7FH2 and 324 Model Generator Issues

AGTServices has repaired and rebuilt many 7FH2 and 324 model generators. Here is an image of a fully repaired, cleaned, painted, and thoroughly tested unit ready for return to service.

See pictures of repairs in the gallery below.

Also see our article on 7FH2 / 324 / 390H Core Looseness.

Stator Belly Bands and Keybar Rattle Mitigation

Since their first major outages, many 7FH2 and 324 model generator owners have suffered through changes in generator acoustic levels. Most attributed to keybar rattle. AGTServices has investigated and repaired many machines. Resolution ranges from simple belly band tightening during minor outages, to the addition of belly bands to further consolidate the core support system, eliminating keybar ratlle altogether.

Collector Terminal Stud Hydrogen Leaks

AGT Services experience in testing, inspecting and repairing 7FH2/324 generators has shown that virtually all of these machines eventually suffer from collector terminal stud seal leaks. This repair solution will help to prevent the potential of explosive H2 gas from leaking into the generator collector regions, which can result in a collector flashover event.

Endwinding Dusting

Since 2001, many owners have reported seeing dusting in the stator endwinding. The dusting has been reported on units as early as their first OEM recommended inspection. AGT Services experience in testing, inspecting and repairing these generators has allowed us to implement repairs to correct this dusting that make these machines better than new.

Stator Wedge Tightness

AGT Services recommends routine wedge tightness surveying to ensure proper wedge system performance. A loose wedge system, which is worsened if exposed to oil, permits stator bar movement. If coupled with a loose endwinding system, degradation can become even more rapid. High quality, high performance, and high thermal tolerance materials are used in all rewedge projects.

Ammortisseur Migration

AGT Services has developed an improved field amortisseur arrangement which eliminates the migration of spring and slot amortisseurs. The migration of these amortisseurs will eventually lead to blockage of the radial ventilation passages of the generator field. This coolant flow restriction may lead to thermal imbalance of the generator field, resulting in excessive field vibration levels and trips which follow.

7FH2 and 324 Model Generator Issues - Ammortisseur Migration
7FH2 and 324 Model Generator Issues - Collector System Degradation and Failure

Collector System Degradation/Failure

AGT Services has the parts and expertise to help maintain your collector systems health. To get best collector brush performance, brushes need to stay in contact with the ring. If they lose contact, the following can possibly happen: Foot Printing, Arcing, Accelerated Collector Ring Wear, Tracking, Reduced Brush Life, Selectivity, Brush Overheating and Burned Off Pigtails.

7FH2 and 324 Generator Repair Gallery

Below are before and after pictures of AGTService repairs.