Service

Expert assessment and diagnostics

After an incident or an anomaly, or on an ageing installation, we look for the cause and set out the actions to take.

Diagnosis starts from the facts, that is, disturbance records, event logs and measurements. Calculation is then used to confirm or rule out a hypothesis. We therefore read the records before forming any hypothesis.

A fault record contains a great deal of information: the faulted phase, the type of fault (bolted, resistive, evolving), the actual current, the operating time of each protection and the circuit-breaker opening time. Comparing it with the protection plan quickly shows whether the system operated as intended.

SCADA logs bring out slow-developing problems, for example a control loop that hunts, a tap changer or capacitor bank circuit-breaker that operates far too often, or a trip that keeps recurring at the same time of day.

01What we do

Incident analysis

Disturbance records and SCADA logs
Reconstruction of events
Failure mechanism

Diagnostics

Substation and protection audits
Ageing and risks
Measurements with Volt Expertise: insulation, partial discharge, power quality, resistivity

02Examples

Fig. 01Phase-to-earth fault on a 20 kV feeder. The 51N picks up, the trip command is issued at 100 ms and interruption occurs at 160 ms, i.e. a circuit-breaker break time of 60 ms.Calculated signals

Fig. 02Energisation of a 5 Mvar capacitor step onto a step already energised. The current reaches a peak of about 10 kA at 5 kHz, which requires a current-limiting reactor.Worked example

03Our offer

Usual content of an offer for this type of assignment. The exact scope, deliverables and price are set in the quotation.

Package 1Collection
Records, logs, settings, history, site visit.
Package 2Timeline
Reconstruction of events.
Package 3Analysis
Failure mechanism, confirmed by calculation or measurement.
Package 4Report
Facts, analysis, conclusion, corrective actions.

04How we work

01Collection
Records, logs, settings, witness accounts, equipment condition.
02Timeline
Reconstruction of events to the millisecond.
03Analysis
Failure mechanism, confirmed by calculation or measurement.
04Conclusions
Cause, technical responsibilities, corrective actions.

05References

Generating substation

Capacitor bank

Analysis of SCADA logs, identification of control hunting and projection of circuit-breaker wear.

Heavy industry

Electrical installation audit

Condition of substations and protection, identified risks and costed recommendations, ranked by priority.

All references

06Frequently asked questions

How long does it take?

A first reading of the records takes a few days. The full timescale depends on the measurements required.

What if it goes to litigation?

See Support in court-appointed expert proceedings.