Technical guide
Detailed information about Thermal Camera Measurement and Predictive Maintenance
thermal camera electrical measurement — this guide covers the scope, application method, quality criteria and reporting process for your needs.
Thermal camera measurement in electrical facilities
Thermal camera electrical measurement converts the infrared energy emitted from the equipment surface into a temperature distribution, making abnormal heating visible. A loose connection, high contact resistance, overload, phase imbalance, harmonic effect, cooling problem, or an internal equipment fault can create a temperature difference. Because thermographic inspection is performed energized and under load, it produces predictive maintenance data without stopping the system.
Plan-Test does not apply thermal camera measurement merely to capture a colored image. The equipment's load, ambient temperature, wind, solar effect, surface material, emissivity, and viewing angle are evaluated together with the result. Similar phases and connections of the same type are compared. A critical finding is reported to the operations responsible on site; in the report, the thermal and normal images, the measurement point, the temperature difference, the possible cause, and the recommended intervention time are presented together.
Application areas in substations, panels, and energy facilities
In a substation thermal scanning study, the power transformer bushings and connections, busbar joints, circuit breaker-disconnector contact areas, cable terminations, instrument transformers, surge arresters, and auxiliary systems are examined. In enclosed cells, suitable viewing windows and safe access options are assessed. In electrical panel thermal measurement, main switches, contactors, fuses, cable lugs, busbars, power electronics, and neutral connections are checked under load.
In RES and GES sites, inverters, transformers, the medium voltage cell, the collector center, and connection points can be scanned on a planned route. In industrial facilities, critical motor feeders, compensation panels, UPS, and distribution panels are examined under production conditions. When the load of the same equipment, which can vary under different operating regimes, is recorded, the result becomes more meaningful. Tying the measurement route to the equipment inventory ensures that no critical point is skipped and that the same points are compared in subsequent scans.
Measurement conditions for accurate thermographic inspection
For hot spot detection, it is preferred that the equipment operates at a representative load. At a very low load, a high-resistance connection may not yet produce a noticeable temperature. For this reason, the current or load percentage, the measurement time, and the operating condition are recorded. Outdoors, solar load, rain, wind, and reflections can affect the result; where possible, a suitable time is chosen and a comparative measurement is made. In enclosed panels, opening the cover safely depends on the operating procedure.
In the thermal camera, the correct emissivity and reflected temperature settings are important. Shiny metal surfaces can reflect hot objects in the surroundings and create a misleading image. Plan-Test makes the settings according to the physical properties of the measurement point and verifies a suspicious finding from a different angle and with visual inspection. The safe approach distance is never violated for the sake of any measurement. In panels with arc flash risk, appropriate personal protective equipment and authorized operational accompaniment are mandatory.
Temperature difference and criticality assessment
The significance of a thermal finding is not determined only by the maximum temperature seen. The difference between phases at similar load, the temperature rise above ambient, the equipment's permissible temperature, the load level, and the rate at which the fault develops are evaluated together. For example, a noticeable phase difference at low load can rapidly reach a critical level at high load. By contrast, a component that runs hot by design may not require immediate intervention if it is within the manufacturer's limits.
Findings are divided into action classes such as urgent, short-term, planned maintenance, and monitoring. For critical connections, load reduction or a safe outage may be recommended. For medium-level findings, torque checking, cleaning, load balancing, or a repeat measurement is planned. Carrying out a verification scan after the intervention under conditions close to the same load shows the effect of the work performed. This risk-based approach ensures that maintenance resources are directed to the most important points.
Photographed thermal reporting and maintenance recommendations
Thermal reporting defines the location of each finding with the equipment code and a site description. The thermal image and the normal photograph are given side by side; the measurement points, maximum-minimum temperatures, load, and environmental conditions are stated. The camera used and its calibration information appear in the report. Possible causes are written not as a definitive failure verdict but as a technical assessment consistent with the available evidence; the required electrical test or physical check is recommended.
The executive summary presents the number of critical findings, the facility section, and the recommended intervention schedule. The technical appendices contain all scan points and reference images. This structure makes it easier for the maintenance team to find the right equipment on site and for management to build the outage plan. When the same coding is used as in previous reports, temperature trends can be tracked. Plan-Test links the thermal measurement results with other maintenance tests to build a stronger condition assessment.
Periodic thermal scanning in a predictive maintenance program
A one-off thermal scan shows the load and environmental conditions of that day. The predictive maintenance value increases when critical equipment is monitored regularly under similar conditions. The period is determined according to equipment criticality, load variation, environmental impact, past findings, and the production plan. Seasonal high-load periods or verification measurements after maintenance can be added to the program. In new facilities, images taken during the first loading period form a baseline for future comparisons.
Regular thermal camera measurement helps reduce the risk of unplanned outages, determine the right maintenance timing, and detect energy losses caused by loose connections. However, thermography does not show all failures; it must be used together with other tests for insulation, mechanical, and protection system problems. Plan-Test builds a scanning route, criticality method, and reporting standard suited to the facility's equipment structure, turning thermal data into a sustainable maintenance decision.
Plan-Test’s quality, safety and reporting approach
Plan-Test does not treat the service scope merely as a list of operations to be performed on site. The facility's operating objective, outage availability, existing documentation, equipment history, and risk level are evaluated together. Before the work begins, responsibilities, access conditions, de-energization and re-energization steps, and reporting expectations are clarified. This is intended to keep teams working from the same plan, prevent critical checks from being skipped, and make efficient use of site time. Because each project is planned according to its own technical conditions, the method, devices, team size, and delivery documents to be used are clearly defined at the proposal stage.
Our quality approach is based on explaining what the result means rather than presenting the measurement result on its own. The calibration status of the test devices used, the ambient and load conditions, the connection arrangement, the applied standard, manufacturer criteria, and any previous measurements are linked together in the report. Nonconformities are classified by severity; findings requiring immediate intervention, issues that can be addressed in planned maintenance, and trends that should be monitored are separated from one another. This method helps the investor, the operations manager, and the site team turn the same technical data into a decision-ready output.
Occupational health and safety is an inseparable part of all services. The site-specific risk assessment, personal protective equipment, lockout-tagout steps, absence-of-voltage verification, and grounding and bonding rules are reviewed before the field work begins. Inspections carried out in an energized facility are based on safe approach distances and operating instructions. Plan-Test's goal is to combine technical verification with a safe working discipline in the same process and deliver sustainable, traceable, and auditable engineering services in 1–380 kV energy facilities.
At the proposal and mobilization stage, clearly defining the scope matters for both the employer and the site team. Plan-Test determines the required activities by reviewing the existing drawings, the equipment list, the facility's operating regime, previous reports, and the employer's expectations. Out-of-scope items, necessary preparatory work, the need for de-energization, operational accompaniment, and third-party responsibilities are put in writing. When a new condition arises on site, no uncontrolled scope change is made before its impact is evaluated in terms of technical, schedule, and resource aspects. In this way, all parties understand throughout the project which activity is being performed and why, which data is expected, and against which criterion acceptance will be made. This clarity reduces repeat visits and misplaced expectations while making the delivered engineering service comparable.
The quality of field work depends on the team's experience and cross-disciplinary communication as much as on the equipment used. Plan-Test assigns tasks according to the test or maintenance steps and opens points requiring primary, secondary, project, and operational knowledge to joint evaluation. Measurement devices are used with accessories suited to the application, their calibration validity is checked, and raw data is stored securely. When a critical result is observed, the connection, device settings, environmental conditions, and the equipment's operating history are reviewed again instead of jumping to a hasty interpretation. Verification with a different method is proposed when necessary. This culture of technical scrutiny helps prevent incidental or erroneous measurements from steering the decision process and helps define the real risk on site more accurately.
Completion of the service does not end with the delivery of the report; the actions in the report must be implementable and traceable. Plan-Test links its recommendations to priority, the responsible discipline, the recommended due date, and the verification method. If the employer wishes, a scope for a technical meeting, post-correction check, or repeat measurement can be established for critical items. When new results are compared with historical data under the same equipment code, the facility's condition trend becomes visible. These records support the preparation of the future maintenance budget, spare parts plan, modernization decisions, and outage calendar. The goal is not to document a single project moment, but to build a corporate technical memory that contributes to safe operation and high availability targets throughout the energy facility's entire life cycle.
In every engagement, the relevant national legislation, the grid operator's requirements, IEC and IEEE standards, and the equipment manufacturer's instructions are considered together. While the general provisions of the standards are adapted to the facility's actual conditions, the contract and approved project requirements are also preserved. Where several criteria give different limits, the acceptance approach used is explained in the report; uncertain points are recorded with the employer as a technical decision. Using unique site codes instead of equipment names in documents strengthens traceability among drawings, test results, photographs, and actions. With this documentation discipline, Plan-Test aims to ensure that the technical evidence needed during an audit, provisional acceptance, warranty discussion, or a future failure investigation can be found quickly and reliably.
For the site program you need, it is sufficient to share the facility type, voltage level, equipment count, location, and target date. After the preliminary review, the technical team clarifies the appropriate scope, preparations, and delivery plan.