What belongs in the clock-basis worksheet?
Begin with the approved test identifier, asset names and the raw exports. Preserve the original files and identify which records were exported together. A screenshot can support a record, but should not replace an available original event export.
The worksheet below is an original review aid. It does not define a synchronization tolerance or a project acceptance criterion. Ask the commissioning lead which evidence and precision the approved scenario requires.
| Field | Record | Review question |
|---|---|---|
| Source | Asset, logger and export file | Can this event be traced to the raw record? |
| Displayed time | Original value and timezone notation | Is local time or UTC explicitly identified? |
| Clock evidence | Configuration or witnessed comparison and time checked | Does the evidence apply during the test? |
| Offset | Measured value, sign and supporting record | Was it measured or merely assumed? |
| Resolution | Displayed precision and logging interval if known | Can the records distinguish these events? |
| Normalized time | Derived value and calculation reference | Can another reviewer reproduce the conversion? |
| Uncertainty | Unknown clock changes or missing evidence | Should the sequence remain unresolved? |
How should an offset calculation be recorded?
Illustrative example. Two fictional logs record the same witnessed reference event. Logger A shows 14:00:10 UTC and logger B shows 14:00:15 UTC. At that comparison, B is five seconds ahead of A. If the project reviewer accepts that offset for the relevant interval, subtract five seconds from B when comparing its timestamps with A.
Keep the raw 14:00:15 value beside the derived 14:00:10 value. Do not edit the original export. Record why the offset applies to later events, including any evidence of clock resets or time-source changes. This arithmetic is not proof that the offset stayed constant.
If the only evidence is that two alarms seem to describe the same event, do not tune an offset until the preferred sequence appears. Mark the sequence unresolved and request independent clock evidence.
What if the clocks cannot be reconciled?
Separate the observations you can support from the sequence you cannot. Record that an alarm appeared, where its original record is stored and which clock uncertainty prevents comparison. Avoid writing that one operation caused another solely because unaligned timestamps look adjacent.
Ask the responsible reviewer whether additional evidence or an approved retest is necessary. Preserve the issue in the deficiency record with an owner and a disposition, rather than silently removing the problematic event from the report.
How does this fit the commissioning process?
The US Department of Energy describes functional testing, monitoring and analysis within investigation, followed by implementation, retesting and final documentation. That process supports keeping results and unresolved issues traceable. It does not prescribe the clock worksheet or numerical example on this page.
The commissioning professional approves actual test procedures and acceptance criteria. Engineering sign-off is performed only by the registered engineer on the job. This guide prepares evidence; it does not authorize testing or certify a sequence.
Sources: US Department of Energy: Commissioning Process for Federal Facilities
Common questions
What else should the bid team know?
Should raw timestamps be replaced with corrected ones?
No. Preserve raw values and show any derived conversion separately with its evidence.
What offset is acceptable?
Use the approved project criteria. This guide does not set a universal clock tolerance.
Does a common timezone establish synchronization?
No. Timezone notation and the actual agreement between clocks are different checks.
Primary sources
- Commissioning Process for Federal FacilitiesUS Department of Energy