Methods of Transformer Oil Filling

Transformer oil after filtration, degassing and dehydration will be injected into transformer oil tank, this step is called as Transformer Oil Filling.

Transformer oil filling usually takes the following two methods:

(1) Vacuum Oil Filling.

According to the requirements of the factory instructions. While keeping the oil tank with a certain degree of vacuum, inject qualified transformer oil slowly from the drain valve at the bottom of the oil tank (the vacuum degree is not released during oil filling).

The use of vacuum oil injection can help prevent the mixing of moisture in the oil and remove the air and moisture remaining in the transformer (because moisture can only be vaporized at 100°C, however in a full vacuum, even room temperature water will vaporize). The higher the rated voltage of the transformer, the stricter the insulation requirements, especially the large-scale high-voltage transformers produced in recent years, which use tangled windings with higher turn-to-turn voltage, thin paper tubes with smaller main insulation gaps, and small oil gaps. The structure, and the forced oil circulation cooling device with more chances of air accumulating in the voids of the body, so vacuum oil injection is more important.

For vacuum oil filling, you may need: Double-Stage High Vacuum Transformer Oil Purifier (suits for above 110KV) | Single-Stage Vacuum Transformer Oil Purifier (suits for 66 KV and below) | Vacuum Pumping System (Transformer Evacuation System)

(2) Conventional Oil Filling.

Under atmospheric pressure, use an oil pump to inject qualified transformer oil into the oil tank. In order to reduce air mixing when filling oil, the oil should be filled slowly from the oil drain valve at the bottom of the oil tank, and all air bleed plugs should be opened at the same time to discharge the air in the oil tank until the oil is discharged from the air plug. This oil injection method is generally suitable for transformers with a voltage of 60kV and below.

For conventional oil filling, you may need: Portable Oil Filter Cart (Oil Transfer Unit).

More details about transformer oil filling and transformer oil maintenance, please contact us freely.