शीर्षस्थानी 10 Dry-Type Transformer Monitoring System Manufacturers: Best 2025 Review

1. FJINNO: Specialist in fluorescence-based Fiber Optic Temperature Sensing (FOTS), offering high-accuracy, EMI-immune direct winding monitoring solutions ideal for dry-type transformers.
2. Tecsystem S.r.l.: Leading Italian manufacturer of dedicated electronic temperature controllers and relays (Pt100-based) providing comprehensive protection and fan control for dry-type transformers.
3. OSENSA Innovations: Develops specialized FOTS systems (PWR+ series) specifically for cast resin transformer winding hot spot monitoring, emphasizing reliability in high-voltage environments.
4. COMEM Group (Hitachi Energy): Offers reliable Pt100-based temperature monitoring units (DTI/eDTI series) tailored for dry-type transformers, integrating protection and control features.
5. Exertherm: Focuses on continuous, non-contact infrared (IR) monitoring of critical electrical connections, a vital supplement for dry-type transformer terminal hot spot detection.

Introduction

Dry-type transformers, including cast resin and vacuum pressure impregnated (VPI) designs, are widely used in indoor applications, industrial settings, and environments where the fire safety and environmental benefits over oil-filled units are paramount. तथापि, like all transformers, they are susceptible to overheating, primarily due to winding insulation degradation under thermal stress. Effective temperature monitoring is crucial for preventing premature failure, ensuring operational safety, optimizing load management, and maximizing the lifespan of these valuable assets. This guide explores the specific monitoring needs of dry-type transformers, reviews the common technologies, and presents the top 10 manufacturers providing dedicated monitoring systems and solutions in 2025.

What is Dry-Type Transformer Temperature Monitoring?

Dry-type transformer temperature monitoring involves measuring the temperature at critical locations within the transformer assembly to ensure it operates within safe thermal limits. The primary focus is typically on the windings, as their insulation dictates the transformer’s thermal rating and lifespan. Monitoring usually involves sensors embedded within or near the windings (most commonly Pt100 RTDs or sometimes FOTS) connected to an external electronic monitoring unit or relay. This unit processes the sensor signals, displays temperatures, activates alarms or trip circuits if preset limits are exceeded, and often controls cooling fans to manage operating temperatures under load.

Why Monitor Dry-Type Transformer Temperature?

• Prevent Insulation Failure: The solid insulation (resin, varnish) used in dry types degrades rapidly if subjected to excessive temperatures. Monitoring helps prevent thermal runaway and insulation breakdown.
• Ensure Safety: Overheating can create fire hazards, especially since dry types are often installed indoors or near personnel. Monitoring reduces this risk.
• Optimize Loading: Accurate temperature data allows operators to understand the transformer’s thermal condition and potentially utilize its full load capacity, or even overload capacity according to standards, without compromising its life.
• Control Cooling Efficiency: Monitoring systems typically control cooling fans (Air Forced – AF cooling), turning them on only when needed, saving energy and reducing noise compared to continuous fan operation.
• Enable Predictive Maintenance: Temperature trends can indicate issues like blocked cooling ducts, fan failures, or developing winding faults, allowing for planned maintenance before failure occurs.
• Extend Asset Life: Keeping the operating temperature within design limits, especially the winding hot spot, is the single most effective way to maximize the transformer’s service life.

How Dry-Type Transformer Monitoring Systems Work

Several technologies are prevalent in monitoring dry-type transformers:

Pt100 RTDs and Controllers

This is the most common method. Pt100 Resistance Temperature Detectors (RTDs) are embedded in the transformer windings (often multiple sensors per phase) during manufacturing. These sensors exhibit a predictable change in electrical resistance with temperature. Wires from these sensors are routed to a dedicated electronic Temperature Monitoring Unit (also called a controller or relay). This unit measures the resistance, converts it to temperature, displays the values (often showing the highest reading or cycling through sensors), compares readings against user-settable Alarm and Trip thresholds, and controls output relays for signaling and cooling fan activation. Manufacturers like Tecsystem, Orion Italia, COMEM, and ZIEHL specialize in these controllers.

Fiber Optic Sensors (FOTS)

Increasingly used, especially for higher voltage dry types, critical units, or installations with high electromagnetic interference (EMI). FOTS sensors (e.g., fluorescence-based or FBG) are embedded in windings similarly to Pt100s but use light signals transmitted via dielectric optical fiber. This makes them completely immune to EMI and provides excellent electrical isolation. An external interrogator unit processes the optical signals to determine temperature. Companies like FJINNO, OSENSA, Qualitrol, आणि Rugged Monitoring offer FOTS solutions suitable for dry-type transformers.

Infrared (IR) Monitoring

While Pt100s and FOTS monitor the windings, IR monitoring focuses on external connections (high and low voltage terminals/bushings and cable lugs). These connections can loosen over time due to thermal cycling and vibration, increasing resistance and generating heat. Continuous IR sensors (like those from Exertherm) or periodic inspections with thermal cameras can detect these hot spots before they cause failure. This complements winding temperature monitoring.

Thermocouples

Less common than Pt100s for primary winding monitoring in dry types, but some monitoring systems (like Qualitrol’s 118 ITM or AMR PEMCO’s STM) are designed to use Type K or other thermocouple inputs. They function similarly to RTD systems but utilize the voltage generated by the thermocouple junction.

शीर्षस्थानी 10 Dry-Type Transformer Monitoring System Manufacturers

This list highlights manufacturers providing dedicated controllers, advanced sensor systems, or integrated solutions specifically relevant to dry-type transformer monitoring.

Frequently Asked Questions (वारंवार विचारले जाणारे प्रश्न)

What is the most common way to monitor dry-type transformer winding temperature?

The standard and most common method is using Pt100 RTD sensors embedded in the windings, connected to a dedicated electronic temperature monitoring controller/relay that provides display, alarms, trip functions, and fan control.

Why would Fiber Optic Sensors (FOTS) be used in a dry-type transformer instead of Pt100s?

FOTS may be preferred for higher voltage dry-type units (e.g., above 35kV), installations with very high electromagnetic interference (EMI), applications requiring the highest accuracy, or where complete electrical isolation between the sensor and monitoring unit is critical.

Is Infrared (IR) monitoring useful for dry-type transformers?

Yes, primarily for monitoring the external connections (high and low voltage terminals and lugs). These bolted connections can develop hot spots due to loosening or corrosion, and IR monitoring (continuous or periodic) is an effective way to detect these issues, complementing the winding temperature monitoring.

What are typical temperature alarm and trip settings for a dry-type transformer?

Settings depend on the transformer’s insulation class (e.g., Class F – 155°C, Class H – 180°C) and manufacturer recommendations. Typically, fan activation might be set below the rated temperature rise, Alarm set near the rated temperature rise limit, and Trip set somewhat higher (e.g., 10-15°C above Alarm) to allow for brief excursions but protect against damaging sustained overheating. Always consult the transformer manufacturer’s specific guidelines.

Can these monitoring systems be integrated into SCADA or building management systems?

Yes, most modern electronic temperature monitoring controllers offer communication ports (commonly RS-485 with Modbus RTU protocol, sometimes Ethernet/Modbus TCP or other protocols) allowing temperature data, alarm status, and other parameters to be transmitted to higher-level supervisory systems.

Conclusion and Recommendation

Monitoring the temperature of dry-type transformers is not merely optional; it is fundamental to their safe and efficient operation. Utilizing dedicated monitoring systems, primarily based on reliable Pt100 sensors and controllers, or increasingly advanced Fiber Optic sensors for specific applications, allows asset owners to protect their investment, ensure personnel safety, and optimize performance. Supplementing winding monitoring with checks on connection points, often using infrared technology, provides a more complete thermal picture.

The market offers excellent solutions from specialized European controller manufacturers, innovative FOTS providers, and large automation companies. Choosing the right system involves matching the technology and features to the transformer’s specifications and the facility’s operational needs.

Disclaimer: This guide provides general information based on publicly available data and search results as of April 2025. Technologies, market positions, and company offerings can change. Always conduct thorough research and consult directly with manufacturers to determine the best solution for your specific application requirements and transformer specifications.

 

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