Functions of Varnish on Transformers
The tiny layer of varnish used on transformers provides a number of necessary functions that are largely connected to insulation and efficiency:
- Insulation
- Reduction of Eddy Currents
- Mechanical Stability
- Environmental Protection
- Thermal Management
1). Insulation
The varnish has the role of an isolation barrier that protects against shortening of electric connections between the windings and other core parts. This insulation is important in preserving the configuration of the electrical system within the transformer particularly in air cooled transformer units where moisture and dust are potential hazards.
2). Reduction of Eddy Currents
Laminations of the core are coated with varnish, which in turn increases the effective resistivity in the circuit and hence restricts eddy current. Eddy currents are those undesirable currents which tend to bring about heat and energy losses on the core of the transformer and therefore a drop in efficiency. The varnish also improves the insulation between the thin steel laminations, thus reducing these unwanted currents.
3). Mechanical Stability
The varnish further assists in immobilizing the windings in a manner that the windings cannot vibrate or move when exposed to the opposite magnetic field. This stabilization decreases mechanical stress that otherwise exerts pressure on the different components of a transformer thus increasing its life span.
4). Environmental Protection
The varnish layer enhances protection from moisture, dust and other conditions that would otherwise impeded the efficiency of the transformer. This is especially true for transformers working in less graceful conditions48.
5). Thermal Management
Some of the insulating varnishes enhance the heat dissipation feature of a product and are useful in products that are used in operations that generate heat. This can result in reduced operating temperatures and the corresponding improvement of 4 parameters of performance.
You can also follow us on AutomationForum.co, Facebook and Linkedin to receive daily Instrumentation updates.
You can also follow us on ForumElectrical.com , Facebook and Linkedin to receive daily Electrical updates.