Pressure to Sign a Witnessed Primary-Injection Test Sheet Before Energisation
A junior electrical engineer is seconded to the commissioning team for a new 132 kV GIS substation. Energisation is fixed for Friday and a ten-day grid tie-in outage has been booked; the client has warned of liquidated damages for delay. On Wednesday the site supervisor asks the engineer to sign the primary-injection test sheet for the busbar protection CTs. The test was scheduled for the previous weekend but the test set was double-booked; instead the supervisor attaches the manufacturer's factory routine-test certificates for the same CT serial numbers and says 'it is effectively the same test, just sign it as witnessed'.
Separately, the engineer notices that the relay configuration backup sheet carries the signature of a colleague who was on annual leave that week, and that the insulation-resistance values on two feeder records are identical to four significant figures, which suggests copying. The engineer is on a three-month probation contract and the supervisor hints that 'young engineers who make things difficult do not get renewed'.
1. Identify the professional obligations engaged and determine whether signing the sheet is permissible.
Read the worked answer
Obligations engaged.
- Paramountcy of public safety, health and welfare. Busbar protection failure at 132 kV endangers site staff and the wider network; this overrides schedule and commercial pressure.
- Competence and honesty in reporting. A signature on a witnessed test sheet asserts a fact: that the named test was performed, in the signatory's presence, with the stated results. That assertion would be false.
- Scope of authority. A professional may sign for work they performed or directly supervised. A factory routine test is neither.
- Obligation to report unprofessional conduct - the reused colleague signature and the duplicated insulation values.
Is signing permissible? No. This is not a matter of engineering judgement about sufficiency of evidence; it is a misrepresentation of fact. The factory certificate verifies that the CT left the works with a given ratio and polarity. It cannot verify the installed ratio and polarity, the secondary wiring to the relay, the CT test-block links, the relay settings actually loaded, or the trip circuit to the breaker - which is precisely what primary injection proves.
Aggravating factors. The request comes from a supervisor, which does not transfer professional responsibility; probation status and liquidated damages are commercial considerations, not technical evidence.
2. Set out the sequence of actions the engineer should take, including escalation and documentation.
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Immediate (same day, in writing). Decline to sign, stating the reason factually: the primary injection was not performed and the factory certificate does not cover installed secondary loops. Propose the alternative that preserves the date - hire a test set locally, or borrow from the neighbouring project, and perform the injection on Thursday. Primary injection of a busbar CT set typically takes a few hours with two people, so the schedule is recoverable.
Do not alter records. Do not amend the existing sheets, do not add a retrospective note, and do not sign anything 'for information only' that could later be read as an endorsement.
Escalate. Raise it with the line manager and the project's technical authority, and inform the client's commissioning engineer that the witness is outstanding so the energisation readiness review sees accurate status. If the supervisor persists, put the objection in writing to the next level of management, referencing the professional code of ethics.
Report the separate integrity issues. The signature of an absent colleague and the duplicated readings should go to the quality manager or the engineering manager as a distinct matter, with copies of the records. Leaving them unreported while objecting to your own sheet undermines the position.
Keep contemporaneous notes - dates, times, who said what, and the documents exchanged. If overruled, record that the energisation proceeded against written technical objection.
3. Give the technical argument that justifies the refusal, using concrete numbers for busbar differential protection.
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What primary injection proves. It injects a known primary current through each CT and its complete secondary loop, verifying ratio as installed, polarity as wired, secondary circuit continuity at the test block, relay measurement, and correct trip output to the breaker. None of these is covered by a factory routine test.
Consequence of a polarity error. Busbar differential protection sums the currents of all incomers and outgoing feeders. For an external through-fault of, say, 2000 A, correctly polarised CTs sum to zero. If one feeder CT is reversed, the relay sees 2000 - (-2000) = 4000 A of differential current. With a high-set element at 8 x In on a 2000/1 CT, that is 16 000 A secondary-equivalent - the element operates and trips the entire busbar for a fault that the feeder protection should have cleared alone. The opposite error, an internal fault that the scheme fails to detect, is worse: the busbar remains energised into a fault, with arc-flash and plant-loss consequences.
Consequence of a ratio error or open circuit. A CT left open-circuited on the secondary during energisation develops dangerous peak voltages at the terminals and can fail explosively; a mis-set ratio defeats the bias characteristic so the scheme becomes either unstable on load or insensitive to genuine faults.
Conclusion. The plant cannot be energised with the busbar protection unproven. If the schedule genuinely cannot absorb a Thursday injection test, the defensible options are to postpone energisation or to energise under a documented, client-accepted interim protection arrangement with the busbar protection isolated and backup protection proven - not to sign a false record.