Microgrid & Distributed Energy Equipment worked example

Protection Relay Test Capacity at 99% test bench uptime: a worked example

What does the result look like when test bench uptime reaches 99%? The full calculation is worked below with real intermediate numbers. Use it when a protection relay test bench is asked to absorb more microgrid and distributed energy work and you need to know whether there is room.

The inputs for this scenario

  • Relays tested per cycle: 4 relays / cycle (unchanged)
  • Available test cycles: 480 cycles (unchanged)
  • Test bench uptime: 99 % (raised for this scenario; the documented default is 90)
  • First-pass test yield: 97 % (unchanged)

Working through the calculation

  • Applying the documented formula (Gross protection relay test capacity = relays tested per cycle × available test cycles) to the inputs above produces each figure below.
  • At this operating point the engine returns 1,844 relays for good protection relay test capacity, the number this scenario is built around.
  • At this operating point the engine returns 1,920 relays for gross protection relay test capacity.
  • At this operating point the engine returns 19.2 relays for protection relay test capacity downtime loss.
  • At this operating point the engine returns 57.02 relays for protection relay test capacity yield loss.

How this compares with the baseline

  • Against the tool's baseline example, where test bench uptime sits at 90% and the headline result is 1,676 relays, this scenario comes in 10% above the baseline at 1,844 relays.
  • A figure at this level is achievable when test bench uptime is genuinely sustained, not just peaked for a shift. It assumes a constant relays-per-cycle rate and one yield figure; mixed relay families with very different test sequences, or re-test loops that recover failures, will distort the good-capacity number.

Results at a glance

  • Good protection relay test capacity: 1,844 relays (headline result)
  • Gross protection relay test capacity: 1,920 relays
  • Protection relay test capacity downtime loss: 19.2 relays
  • Protection relay test capacity yield loss: 57.02 relays

Run it with your numbers

  • Every input above is editable in the live Protection Relay Test Capacity calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.