Core Looseness in GE 7FH2 / 324 / 390H Models

7fh2 core looseness
7FH2 Core Failure

7FH2 Core Looseness

Deal with core looseness before it costs you downtime and expensive repairs.

In addition to generator testing and inspection, AGTServices provides the material and expertise to inspect and mitigate failure due to loose stator core iron.

Core Failures

AGTServices experience in testing, inspecting and repairing large air and hydrogen cooled generators has shown that as this fleet of machines continue to age, coupled with major increases in cyclic duty demands, is resulting in several instances of very expensive and long scheduled repairs, as well as unplanned additional work during planned outages, all due to loose core laminations, loss of core iron “pieces” and stator/core winding failure. Let AGTServices assess your GT and/or ST generator stator core and perform tightening sequences, before this issue takes your unit offline…for a while! We can fix those that have already failed, too!

AGTServices Loose Core Assessment

  • Whether it’s a field-in “minor” (using AGTServices Robotic Inspection Vehicle) or a field-out “major”, we can perform the full range of stator and field testing, inspections and all repairs
  • Perform visual inspection and "knife check" for mechanical illustration of core loosening
  • Perform keybar nut torque checks - too low a torque value means a loose core!
  • Since the majority of all of this fleet of units fail one/all of the above assessments, we arrive prepared to perform a full stator keybar nut retorque - 3000 ft-lbs is the target! Less is insufficient no matter who is telling you!!!
  • Core tightening is the BEST performed with stator wedges out and belly bands loosened!
  • If rewedging, ONLY use Low Shrink Black Canvas or G11, TRS and Tapered Slides!
    • Or you'll be rewedging again in 5-10 years!
  • Certain 7FH2's built by MHI are more prone to core iron failure / core looseness - at least 4 stator rewinds (with partial restacks or repairs in 2020 alone!!)
  • Larger GT and ST driven 324/390H models are susceptible to Outside Spaceblock Migration, where iron migrates radially inward, penetrating bottom bar insulation! Contact AGTServices for those specialized repairs and mitigations!
GE 7fh2 core failure
Mitsubishi Built 7fh2

AGTServices has the capability and knowedge to perform all the 7FH2/324/390H repair recommendations listed above.