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Jan 10, 2017 - Single-Phase Motor - Types, Uses, Advantages and Disadvantages

Depending on the type of machine and application you require, some motors will work better than others. If you are running smaller equipment that requires less horsepower, a single-phase motor will work best for your needs.

While this type of motor typically lasts for years, over time it will wear out. If you are looking to replace a single-phase motor, Bonfiglio has a range of BS - Single Phase Motors. These motors are manufactured to the applicable IEC standards and are of the enclosed type, externally ventilated and with run capacitor permanently connected. If you are interested in installing a new single-phase motor, request a quote from Gordon Russell today. Keep reading to find out more about single-phase motors.

Difference Between Single and Three Phase

There are two types of motors, a single-phase motor and a three-phase motor. Single-phase motors need less maintenance than three-phase motors, and will often last for years longer. These motors are typically used in devices and equipment that require lower levels of horsepower, or when it is inefficient to use a three-phase motor.

Single phase motors have a similar construction to the three phase motor, including an AC winding that is placed on the stator, and short-circuited conductors that are placed in a cylindrical rotor. The biggest difference between the two motors is that with a single phase motor, there is only one phase supply to the stator (hence the name).

Single-Phase Motors Summary

Types: There are a few different types of single-phase motors; some of these are two-valve capacitor, capacitor-start, split-phase, permanent-split capacitor, wound rotor and shaded-pole motors. Each type of motor has its own unique advantages and disadvantages.

Uses: Single-phase motors are used in equipment and machines that are smaller in size and require lower horsepower (for example, one horsepower). This include equipment such as pumps, refrigerators, fans, compressors, and portable drills.

Operation: Single-phase induction motors are not self-starting without an auxiliary stator winding driven by an out of phase current. The auxiliary winding of a permanent-split capacitor motor has a capacitor in series with it during starting and running. Single-phase motors don’t create a magnetic field on their own, so they must be switch activated in order to make the rotor move. This type of motor is only able to operate once the rotor is set in motion and a magnetic field is created.

Advantages:  There are many benefits to single-phase motors. For starters, single-phase motors are less expensive to manufacture than most other types of motors. Single-phase motors typically require very little maintenance, don’t often require repairs, and when they do they are fairly easy to complete. Single-phase motors will last for years as well, and usually most failures from single-phase motors are a result of inappropriate application rather than a manufacturing defect from the motor itself.  

Disadvantages: While single-phase motors are simple mechanics-wise, this does not mean that they are perfect and nothing can go wrong. On occasion they have been known to run slow, overheat, or even fail to start, overheat or run slow. If a shock is felt while touching the motor, there is a problem with the motor that will need to be repaired immediately.

Interested in installing or upgrading to the Bonfiglioli single-phase motor? Call Gordon Russell at at (604) 940-1627 (BC), or (403) 340-8856 (Alberta). Or request a quote online today!

Ask the Editors: The Aviation Week Network invites our readers to submit questions to our editors and analysts. We’ll answer them, and if we can’t we’ll reach out to our wide network of experts for advice. 

What Advantages Does Electric Propulsion Offer Over Gas Turbine Engines?

Executive Editor, Technology, Graham Warwick responds:

There are several advantages claimed for electric motors over gas turbines, but motors are only one part of an electric propulsion system. Just as turbine engines need fuel tanks, pumps, pipes and other systems, electric propulsion needs energy storage, power electronics, distribution buses and cooling systems. It is at the system level that electrified propulsion faces challenges.

One advantage is noise. An electric motor is quieter than an engine that combusts fuel. It still has to drive a propulsor—rotor, propeller or fan—and that produces noise on takeoff and climbout. But electric propulsion will be quieter when taxiing and cruising. Electric motors also enable distributed propulsion systems with multiple smaller, quieter rotors or fans.

Efficiency is another advantage. Electric drivetrains can be more than 90% efficient, compared with 55% for today’s large turbofans and 35% for small turboprops. That disparity in efficiency between large and small turbines is one reason why the electrification of propulsion is beginning with the modification of regional aircraft powered by turboprops such as the Pratt & Whitney PT6.

Another advantage is scalability. Whether you use one or two large motors or many small motors in a distributed electric propulsion architecture, performance is about the same. That is not the case with turbines. Development of electric motors for aircraft is still in its early days with many different topologies to pursue—both conventional and superconducting—so time will tell.

But the biggest challenge in electrifying propulsion is energy storage. Current batteries have a fraction of the energy density of aviation fuels. That is why all-electric propulsion is starting with small, short-range air taxis—with typically an hour’s flight endurance. Even hybrid-electric aircraft are starting with shorter-range regional aircraft.

There are higher-performing battery chemistries than today’s lithium-ion designs, but they have yet to be commercialized. Other forms of energy storage, such as hydrogen fuel cells, are being fielded by the automotive industry. New ways of storing energy are in early development, such as the flow battery, which NASA is adapting to aircraft propulsion under the Aquifer project.

Battery limitations are why initial applications of electric propulsion are targeting markets that are new to aviation, such as urban air mobility and regional air logistics, now the domain of road and rail transportation. It will take longer to electrify the short- and medium-range aircraft that make up the bulk of commercial aviation, while long-haul aircraft are considered likely to remain reliant on liquid fuels.

But there are signs that short- and -medium-range propulsion will become, if not all-electric, at least more electric. Integrating a megawatt-class motor/generator into a turbofan would allow power to be added as well as extracted. This could be used to boost takeoff power, allowing use of smaller, more efficient turbine engines. Using stored energy to manage the engine cycle could improve efficiency. 

The road to propulsion electrification has a long way to go, but the European Union Aviation Safety Agency says the type certification of Pipistrel’s Velis Electro trainer in June has laid the first regulatory bricks on that path.