Pump Controller Protection Design: Dry-Run, Over-Current, and Restart Decisions

Prepared by the Sankey Engineering Team. Updated August 21, 2026.

Pump controllers protect a rotating system whose load can change with fluid, plumbing, installation, and maintenance. Dry-run and over-current decisions therefore need an application-specific evidence plan. This guide is prepared by the Sankey Engineering Team to help OEM teams define the logic and verification boundary before release.

Describe the hydraulic and electrical cases

List normal flow, restricted flow, blocked or stalled conditions, priming or dry-run risk, starts after rest, supply variation, and expected duty cycle. Identify which cases are confirmed requirements and which are engineering investigations.

Use the approved pump, motor, fluid, and installation representation. A current trace on a bench may not distinguish all hydraulic conditions in the finished product.

Define protection responses

For each protection, state the observable trigger, controller response, user or service indication, reset path, and retest condition. Possible responses include limiting output, stopping, latching, or controlled retry, but the responsible product team must approve the behaviour.

Do not publish a universal current or time threshold. Component limits, motor data, fluid, ambient, and target-market requirements determine the appropriate values.

Validate restart and recovery

Test recovery after a normal stop, supply interruption, cleared fault, and approved dry-run or blocked-load event. Confirm whether automatic restart is allowed and what state the user sees.

Record the number of attempts or timing rules only when they are part of the approved specification. Recovery must leave the appliance in a safe, understandable state.

Connect firmware to production evidence

The firmware build, programmed parameters, motor configuration, and test result should be linked. A production fixture can confirm repeatable functions, while longer endurance or abnormal-load work remains in engineering validation.

Failed units should be labelled and preserved for review. Retest and rework decisions belong to the controlled quality process, not an informal override.

Prepare the OEM handoff

Release the protection matrix, wiring and sensor assumptions, test setup, acceptance criteria, service instructions, and change log. Review the package when the pump, motor, fluid, enclosure, or firmware changes.

See pump controller solutions and share your pump duty and protection requirements with Sankey.

Make the review decision-ready

Use a defined pump, motor, fluid or representative medium, plumbing condition, supply range, duty profile, and enclosure for the review. Identify which fault cases can be created safely and how the product owner expects the appliance to respond. A protection decision should be connected to the actual hydraulic and electrical system, not an abstract controller input.

Retain evidence that can be reviewed later

Retain the protection matrix, parameter and firmware revision, pump setup, triggered condition, controller response, reset path, and retest result. If a threshold is being explored, mark it clearly as provisional. This preserves the distinction between development learning and a released production criterion.

Use a cross-functional release gate

Before pilot production, review the current hardware and firmware identifiers, interface and wiring drawings, representative product setup, test matrix, results, unresolved risks, and any proposed changes with the OEM product owner, engineering, and production representatives. The release decision should state what was checked, what remains outside scope, and which change will require a repeat review. This is stronger evidence than a broad claim that the design has been “tested”.

Scope and responsible owners

This engineering resource describes a planning method. It does not replace product safety, EMC, wireless, regulatory, reliability, privacy, or market-access assessment. Those workstreams need their own applicable requirements, responsible parties, and evidence for the confirmed product and destination market.

Frequently asked questions

Can dry-run be detected from current alone?

Sometimes current is useful evidence, but suitability depends on the motor, pump, fluid, and approved detection method. Validate the actual application.

Should automatic restart always be enabled?

No. Restart behaviour is a product and safety decision. Define the allowed state and user indication for each fault.