Industrial Cybersecurity & OT Risk worked example

PLC Recovery Time at 25% validation and restart allowance: a worked example

This worked example runs the plc recovery time numbers for a tougher week than the baseline: 25% validation and restart allowance instead of the typical 35%. Estimate PLC recovery effort using controller count, recovery completion rate, and allowance for validation and restart checks.

The inputs for this scenario

  • PLCs or controller projects to recover: 12 controllers (held at the documented default)
  • PLC recovery completion rate: 0.8 controllers / hr (held at the documented default)
  • Validation and restart allowance: 25 % (the input this scenario stresses; the baseline uses 35)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base PLC recovery time = PLCs or controller projects to recover รท PLC recovery completion rate.
  • Required PLC recovery time works out to 18.75 hr at these inputs, and this is the headline figure for the scenario.
  • Base PLC recovery time works out to 15 hr at these inputs.
  • Validation and restart allowance works out to 25 % at these inputs.
  • PLC recovery completion rate works out to 0.8 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where validation and restart allowance sits at 35% and the headline result is 20.25 hr, this scenario comes in 7.41% below the baseline at 18.75 hr.
  • Use it when building or stress-testing an OT recovery plan, sizing a restoration crew, or setting a controller RTO. 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

  • Required PLC recovery time: 18.75 hr (headline result)
  • Base PLC recovery time: 15 hr
  • Validation and restart allowance: 25 %
  • PLC recovery completion rate: 0.8 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live PLC Recovery Time calculator, set validation and restart allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.