Rotating Equipment Service Center

NEC's RESC offers comprehensive services for turbogenerator rotors and rotating exciters, as well as for salient pole rotors.

Wind Rotor Serving the entire power generation sector — utilities, cogenerators, refineries, paper mills and other industries — NEC can handle rotor problems, large or small. We've seen a full range of failure modes or near-failure conditions for machines of almost every make and model. Our engineers and technicians can diagnose a full range of problems, electrical or mechanical. They are skilled in dealing with rotors with shorts, grounds, or coil damage. Repairing damage to rotor forgings or retaining rings is a particular specialty. Our full machine shop capabilities make it possible for us to design and manufacture a replacement for almost any rotor component.  Our ISO 9001:2008-certified quality management system and our premier balancing facility make NEC one of the top specialists for turbogenerator rotors in the USA.

With no loyalty to a particular machine design, our engineers can look instead to a wide range of makes and models to analyze which design solutions have worked effectively and which have not. This broader perspective can provide you with a more innovative and cost-effective approach to your rotor repair. When we do a complete evaluation of your rotor, we also recommend repairs to correct problems and prevent them from occurring in the future.

High-Speed Balancing & Running Electrical Testing

Balance Pit Features

  • Ability to accommodate rotors up to 45 feet long
  • 30-, 50- and 85-ton cranes for pit service
  • Rail-guided transport dollies for the larger rotors above crane capacity, up to 100 tons
  • Large inventory of bearings and stub shafts to fit nearly every rotor
  • SCR Digital Drive System and 4000 HP drive train motor
  • System redundancies and 24/7 availability
  • Proven track record balancing large three-bearing rotors, as well as, exciter assemblies, salient pole rotors and other rotating electrical apparatus

Testing Capabilities

  • Overspeed testing at rotations up to 3960 RPM
  • Running electrical tests for Insulation Resistance, Impedance and Flux Probe
  • Rotor Thermal Sensitivity Testing, including performing Heat Runs and locating Running Shorts
  • Absolute Vibration Monitoring System for detection of shaft vibration, as well as seismic probes for bearing and pedestals

Salient Pole Rotor Balancing

Wind Rotor Salient pole rotors may also need balancing, especially after repairs and refurbishments. NEC has shaft extensions, pedestals (photo, right) and other accommodations, that it makes in its balance pit to make sure changes made to the rotor do not adversely affect spider balance. Balancing takes place with the poles installed.

Stator End-Winding Support Systems
NEC has the ability to engineer and retrofit major machine components, such as the end winding support system, for units experiencing problems related to their original designs. View this Case Study.
Overhaul of a Hydrogen-Cooled Exciter
Exciters of this size are rare in the industry. NEC's RESC performed extensive refurbishment and repair to all components of this exciter, including the manufacture and installation of a new armature winding. View More about this project.
Re-qualifying Hydro Spider
A number of rotor mechanical issues should be considered and analyzed when a hydrogenerator stator winding is uprated. Bill Moore's article, Advances in Hydrogenerator Refurbishment provides a case study for a hydro spider forging that was repaired and re-qualified for return to service at our RESC.