Cost effective repairing of ceiling fan and energy efficient regulator

8/12/2019 Cost effective repairing of ceiling fan and energy efficient regulator

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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


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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


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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


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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


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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


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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


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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.


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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:


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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.


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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


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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.


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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.


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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.


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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


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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/

Date post:	03-Jun-2018
Category:	Documents
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Cost effective repairing of ceiling fan and energy efficient regulator

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