East West Manufacturing Blog

8 Reasons Why EC Motors are Plastic: Part 1

Written by Andy Reese | October 14, 2014

In recent years it has been determined that you can improve EC Refrigeration Motor performance with advanced plastics. In this two part series we’ll provide you with 8 reasons that will help explain why! Read on below for the first 4 reasons why EC Motors are made of plastic.

Advanced plastics are being increasingly used in the motor industry, not only for insulation materials, replacing traditional materials such as papers or ceramics, but also for structural parts and enclosures, replacing metals such as steel and aluminum.

1. Thermal Insulation

The major advantage of metals in traditional motors is their thermal properties. Metals are good thermal conductors. This makes them effective at transferring waste heat from the motor to the outside atmosphere. In low efficiency motors, or in high powered motors, this is an important property, as large amounts of waste heat must be dissipated. However, in a small energy saving EC Motor there is very little waste heat, so this property of metals is not important.

In fact for motors of this type, rather than encouraging heat transfer, it can be preferable to minimize it. Using a plastic housing slows the heat transfer: this gives a more stable environment both inside the motor (protecting the bearings and electronics from thermal shocks and extreme low temperatures) and outside the motor (improving temperature control).

2. Low Temperature Tolerance

For commercial refrigeration and other low temperature applications, correct material selection is extremely important, as some metals (including most steels) and many plastics become brittle below about -10°C (14°F). Advanced plastics rated for low temperature use, retain over 80% of their impact strength at -30°C (-22°F). Thermal insulation properties of plastics are also helpful at low temperatures because they allow the motor to warm up, preventing it from being exposed to long periods of vibration while extremely cold.

3. High Temperature Tolerance

Most commonly used metals can tolerate temperatures far above what is encountered in motors. Only a few plastics are able to tolerate such extreme temperatures. However, a variety of advanced plastics are available which will tolerate the temperatures found in motors. For example, the highest internal temperature of our ECR motors is below 105°C or 221°F (Class A). The grades of plastic we used in these EC Motors are UL rated for normal operating temperatures up to 155°C or 311°F (Class F).

4. Electrical Insulation

While aluminum and other metals conduct electricity, plastics are good electrical insulators. This is a major disadvantage of metals, as a ground connection is required to maintain safety when metal is used. This poses the risk that if the connection corrodes or is incorrectly fitted, the motor could become unsafe. Use of an advanced plastic housing and rotor hub allows Wellington’s ECR series to meet double insulated standards, avoiding the need for a ground connection while keeping installation and maintenance personnel safe.

Stay tuned for our second installment of "8 Reasons Why EC Motors are Plastic" next week! Check out our EC Motor page to learn more about the EC Motors East West makes.

By the way, have you heard of the new recently passed U.S. Department of Energy regulations that will be going into effect within a few short years? We've put together a FREE helpful eBook that will help explain the guidelines and how they will affect your business. Just click the link below to download!