📌 Executive Summary (Direct Answer)
Continuous Thermal Monitoring (CTM) is an advanced 24/7 condition monitoring system that measures real-time contact temperatures at critical electrical junctions (busbar joints, circuit breaker contacts, and cable terminations) using dedicated, battery-free wireless sensors. This technology completely eliminates the dangerous blind spots and intermittent sampling of periodic infrared (IR) camera inspections, while directly fulfilling the requirements of IEEE 2969-2025, CIGRE Technical Brochure 999, and NFPA 70B (2026 Edition) to proactively prevent arc-flash explosions and equipment failures.
1. What is Continuous Thermal Monitoring (CTM)?
Continuous Thermal Monitoring (CTM) is an advanced system designed to ensure optimal performance and safety for industrial operations that rely on electrical power. The technology uses dedicated sensors installed at critical equipment and components to measure temperature variations in real time.
This continuous stream of data is essential for maintaining the integrity and efficiency of the overall system. Grid operators and facility engineers no longer have to guess equipment health between manual inspection intervals spaced months or even years apart.
2. How Does a CTM System Work?
An industrial CTM system operates on a 5-step closed-loop lifecycle, bridging physical sensing on energized assets to automated maintenance decision-making:
Strategic Sensor Placement
Sensors are integrated at locations prone to overheating or failure, including connections, transition points, and contact points in motors, transformers, generators, and busbars.
Continuous Data Collection
Sensors continuously transmit temperature data to a central monitoring system (or local gateway) for analysis and comparison against predefined safe temperature thresholds.
Real-Time Alerts
As soon as a temperature exceeds a safe limit or exhibits an abnormal rate-of-rise, the system immediately sends instant alerts to the maintenance team via SCADA, SMS, or email.
Early Intervention
Real-time data enables maintenance personnel to accurately identify the affected component and carry out planned repairs before a major failure or arc-flash incident occurs.
Trend Analysis: Accumulated data over time helps identify points at risk of failure and supports the strategic transition to Condition-Based Maintenance (CBM) and Reliability-Centered Maintenance (RBM).
3. Recommendations for CTM Application from the Perspective of International Technical Standards (2025–2026)
The adoption of technologies such as CTM is becoming increasingly important and urgent as international standards in the power industry become more stringent and are continuously updated:
IEEE 2969-2025 International Standard
Issued in 2026, IEEE 2969-2025 (IEEE Guide for Continuous Thermal Monitoring of Switchgear and Motor Control Centers up to 52 kV) provides formal guidance on continuous thermal monitoring methods for switchgear and motor control centers.
CIGRE Technical Brochure 999
Published by Joint Working Group B3.D2.62 (August 2026, ISBN 978-2-85873-704-8), CIGRE TB 999 (Lifelong Supervision and Management of Substations by Use of Sensors, Mobile Devices, Information and Communication Technologies) recommends continuous thermal monitoring systems as an indispensable part of a condition monitoring and lifecycle management solution for substation assets.
Continuous temperature data collection at critical locations—such as transformers, connections, busbars, cables, and switchgear—helps detect overheating, hot spots, and abnormal signs of degradation at an early stage. Measurement data should be integrated with SCADA/asset monitoring systems for trend analysis, early warning, and condition-based maintenance, thereby improving operational reliability, reducing outage risks, and optimizing asset management throughout the equipment lifecycle.
Furthermore, in Table 2.8-1, CIGRE TB 999 explicitly identifies the energy harvesting thermal sensor as the recommended mitigation technology for both transformer and circuit-breaker thermal risks.
NFPA 70B, Standard for Electrical Equipment Maintenance – 2026 Edition (USA)
Under NFPA 70B (2026 Edition), electrical equipment condition should be maintained through a systematic maintenance program that combines condition monitoring with early detection of abnormal conditions.
4. How Does CTM Differ from Infrared (IR) Thermal Camera Inspection?
Many utilities and industrial plants historically relied on periodic infrared inspection using handheld thermal cameras. However, periodic infrared inspection has several critical limitations:
- Intermittent Snapshot Nature: Thermal scans capture temperature only at a single moment in time (e.g., once every 3 to 12 months). If the electrical circuit is lightly loaded during inspection, severe contact resistance issues remain completely concealed.
- Physical Blind Spots: In metal-enclosed switchgear (Metal-clad Switchgear), bolted busbar joints behind phase barriers, partition sheets, or insulation boots cannot be seen by an external infrared camera.
- Personnel Safety Hazards: Technicians must approach energized medium- and high-voltage equipment, frequently opening enclosure doors and exposing personnel to fatal Arc Flash and electrocution hazards.
In contrast, CTM provides 24/7 system monitoring, eliminates blind spots, and does not require personnel to directly open electrical enclosures, thereby enhancing safety and providing accurate trend data in line with the recommendations of IEEE 2969-2025.
Figure 3: CTM eliminates blind spots in monitoring the temperature of contact points inside enclosed electrical cabinets.
| Comparison Criteria | Periodic IR Camera Inspection | 24/7 Continuous Thermal Monitoring (CTM) |
|---|---|---|
| Monitoring Frequency | Intermittent Periodic every 3–12 months | Continuous 24/7/365 in real time |
| Load Correlation | Reflects load only at the moment of inspection (easily misses peak load) | Tracks continuous temperature variation synchronized with full load cycles |
| Visual Accessibility | Obstructed by metal enclosure, partition sheets, and insulation boots | Probes measure directly at conductive surfaces, eliminating all blind spots |
| Operational Safety | Requires opening live cabinet doors, risking fatal Arc Flash events | Cabinet doors remain 100% sealed; remote data via SCADA / Cloud |
| Maintenance Strategy | Reactive, addressing overheating only after significant degradation | Enables Condition-Based Maintenance (CBM) & Reliability-Centered Maintenance (RBM) |
| Standards Compliance | Point-in-time check only, no continuous trend data | Directly satisfies IEEE 2969-2025, CIGRE TB 999, and NFPA 70B §7.4.5 |
5. Hot Spot Monitor Solution from Viet Tech Invest Corporation JSC
To bring CTM into practical application and fully address the latest standards, Viet Tech Invest Corporation JSC (VTI Corp) provides an end-to-end Hot Spot Monitoring System solution:
Intelligent Early Warning
Proprietary algorithms immediately detect abnormal thermal conditions, absolute temperature limits, and abnormal Rate-of-Rise (RoR) patterns.
Safe & Easy Installation
Uses non-conductive probes mounted directly on busbars and circuit breakers without affecting the system’s structure or electrical clearance.
Compatibility & Compliance
Safe for all voltage levels (LV to 500 kV), compatible with industrial protocols (Modbus TCP, MQTT over TLS, IEC 60870-5-104), and supports compliance with IEEE 2969-2025, CIGRE TB 999, and NFPA 70B.
Energy Harvesting — 100% Battery-Free
The VTI-TS-22 and VTI-TS-26 sensor series harvest energy directly from primary current (≥1 A), completely eliminating battery replacement costs and hazards.
6. What Is Your Next Step?
Equipping electrical energy infrastructure with a CTM system not only makes it safer but also represents a smart investment to maintain operations in compliance with the latest international technical standards (IEEE 2969-2025, CIGRE TB 999, NFPA 70B).
As a specialist in electrical system safety and self-powered wireless sensor systems, Viet Tech Invest Corporation JSC (VTI Corp) is committed to delivering modern, standards-compliant maintenance solutions that optimize productivity and eliminate catastrophic electrical outages.
Upgrade Your System to the Latest CTM Standards
Contact VTI Corp today for expert technical advice, site surveys, and a live Hot Spot Monitor solution demonstration tailored to your switchgear and substation infrastructure!
Request a Consultation & Free Quote →7. Frequently Asked Questions (FAQ) Regarding CTM
What does IEEE Std 2969-2025 require for Continuous Thermal Monitoring?
IEEE Std 2969-2025 provides official guidance for continuous thermal monitoring of switchgear and motor control centers up to 52 kV. It specifies sensor placement at critical joints and terminations, establishes that CTM can supplement or replace periodic infrared inspection, and requires that sensor installation does not degrade equipment insulation or dielectric clearance.
What does CIGRE Technical Brochure 999 recommend for substation assets?
In Table 2.8-1, CIGRE TB 999 names the energy harvesting thermal sensor as the recommended mitigation technology for both transformer and circuit-breaker thermal risks. It advises continuous temperature data collection integrated into SCADA/CBM systems for trend analysis and asset health indexing.
Can CTM officially replace periodic infrared thermography under NFPA 70B?
Yes. Under NFPA 70B (2026 Edition) Section 7.4.5, permanently installed, continuously monitoring temperature measurement devices are explicitly permitted to satisfy the standard's infrared thermography requirements, eliminating recurring inspection expenses and Arc Flash risks.
Is a power outage required to install VTI-TS sensors?
Yes. Installing clamp-on sensors onto busbars or circuit breaker terminals must be performed during a scheduled maintenance outage in compliance with electrical safety rules (disconnect, ground, verify zero voltage). Because the sensors are wireless and self-powered with no external wiring, installation takes only 2–3 minutes per point.
How do VTI-TS sensors operate without batteries?
VTI-TS sensors feature integrated micro current-transformer energy harvesters that extract operating power directly from the magnetic field generated by the conductor's load current (operating continuously from ≥1 A primary current). This 100% battery-free design eliminates replacement maintenance and chemical leakage risks.
