About YAAN

Henan Yaan Insulation Material Plant Co., Ltd

Add: No1.West Shunxiang Road, Weidu district, Xuchang City, Henan Province,China 461000.

Tel: +86-199 3740 8623

Yaan insulation

Insulation experts around the enterprise

Four Types of Insulation Varnishing Methods

Insulating varnishes and impregnating resins are thermosetting resins such as epoxies or phenolics. They are used to ensure that electrical devices, including motors, generators, transformers, sensors, and other devices that function by electromagnetic induction, have the necessary electrical insulation and structural integrity for operation. These materials crosslink when applied and are, therefore, inherently strong, environmentally stable, impervious, and durable. Transformers, for instance, are comprised of coil windings where the electric wires are protected by a thermosetting resin or an insulating varnish (also called a wire enamel or primary insulation) to prevent electrical shorting. The completed transformer, comprised of an assembly of coil windings and insulating paper, is sealed with a thermosetting resin to provide environmental protection (especially from moisture and dust) to eliminate air in the transformer that can conduct electricity and heat, and to provide strength.

After a motor is rewound, the windings must be further insulated with resin or varnish. This insulation protects the windings from contamination, shorting electrically, and also make the windings more mechanically rigid. There are four types of varnishing methods that we will describe below: Dip and Bake Epoxy Varnishing, Trickle Varnishing, Vacuum Pressure Impregnation, and Ultra-Sealed Winding.

Dip and Bake is a standard varnishing technique where the motor windings are dipped into a varnish tank and then set to cure in an oven. Typically, a new motor winding should be dipped twice (double dip and bake) to ensure the varnish fully covers the windings.

Trickle Varnishing The winding is connected to a rotating table and electrical wires. Using electrical resistance, the winding gets heated while spinning. Once at temperature, a tiny stream of varnish is trickled onto the winding head. The varnish follows the wire into the entirety of the slot, eliminating chances for partial discharge in random windings. Once fully saturated, the current is increased in the windings, resulting in the varnish curing while on the machine. This process is faster and better than the traditional dip and bake process because it cures on the machine – making it ideal for emergency repairs.

Vacuum Pressure Impregnation (VPI) utilizes a vacuum pressure tank filled with varnish to fully impregnate motor windings and insulation with resin or varnish. At Dreisilker, we preheat our windings, place the windings in our 10 ft. diameter tank, draw a vacuum, fill the tank until the resin or varnish covers all of the winding, then pressurize the tank.

Ultra-Seal Winding is an alternative method of insulating a motor’s windings. Ultra-Sealed windings are completely impregnated and seals the coils with high molecular weight thermoset polymer resin. This allows for total protection against moisture, contaminants, and more efficient cooling.