The following was received via e-mail:
COMPONENT DESCRIPTION: AMETEK part number 80-315382-90, T801 main transformer.
PROBLEM YOU COULD SEE: Overheating and failure of transformers installed in equipment with 0.7 power factor load requirements
CAUSE: The inverters on AMETEK job number C72143 were required to support a 0.7 power factor load. To meet this requirement, CVT capacitors were added which led to overcurrent on the capacitor current windings and overheating. The overheating led to a breakdown in insulation between windings, causing a premature failure of the transformer set and inverter relative to its 40-year qualification life.
EFFECT ON SYSTEM PERFORMANCE: The overheating accelerates the degradation of the insulation between windings and eventually leads to shorting. This will cause an inverter failure and require the load to be transferred to bypass.
ACTION REQUIRED: This is the only instance AMETEK has experienced for this issue. Therefore, action is only required for the equipment on AMETEK job number C72143, located at TVA Sequoyah. New transformers have been provided as replacements that require fewer capacitors, contain additional venting to improve cooling, and include larger winding material to reduce current density. The main transformers (T801) installed in the serial numbers associated with this job (C72143-0111 through 0911) should be replaced to prevent any similar occurrences.
AMETEK SOLIDSTATE CONTROLS CORRECTIVE ACTION: AMETEK has enhanced this particular transformer design to improve cooling and reduce capacitor current. Additionally, corrective action #175 has been issued in AMETEK's system.
If you have any questions, please contact Mr. Mark Shreve of the Client Services group at 1- 800-222-9079 or 1-614-846-7500 ext. 6332. mark.shreve@ametek.com.
Sequoyah is the only site affected by this Part 21 Report.