Transformers, Coils & Magnetics Manufacturing worked example

Thermal Rise Margin with measured allowable temperature rise of 63 units: a worked example

This worked example runs the thermal rise margin numbers for a tougher week than the baseline: measured allowable temperature rise of 63 units instead of the typical 125 units. Thermal rise margin measures the headroom between a transformer or coil's allowable temperature rise and its actual measured rise, expressed against an insulation-class reference.

The inputs for this scenario

  • Measured allowable temperature rise: 63 units (the input this scenario stresses; the baseline uses 125)
  • Actual measured temperature rise: 100 units (held at the documented default)
  • Insulation-class rise limit (reference): 100 units (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Thermal Rise Margin margin = available value - required value.
  • Margin works out to -37 % at these inputs, and this is the headline figure for the scenario.
  • Absolute margin works out to -37 value at these inputs.
  • Available amount works out to 63 value at these inputs.
  • Required amount works out to 100 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where measured allowable temperature rise sits at 125 units and the headline result is 25 %, this scenario comes in 248% below the baseline at -37 %.
  • Use it after a heat-run or resistance-rise test to verify a design sits safely within its insulation class or overload spec. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Margin: -37 % (headline result)
  • Absolute margin: -37 value
  • Available amount: 63 value
  • Required amount: 100 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Thermal Rise Margin calculator, set measured allowable temperature rise to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.