National Electric Coil (NEC) services

Hydrogenerators and other salient pole machines consist of a rotating spider mounted on a shaft with field poles mounted on the spider rim. We have manufactured new field poles for more than a dozen units whose frequency was increased from 25 cycles to 60 cycles, as well as cases where pole laminations were damaged in some way. We have also repaired casting cracks in older rotors, and we have made modifications to rotor rims and pole key assemblies to allow more pole weight and resolve distortion and re-fit issues. Because of the long lead time required to fabricated replacement rotors, our ability to fully rehabilitate these rotors can benefit your project budget and schedule.

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.

National Electric Coil has developed proven solutions for a number of generic design issues discussed in various OEM TILs and OMMs. These problems can be unique to machines of a certain age or to those made by specific OEMs.

In the hands of the inexperienced, brushless exciters appear deceptively simple. The real expert will not fail to recognize their innate complexity. Indeed, the design of the brushless exciter – with its many rotating and high-voltage component parts – is often at the root of the most common failure modes. Age, contamination and stress are the triple enemies of reliable operation of rotating brushless exciters. NEC`s exciter rewind and maintenance programs assign the highest priorities to schedule and customer service. Our engineers and electromechanical technicians have extensive experience with all standard exciter failure modes and maintenance requirements. NEC manufactures replacement armature coils, leads and other electrical parts. Whether a complete refurbishment, including rewind, as shown in the picture above, or a maintenance overhaul and cleaning, NEC`s goal is to get your machine back in operation expeditiously.

Outages are major events at any power plant. Our full range of services are designed to anticipate any generator outage need, from inspections, testing, and basic cleaning to troubleshooting failures, to complete generator overhauls. Large or small, your outage is important to us!