Electronics Thermal Derating Life Calculator

Exponentially: each 10 K above the 40 °C reference halves expected life, and each 10 K below roughly doubles it (the 10-degree Arrhenius rule-of-thumb for electronics dominated by electrolytic capacitors and similar temperature-driven mechanisms). A sustained 20 K overshoot quarters the life — which is why a 'small' cooling problem is never small over the years.

By the temperature delta you need and the environment's dust/oil load: filter fans only bring panel air toward room temperature (good when the room is decent and air is clean-ish), while heat exchangers and AC units pull below ambient and seal the panel (mandatory in washdown, dusty or hot rooms). Compute the panel heat load (sum component dissipation), target ≤10 K over a sane room temperature, and let this calculator price the life difference each option buys — AC routinely pays for itself in avoided drive/PSU deaths alone.

It is the engineering linearisation of the Arrhenius equation over the normal operating window, adopted by the relevant standards because it matches test data well within ±20–30 °C of the reference. Far outside that window (or where a different failure mechanism takes over, e.g. mechanical wear) the rule loses authority — treat extreme extrapolations as indicative only.

The hot-spot (the hottest point of the insulation/material), because chemistry happens at the hottest spot. If you can only measure surface or ambient, add the typical rise for your equipment class — datasheets usually state hot-spot rise over ambient at rated load — and remember intermittent peaks age the asset during the peak hours, not the average.