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Difference between Universal Motor and Induction Motor

By May | Published on Sep 17,2015

Presently, I have seen many questions on this from some forums and I have sensed that there is a lack of understanding in respect to the difference between the universal and the induction motors. There is a big difference, and I hope that the following discussion will help you to become more informed when shopping for new tools and spend their hard earned cash.

1.Size and Weight
Generally, induction motors are heavier than universal motors, making them ideal choice for stationary tools that need the extra weight anyways to reduce rattling and improve stability.

Apparently it is their weight and size that make poor candidates for hand-held or portable tools. That’s why universal motors come in to use. Their smaller size and weight make them ideal for circular saws, bench top planers and your shop vacuum.

2.Torque at Start Up
Induction motors have less torque at start up. Once they’re at cruising speed they’re good to go, but typically they are not likely to be stopped and started frequently. While universal motors have great torque at start up to get get blades chewing through tough spots.

Induction motors typically have a slower max speed. Universal motors are only limited by friction.

Induction motors are long-lived and durable. There are stories that woodworkers are using induction motor powered tools passed on by their grandfathers. Universal motors are more likely to break out in a shorter period of time. There are some possibility of universal motors to last for 20 years and more, but, in general, universal motors don’t last as long as induction motors.

5.Energy Efficiency
Induction motors are highly efficient that require less supply source per horse power. Universal motors require more supply source per horse power than induction motors. All this extra energy is turned into heat in the motor which will sometimes burn them out if they are used for extended periods of time.

Induction motors have been standardized by NEMA, which tells you that it’s easy to replace induction motors in your machines with standard motors from different manufacturers because of standard frames, shaft sizes, mounting dimensions and more. Universal motors are featured by their lack of standardization, which means its hard to achieve replacement.

7. Noise
Induction motors are further quieter than universal motors.

As we all know, universal motors are famous for their shriek and they are banned on many residential areas after a certain time of day.

8. Cost
Induction motors are more expensive and found often used in the top of the line electric power tools these days. They’re made up with more copper, aluminum and steel than universal motors.

Universal motors are less expensive and found in just bout every electric power tool known to man.

With price driving of the big retailers in today’s market, more and more stationary tools, including table saws showing up are driven with universal motors. This is a perfect example of “you get what you pay for”. The uninformed consumer may not be getting a “good buy” or even a satisfactory tool.


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