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VPI: Why Insulation Is Important For Your Motor Windings

VPI: Why Insulation Is Important For Your Motor Windings

Electric motors are machines. Hence, they are susceptible to damage or deterioration in their efficiency. When this occurs, your electric motor will most likely require repairs or electric motor rewinds. Electric motor rewinding is a winding process that aims to enhance the efficiency of motors, especially those that have experienced deterioration.

After an electric motor is rewound, its windings need further insulation with varnish or resin. There are four main varnishing methods, but the most common ones are dip and bake epoxy varnishing and vacuum pressure impregnation.

The Importance of Motor Winding Insulation

As mentioned earlier, insulation is a necessary process after an electric motor is rewound. This insulation protects the motor windings from shorting electrically and contamination, and it also makes the windings more mechanically firm and secure. Additionally, insulation dissipates the heat generated by the windings. All of these are essential for the efficient operation of your electric motor.

Essential Steps in the VPI Process

Vacuum pressure impregnation (VPI) is one of the most common methods of insulating electric motor windings. However, compared to its closest alternative – dip and bake – VPI is the more modern and technologically savvy technique for insulating electric motor coils. The ultimate result of the VPI procedure is a 4 to 5-millilitre insulation build that is essentially void-free.

Here are the basic steps in the VPI procedure:

  • Step 1: Preheat the winding that comes with green coils in it.
  • Step 2: After preheating, lower the winding into a pressure chamber known as the “impregnation chamber.”
  • Step 3: Seal the chamber and draw a vacuum.
  • Step 4: As the vacuum is drawn, let the solventless epoxy resin flow from the resin vessel into the chamber until the full winding is submerged.
  • Step 5: Apply pressure to the chamber until the winding becomes extensively impregnated with epoxy resin.
  • Step 6: Remove the winding from the pressure chamber, and put it in a baking oven until the resin is completely cured.

The Difference Between VPI and Dip and Bake

Alongside VPI, dip and bake is one of the most common varnishing methods. These processes are essentially different from each other. In dip and bake, the electric motor windings are immersed into the varnish tank and set to cure in an oven. Most of the time, a new motor winding needs to be dipped twice to ensure that the varnish completely covers the windings.

On the other hand, in VPI, a vacuum pressure tank full of varnish is utilised to impregnate the motor windings completely. Insulation is also used with varnish or resin. Compared to dip and bake, VPI is practically free from the void, resulting in insulation with much-improved quality. Moreover, it will not be susceptible to conduction contamination since the coils are insulated using a basic varnish dipping.

VPI is also better for those who want insulation that can effectively conduct heat away. With VPI, the insulation process will have a cooler operating temperature and a far less risk of heat-related degeneration. Dip and bake cannot offer the same results due to voids and air gaps in the insulation.

Because of the integrity of VPI’s insulation process, you can expect your motor windings to become more rigid and tight than those done through varnish dipping. This can substantially impact the length of the coils’ life since rigid insulation minimises the possibility of abrasion and rubbing, which are common culprits that can severely compromise the windings’ ability to perform their job.

Conclusion

Electric motor rewinds can cost a lot, so it is important to make the right decision regarding how you want the insulation process to be. If you are looking for an insulation method that is practically void-free, significantly lessens motor failure probability, improves motor performance and mechanical winding design, and facilitates better efficiency, VPI is undoubtedly the approach you need!\

However, to ensure the benefits of VPI are achieved, it is highly advised that you seek the help and guidance of specialists from a reliable company in mechanical and electrical engineering in Singapore. These companies typically have the expertise necessary to conduct intricate processes like VPI and maintain electric motors. They can most safely and efficiently provide mechanical and electric services, such as generator overhauling and motor rewinding.