What Causes Problems With a Fan Motor?
Fan motors are used in a variety of settings, from the cooling of homes to the ventilation of large industrial facilities. They are relatively simple, making them easy to repair and maintain.
It is important to understand that the percentage indicated on a controller does not translate linearly into fan speed or airflow rate (CFM). Understanding this can help prevent costly mistakes and energy waste.
What is a Fan Motor?
A fan motor is the powerhouse that moves your air conditioner’s cooling blades to move cool air around your home or business. It’s essential to keeping your HVAC system working properly, and it’s important to understand what causes problems with fan motors so that you can call a professional as soon as possible. Some common problems include a lack of movement, rattling noises, and burning smells.
The type of fan motor used depends on the application and its environment. For example, PC cooling fans use brushless DC motors, while those that Air conditioner plug into a wall outlet usually have AC induction fan motors.
One common type of fan motor is a capacitor start, cap run motor, also known as a two value capacitor motor. This kind of fan motor uses a cage rotor with a stator with two windings, one for starting and the other for continuous running.
A capacitor start, cap run fan motor is often used in AC condenser units and is rated for outdoor use. Since it will be exposed to the elements, this type of fan motor is sealed up on the sides and ends to keep out water. These kinds of fan motors are usually one speed, with a horsepower range from 1/6 hp to 1/3 hp and have a rotary switch for control.
Motor Design
The motor drives a shaft with the propeller attached to it. When it’s on, the propeller migrates air efficiently to cool a heat source, ventilate space, or other tasks. It can take in a large volume of air and move it out at high speed without losing power.
To make this happen, the motor generates electrical energy by utilizing magnetic fields with a cage rotor that’s supported by a stator with main and auxiliary windings. Then, the current in the windings is cut by the magnetic field and converted into rotary mechanical energy. This energy travels to the rotor via the shaft, and then the motor rotates to generate constant torque.
Most fan motors have bronze sleeve bearings that are lubricated with oil. Over time this oil can wear off causing metal to metal contact. This can lead to premature failure of the motor.
To avoid this, motor designers are trying to find better materials that allow for more efficient production and longer lifespans. There are many ways to achieve this. One way is to use a hybrid shaft that combines stainless steel with carbon-reinforced plastic. Another is to design the shaft using the SMC or AFP/ATL manufacturing process that offers more design freedom.
Ansys Motor-CAD provides a robust toolkit for designing electric motors. It has templates for PMSMs, induction machines and brush motors. It enables engineers to easily decide rough physical size by entering the expected output of the motor. It also calculates thermal properties with a built-in 3D thermal network.
Motor Types
There are several different types of motors used for fans. The most common is an Air conditioner distributor AC induction motor. These motors have a long lifespan and operate efficiently. They are also inexpensive and easy to replace. Other types of fan motors include PSC and BLDC. PSC motors are more expensive than shaded pole motors but they have a higher efficiency rating and do not require a centrifugal switch.
BLDC motors have an internal smart board and can adjust their speed to match the demand of the cooling system. They can also lower operating costs through energy savings. These motors are quieter than traditional AC fan motors.
Single-Phase Motors – Single-phase motors connect to most smaller sized fans and run on existing power sources. These motors have a cycle that dips and tops, reducing electrical consumption.
Shaded Pole Motors – These motors are found in household fans and other small applications. They have a low starting torque and are not well suited for continuous operation.
Combustion Fan Motors – These motors are used in gas furnaces to move air over a burner, which helps create a flame to burn up the fuel that’s burning inside the furnace. These motors have a simple design and do not use a capacitor.
Axial Fan Motors – These motors have a propeller that moves air to cool a heat source or ventilate an area. These motors can migrate a large amount of air, making them ideal for larger cooling and ventilation applications.
Motor Maintenance
Regardless of the type of fan motor, regular maintenance is important. This involves cleaning and lubricating. Lubrication helps to reduce friction that can cause wear and tear. It also prevents moisture from building up and causing corrosion.
When it comes to cleaning, non-abrasive brushes or clean cotton rags are suitable. A jet of compressed air can also be used to remove any accumulated dust. It is recommended that you disconnect the power supply before performing any maintenance on a fan motor. This can be done by turning on the fan or using a voltage tester. Once the power has been disconnected, you can begin examining the fan motor for signs of wear and damage.
Look for rust and corrosion on the metal components of the motor. Also, pay attention to the ventilation paths. If they are blocked, this can cause overheating.
If you see any signs of overheating, you may need to lubricate the pin or bearings. Most old fans have a hole or two on the top where you can add oil. Newer fans don’t have this option, so you may need to buy a bottle of motor oil at an auto parts store or a home improvement store. Be sure to use lubricating oil and not engine oil, as this is toxic to the motor.
