Transformer Scrap/Repair Decision Software

Transformers come back to the shop or warehouse from the system for various reasons including failure, changes in loading, and line reconstruction. The decision whether to return the unit to inventory for reuse depends on many economic factors including the cost of repairs or refurbishment, the expected remaining life, loss levels compared to new units, cost of new units of the same size, installation costs, and utility economic parameters. Even where the returned unit is undamaged and physically ready to go back into the system, the economics can indicate that it might better be scrapped if its losses or the installation costs do not justify saving it.

TSRDS_flowchart.jpgDSTAR has developed a Transformer Scrap / Repair Decision Software to help make this decision.

The flow of the software decision-making process is shown to the right. The benefits and challenges of scrap/repair decision making process are summarized as below:

To scrap a transformer, the followings need to be concerned:

  • New First Cost
  • Disposal Cost
  • Load Loss
  • No-Load Loss
  • Life

To remove from service, the followings challenges present:

  • Failure
  • Over-/Under -loading
  • Line Upgrade
  • Line Reroute
  • Accidents (traffic)
  • Incidents (severe weather)

To repair a transformer, the following costs need to be considered.

  • Refurbish Cost
  • Disposal Cost
  • Load Loss
  • No-Load Loss
  • Remaining Life
  • (Ns) Years Later
  • New First Cost
  • Disposal Cost
  • Installation Cost (emergency)
  • Load Loss
  • No-Load Loss
  • Life

TS/RDS is designed to generate tables of maximum repair costs for transformers in the system which may come back into the shop. Maybe once a year, an engineer or technician will run the program. The table generated might indicate that a Brand X unit with a serial number in a certain range (indicating age, size, and loss parameters) has a maximum justified repair cost of $150. When the shop receives such a unit with only a cracked bushing, and checks the table, the shop would go ahead and repair the unit. If the unit needs a rewind, then it would go to scrap.

TSRDS_chart.jpg

TSRDS was created, modified, enhanced in the following projects: P7-3