Operations engineers
Live hot-spot alarms and load-correlated trends, so a degrading joint is fixed in a planned outage instead of after a fault.
Battery-free · Self-powered from 1 A · PD < 10 pC at 500 kV test level
Continuous thermal monitoring (CTM) means permanently installed sensors that measure the temperature of electrical connections around the clock, instead of a single snapshot during a periodic survey. IEEE Std 2969-2025, the IEEE guide for switchgear and motor control centers up to 52 kV, states (§1.2) that CTM "can complement or replace traditional periodic infrared thermographic surveys".
Every connection failure shows a thermal signature before it burns. VTI builds battery-free, self-powered wireless IoT temperature sensors (VTI-TS-22 / VTI-TS-26) that continuously measure the real hot spots — busbar joints, switchgear contacts, cable terminations and 110–500 kV line connectors — and turn them into early warnings feeding your condition-based (CBM) and risk-based (RBM) maintenance for the smart grid.
Who it's for
VTI sensors are specified by the people accountable for grid uptime and safety. Each role gets a different value from the same continuous temperature stream.
Live hot-spot alarms and load-correlated trends, so a degrading joint is fixed in a planned outage instead of after a fault.
Real thermal behaviour of connections and ratings to validate designs, retrofits and dynamic line rating (DLR).
Early detection of overheating contacts cuts arc-flash and fire risk on energized switchgear and lines.
Objective asset-health data to move from time-based servicing to CBM/RBM and defensible capex decisions.
Sensors
The VTI-TS series harvests energy from the conductor's own magnetic field — no battery to replace, no auxiliary supply, no wiring. Each unit measures the contact-point temperature it is clamped to and transmits over an EMI-immune wireless link to a VTI gateway.
Switchgear & busbar
For busbar joints, isolator contacts and cable lugs in MV/HV switchgear. Battery-free, clamp-on, no wiring across the insulation boundary.
Transmission & distribution
Long-range outdoor unit for line splices, dead-ends and lug landings, with a sealed UV-stable enclosure for harsh field conditions.
*Representative values; final figures per product datasheet. Request the datasheet →
From data to maintenance strategy
Time-based servicing either over-maintains healthy assets or misses degrading ones. Continuous temperature is one of the strongest leading indicators of connection failure — the input CBM and RBM need.
Trigger maintenance on actual condition, not the calendar. Rising contact temperature at a given load flags loosening or oxidation early, so crews intervene only when needed.
Combine probability of failure (thermal trend severity) with consequence (asset criticality) to rank work by risk — aligning crews and capex with ISO 55000 asset management.
Temperature-vs-load trending builds an objective health signal per connection point, supporting hot-spot detection, ampacity decisions and end-of-life planning.
Self-powered sensor measures contact temperature on the energized asset.
EMI-immune wireless link to a gateway aggregating up to 1,000 points.
Temperature-vs-load trends, thresholds and alarms feed CBM/RBM logic.
Work orders ranked by risk; intervene before failure, avoid outages.
Read the full technical guide: CBM & RBM with thermal data →
Applications
From a single switchgear panel to a national fleet and a full transmission corridor — covering every connection where resistance, load and ageing create heat.
Circuit-breaker contacts, busbar joints and cable terminations in MV/HV switchgear — the most common thermal failure points.
Bushings, disconnectors and unmanned substations — online temperature/humidity with no cap on sensors or sites.
Splices, dead-ends and lug landings on 110–500 kV lines — hot-spot detection and inputs for dynamic line rating.
Stream point-temperature into SCADA/DMS and asset-management platforms for fleet-wide visibility.
Fiber-optic DTS for buried/long-run cables — a continuous thermal profile alongside point sensors.
Plant switchrooms, large industrial loads and data-center power rooms where downtime is costly.
Platform
Sensors are half the system. VTI ties every measurement point into one platform so operators and asset managers see the whole network on one screen and push data downstream.
Concentrator collecting up to 1,000 sensors and forwarding to your server; GW22-D is the dual-band (BLE + LoRa) version.
Browser dashboards, configurable thresholds, alarms and historical trends — no limit on sensors per site or sites per fleet.
Fiber-optic DTS for power cables, plus Modbus TCP or MQTT from the gateway and IEC 60870-5-104 from the VTI platform for SCADA and cloud.
Comprehensive Safety Monitoring Solution for Critical Infrastructure · 25-page technical guide covering Raman OTDR principles, 4-channel 20 km controller & armored sensing cable specs, SCADA integration, and delivered project deployments.
Standards & integration
VTI monitoring is designed to slot into the standards and systems grid owners already run.
IEEE Guide for Continuous Thermal Monitoring of Switchgear and Motor Control Centers up to 52 kV (published May 2026). A Guide, not a certification: VTI maps its sensors clause by clause.
CIGRE Technical Brochure 999 (JWG B3.D2.62, August 2026). Table 2.8-1 (pp. 101–102) lists the energy-harvesting thermal sensor for transformer and circuit-breaker thermal needs, HV-MV and MV-LV.
HV switchgear & assemblies — temperature-rise context for switchgear monitoring.
Switchgear ratings and allowable temperature limits for contacts and connections.
The gateway outputs Modbus TCP or MQTT (one per order code); the VTI platform delivers IEC 60870-5-104 to SCADA.
Asset-management framework that CBM/RBM thermal data directly supports.
System architecture
VTI delivers the whole chain, not loose sensors: self-powered sensors → gateway → software/cloud hosted in-country → real-time alarms and SCADA integration.
Model selection
Every point on the grid has a right configuration. Here is the product range and a quick selection guide.
| Device | Power | Range / Accuracy | Voltage | Typical mounting |
|---|---|---|---|---|
| VTI-TS-22 | Self-powered ≥1 A (battery-free energy harvesting) | −40…+125 °C · ±0.2 °C | Type-tested at 500 kV | Busbar joints, lugs, MV switchgear contacts |
| VTI-TS-26 | Self-powered ≥1 A (battery-free energy harvesting) | −40…+125 °C · ±0.2 °C | Type-tested at 500 kV | Transmission lines, outdoor (IP, UV-resistant) |
| VTI Gateway GW22 | AC/DC supply | — | — | Aggregates up to 1,000 sensors to the software |
| VTI Software | On-prem / Cloud | — | — | 24/7 monitoring, alarms, history, CBM/RBM |
→ VTI-TS-22, clamp-on, fitted during a planned outage.
→ VTI-TS-26 long-range, outdoor housing, UHV EMI immunity.
→ Add the VTI Gateway GW22 (up to 1,000 sensors).
→ Add VTI Software, on-prem or in-country hosting.
Low-current points (<5 A) or special locations: contact VTI for the right configuration. Detailed specs per model datasheet.
Integration & protocols
The VTI gateway and software support standard industrial protocols so temperature data flows directly into your SCADA/DMS and asset-management systems.
Connect directly to PLC/RTU and existing SCADA systems.
Publish thermal data to monitoring software and IoT platforms over MQTT with TLS.
Relay outputs trigger sirens/lights or protection interlocks on temperature threshold.
Push data to the monitoring software; data sovereignty stays with the operator.
Add gateways as the radio survey requires — no limit on the number of sites.
Host in your own jurisdiction — suited to critical infrastructure, no foreign-platform dependency.
Exact protocol support varies by gateway model — see the datasheet or contact a VTI engineer. IEC 61850 is on the roadmap.
Industries
Anywhere high-current connections must be watched for overheating — from national smart grids to plants and digital infrastructure. This block is maintained by VTI staff.
Substations, MV switchgear and 110–500 kV lines operated by utilities and high-voltage grid companies.
Steel, cement, paper and chemical plants — high load, hot busbars and distribution boards under harsh duty cycles.
Wind/solar collection substations, inverters and outdoor connection cabinets where joints degrade fast under weather and thermal cycling.
Hazardous, explosion-risk areas needing early hot-spot detection to prevent incidents and protect personnel.
Electrical rooms and power distribution (PDU/MSB) where downtime is extremely costly and 24/7 thermal monitoring is essential.
Metro, electrified rail and traction substations — heavily loaded boards and busbars with continuous switching.
Case studies
Representative deployments of VTI battery-free wireless IoT sensors for condition- and risk-based maintenance (CBM/RBM) on grids and in plants.
Field reference: EVNNPC substation temperature monitoring case study — 110 kV Hoi Hop and 22/0.4 kV Ao Hai, two defects found, readings within 0.4–3.2 °C of handheld infrared.
110 kV substation · EVNNPC
At Hoi Hop substation the 110 kV bushing terminals of transformer T2 ran above the middle phase at evening peak load. The cause was traced to a copper–aluminium contact inside the terminal.
At Ao Hai, phase C of branch MCCB 2 ran above phases A and B. It was confirmed on site on 21 Nov 2023; the contacts were reworked and the terminal re-crimped on 27 Nov 2023.
22 kV substation · EVNHANOI
At Thach Ban 16 substation a cable termination ran above 70 °C under its silicone boot. Handheld infrared surveys had not detected it; a contact sensor under the boot did.
Featured projects
Photos and scope of representative temperature-monitoring projects. See the full photo gallery →
Self-powered VTI-TS sensors on the bushing terminals of 500 kV transformers and shunt reactors, reporting to gateways in each substation.
Wireless temperature sensors on substation equipment, supporting condition-based maintenance.
Monitoring of HV/MV cable terminations, 110 kV transformers, RMUs and LV boards in a city distribution network.
Temperature monitoring of main transformers, generators and generator circuit breakers.
FAQ
Contact temperature, normalized against load current, is a leading indicator of connection degradation (loosening, oxidation, undersized joints). CBM uses rising temperature-at-load to trigger intervention on actual condition; RBM combines that probability-of-failure signal with asset criticality to prioritize work by risk, in line with ISO 55000.
It harvests energy from the magnetic field of the current in the monitored conductor, powering measurement and the wireless transmitter. There is no battery to replace and no auxiliary supply — important for thousands of points across a fleet.
Yes. The wireless link and electronics are engineered to reject the electromagnetic interference present in high- and ultra-high-voltage fields; both VTI-TS-22 and VTI-TS-26 are type-tested at 500 kV (partial discharge 8.7 pC, lightning impulse withstand −1500 kV).
With the circuit isolated, earthed and proved dead, as IEEE Std 2969-2025 expects for retrofit work. Clamp-on fixing (magnetic strap and stainless-steel tie) with no wiring across the insulation boundary keeps installation short, so a panel is normally fitted within a planned maintenance outage.
The GW22 gateway aggregates up to 1,000 sensors and forwards data to your server (GW22-D for dual-band BLE + LoRa); it integrates via Modbus TCP, MQTT over TLS or IEC 60870-5-104 into SCADA so temperature and alarms reach your DMS and asset-management tools.
CTM is the permanent, around-the-clock measurement of connection temperatures by installed sensors, rather than a snapshot during a periodic infrared survey. IEEE Std 2969-2025 (§1.2) states that CTM "can complement or replace traditional periodic infrared thermographic surveys", and its Annex A.2 notes that "the accuracy of the measurement is potentially less important than detecting temperature changes over time".
IEEE Std 2969-2025 is a Guide for switchgear and MCCs up to 52 kV, so there is no certification; VTI maps the VTI-TS series against it clause by clause. CIGRE Technical Brochure 999 lists the energy-harvesting thermal sensor in Table 2.8-1 for transformer and circuit-breaker thermal needs. The full mapping is on the standards page.
Point sensors (VTI-TS) target discrete contact points — joints, terminations, splices. DTS uses fiber to profile temperature continuously along a cable, ideal for buried/long runs and dynamic rating. VTI offers both on one platform.
Tell us about your switchgear, substations or transmission lines and our engineers will scope the right sensors, gateway and integration — and send full datasheets.