The "Five Senses" And "Nerves" of An Oil-Immersed Transformer

In the grand scheme of the power system, oil-immersed transformers act like a steady and powerful "heart," continuously converting and transmitting energy. However, the strength and intelligence of this "heart" rely not only on the perfect design of its core and windings but also on the crucial system of components surrounding it, each performing its own dedicated function. These components are the transformer's senses, armor, and control center, working together to ensure decades of safe, efficient, and intelligent operation. This article systematically analyzes the key components of oil-immersed transformers, revealing the vital roles of these "unsung heroes."

I. Safety Protection System: The Transformer's "Vital Signs Monitor" and "Immune System"

Safety is the top priority in transformer operation. The related components form a multi-level protection system.

1. Conservator (Oil Tank) & Breather

• Function: The conservator acts like the transformer's "breathing lung," balancing oil volume changes caused by temperature fluctuations to ensure the main tank is always full, preventing air and moisture ingress. The breather (or dehydrating breather) is its "air filter"; the silica gel inside absorbs moisture from the air, keeping the internal environment dry.

• Evolution: Modern diaphragm or bladder-type conservators completely isolate the oil from the air, fundamentally preventing oil oxidation and moisture ingress.

2. Buchholz Relay & Pressure Relief Device

• Function: These are the core "safety fuses" of the transformer. The Buchholz Relay (gas relay), installed on the pipe between the conservator and the main tank, sensitively detects the generation of minor gases (indicating potential faults) or sudden oil flow (e.g., from a severe internal fault), triggering alarms or trip signals. The Pressure Relief Device is the final pressure relief port, opening rapidly during a drastic internal pressure surge to prevent tank rupture.

3. Sudden Pressure Relay

• Function: Compared to the Buchholz relay, it reacts much faster (in milliseconds) to a sudden pressure rise within the tank, providing quicker protection against sudden severe faults like internal arcing.

II. Performance & Efficiency Assurance System: The Transformer's "Health Manager"

These components are dedicated to maintaining and optimizing the transformer's operating condition.

1. Cooling System

• Function: The transformer's "cooling system." Includes radiators, cooling fans, and oil pumps. It effectively dissipates heat generated during operation, preventing thermal aging of the insulation. Intelligently controlled fans can start and stop automatically based on oil temperature, saving energy.

2. On-Load Tap Changer

• Function: The transformer's "intelligent voltage regulation hub." It allows for automatic or manual adjustment of the output voltage without interrupting the load, making it the core precision component for stabilizing grid voltage and optimizing power quality. Its internal diverter switch, selector, and online oil filtration unit demand extremely high reliability.

III. Condition Sensing & Intelligence System: The Transformer's "Digital Nerves"

Modern transformers are evolving towards intelligence, with related components serving as their data sources.

1. Bushings

• Function: They are both insulating supports for high-voltage leads and platforms for sensor integration. Modern intelligent bushings can have built-in capacitance taps for online monitoring of parameters like dielectric loss, capacitance, and partial discharge to assess insulation aging.

2. Online Monitoring Devices

• Dissolved Gas Analysis (DGA): The most effective early warning tool. Analyzing characteristic gases like H₂, CH₄, C₂H₂ can detect latent faults such as overheating or discharge at an early stage.

• Fiber Optic Winding Temperature Measurement: Provides direct and accurate measurement of winding hot-spot temperature, reflecting true loading capacity better than traditional oil temperature gauges.

• Partial Discharge Monitoring: Captures weak discharge signals from internal insulation defects.

• Moisture-in-Oil Monitoring: Tracks the water content in the insulating oil in real-time.

• Function: The transformer's "24/7 physical examiner." Common monitoring includes:

3. Intelligent Control Cabinet

• Function: Integrates data from all the above sensors for local analysis and display. It can also transmit data to a central station via communication interfaces (e.g., IEC 61850) for remote condition assessment, fault diagnosis, and predictive maintenance.

IV. Foundational & Auxiliary Components: The Indispensable "Cornerstones"

1. Tank & Valves: The transformer's "body" and "joints," requiring high mechanical strength and excellent sealing.

2. Thermometers & Level Gauges: The most basic "thermometer" and "fuel gauge," providing direct visual indication of oil temperature and level.

3. Grounding Terminals & Nameplate: Essential for safe grounding and the equipment's "identification card."

Conclusion: The Component System—A Value Evolution from Passive Protection to Active Sensing

In the past, transformer components primarily played a role of "passive protection." Today, they have evolved into a comprehensive system that integrates safety protection, condition sensing, intelligent control, and efficiency optimization. Choosing high-quality, well-matched components is no longer a simple "add-on" but a strategic investment in the transformer's lifecycle reliability, economy, and intelligence.

For power users, a deep understanding of these components means better maintenance strategies, improved interpretation of early warnings, and extended equipment life. For manufacturers, providing advanced, integrated component solutions is a concentrated reflection of technical strength and customer value.