What are the transformer oil purification equipment?

Transformer oil purification equipment is primarily used to remove moisture, gases, particulate matter, and oxidation products from the oil, thereby restoring the insulation performance and chemical stability of the oil. The following are the common classifications and characteristics of transformer oil purification equipment:

Main types of transformer oil purification equipment

(1) Vacuum oil filter (core equipment)

Function:

Dehydration (can treat free water and dissolved water to make the moisture content ≤5ppm).

Degassing (remove dissolved air, hydrogen, etc., gas content ≤0.1%).

Filter particles (cleanliness reaches NAS 1638 level 6 or higher).

Working principle:

Vacuum flash evaporation: The oil is atomized in the vacuum tank, and the moisture and gas evaporate at low temperature.

Multi-stage filtration: pre-filtration (10μm) → fine filtration (1-3μm) → coalescence separation (optional).

Applicable scenarios: new oil treatment, running oil regeneration, transformer installation/maintenance.

(2) Pressure oil filter

Function:

Mainly remove mechanical impurities (such as metal chips, fibers), with a filtration accuracy of 1-5μm.

Can be used with adsorbents (silica gel, activated alumina) to remove acidic substances.

Features:

Simple structure, suitable for rapid on-site purification, but weak dehydration ability.

(3) Centrifugal oil filter

Function:

Separates water and heavy pollutants through centrifugal force (suitable for large amounts of free water or sludge).

Disadvantages:

Unable to remove dissolved water; requires use with vacuum equipment.

(4) Adsorption oil purification system (such as RTL regeneration device)

Function:

Deeply remove acidic compounds, colloids, and pigments (acid value ≤0.01mg KOH/g).

Commonly used adsorbents: kaolin, silica gel, molecular sieve.

Applicable scenarios: Regeneration of aged oil (when the dielectric loss value is high or the acid value exceeds the standard).

(5) Online monitoring + automatic purification system

Function:

Real-time monitoring of moisture, particles, and dielectric loss, triggering automatic purification (such as intelligent maintenance during live transformer operation).

Key performance parameters

Indicator Requirements

Moisture after treatment ≤5ppm (≤3ppm for ultra-high voltage transformers)

Gas content ≤0.1% (volume ratio)

Breakdown voltage ≥60kV (new oil standard)

Particle cleanliness NAS 1638 level 5-6 or ISO 4406 14/12/9

Acid value ≤0.03mg KOH/g

Selection recommendations

Mild pollution (daily maintenance):

ｓｅｌｅｃｔ a vacuum oil filter (with heating function, flow matching transformer oil volume).

Severe aging (high acid value, dark color):

Vacuum oil filter + adsorption regeneration device (such as RTL tower).

Live operation:

Use a two-stage vacuum oil filter (explosion-proof type) to avoid downtime.

Operation precautions

Temperature control: The recommended heating oil temperature is 50-65℃ (too high will accelerate oxidation).

Vacuum degree: Maintain ≤-0.095MPa to improve dehydration efficiency.

Prevent secondary pollution: Pipes and storage tanks must be cleaned in advance and made of stainless steel.