AIR COOLED TURBOGENERATORS


Air-cooled turbogenerators provide a modern, highly compact solution for:

  • base and peak load operation
  • daily startup and shutdown
  • easy low cost maintenance


A range of models offering high efficiency, excellent quality and optimum reliability are available to meet turbine requirements. The reduced impact of auxiliary systems simplifies unit management and cuts the cost of spare parts.

 


Design features and manufacture
 

Ansaldo Energia air cooled generator technology is continuously upgraded and enhanced by dedicated R&D work and new design tools, including finite element 3D analysis of mechanical, electrical and fluid behavior.
Turbogenerators have indirectly cooled stator windings and directly cooled rotor windings and are self-ventilated in a closed circuit with air to water coolers.
Special make-up or active-carbon filters can be provided if needed (e.g. air contamination).


Stator

The stator comprises the two horizontally split frame sections bolted together, the assembled stator core and the winding. Splitting the frame into sections speeds up generator delivery and facilitates stator erection and maintenance operations.
The core is cooled by air passing through radial ducts between lamination packets.

The self-supporting stator core is assembled and welded to the lower part of the housing in such a way as to permit thermal expansion and core vibration without transmission to the foundation. The stator has a two-layer transposed bar winding insulated with class F mica paper on glass-fibre tape (resin rich insulation system).
Bars are firmly braced in the slots by means of epoxy-glass slot wedges and a ripple spring to prevent loosening after long service.


Rotor

The rotor body is machined from a single alloy steel forging with excellent magnetic and mechanical properties. Forgings are purchased only from qualified suppliers and comprehensively inspected by sampling and ultrasonic testing.

The rotor winding consists of hollow rectangular conductors made of hard-drawn copper alloyed with silver to increase strength at operating temperature. The rotor winding can expand uniformly lengthwise to ensure smooth running and minimum sensitivity to rapid load changes. All the insulation materials used in the rotor comply with class F specifications.
The rotor surface is protected against circulating currents caused by unbalanced loads through special high conductivity wedges and short circuit rings under retaining rings.
The retaining rings hold the rotor end winding in place.
The rotor is supported by two bearings with white metal bushes carried in bearing pedestals.
 

Diagnostics
 

Ansaldo Energia introduced diagnostics for air cooled turbogenerators in order to monitor the unit’s “Life Parameters”.
Ansaldo Energia turbogenerators have a dedicated sensor package complete with various instruments to collect data, depending on customer requirements, e.g. on line, continuous, connected to distributed control system (DCS), remotable.

 

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