Post on 03-Jun-2018
transcript
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
1/15
Cost effective repairing unit
to monitor efficient working of
Electric fans in college
Under the Guidance of Asst. Prof. Ms. Shilpi
Report by : Group 10
Jibin Job
Midhun Viswanath
Muhammad Mijas
Muhammad Zeeshan
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
2/15
CONTENTS
1)Introduction
1.1)working principle of ceiling fan
2)Construction
2.1)Capacitor
2.2)Bearing
2.3)Windings
Starting winding
Running winding
3)Types of faults(daigonosis and corrections)
3.1)capacitor faults
3.2)winding faults
3.3)bearing faults
4)Ceiling fan winding machine
4.1)Automatic ceiling fan winding machine
4.2)Manual ceiling fan winding machine
4.3)Procedure for winding
5)Cost estimation
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
3/15
1)INTRODUCTION
1.1)working principle of ceiling fan
The ceiling fan motor works on principle of single phase induction
motor using capacitor.
Working of capacitor start motor: The stator consists of the main
winding and a starting winding (auxiliary). The starting winding isconnected in parallel with the main winding and is placed physically
at right angles to it. A 90-degree electrical phase difference between
the two windings is obtained by connecting the auxiliary winding in
series with a capacitor and centrifugal switch. When the motor is first
energized, the centrifugal switch is closed. This places the capacitor
in series with the auxiliary winding. The capacitor is of such value that
the auxiliary circuit is effectively a resistive-capacitive circuit (referred
to as capacitive reactance and expressed as XC). In this circuit the
current leads the line voltage by about 45 (because XCabout equals
R). The main winding has enough resistance-inductance (referred to
as inductive reactance and expressed as XL) to cause the current to
lag the line voltage by about 45 (because XLabout equals R). The
currents in each winding are therefore 90 out of phase - so are the
magnetic fields that are generated. The effect is that the two
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
4/15
windings act like a two-phase stator and produce the rotating field
required to start the motor. When nearly full speed is obtained, a
centrifugal switch cuts out the starting winding. The motor then runs
as a plain single-phase induction motor.
2)CONSTRUCTION
2.1)capacitor
In a ceiling fan there is an single phase induction motor.
Single phase stator produces a non rotating, pulsating magnetic
field.The single coil excited by a single phase current produces
two counter rotating magnetic field phases, coinciding twice per
revolution at 0 degrees and 180 degrees. When the phases
rotate to 90 degree and -90 degree they cancel. At 45 deg and -45 deg they are partially additive along the +x axis and cancel
along the y axis. The sum of these two phases is a phasor
stationary in space, but alternating polarity in time.
The two windings are wound with a geometric offset, effectively
making a second set of poles phase shifted within the stator.
The capacitor provides a phase shift to the current flowing inW1 and we therefore have a "two phase" motor while the switch
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
5/15
is closed. When the motor is almost up to speed, the switch
opens disconnecting W1 and the capacitor. The motor can be
reversed by reversing the connections of either W1 or W2 (but
not both).The fan capacitor produces a rotating magnetic field. This magnetic
field makes the motor turn. If the capacitor is not working correctly,
your motor will not function properly. If your motor is not working
properly, you may hear a humming sound.
The lower the capacitor rating you go the higher the chance the fan
motor will not start (not enough capacitance).
The higher the capacitor rating is, the motor will draw more amps
when running. The motor could overheat and shut down on thermal
overload.
2.2)Bearing
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
6/15
2.3)Windings
The stator consists of the main winding and a starting winding
(auxiliary). The starting winding is connected in parallel with the main
winding and is placed physically at right angles to it. A
90-degree electrical phase difference between the two windings is
obtained by connecting the auxiliary winding in series with a
capacitor and centrifugal switch. When the motor is first energized,
the centrifugal switch is closed. This places the capacitor in series
with the auxiliary winding. The capacitor is of such value that the
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
7/15
auxiliary circuit is effectively a resistive-capacitive circuit (referred to
as capacitive reactance and expressed as XC). In this circuit the
current leads the line voltage by about 45 (because XCabout equals
R). The main winding has enough resistance-inductance (referred toas inductive reactance and expressed as XL) to cause the current to
lag the line voltage by about 45 (because XLabout equals R). The
currents in each winding are therefore 90 out of phase - so are the
magnetic fields that are generated. The effect is that the two
windings act like a two-phase stator and produce the rotating field
required to start the motor. When nearly full speed is obtained, a
centrifugal switch cuts out the starting winding. The motor then runs
as a plain single-phase induction motor.
3)TYPES OF FAULTS
3.1)Capacitor faults:
In order for an electric fan to work correctly, the ceiling
fan capacitor must be fully functional. A ceiling fan
capacitor has two important roles: to create a magneticfield when the fan is first turned on, and to change the
direction of the fan, when the unit is switched into reverse.
Not all fans have reverse direction, but this is a particularly
useful feature during the cold weather season, to
circulate warm air downward and lower overall heating
costs.
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
8/15
If the fan capacitor is not working correctly, then the fan
may exhibit the following problems:
The fan wont spin on its own. Notice whether a humming
sound can be heard when the fan is switched on, or
whether you need to help it along for it to start spinning.
In this case, a ceiling fan would either not turn, or would
spin extremely slowly (regardless of the speed setting
selected).
Use your senses: if you smell a burning odor, or you see a
burned or melted black box, this could mean a problem
with the ceiling fan capacitor.
These are obvious signs of a bad ceiling fan capacitor.
Often, the ceiling fan capacitor itself would appear to be
bulging or malformed. Examine the ceiling fan capacitor
for evidence of bulging, burns, or cracks? If the answer is
yes, then one of the capacitors has blown. Capacitors
tend to get really hot before shorting out, which results in
the melting and scorching.. If you have a fan with multiple
capacitors, a single ceiling fan capacitor may blow out,
while the others may remain in good working order.
3.2)winding fault:
winding fault mainly occurs due to voltage fluctuations inthe supply.It can be detected by means of series bulb
test.winding fault can be visually diagonised by burned
out windings or broken winding.
3.3)Bearing fault:
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
9/15
Bearing faults occurs due to wear and tear in the
bearing.It will cause the rotor to come in contact with the
stator and get locked.if there is bearing fault,then there
will be a ahumming sound and also there are chancesthat the fan doesnt run at all.
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
10/15
4)CEILING FAN WINDING MACHINEThere are two types of winding machines:
Automatic ceiling fan winding machine. Manual ceiling fan winding machine.
4.1)Automatic ceiling fan winding machine
Acknowledged for its durability, high reliability, least maintenance
and reduced break down time, Automatic Ceiling Fan Stator Winding
Machine can accommodate and work with different type of stator.
Manufactured using superior quality raw material and hi-tech
machines, these are suitable for repair shop. Available in various
specifications and custom designs, the range is offered at cost
effective prices.Specifications:
Wire Size: 0.1mm to 1.2 mm
Stator Diameter: 35mm to 180mm
Stator Thickness: 08mm to 36mm
Max. Speed: 4500 rpm
power: 220volt (50 hz) main motor
Production Capacity: 85 stators/ hour
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
11/15
4.2)Manual ceiling fan winding machine
This machine is ideally suited for repair shops. Different type of
stator can be accommodated. Hence making it highly reliable and
maintenance free hence reducing break down time.
Specifications:
Stack Height : 2"- 6" approx Wire Diameter : 26 Swg to 38 Swg
Winding Speed : 960/1440 RPM
Winding Direction : Clock wise and Anti Clock wise.
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
12/15
4.3)Winding steps
First of all you would find the no of turns in the coil by countingone by one.
Then you would make coils according to the no of turns.
Insulate the stator holes with a paper to avoid the contact of coilwith the stator.
Now place the coils one by one on the stator
The process of placing coils is done for both starting andrunning winding.
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
13/15
After the completion of placing coils you would give connectionof coils in both windings.
In last you would leave four wires, two of them are connectedwith each other which is known as common.
The starting winding is now connected with capacitor and therunning winding is directly connected with main supply.
Then the capacitor is connected with main supply.
After the connections the fan is closed and is connected with themain supply.
If the fan is moving in anticlockwise direction, then its
connections are reversed.
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
14/15
5)COST ESTIMATION
Cost of repairing 1 fan : Rs 100
Winding Copper : Rs. 50 (250g)
Capacitor : Rs. 35
Milnex paper, sleeve, : Rs. 15
hook up wire, tie, varnish
Cost of repairing faulty fans in college : Rs 18,000
Number of faulty fans in college : 66
Cost of Materials : Rs. 6000
Cost of Machine : Rs. 12000
Current cost of repairing : Rs 23,000
Average cost per fan : Rs. 350
8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator
15/15
REFERENCE
Theory of Electrical MachinesP.S.Bimbhra
Electrical TechnologyB.L. Theraja
WikiHowwww.wikihow.com
Red BeaconA manual on repairing ceiling fan
Other electrical enthusiasts online forum
http://www.wikihow.com/http://www.wikihow.com/http://www.wikihow.com/http://www.wikihow.com/