B Duncan Ltd
Electrical System Diagnostics
Electrical, EMC, and control system fault investigation on your equipment, at your site, anywhere in New Zealand.
Problems
Faults we investigate
Clients come to us with a symptom, not a specification. These are the ones we see most.
Intermittent network dropouts
Communication failures on industrial networks with no consistent trigger and no agreement on the cause.
VFD interference
Variable frequency drive noise on power rails, signal lines, or communication networks.
Earthing & shielding issues
Incorrect earthing or shielding causing interference between systems, often introduced at installation.
Unexplained equipment restarts
Equipment that resets or misbehaves only under certain operating conditions.
Unexplained noise or ripple
Noise on a power or signal rail that others have checked and found nothing.
An investigation that found nothing
A fault one or more firms have already investigated without identifying the cause.
Why us
Why choose us
On-site anywhere in New Zealand
Full test capability at your facility, on a vessel, in a factory, or in our Auckland lab.
Called in after others
A good share of our work is faults that have already been investigated without a cause being found.
Measurement, not replacement
Causes ruled in and out by measurement, rather than by swapping parts and watching.
Defensible reporting
Reports suitable for internal review, manufacturers, insurers, and legal proceedings.
Capability
What we bring on site
We bring every instrument with us. No reliance on site equipment and no delay waiting for it.
Measurement
- Spectrum analysers for conducted and radiated emissions at the system level.
- RF current transformers for cable noise and shielding effectiveness, without breaking the circuit.
- Differential and current probes for common-mode and differential-mode decomposition.
- LISN for conducted emissions on AC and DC power lines to a standardized source impedance.
- Thermal imaging, insulation resistance, and impedance measurement.
Networks and control
- PROFINET, fieldbus, and industrial Ethernet analysis on live systems.
- Packet capture and timing analysis where data errors are involved.
- Earthing, isolation, and ground-loop analysis on IT and floating systems.
- Controlled common-mode injection to find immunity thresholds rather than wait for a failure.
Sectors
Industries we work with
Industries where interference, communication failure, or power supply problems carry real consequences.
Marine
Vessels and offshore
Industrial
Factories and plants
Electronics
Product development
Energy
Generation and grid
Commercial
Buildings and fit-out
Process
How an investigation runs
1. Symptom We start from what is actually happening, and when.
2. Instrument Monitoring goes onto the suspect points to capture live data under real operating conditions before anything is changed.
3. Narrow Subsystems are isolated one at a time. Where immunity is in question, we inject a controlled disturbance to find the level at which the fault appears.
4. Root cause A cause backed by measurements, written up so it can be acted on or presented.
5. Verify The fix is confirmed by the same measurement that found the fault.
Expert witness
Independent investigation and expert witness
Where a failure has become a dispute, an insurance claim, or a legal proceeding, we provide independent root-cause investigation with written findings suitable for claims and proceedings.
We have no stake in the original design or installation, and we report the cause the evidence supports, including where the evidence is incomplete.
FAQ
Common questions
How quickly can you attend?
It depends on current commitments and location. Tell us what the fault is costing you and we will be straight about what we can do and when.
What if the fault will not reproduce while you are there?
Common with intermittent faults. We run continuous max-hold capture on the suspect points while a second instrument roves, so an event that happens once is still recorded. Where a fault is rare enough that this is not practical, we agree an approach before the visit.
Can you work on equipment you did not supply?
Almost always the case. We work on installed equipment from any manufacturer, and having no stake in the original design is usually why we get called.
Will the report stand up in a dispute?
Reports document the procedure, the measurements, and the conclusion in a form suitable for internal review, manufacturers, insurers, and legal proceedings. We do expert witness work on that basis.
Do you fix it, or just find it?
The investigation identifies the cause and the recommended remedy. Where the fix is firmware or electronics, that can be a follow-on engagement with us. Physical work on installed plant is normally done by your own contractor or the equipment supplier, working to our findings.
Related services
Other services you may need
EMC Pre-Compliance Testing
Catch EMC issues during development, in our own pre-compliance lab, before they reach an installation, so emissions and immunity problems are designed out rather than discovered in the field.
Power Systems
Protection, SCADA, and control-system engineering for utilities and industry, including the protocols and equipment behind distribution networks.
Electronics Design
When the fault turns out to be in the product rather than the installation, we review and redesign the electronics.
Discuss a fault
Tell us what you’re seeing and we’ll tell you whether it’s something we can help with.