ALTERREX™ Excitation Retrofit and Refurbishment Products

ALTERREX Excitation Systems

A Wide Range of Products to Maintain and Modernize the GE ALTERREX Excitation System

Choose from a portfolio of retrofit options including voltage regulators, stationary diode bridge services and replacement products, and conversion of the ALTERREX system to a full static configuration.
 
Overview

ALTERREX excitation systems were supplied for large steam turbine-generators between 1965 and 1992. Excitation power for these systems is supplied by a shaft-driven alternator-exciter with a stationary armature and rotating field. The alternator output is rectified by a set of stationary diode bridges and then applied to the main generator field. Today, these systems exhibit the same characteristics as any aging control system with parts availability, service availability, increased maintenance and limited data access for operations and maintenance. In addition, the AC generators still require maintenance of the commutator and brush rigging along with balancing, bearings and cooling systems.

Control Platform

Diode Bridge Refurbishment

Product Description
A customizable maintenance product to address cooling water leaks in the power diode bridge assemblies and grounds due to copper and copper-oxide deposits in the tubes (see GE TIL 1027). The diode bridge cabinets are removed sent to a GE facility for service during a scheduled outage. The program provides maintenance for:
  • Brass fittings and brazes
  • Heat sinks
  • Copper tubing
  • Isolation valves
  • Enunciating lights
  • Bridge disconnect switches
  • Rust and corrosion
The entire bridge assembly is reconditioned and re-tested to the original factory electrical and hydraulic specifications.
Value

When coupled with a pre-service engineering assessment and expert removal, installation and re-commissioning services, the diode bridge refurbishment program greatly reduces maintenance issues and extends the reliable life of the system.

Diode Bridge Replacement

Product Description
A new, liquid cooled drop-in rectifier bridge is custom designed for replacement of the original bridge and mounting in the existing cubicle. The retrofit includes new bridges, stainless steel manifolds and valves, replacement enunciation panels, replacement wiring harnesses and a modular system relay interface. Features of new bridge:
  • A single stainless and aluminum head sink
  • Smart-simple design
  • High-quality valves and fittings
  • Easy to repair with accessible components

    • Value
    • Eliminated all copper piping
    • Eliminates TIL-1027 maintenance requirements
    • Reliable bridge diagnostics (improved with EX2100 ALTERREX Voltage Regulator)
    • Minimum installation time
    Services

    GE provides a variety of service offerings to support the diode bridge replacement product. The diode cabinets can be removed from the ALTERREX dog-house and shipped to a GE service facility for a full cabinet refurbishment. The new bridges, manifolds, enunciation panels and wiring is completed along with your choice of bus, switch and cabinet refurbishment scopes, virtually resetting the hardware life cycle clock during a single outage.

    The replacement system can also be completed by the GE team on the customer site, or purchased as kits for customer installation with optional GE technical direction.

    Voltage Regulators and Full Static Retrofits

    Voltage Regulators – The EX2100 is available for ALTERREX voltage regulator applications as a fully redundant
    system. A voltage regulator upgrade provides the improved reliability and flexibility of a new, advanced digital control, but at a cost that can be better suited to some customer needs.

    Full Static Retrofits – The EX2100 multi-bridge excitation retrofit represents a complete modernization of the excitation system. Fully digital control, high performance power electronics and elimination of the rotating ALTERREX alternator and diode banks improve system response and reliability while reducing maintenance. A GE Static Retrofit goes well beyond the power electronics, with full lateral and tortional analytical and test capabilities to insure the full turbine-generator train performance once the alternator is removed.

    GE specializes in the modernization of large steam turbine generator excitation systems, with expertise in the application and installation of the large power potential transformers, bus and the engineering to bring it all together.
    Value
    Whether choosing a voltage regulator only or full static conversion, an EX2100 retrofit improves performance by eliminating the old analog controls with their inherent thermal drift and electro-mechanical components, such as motor operated setpoint adjusters. Powerful system diagnostics, clear alarm messages and modern software maintenance tools reduce roubleshooting time and support on-line repair capabilities. Advanced features, such as power system stabilizer, trending and oscillography are available in software. New static exciters provide high initial response exceeding IEEE-421 and eliminate the maintenance and reliability concerns of the water cooled diodes and rotating generator. Comprehensive engineering design packages help ensure seamless integration with the existing plant systems, and expert mechanical assessments of the generator modifications alleviate lateral and torsional concerns post retrofit. All installed, commissioned and backed by GE.

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