Winding Temperature
Direct or indicated winding temperature helps show the thermal condition of the conductor region under load.
Applications › Transformers
Transformer Temperature Monitoring with Fiber Optic Winding Sensors
Transformer temperature monitoring combines winding temperature, selected hot-spot locations and other thermal points to show how a transformer behaves under load. Fluorescence-based fiber optic sensors provide direct temperature measurement at defined winding locations without electrical signal wiring at the sensing point.
For oil-immersed and dry-type transformers, multiple probes can be connected to a compatible monitoring instrument for local display, alarms and integration with higher-level monitoring systems.
Direct Winding Measurement
Electrical Isolation
Multi-Point Monitoring
PLC / SCADA Integration
What Temperatures Should Be Monitored in a Transformer?
Transformer thermal condition cannot be represented by one temperature value. The required measurement points depend on the transformer design and monitoring objective, but winding temperature, top-oil temperature and known thermally critical locations are common considerations.
Top-Oil Temperature
Top-oil temperature represents the thermal condition of the transformer oil at the selected measurement location.
Known Hot-Spot Locations
When a thermally critical winding location has been identified, a point fiber optic sensor can measure temperature directly at that installed position.
Direct hot-spot monitoringOil-Immersed Transformer Temperature Monitoring
For oil-immersed transformers, fiber optic probes can be positioned at selected winding locations and routed through the transformer tank to an external monitoring instrument. Probe construction, fiber routing, tank penetration and channel count should be planned together.
Winding Fiber Optic Temperature Probes
Direct point temperature measurement at selected winding locations.
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Tank Feedthrough & Flange Components
Route optical fibers from internal sensing points through the transformer tank.
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Fiber Optic Extension Cables
Extend the optical path between internal probes and the external monitoring instrument.
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Multi-Channel Temperature Demodulator / Host
Acquire and display temperature data from multiple independent winding measurement points.
→Dry-Type Transformer Temperature Monitoring
For dry-type transformers, fiber optic probes can measure selected winding or coil locations directly. The number of probes, channel count, sensor structure and fiber route should match the winding geometry and available installation space.
Fiber Optic Temperature Probes
Direct temperature measurement at selected dry-type transformer winding and coil locations.
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Custom Multi-Channel Temperature Measurement
Channel count can be configured according to the number of winding measurement points.
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Fiber Optic Temperature Monitoring Systems
Centralized temperature monitoring, alarms and communication for dry-type transformer applications.
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Monitoring Software & Accessories
Software and compatible accessories for temperature display, data recording and monitoring configuration.
→View all transformer temperature monitoring products
Transformer Winding Temperature, Top-Oil Temperature and WTI / OTI
Transformer temperature monitoring often combines different thermal values. These measurements describe different physical locations or use different measurement methods and should not be treated as interchangeable.
Direct Winding Temperature
A fiber optic probe measures temperature at the physical winding location where its sensing tip is installed.
WTI — Winding Temperature Indicator
A WTI provides a winding temperature indication according to the design of the instrument and its measurement arrangement. It is not necessarily a sensor embedded directly at the winding hot-spot location.
OTI — Oil Temperature Indicator
An OTI indicates transformer oil temperature at its sensing location rather than conductor temperature inside the winding.
Direct winding temperature, WTI and OTI can provide complementary thermal information. The required combination depends on the transformer design and monitoring objective.
Why Use Fiber Optic Sensors for Transformer Winding Temperature?
Direct Point Measurement
Measures temperature at the defined physical location where the probe is installed.
Electrical Isolation
The sensing point does not require metallic electrical signal wiring.
EMI Immunity
The measurement signal is transmitted optically through the fiber.
Multi-Point Measurement
Several selected winding locations can be measured with separate probes and monitoring channels.
What Can Transformer Temperature Monitoring Show?
Direct and multi-point temperature data can show how selected transformer locations respond to loading, cooling and changing operating conditions.
1Measured Winding Temperature
Measure temperature at the physical winding locations where fiber optic probes are installed.
2Temperature Rise Under Load
Track how measured winding temperature changes as transformer loading and operating conditions vary.
3Multi-Point Temperature Differences
Compare several selected winding or transformer locations on independent channels.
4Cooling Response
Observe temperature changes as cooling conditions or cooling stages change.
5Abnormal Temperature Trends
Identify changes or deviations in the monitored temperature points over time.
6System Integration
Send temperature values from the monitoring instrument to compatible local or higher-level monitoring systems.
Transformer Temperature Monitoring System Architecture
A transformer temperature monitoring system combines the sensing points, optical signal path, monitoring instrument and required plant interface. The number of probes and channels should follow the number of independent temperature locations that need to be measured.
1Fiber Optic Temperature Sensors
Measure temperature directly at defined winding or transformer locations.
2Monitoring Instrument
Excites the probes, evaluates the optical response and converts it into temperature data.
3Local Display & Monitoring
Displays selected channel temperatures, alarms or trends when supported by the configured instrument.
4PLC / SCADA Integration
Transfers temperature values to a compatible higher-level monitoring or control system.
Documented Transformer Temperature Monitoring Cases
These field records show actual transformer temperature monitoring arrangements, including controller installation and direct winding probe routing.
Transformer Controller Field Installation
A documented local controller and alarm interface at a dry-type transformer installation.
Read documented case →
Dry-Type Transformer Winding Monitoring
A documented probe-routing arrangement for direct winding temperature measurement.
Read documented case →Direct Winding Measurement vs. Indirect Temperature Estimation
Direct fiber optic measurement and indirect temperature estimation provide different types of transformer thermal information. They can be used separately or together depending on the monitoring objective.
| Aspect | Direct Fiber Optic Measurement | Indirect Temperature Estimation |
|---|---|---|
| Measurement basis | Sensor installed at a defined physical location | Temperature calculated or indicated from other measured inputs and a thermal model or instrument method |
| Reported value | Measured temperature at the installed sensing point | Estimated or indicated temperature for the modeled parameter |
| Physical coverage | Only the locations where sensors are installed | The location or parameter represented by the selected model or indication method |
| Installation | Requires physical sensor placement and fiber routing | Does not require an embedded fiber optic sensor at every modeled location |
| Typical use | Verify or monitor selected winding and thermal points directly | Provide continuous temperature indication where direct embedded sensing is not used |
| Combined use | Can be compared with indirect temperature values | Can be used together with direct point measurements |
Direct measurement and indirect estimation are complementary methods when their measurement locations and assumptions are clearly understood.
Transformer Temperature Monitoring Outputs
Available outputs depend on the selected monitoring instrument and system configuration.
Local Temperature Display
View temperatures from selected sensing channels on a compatible local display or monitoring host.
Alarm Handling
Use configured temperature thresholds or alarm functions when supported by the selected monitoring instrument.
Industrial Communication
Transfer temperature values through communication interfaces supported by the configured monitoring instrument.
PLC / SCADA Integration
Map transformer temperature data into a compatible plant or substation monitoring system.
Plan a Transformer Temperature Monitoring System
Share the transformer type, winding arrangement, target measurement locations, expected temperature range, number of sensing points and required monitoring interface. INNO can help match the probe structure, channel count and monitoring instrument to the application.
- Transformer type
- Oil-immersed or dry-type
- Target winding / temperature locations
- Expected temperature range
- Number of sensing points
- Approximate fiber route
- Display / PLC / SCADA requirement
Transformer Temperature Monitoring FAQs
What is transformer temperature monitoring?⌄
Transformer temperature monitoring tracks selected thermal locations such as winding points, top-oil temperature and other defined measurement points. A monitoring system can combine several temperature channels and pass the resulting values to local or higher-level monitoring equipment.
How is transformer winding temperature measured directly?⌄
A fiber optic temperature probe can be positioned at a selected winding location. The sensing tip measures the temperature at that physical point, while optical fiber carries the signal to an external monitoring instrument.
What is the difference between winding temperature and top-oil temperature?⌄
Winding temperature represents the conductor region at the selected winding measurement location, while top-oil temperature represents transformer oil temperature at its sensing location. The two values describe different parts of the transformer thermal condition.
What is the difference between a WTI and direct fiber optic winding temperature measurement?⌄
A WTI provides a winding temperature indication according to the design of the instrument and its measurement arrangement. Direct fiber optic measurement places a sensing tip at a physical winding location and reports the temperature measured at that point.
How many fiber optic temperature sensors are needed in a transformer?⌄
The required number depends on the transformer design and the number of thermal locations that need to be measured independently. For point sensing, each monitored physical location normally uses one probe and one active monitoring channel.
Can fiber optic temperature monitoring be used in both oil-immersed and dry-type transformers?⌄
Yes. The sensing and installation arrangement differs between transformer types. Oil-immersed applications may require internal fiber routing and tank penetration components, while dry-type installations depend on the winding structure, available space and required probe placement.
Can transformer temperature data be sent to PLC or SCADA?⌄
Yes, when the selected monitoring instrument provides a compatible communication interface. The fiber optic probes connect to the monitoring instrument, which then provides the temperature data for the higher-level monitoring or control system.
Discuss Your Transformer Temperature Monitoring Project
Share the transformer type, target measurement locations, number of sensing points and required monitoring interface with INNO.