, flat and corrugated fillings, separators, rings and all the materials of assembly, using the most modern ones. Particular care is taken to ensure that no part of the coils or connections can vibrate and wear insulation or electric field relief and graduation structures.

Diagnosis of Generator and Motor Windings by Visual Inspection and Electrical Testing

Of all the techniques used to determine the condition of a rotary electric machine, none is as revealing as a thorough visual inspection by experienced personnel. GENERMEX has extensive experience and specialized human resources to perform visual inspections on generators.

To diagnose the condition of parts and assemblies of a generator, it is necessary to supplement the visual observations and the operating experiences, with results of the following electrical and mechanical tests, offered by GENERMEX.

Electrical testing

  • Insulation resistance
  • Polarization index
  • Resistance ohmic to windings
  • Power factor and “Tip-Up” to windings
  • Partial discharge to windings
  • Rotation Impedance
  • Voltage balance at rotor poles
  • Detection of hot spots in stator laminations.

The test known as “ELCID” (Electromagnetic Core Imperfection Detection) allows us to evaluate the state of the interlaminar insulation of the stator core. This test uses little energy and is very effective.
If necessary, it is possible to perform a test that requires high energy and is known as Toroid.

Mechanical Testing

Perpendicularity, concentricity and circularity of couplings Concentration, circularity and cone knowledge
Perpendicularity, concentricity, circularity, conicity, smoothness and groove depth of collector rings.

Operational Condition Diagnostics

The test results allow us to know the state of the insulation in stator, rotor and core coils; Semiconductor structures that alleviate and graduate electric field efforts; The systems of subjection of the windings that avoid their vibration and wear; Ventilation and cooling systems; Electrical connections and contacts; And laminations of electromagnetic cores, among other components of the generator. With these results we can decide if a generator is in conditions of safe and reliable operation.


GENERMEX, offers a Course on Power Generators, oriented towards the maintenance of such equipment. The Course is divided into Modules, each of which can be taught in one or more sessions, depending on the needs and possibilities of the interested staff.

This course seeks to identify and assimilate the technological knowledge associated with the generators that our customers operate and maintain. This will help them improve their continuity, reliability, safety, and cost ratios.

The content of the Course can be synthesized in four areas of specialty:

1) Generator Design and Construction
2) Efforts in its parts and materials, derived from the particular characteristics of its actual operation
3) Qualifying Tests and Acceptance Values
4) Proven actions to extend the life of such equipment.