TRANSEC CL3A On-Line molecular sieve drying unit suitable for power transformers with an oil volume exceeding 10,000 litres.

TRANSEC CL1 On-Line molecular sieve drying unit suitable for power transformers with an oil volume of less than 10,000 litres.


When a new transformer  leaves the factory, the insulation has been kiln dried and will probably have a moisture content of approximately 0.3% of the dry weight of the insulation.  Under normal operating conditions that moisture content will start to rise very gradually from the date of supply and  will increase in an exponential manner as the transformer ages.

If a TRANSEC On-line drying unit is installed when the transformer is commissioned it will ensure that the oil remains dry, and hence the insulation will remain dry.  It breaks the ageing pattern of a normal transformer, and will significantly extend the life of the transformer.

Because the transformer is dry, the molecular sieve will only remove small amounts of water, so the period before regeneration is required will be quite long.

………….CL1 Standard Unit

An existing wet transformer will benefit from the installation of TRANSEC on-line drying unit  to reduce the volume of water contained within the solid insulation.  This has the benefit of slowing the rate of ageing, and also reducing the vulnerability of the transformer to life threatening events such as through faults.

Unlike some other methods of  drying, using heat and vacuum,  the TRANSEC method of water  removal  is gradual and non-invasive.  The rate of removal will depend on many factors, primarily  being the quantity of water available to be adsorbed, but also operating temperature and ambient conditions.


A spare transformer must be ready to be put into service at a moments notice, and therefore must be in a dry condition whilst in storage.  TRANSEC will ensure that the oil remains dry whilst it is un-energised and prone to condensation.