Vacuum Dehydration Unit: Why Is It Used in Power Systems?

The modern electric power system is crucial to today’s civilization and is heavily relied on to function reliably and without interruption. Transformers, the heart of the system, facilitate the economical transfer of power across vast distances and its disbursement locally by stepping the voltage up and down. The enduring and faultless operation of the transformers, however, is fully reliant on the state of the insulating medium, primarily transformer oil. It is in this aspect that the oil dehydration unit, or vacuum transformer oil dehydration machine, fulfills its vital function as the keeper of grid stability.

Part 1: Understanding Vacuum Dehydration Units and the Principle of Water Removal Through Vacuum Technology

A vacuum dehydration unit is one of the purification units designed for the removal of water, gas, and solid impurities from the transformer insulating oil. It works on the principle of how pressure and evaporation work in physics.  Under vacuum conditions, water boils at a much lower temperature; hence, water easily evaporates and is removed from the oil in a vacuum chamber at lower temperatures (60 to 70 °C) as compared to the boiling temperature of water.

During the dehydration of oil, the water evaporates, and the gas removed in the transformer oil series is then degassed in the vacuum chamber, and the evaporated water vapor is removed through the vacuum pump system. The dehydrated oil is then returned to the transformer or storage tank. This method is far better than mechanical filtration or centrifugal separation and achieves a moisture content of less than 5 parts per million.

Part 2: The Function of the Vacuum Dehydration Unit in Power Systems

1. Safety, Stability, and Uninterrupted Supply in Power Systems

For every power grid operator, the overriding goal is the uninterrupted and safe provision of electricity. The consequence of failing to deliver this fundamental service can result from not only the huge economic impact and safety risks that arise from widespread blackouts, but also the failure of critical grid elements such as large power transformers.

2. Transformers and Insulating Oil

The power transformer is one of the most vital and costly assets in the grid. It has two main components: the copper windings and the insulating system, which includes cellulose paper (solid insulation) and insulating oil (liquid insulation). The oil performs two important tasks: it cools the windings and provides the main dielectric strength to prevent electrical discharge (arcing).

3. The Deadly Harm of Moisture

Water is the most destructive contaminant in transformer oil. Even tiny amounts of water can set off a sequence of serious problems.  

• Reduced Dielectric Strength: Water greatly weakens the oil’s breakdown voltage and insulating capabilities. This markedly increases the chances of flashover and catastrophic internal faults. Increasing the water content from 10 ppm to 50 ppm can reduce the dielectric strength by more than 50%.  
• Accelerated Insulation Aging: Moisture speeds up the hydrolysis of solid cellulose insulation (paper), producing more water and acid, in a vicious cycle. This can reduce the transformer’s life by decades.  
• Bubble Formation: During high-temperature operation or heavy loading, moisture contained in solid insulation can vaporize and form low dielectric strength bubbles which can result in immediate electrical failure.

4. The Vacuum Dehydration Unit is Irreplaceable

Due to the critical sensitivity of transformer insulation to moisture, traditional methods of filtration which can remove free and emulsified moisture, become inadequate. It is only the vacuum dehydration unit that can remove dissolved water and dissolved gases to levels often less than 5 ppm. This ability renders the vacuum process the gold standard and, indeed, the vacuum dehydration unit becomes irreplaceable for the deep purification needed to preserve and repair the insulating quality of transformer oil and the solid insulation of the transformer.

Part 3: Common Applications in Power Systems

The application of the vacuum dehydration unit extends across the entire lifecycle of power equipment:

Application Context	Application Background	Process Summary	Importance
1. Pre-treatment of New Oil	Although new oil might appear demeaned and “fresh”, there is a high likelihood that relaxing might still hold some unacceptable volume of moisture and gas that is absorbed while in transit and during the period of storage.	Taking into consideration the unit, it tends to new oil before it gets injected, and at times, in a single pass.	Guarantees and protects that the initial filling is in compliance and does not contaminate the transformer’s solid insulation.
2. Deep Drying After Installation/Overhaul	Moisture absorbed during operation and not removed before post-installation or major repair works on the transformer’s core and the windings with the cellulose insulation.	The unit performs a “Hot Oil Circulation Drying” where hot, ultra-dry oil is circulated repeatedly through the transformer. The ultra-dry oil sucks moisture out of the oil and out of the solid insulation, and the unit exhausts the oil moisture.	Moisture is strategically positioned during post-dry operations, the insulation that determines the life of the transformer.
3. Online/Offline Oil Maintenance	Transformers working for long duration periods through breathing, micro-leaks, and oil degradation, naturally absorb moisture and gases over time.	The unit is connected for online purification to the running transformer, while for offline maintenance, it’s connected to the oil storage tank.	It removes the particulates and other impurities and maintains cleansing of the oil. Enhances the lifespan of the oil and the transformer. Avoiding unforeseen failures and guaranteeing optimal oil quality in the course of its service life.
4. Accident Repair and Recovery	It can happen that when an oil has an internal defect or Contaminants have entered the oil through an ingress seal, it can cause severe degradation in the quality.	It is of a unit that is deployed to, along with full regeneration, to process the contaminated oil, under specific conditions, to stabilize the properties of the oil for immediate system recovery.	Indispensable in saving the grid from failure and minimizing additional damage to equipment in critical scenarios.

Part 4: Value and Benefits in Power System Operations

Vacuum dehydration units that are applied in the power sector show great value and benefits, such as:  

• Ensuring Grid Safety: The unit preserves critical insulating oil and flashover dielectric oil, which otherwise leads to electric faults, thus stabilizing the power system.  
• Prolonging Equipment Lifespan: The deep drying of cellulose insulation and transformers, which preserves their aging, adds more value as these transformers are multi-million-dollar assets.  
• Increasing Supply Reliability: Users and the power sectors benefit greatly due to the improved and clean oil that eliminates insulation failure, which eliminates downtimes and outages.  
• Enhanced Economic Value: Power firms maximize their assets and save on equipment that is cheap for electronics value in equipment that extends lifespans, unplanned downtimes, oil changes, and transformer overhauls.

Part 5: Recommendation

For the professionals in the power system industry, the choice of transformer oil purification machine has significant consequences in terms of the condition of the assets and the safety of the power grid. In this context, we suggest that users seeking reliable and high-efficiency vacuum dehydrators manufactured by Chongqing Yuneng.  

Advanced vacuum technology, strong equipment construction, and the ability to meet virtually any international standard are all hallmarks of this oil purification machine manufacturer. Reliability, safety, and system efficiency are all dramatically improved with the use of Yuneng oil purifiers. Don’t wait to check Yuneng’s official webpage – These are advantages that your operations simply cannot afford to miss.