Video: AE865C

Video transcript

What the AE865C does to insulating oil, how its vacuum process works step by step, and how the cart is used beside the equipment. Insulating oil picks up 3 kinds of contamination: water, dissolved gas and particles. All 3 lower its dielectric strength, and oil saturated with gas forms bubbles more easily. Left in, they also speed up the ageing of the oil. Transformer manufacturers recommend less than 10 parts per 1000000 of water.

For small volumes, a full-size purifier is out of proportion. The AE865C treats 230 litres an hour, and leaves the oil with less than 10 parts per 1000000 of water and less than 0.25% of gas, under a vacuum below 0.025 millibar. The process, in 5 steps. The oil is heated. In the vacuum chamber it spreads as a thin film. The vacuum pump draws off the water vapour and the gases. The outlet pump takes the treated oil out, and a fine filter holds back the particles.

The circuit, from left to right. The oil comes in through a camlock hose and passes the 3 kilowatt heater. It enters the top of the vacuum chamber, filled with accelerator elements. The vacuum pump works on the top of the chamber. From the bottom, the outlet pump sends the oil through the 3 micron after-filter, back to the equipment. Heating first. The process works on warm oil: the 3 kilowatt heater brings the oil to process

temperature on its way from the equipment to the chamber. Inside the chamber, the accelerator elements do 4 things. Their depth structure makes free water coalesce and separate, even before it evaporates. 1000000 of glass fibres, 3 to 10 micrometres thick, spread the oil into a thin film with a large surface exposed to the vacuum. The sharp points of the fibres release the gases quickly. And the elements also act as a fine filter.

The vacuum pump keeps the chamber below 0.025 millibar. At that pressure the water in the oil evaporates, and it leaves with the dissolved air and gases through the pump. Dehydration and degassing happen together, in one continuous pass. The treated oil collects at the bottom of the chamber. The outlet pump takes it out, with its pressure shown on the outlet gauge, and pushes it through the 3 micron after-filter and back to the equipment through the camlock outlet.

The cart, from the back: the vacuum pump in the middle, the vacuum chamber behind it, the camlock oil connections with their valves at the side, and two pneumatic tyres of 250 millimetres. It weighs 125 kilograms, and goes where the oil is. On the front, the controls are two switches: one for the vacuum pump and one for the outlet pump. Beside them, the vacuum chamber. Below, the oil outlet pump, and the gauge that shows the outlet pressure.

In outline: the two camlock hoses between the unit and the equipment, the 3 metre cord to a 230 volt single-phase supply, and the two pump switches. From there the unit works unattended, and an optional vacuum controller automates the cycle further. The results are measured by standard methods. Water below 10 parts per 1000000, by Karl Fischer titration. Total gas below 0.25%. And new oil reaches at least 40 kilovolts of dielectric strength. And how it compares with the AEHV series.

The AE865C treats 230 litres an hour, on a cart of 125 kilograms. The AEHV goes from 200 to 12000 litres an hour, on skids, trailers or containers, for up to 60000 kilograms of oil. And the specification, in one table. Where it is used: the oil of pole-mounted transformers, bushings, conservators and other small volumes, individual drums of insulating fluid, and periodic drying and degassing during maintenance. Insulating oil treatment, from Amperis.