Power Electronics, Motors & Drives worked example

Drive Warranty Reserve at 58% expected warranty claim rate: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop expected warranty claim rate to 58%, then walk the calculation through step by step. Estimate warranty reserve for drives, inverters, or converters from installed population, expected claim cost, occurrence share, and fixed support cost.

The inputs for this scenario

  • Drives in service under warranty: 100 drives (held at the documented default)
  • Expected warranty claim cost per drive: 45 $ / drive (held at the documented default)
  • Expected warranty claim rate: 58 % (the input this scenario stresses; the baseline uses 80)
  • Fixed warranty program support cost: 250 $ (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Variable drive warranty reserve = drive population in service × expected warranty cost per drive × expected warranty occurrence.
  • Total drive warranty reserve works out to 2,860 $ at these inputs, and this is the headline figure for the scenario.
  • Warranty reserve per shipped drive works out to 28.6 $ / piece at these inputs.
  • Variable drive warranty reserve works out to 2,610 $ at these inputs.
  • Fixed warranty support cost works out to 250 $ at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where expected warranty claim rate sits at 80% and the headline result is 3,850 $, this scenario comes in 25.71% below the baseline at 2,860 $.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to expected warranty claim rate, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It uses a single average claim rate and cost; a batch defect or an aging fleet with rising failure rates will need a higher reserve than this linear model shows.

Results at a glance

  • Total drive warranty reserve: 2,860 $ (headline result)
  • Warranty reserve per shipped drive: 28.6 $ / piece
  • Variable drive warranty reserve: 2,610 $
  • Fixed warranty support cost: 250 $

Run it with your numbers

  • To rerun this with your own numbers, open the live Drive Warranty Reserve calculator, set expected warranty claim rate to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.