Hydro power generation

When reconditioning/rewinding an alternator group in a hydro power plant, mechanical and electrical constraints prohibit major changes to the original designs.  However, new materials and technologies allow for upgrades within the old shell.  Such upgrades have many advantages: they improve the unit’s output performance and its overall uptime but most of all, they can be performed in a much shorter time, putting the unit online quickly because they don’t require major civil engineering design.

Motion Electric Motor Services is a key partner when it comes to renovating/refurbishing alternator groups in a hydro power generation station.  With our decades of experience, we offer a complete service,including redesign, rewinding and refurbishment.  We manufacture our own VPI or B-Stage coils in-house, own a 16-feet VPI tank and have teams of engineers and on-site winders.  Covering all aspects of a hydro power generation station overhaul enables Motion Electric Motor Services to dramatically reduce lead time.  Taking care of the entire unit; rotor, stator and exciter ensures a precise fit of all refurbished components, reducing the installation time as well.

We offer specialized services to hydro power generation stations of all sizes:

  • Large hydro power generation stations
  • Small hydro power generation stations
  • Micro hydro power generation stations


Conversion of a DC exciter to a brushless exciter offers many advantages aside from the obvious savings in maintenance time due to the removal of the DC commutation system and thus, increased machine availability.

In fact, this patented process will re-use the same carcass, eliminating the need for long and costly structural evaluation and civil works.  The windings of the exciter’s stator and rotor are completely redesigned to function with a diode bridge instead of carbon brushes and a commutator.  The shunt breaker is also removed.

Since every exciter has its own specific challenges, the entire engineering process is provided by Motion Electric Motor Services’ experienced team and is performed completely in-house.

A conversion to a brushless exciter should always be considered when refurbishing a small hydro power generation station as it has many advantages:

  • No more conductive carbon dust contamination
  • Significantly less maintenance
  • Use of the original carcass
  • Same weight constraint on the main shaft
  • Same response time on the grid
  • New current regulator



  • Commutator removal
  • Complete restack & rewind
  • VPI insulation
  • Installation of brushless excitation (diodes)


  • Complete unit rewind, on-site or in-shop
  • In-house coil manufacturing
    • VPI diamond coils
    • B-Stage coils
    • Push Through coils
    • Robel bars (transposition bars)
  • Magnetic wedge replacement
  • Power increase and complete generator upgrades
  • Winding conversion from push through coils to diamond coils
  • DC commutation cleaning
  • Brush replacement
  • On-site predictive electrical tests
  • On-site predictive mechanical tests
  • On-site re-wedging