Homepage » News and Case Studies » Approfondimenti » Advantages and Disadvantages of Electro-insulating Varnishes for Electrical Equipment

Advantages and Disadvantages of Electro-insulating Varnishes for Electrical Equipment

Varnishing an electric motor is necessary to maximize operational performance over time. We have seen that an electro-insulating varnish must ensure electrical insulation and protection of the equipment, and the choice varies depending on the component to be impregnated. You can explore the characteristics of these varnishes in this article.

However, it is also important to know that each varnish or impregnation resin has some advantages and disadvantages related to its specific characteristics. Knowing these will help you understand which might be the best choice for your electric motors.

Advantages and Disadvantages of Solvent-Based Electro-insulating Varnishes

Solvent-based varnishes can be either air-drying or oven-drying (the latter are also called thermosetting). Both are easy to use, stable in the tank, and provide good coverage and performance.

On the other hand, they have a series of disadvantages, particularly related to environmental factors:

  1. They are flammable products.
  2. They cause atmospheric emissions that require abatement systems.
  3. They are hazardous to health if handled in unsuitable facilities.

While air-drying paints have a stable market, thermosetting ones are in sharp decline, and both are beginning to be supplanted by water-based varnishes.

Oven-Drying Water-Based Varnishes

The market for thermosetting water-based varnishes is rapidly increasing. This type of impregnant does have some disadvantages. For example, it is less stable in the tank and provides a thinner protective dry film compared to solvent-based varnishes.

The advantages, however, are numerous. Firstly, atmospheric emissions are minimal or non-existent. Secondly, they are non-flammable, making transportation and storage simpler. The reaction odor is low, and they are easy to use as they can be diluted with potable water, resulting in significant overall cost reduction.

Not Just Varnishes: Advantages and Disadvantages of Resins as Impregnants

Resins are the other type of impregnant for electric motors, and again, there are different products with different market trends. Unsaturated polyester resins, for example, are slightly declining, which could be due to various technological and environmental factors.

They can be replaced by the latest generation of less expensive and more practical water-based varnishes. They can pose flammability issues (in the case of polyesters in styrene and vinyltoluene), irritation and strong odor problems (in the case of polyesters in acrylic oligomers or DAP), especially if used in outdated or unsuitable facilities. On the other hand, they are highly stable in the tank, have high reactivity for short baking cycles, and provide good overall performance.

Other types of resins have a growing market. Epoxy resins are stable in the tank, VOC-free, and have almost no emissions. However, they require longer baking times than polyesters, do not offer optimal external coverage, and are generally more expensive. On the other hand, they have high toughness, strong adhesion to all types of substrates, and superior chemical resistance.

Varnishes and resins for impregnating electrical equipment have various characteristics that define their advantages and disadvantages: in any case, the context must be analyzed to understand which product is best to ensure maximum performance.