As the name implies, a sealed coil is an electric coil that has been sealed by some form of material, which can be a polymer resin or some type of rubber. Though a coil may have insulation, sealing it offers an extra layer of protection as well as insulation. The biggest advantage to a sealed coil is the assurance that it is totally protected against moisture. One of the problems that needs to be avoided with a coil is the accumulation of heat that can damage the coil and cause excessive wear. The various materials that are used to seal a coil are designed to increase heat transfer and keep the coil cool. This particular feature is one of the reasons that sealed coils are an excellent addition to an electric motor.
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Applications of Sealed Coils
The purpose of sealing a coil is to prevent it from being damaged by intrusive factors, such as moisture and random electrical charges. The added sealing material offers the benefit of a front line against damage to the coil. Coils that are wells sealed are normally found in environments that have harsh conditions such as inclement weather and immersion in water. The high resistance of the sealing material and its protective qualities ensures the life span of the coil.
Sealed Coil Design and Function
A common part of any electronic device is the coil that assists in creating the energy for the motor. The types of coils used in a motor vary depending on the application the motor is being used for and the amount of current needed. In simple terms, a coil is wire that is tightly wound so that the wires overlap to form a cylinder. This technique increases the amount of force produced by using the multiple windings of the wire. Coils are made of various forms of wire that have high conductivity, are ductile, and easy to form into a variety of configurations. A necessary part of a coil is its insulation, which is designed to prevent current from passing between the overlapping wires. For the greatest amount of protection, coils have insulation but are dipped and baked in an extra material that completely seals the coil. This type of process creates a sealed coil.
There are several varieties of materials that are used in the production of a sealed coil. One such material is epoxy, which provides thermal stability and resistance to moisture, chemicals, vibration, and impact. An extra feature of epoxy is its gap filling capabilities. Every coil, when it is wound, leaves gaps. For the greatest efficiency, the gaps need to be filled, which is easily done with sealing materials, such as epoxy. Silicon resin has all of the properties of epoxy with the additional ability to resist a wide range of temperatures. It is impregnated as a sealant into electronic coils as a filler and insulation. Polymer resin is used as a sealant for its ability to solidify windings and laminations as well as dampen noise and lessen the influence of vibrations in high speed and spindle applications. One of the main benefits of using a polymer resin is how it converts into a rigid material once it has been cured.