Transformer breathers are an important component to keep transformers running in good condition for longer. As a transformer heats up and cools down during use, air passes in and out of it, which over time can lead to abrasion and corrosion.

By equipping the transformer with a silica gel breather, you remove the moisture from the air passing through the housing. This ensures that the working parts of the transformer are not exposed to excess humidity, reducing the need for maintenance and repairs.


What is a transformer breather?

A transformer breather acts like a filter to remove unwanted moisture from the air entering the transformer casing. When the transformer is turned on and heats up, the temperature gradient leads to air moving through the equipment, exposing the interior to humidity.

Cable Systems stock several CSL transformer breather types to prevent this moisture from reaching the inner component parts of the transformer:

This variety of transformer breather types suits different budgets and especially different sizes of transformer, with economical CSL HBP transformer breathers for smaller units and CSL HB Multiple breather units for intensive applications.

We also stock CSL Desiccant Breather Mounting Brackets, to ensure that your CSL transformer breather is always positioned correctly and fitted securely in place.


Do all transformers need a breather?

In general, a desiccant transformer breather is a good addition to any transformer. Adding a breather acts as an affordable precaution against moisture ingress into the transformer unit, reducing demand for maintenance and repairs, and lowering long-term running costs.

Transformers with a silica gel breather installed will generally offer better reliability and efficiency over time, particularly when running in humid and dirty environments with a high risk of abrasion, adhesion, erosion or fatigue.


Silica gel in transformer breathers

A silica gel breather uses a desiccant cartridge called a ‘charge’ to extract moisture from the air that passes through it. The silica gel charge is coloured a bright orange, which fades to clear as the desiccant becomes fully saturated.

Saturated charges can be replaced, with the colour of the silica gel providing an easy way to see when a replacement charge is needed. The specialist CSL Breather Dryer Unit can be used to dry saturated charges, allowing them to be reused up to three further times.


Different silica gel colours

Different transformer breather types may use different silica gel colours. Three of the most common colours of silica gel include white, blue indicating and orange indicating. Both blue and orange silica gel can indicate when the gel is saturated and needs to be replenished.

The silica gel in transformer breathers stocked by Cable Systems is typically orange. This bright colouration makes it as easy as possible to see the charge at a distance, with maximum contrast between a new, dry charge and a saturated charge with clear gel.


When should I replace transformer silica gel?

It’s important to replace silica gel in transformer breathers when it becomes saturated (i.e. when the charge turns clear, in the case of blue or orange indicating silica gel). Doing so promptly will ensure that the breather unit continues to function as intended, without allowing moisture into the transformer.

Replacing the charge is easy and full instructions are provided in each breather’s downloadable data sheet and/or installation directions. In general, just unscrew the oil cup and remove any protective shield, unscrew the saturated charge and replace it with a dry desiccant – the entire process should be completed in a matter of minutes.


How to replace power transformer silica gel

There should be no need to replace the silica gel inside a charge; instead, the entire desiccant unit is unscrewed and a new one installed in its place. This ensures that there is no mess, and means personnel do not need to directly handle loose silica gel.

When the charge is saturated (i.e. when the orange colour fades to pale yellow) it should be removed and replaced in accordance with the installation instructions for your model of transformer breather. Saturated charges can be replenished up to three times using the CSL Breather Dryer Unit.

Transformers are essential to operations in many businesses, but are often installed in dirty, humid environments. By adding a CSL transformer breather from Cable Systems, you protect this crucial component against long-term accumulated dirt and damage from the air that passes through it.

If you would like to know more about any of the types of transformer breather mentioned above, please visit the individual product pages and choose the ‘Downloads’ tab for data sheets, catalogues and assembly instructions.