In our everyday life, in shops, hotels, offices, etc., Electric Fan is a very important electrical appliance. Without which it is difficult for an ordinary person to live comfortably.
Where and why are electric fans used?
- To keep the wind playing and fluctuating in summer days.
- To throw out the hot air or contaminated air of the room.
- To take the cold outside or pure air inside the room.
- As a cooling fan to keep a large or small electrical appliance cool.
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How many types of electric fans are there?
According to the method of using the electric fan and the place the fan is used, the types of electric fan (fan) are mentioned below.
- Table Fan
- Ceiling Fan
- Exhaust fan
- Pedestal Fan
- Cabin Fan
- Cooling Fan
What are the main parts of an electric fan?
- Electric Motor
- Fan Blade
- Oscillating mechanism
- Fan Regulator
A single phase 230 volt motor is used for the fan. In many places, a motor running at more or less voltage is used according to the need. Generally, permanent capacitor motors are used for ceiling and exhaust fans and permanent capacitor motors or shaded pole motors are used for table fans.
This motor comes with 1/16 1/8 ratings.
The fan blades are mounted on the front of the shaft on which the rotor of the electric fan is located. Fan blades are made of metal or PVC. The fan blades are bent from side to side into a cone to give them a distinctive shape.
Due to the fan blade being bent at a particular angle, air is thrown from it to the front or down (downwards in the ceiling fan).
The blade size for pedestal, cabin, and table fans is 400 mm. So for ceiling fan, this size is 900 mm, 1050 mm, 1200 mm, 1400 mm and 1500 mm.
So the size of fan blade for exhaust fan is 200mm, 225mm, 250mm and 300. The size of the fan blade means when the fan spins. Then it becomes the full diameter.
Friends, you must have seen a table fan or wall fan moving in the running position, right left. The mechanism used to rotate this type of fan left and right is called oscillating mechanism.
During this process the table fan or wall fan rotates right and left at a angle of 120°. This mechanism is available only in Table Fan, Pedestal Fan and Cabin Fan (Wall Fan).
Ceiling fans and exhaust fans do not require this type of oscillating mechanism.
The structure of the oscillating mechanism of the fan
The oscillating mechanism is located at the rear of the fan. A wormshaft is attached to the fan shaft. Which is done oscillating the fan with the help of verma gear and worm wheel. There are many types of fans available in the market.
Every fan company makes its own oscillating mechanism according to its need.
If a shaded pole motor is used as a fan motor, it does not have a capacitor. But if a permanent capacitor motor is used, then a capacitor is connected in series to the starting or auxiliary winding of that fan motor. The capacities used in the fan are 2 to 4 microfarads.
Why is a capacitor used in an electric fan?
Friends, the electric fan used in our house has a single phase induction motor. To start a single phase motor, only a single phase supply is not enough.
Initially, this motor needs a separate force to make the fan spin. If once this motor rotates with the help of another force, then later this single phase induction motor starts rotating with single phase itself.
This second force is created by the capacitor of the fan. Single phase induction motor has running winding and starting winding. The magnetic field created in the running winding keeps the fan moving.
So the starting winding is used to give the starting force i.e. starting torque to the fan. But the supply coming in our house is a single phase supply.
If this single phase supply is given to the starting and running winding of the fan, then the fan does not get torque. For starting torque, it is necessary to supply 2 separate phases to both the windings.
Capacitor converts 1 phase to 2 phase.
The capacitor is applied in series with the starting and running windings. The fan rotor gets the starting torque from the starting winding by applying capacitors. And the fan starts spinning. Therefore, a capacitor is installed in the fan to make the fan spin initially.
The fan regulator is used to increase or decrease the speed of the fan as per the requirement. This regulator is connected in series with the fan. The fan speed is regulated by regulating the voltage received from the regulator to the fan.
There are three types of regulators used for fans.
- Resistance Regulator
- Choke Regulator
- Electronic Regulator
This type of fan regulator has a resistance to the uric wire. Some of the tapings have come out. These tapings are connected to a rotary switch. The voltage to the fan motor is reduced by using tapings with increased resistance. Because of which the fan spins slowly.
As the resistance is changed by rotating the rotary switch. By the way, the speed of the fan motor is increased or decreased. The resistance regulator is used to control the speed of the fan.
This regulator is also called inductance regulator. In this type of regulator, enamelled copper wire is wrapped over a laminated iron core. Some of the tapings have come out. These tapings are connected to a rotary switch.
More or less resistance is added to the fan series by rotating the rotary switch to increase or decrease the fan speed according to the need. Due to which the impedance of the circuit is increased or decreased.
Due to which the voltage received by the fan is also more or less. In this way, the speed of the fan is increased or decreased by using a choke regulator. Not much heat builds up in this type of regular. Therefore the choke regulator is more efficient.
This type of regulator consists of such electronics components as inductance, capacitance, resistance, diode and voltage regulated IC (integrated circuit). Due to which the speed of the fan is increased or decreased due to change in voltage.
Advantages of Electronic Regulator
- This regulator is smaller than the rest of the regulators. It was not hot
- Is easy to use.
- looks attractive
A single phase motor is fixed on it by placing a standing stand on a base. Normally shaded pole motor or permanent capacitor motor is used for this function.
Oscillating mechanism is installed on the rear part of the shaft of this motor. The fan blades are mounted on the shaft on the front of the motor. The fan blade is covered with a safety guard. A regulated fan is fitted inside the base to control the fan speed. The knob or button to operate the regulator is placed outside the base body.
How does a table fan work?
After starting the supply of fan motor and operating the regulator knob or button, the fan starts spinning. Then the fan starts blowing air. The direction of the wind coming from this fan is horizontal and forward.
When the fan is rotated to the right or left, the oscillating switch of the fan is rotated or pushed. By which the oscillating gear is connected to the fan shaft. And the oscillating mechanism starts working. The fan rotates left and right to spread the air around the room. This is how the table fan works.
Table fan faults, causes and remedies for faults.
Q.1 why is the table fan not turning on?
Reason 1:- Fan bearing or bush may be jammed.
Remedy: – Switch off the supply and rotate the fan blade with a screw driver. If the blade is jammed, greasing the bearing/bush.
Reason 2:- The supply cord may be open.
Remedy:- Check the supply provided at the fan’s supply terminals whether the phase neutral is coming or not. If the supply is not coming, then check the cord with the help of series testing or multimeter. Replace the faulty cord and insert a new cord.
Reason 3:- There may be regulated open.
So change the regulator.
Reason 4: Capacitor may be open or defective.
Reason 5:- Fan winding may be open.
Remedy:- Check the winding with the help of series testing or multimeter. If the winding is open or burnt out, get the fan rewinding done.
Q.2 Why does the sound come when the fan rotates?
Reason 1: Fan blades may become loose.
Remedy:- Tighten the fan blade well.
Reason 2 :- The safety mesh of the fan may be loose.
Remedy:- Tighten the safety mesh of the fan properly.
Reason 3:- Due to the lubricant running out of the bush bearing
Remedy:- Grease the bush bearing.
Reason 4 :- Due to play coming in rotor
Remedy: Reduce the play by inserting spacer washers into the shaft.
Reason 5 :- Due to friction between rotor and stator
Remedy :- Check and repair the shaft.
Reason 6 :- Due to the fan blade being attached to the safety mesh
Remedy :- Keep a safe gap between the safety net and the fan blade.
Q.3 Why does the fan throw less air?
Reason 1 :- This can happen due to the fan blade being bent.
Remedy: Align the fan blades.
Reason 2 :- Due to slow fan speed
Remedy: Increase the speed with the regulator.
Q.4 Why is the fan not oscillating?
Reason :- Due to bad mechanism
Remedy :- After checking, replace the worn gears.
How to service a table fan?
Perform servicing by opening the table fan as described below.
- Open the cover of the mechanism on the back of the table fan.
- Separate the fan blade from the fan by removing the front safety net.
- Detach the oscillating mechanism by removing the bar attached to the table fan.
- Detach the motor cover by removing the nuts on the motor body.
- Take out the rotor. Take care not to damage the stator winding while the rotor is out.
- Remove the washers on either side of the rotor shaft. Bush then exits.
- Keep all the discarded parts in a tray. Wash these parts thoroughly with kerosene or carbon tetrachloride. If there is some dirt inside any part, then clean that part thoroughly with a brush.
- Wipe all washed parts with a soft cloth.
- Take a look at the parts that have been wiped dry. Replace the parts that are worn or broken and make arrangements for new parts.
- Inspect the rotor thoroughly. If the shaft is bent, insert a new shaft. If the bearing is bad, replace it with a new bearing. When installing a new bearing, the number or size of the old bearing should be fitted with the same number or size bearing.
- Take a continuity test, insulation resistance test, of the fan motor winding with a test lamp, multimeter or megger. After testing, if the winding is not easily repaired when it is open or short, then get the rewinding done. Note the gauge, turns, and pitch of the old winding wire before rewinding, and do the new rewinding in the same manner.
- Take open, continuity and short circuit test of regulator and capacitor.
- Wash table fan safety nets and fan blades thoroughly. Re-assemble the table fan in exactly the reverse order of action from which the table fan was opened from the beginning.
- When assembling the table fan, oil and grease the parts that require oil and greasing.
- After all parts are fitted properly, try rotating the fan blades by hand. Take care that the fan blade is not worn by the safety net of the fan.
- After making sure all this, make the connection of the Winding, Capacitor and Regulator of the table fan.
And again try starting the fan by supplying the series testing lamp in series with the fan. If the table fan starts spinning slowly after lighting the lamp dim, then the table fan has been serviced well. Then understand that the table fan is ready to give direct supply.
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