Why Substation Work Has Its Own Requirements

A substation inspector typically works at greater distances than an indoor panel inspector. Transformer bushings, busbar joints, isolator contacts and overhead terminations may be 5 to 20 metres away, sometimes behind a safety barrier. At those distances, a low-resolution detector cannot resolve a small hot joint reliably.

Substation thermography is also outdoor work: solar loading, wind and changing emissivity of bare conductors all affect readings. The camera is part of a procedure that includes load measurement, emissivity estimation and repeat scans under similar conditions.

Substation Assets and Their Thermal Signatures

Asset	What to look for	Typical scan distance
Transformer tank and bushings	Hot spots, blocked radiators, bushing temperature gradients	3-10 m
Busbar and bolted joints	Uneven heating across the connection	5-15 m
Isolator / disconnector contacts	Localised hot contact faces	5-20 m
Circuit breaker terminations	Loose lug or connection heating	3-10 m
Capacitor banks and reactors	Overheating elements or connections	5-15 m
Cable terminations and surge arresters	Surface temperature anomalies	3-8 m

Resolution and Distance Planning

For a small joint at 10 metres, a 640×512 detector gives substantially better spatial resolution than a 384×288 detector of the same field of view. If your substation work includes busbars and isolators at distance, choose 640×512 as the baseline.

For crews that mostly scan indoor switchgear and transformer cabinets at close range, 384×288 is a practical and lower-cost starting point. Many utilities operate both classes: 384×288 units for daily indoor rounds and 640×512 units for outdoor and transmission inspections.

NETD, Accuracy and Emissivity

NETD (noise equivalent temperature difference) tells you the smallest temperature difference the camera can distinguish. For electrical inspection, prefer a camera with NETD ≤40 mK, ideally ≤30 mK, so fine differences across a suspect connection are visible before they become critical.

Accuracy is usually stated as ±2 °C or ±2% of reading. Emissivity settings matter outdoors: painted surfaces, porcelain, bare copper and aluminium all reflect differently. Set emissivity per surface and avoid scanning in direct sun when comparing readings over time.

Lens, Focus and Field of View

Substation work benefits from:

• Interchangeable lenses — a telephoto lens (e.g. 25° or narrower) for distant busbar joints, a standard lens for general scans.
• Manual or autofocus with a clear near limit — out-of-focus images destroy small-target accuracy.
• A bright, high-resolution viewfinder or screen — outdoor daylight makes a small screen hard to read; models with a viewfinder or large bright display are easier in the field.

Safety and Access Considerations

Live substation work follows access rules that may keep you outside a safety distance. That makes lens choice and resolution even more important. Some inspections are performed from a vehicle or a corridor behind a barrier — plan the maximum distance before selecting the detector and lens combination.

Recommended Unitech Tools Models

Work scope	Model	Why it fits
Indoor switchgear and transformer cabinets	SC-A Series	384×288 / 640×512 options, tool-style, report-ready
General substation, distance scanning	E Series (E600)	640×512, 12 µm, interchangeable-lens platform
High-end substation and transmission	SC-B Series	640×512, autofocus, laser ranging, ±1 °C class accuracy
HD thermography / major asset reports	PT II Series	up to 1280×1024, highest detail for formal reports

Reporting and Follow-Up

A substation thermography report should include the thermal image, the visual reference, load at the time of scan, emissivity used, weather conditions, and a severity classification. Confirm the reporting software and report format with your supplier before purchase, and confirm whether calibration certificates are available per model.