Fans - Pdt. Knowledge - Technical.pptx

TRAINING MODULE
PRODUCT KNOWLEDGE
-
ELECTRIC FANS

•The first ceiling fans appeared in the 1860s and 1870s, in the United States
•The electrically-powered ceiling fan was invented in1882 by Philip Diehl
HISTORY OF FAN
2

A device having two or more blades, driven by an electric motor to
circulate air in order to produce a cooling effect is called fan
FAN SWEEP:
The diameter of the circle traced by extreme tip of the blades when
mounted on fan motor.
FAN ?
3

4
ELECTRICAL MAIN SUPPLY
In India, it is alternating current with frequency of 50 cycles / sec.
Standard voltage is 230 Volts.
•If the current flows always in the same direction, it is called 'direct current'. Direction current is
represented as DC or dc. The current derived from a cell or a battery is direct current - since it is
unidirectional. The positive and negative terminals are fixed.
• If the current changes direction after equal intervals of time, it is called alternating current.
Alternating current can be written as AC or ac. Most of the power stations generate alternating
current. The following are the circuit elements representing dc and ac.
DC & AC Voltage

Electromagnet
When current flows through a conductor a magnetic field is produced around
the conductor. The magnetic field is made up of lines of flux, just like a natural
magnet. The size and strength of the magnetic field will increase and
decrease as the current flow strength increases and decreases.

A definite relationship exists between the direction of current flow and the
direction of the magnetic field. The left hand rule for conductors demonstrates
this relationship. If a current carrying conductor is grasped with the left hand
with thumb pointing in the direction of electron flow, the fingers will point in
the direction of magnetic lines of flux.
Left hand Rule for Conductors

If current is passed through a coil it behaves like a magnet with defined poles.
It was also noticed when the direction of current is reversed. This important
observation implies that an alternating current passing through a coil would
produce a magnet with alternating poles. This is to say this coil magnet would
alternatively attract and then repel another magnet.
The second major observation was that if a coil was short circuited i.e. its two
ends joined and placed close to a coil magnet a current would be INDUCED
in this short circuited coil enabling it to act as a magnet also.
Coil as a Magnet

There are two types of coils namely auxiliary and main winding as shown, it
may seen that coils interact with each other in a particular sequence of
attraction and repulsion to produce motion of the rotor inside the motor.
THE ACTION OF A MOTOR
The Motor Concept

The current carrying coil-A induces current and therefore magnet in the short-
circuited coil - B, attracting it towards itself from position-I to position-II. By the
time coil-B reaches position II the polarity has started changing and now coil
A starts repelling coil-B to position-III. At position-III the adjacent coil on the
stator to coil-A starts acting and produces a similar cycle and therefore a
continuous motion has been produced. To ensure this adjacent coil attracts
coil-B when coil-A is repelling it, it has a circuit to ensure the polarity is
opposite to coil-A.
Voltage
CYCLE
I
III
II
Note :- the direction of current in the two
coils of the stator is always opposite. In
practical the reversal in the direction of
the winding is done to produce opposite
polarities.

POLARITY
The magnetic field of an electromagnet has the same characteristics as a
natural magnet, including a north and south pole. However, when the
direction of current flow through the electromagnet changes, the polarity of
the electromagnet changes.
The polarity of an electromagnet connected to an AC source will change at
the same frequency as the frequency of the AC source.
Orientation of the magnet depends upon the direction of the current. In an
alternating current supply the direction of current reverses. A.C. Voltage is
positive for half a cycle and negative for the second half. Accordingly we can
consider polarity on the basis of this voltage. Reversal of polarity would
therefore mean the reversal of the voltage in the cycle. The difference in
polarities of two coils would now be indicated by the direction of current flow
in these coils at any particular instant.

Even No. of Poles
It has earlier been indicated that for continuous movement in a motor two
adjacent coils must have opposite polarity. Assuming there is a motor with
five poles, the coils would have polarities as under
First Coil - +ve
Second Coil - -ve
Third Coil - +ve
Fourth Coil - -ve
Fifth Coil - +ve
The first and the fifth coils are also adjacent to each other since they are
placed on a circle. It can be noticed that they have the same polarity. If there
was a sixth coil it would have -ve polarity to ensure all adjacent coils have
opposite polarities. Accordingly only an even number of coils of poles are
possible for continuous movement.

The strength of the magnetic field in the electromagnet can be increased by
increasing the number of turns in the coil. The greater the number of turns the
stronger the magnetic field will be.
No. of Turns

A conductor moving through a magnetic field will have a voltage induced into it. This
electrical principle is used in the operation of AC induction motors. In the following
illustration an electromagnet is connected to an AC power source. Another
electromagnet is placed above it. The second electromagnet is in a separate circuit.
There is no physical connection between the two circuits. Voltage and current are zero
in both circuits at Time 1.
At Time 2 voltage and current are increasing in the bottom circuit. A magnetic field
builds up in the bottom electromagnet. Lines of flux from the magnetic field building up
in the bottom electromagnet cut across the top electromagnet. A voltage is induced in
the top electromagnet and current flows through it.
At Time 3 current flow has reached its peak. Maximum current is flowing in both
circuits. The magnetic field around the coil continues to build up and collapse as the
alternating current continues to increase and decrease. As the magnetic field moves
through space, moving out from the coil as it builds up and back towards the coil as it
collapses, lines of flux cut across the top coil. As current flows in the top
electromagnet it creates its own magnetic field.
INDUCED VOLTAGE

The polarity of the magnetic field induced in the top electromagnet is opposite the
polarity of the magnetic field in the bottom electromagnet. Since opposite poles attract,
the top electromagnet will follow the bottom electromagnet when it is moved.
ELECTROMAGNETIC ATTRACTION

The principles of electromagnetism explain the shaft rotation of an AC motor. Recall
that the stator of an AC motor is a hollow cylinder in which coils of insulated wire are
inserted.
STATOR COIL ARRANGEMENT:
The following schematic illustrates the relationship of the coils. In this example six
coils are used, two coils for each of the three phases. The coils operate in pairs. The
coils are wrapped around the soft iron core material of the stator. These coils are
referred to as motor windings. Each motor winding becomes a separate
electromagnet. The coils are wound in such a way that when current flows in them
one coil is a north pole and its pair is a south pole. For example, if A1 were a north
pole then A2 would be a south pole. When current reverses direction the polarity of
the poles would also reverse.
DEVELOPING A ROTATING MAGNETIC FIELD

The stator is connected to a 3-phase AC power supply. In the following illustration
phase A is connected to phase A of the power supply. Phase B and C would also be
connected to phases B and C of the power supply respectively.
Phase windings (A, B, and C) are placed 120° apart. In this example, a second set of
three-phase windings is installed. The number of poles is determined by how many
times a phase winding appears. In this example, each phase winding appears two
times. This is a two-pole stator. If each phase winding appeared four times it would be
a four-pole stator
POWER SUPPLY

When AC voltage is applied to the stator, current flows through the windings. The
magnetic field developed in a phase winding depends on the direction of current
flow through that winding. The following chart is used here for explanation only. It
will be used in the next few illustrations to demonstrate how a rotating magnetic
field is developed. It assumes that a positive current flow in the A1, B1 and C1
windings result in a north pole.
Winding Current Flow Direction
Positive Negative
A1 North South
A2 South North
B1 North South
B2 South North
C1 North South
C2 South North

START:
It is easier to visualize a magnetic field if a start time is picked when no current is
flowing through one phase. In the following illustration, for example, a start time has
been selected during which phase A has no current flow, phase B has current flow
in a negative direction and phase C has current flow in a positive direction. Based
on the above chart, B1 and C2 are south poles and B2 and C1 are north poles.
Magnetic lines of flux leave the B2 north pole and enter the nearest south pole, C2.
Magnetic lines of flux also leave the C1 north pole and enter the nearest south pole,
B1. A magnetic field results, as indicated by the arrow.

TIME 1:
If the field is evaluated at 60° intervals from the starting point, at Time 1, it can be
seen that the field will rotate 60°. At Time 1 phase C has no current flow, phase A has
current flow in a positive direction and phase B has current flow in a negative
direction. Following the same logic as used for the starting point, windings A1 and B2
are north poles and windings A2 and B1 are south poles.
60 deg means 1/300 seconds

TIME 2:
At Time 2 the magnetic field has rotated 60°. Phase B has no current flow. Although
current is decreasing in phase A it is still flowing in a positive direction. Phase C is
now flowing in a negative direction. At start it was flowing in a positive direction.
Current flow has changed directions in the phase C windings and the magnetic poles
have reversed polarity.

360 degree ROTATION:
At the end of six such time intervals the magnetic field will have rotated one full
revolution or 360°. This process will repeat 60 times a second on a 60 Hz power
supply.

lThe fan motor is a single phase capacitor start-run induction motor.
When the electrical supply is given to stator, a magnetic field is
induced in the stator coil which act as a force called electromagnetic
force (emf), which is stationary if we use only one coil.
•This force is not capable to rotate the motor or rotor. So we use two
coils (main and auxiliary).
•When the electrical supply is given to stator, emf is induced in both
coils and have a phase difference (With Capacitor) of less then 90
degree, So a revolving force is produced which is capable to rotate
the rotor or motor.
How does Ceiling Fan Operates ?

STATOR CONSTRUCTION
The current carrying coils are mounted on a block made of electrical steel
sheets. This block with the coils forms the stator.
Stator Stamping
Wound Stator

The efficiency of the coil depends upon the following;
Number of turns & Gauge of the wire
Length of wire
Mode of winding
The inter-acting strength of the stator and the rotor is determined by the height
of laminations i.e. the electrical steel sheets stack forming the laminations is
called the STACK HEIGHT. This stack height in large measure determines the
power of the motor.
In similar terms the coil structure remaining the same then power output or the
load carrying capacity of the motor is determined by the stack height,

ROTOR
Electrical steel sheets are cut into circular strips and in a bunch stacked
together equivalent to the rotor stack, holes are punched. By the process of die
casting these holes are filled with aluminium to form conductor bars.
Accordingly the stator performance is determined by the following:-
Slot design,
Stack height,
Quality of laminations,
Coil construction

32
MOTOR PERFORMANCE
a. The stack height
Greater stack height implies greater power output of the motor.
b. Air gap
Lower air gap would therefore imply better power output.
c. Slot design
d. Quality of laminations
The magnitude of the resistance depends on the quality of
laminations and also determines the eddy current losses.
e. Coil construction

The rpm of a motor depends upon the following;
lThe magnitude of load. Increased load obviously would imply lower speed.
lNo. of poles. The lower the No. of poles, higher the rpm of the motor.
lPower output. The power output would determine the rpm from consideration
of load carrying ability or efficiency.
Ns = (60 x 2 x f) / P = 120 x f / P
where f is frequency, P is number of poles &
Ns is Synchronous speed
Note: Reversal in Polarities occur in half a cycle
SYNCHRONOUS RPM

NO OF POLES SYNCHRONOUS RPM
2 3000
4 1500
6 1000
8 750
10 600
12 500
14 428.6
16 375
18 333.3
20 300
Note : Under actual conditions friction, magnetic and electrical losses also come into the picture.
In fact, under conditions of no load, synchronous rpm can not be achieved due to these losses.

There must be a relative difference in speed between the rotor and the rotating
magnetic field. If the rotor and the rotating magnetic field were turning at the same
speed no relative motion would exist between the two, therefore no lines of flux
would be cut, and no voltage would be induced in the rotor. The difference in speed
is called slip. Slip is necessary to produce torque. Slip is dependent on load. An
increase in load will cause the rotor to slow down or increase slip. A decrease in load
will cause the rotor to speed up or decrease slip. Slip is expressed as a percentage
and can be determined with the following formula.
% Slip = (Ns - Nr) x 100/Ns
For example, a four-pole motor operated at 60 Hz has a synchronous speed (NS) of
1800 RPM. If the rotor speed at full load is 1765 RPM (NR), then slip is 1.9%.
% Slip = (1800 - 1765) x 100 / 1800
% Slip = 1.9%
SLIP

Motor efficiency
The useful output of a fan motor is the air delivery, while the input is
the electric watts. Efficiency the ratio of output and input is known
as the service value of a fan.
Efficiency = Service Value = Output / Input
= Air Delivery / Wattage = CMM / Watts

RADIAL DISTRIBUTION OF AIR VELOCITIES
Note :- The shaded area gives graphical measures of air delivery.
Centre of fan
Peak Air Velocity
Distance from centre
of fan
Air Velocity

38
AIR DELIVERY OF AN ELECTRIC FAN
The distribution as well as the maximas i.e. peak air velocity depends upon the
following:-
Blade design
Power output of motor
RPM
RPM is a function of a power output of a motor, No. of poles and the
blade design. Accordingly the most important factor that determines
air delivery or distribution of air velocity is the blade design.

39
The important features of the blade design are as under;
a. Blade angles;
The blade has 3 angles as follows:-
Angle at motor end
Angle at blade tip
The dihedral angle
b. Blade depth and profile
c. Blade width
d. Blade gauge

40
MOTOR
The motor can be divided into 3 parts from fabrication point of view.
These parts are as under:
Rotor
Stator
Motor Housing
The Motor Housing is made by the process of casting / sheet metal fabrication.
The top & bottom covers of the motor housing are accurately machined and by
the process of buffing / pre-treatment the outer surfaces are given a smooth
finish. The covers are then painted by the process of electrostatic painting.

THE STATOR
The fabrication of the stator and the rotor starts at the same time. Electrical
steel sheets are cut into circles and outer ring is removed from this circle and
is used for the production of the rotor. These are Hi-perm in case these are
required. Mylor papers are now put in the slots. Coils are constructed on the
stator by an automatic coil winding machine to ensure compact and rigid
windings. Super enameled copper wire with E class insulation is used for
these windings. The stator is now dipped in varnish, Dr. Beck's varnish in our
case, and is baked to harden the varnish.

42
CLASSIFICATION OF INSULATION
Class of Insulation Max. temperature that winding can
withstand in 0 Celsius
Y 90
A 105
E 120
B 130
F 155
H 180
Note: Room temperature of 45 degree is added to temperature rise values

43
ROTOR
Holes are made all along the rings and a set of such rings are put together
with the holes aligned and filled with aluminium by the process of die-casting.
BLADES
Sheets, 3/4, hard are cut into desired blade shape. These blades are now
formed into the desired blade profile.

44
BLADE PROFILES AND BLADE DEPTH
SOME TYPICAL BLADE PROFILES
w = Blade width
R = Blade radius
h = Blade depth
h = R-0.25_/ ((2R-w) (2R+w))
w
h
R
1. 3.
2.

45
SUSPENSION SYSTEM
All the Fan manufacturers are using the socket less suspension system that
works as under:
lNo socket or coupling device between downrod and shaft.
lDownrod end, duly slit is guided over the shaft and secured by means of
bolt/nut and spring washer.
lCondenser is housed off centre.
Since the entire weight is taken by the bolts, hence high quality nuts and bolts
are used. The down rod pipe is slit at shaft engagement end so that it sits
firmly on the periphery of the shaft.

46
CANOPIES
lThe canopies are normally made of polypropylene
DOWNROD
lThe metal pipe that extends from the ceiling bracket to the top of the fan.
REGULATOR
The purpose of the regulator is to provide speed control and therefore control
of air delivery to the consumer. This control is most easily affected by
controlling the input voltage of the motor.

47
The common types of regulators are as under;
RESISTANCE TYPE
Open
Tubular
CHOKE TYPE
ELECTRONIC TYPE
Resistance Type Regulator
The voltage in this case is controlled by varying the regulator resistance. A
length of resistance wire is used for providing speed variation and different
length is brought into the circuit.

48
Choke Type Regulator
Choke type regulator is, as the name implies, a small transformer. The use of
multiple output points on the transformer gives variable voltages for different
speeds.
Electronic Regulator (Hum free – Capacitor Type)
The cost of electronic regulators is Rs. 30/- to Rs.50/- higher than Res. type
regulator. Their wattage consumption is however extremely low up to a
maximum of one or two watts.

IMPORTANT ASPECTS OF FABRICATION
The process of fabrication as well as the quality of material used determines
the eventual performance of a fan. Some of the most important aspects have
been discussed below to highlight the above.
lQuality of laminations
lCopper wire
lMode of winding
lInsulation
lAir Gap
lRotor Die Casting
lBall Bearings
lBlades

50
Condensers / Capacitors
The capacitance of condensers varies largely. This variation can result in low
speed if the capacitance is low and can seriously damage the motor if it is too
high.
MOTOR CIRCUIT
Condenser
Main Winding
Aux Winding
Mains
PHASE DIFFERENCE
VOLTAGE
PHASE
Time
A B
Voltage

51
THE PRODUCT – CHOOSING
THE FAN
The type of fan the customer buys depends largely on the following:
lWhere he would like to place it, and
lThe size of his room.
Ceiling Fans
In most permanent constructions where a fixed arrangement for air delivery
and distribution is required the ceiling fan is the ideal choice.
In such a case, the only question, when buying a C/fan would be, to determine
what is the optimum sized fan for his requirements.

52
SWEEP OF FAN 36” 42” 48”
56”
CENTRE OF DIFFERENCE1.8M 2M 2.5M
3M
Important: - To optimize air-delivery, your fan should be approximately
3metres from the ground
If the fan the customer intends purchasing is for large rooms like these in
factories, reception halls, auditoriums, etc., more than one fan is necessary
and the fans must be fixed at a center difference between each other, as
under, depending on the sweep of the fan.:

53
Room Size Fan Size
4mX5m to 4.5mX4.5m 1400MM
3.3mX4m to 3.7mX3.7m 1200MM
2.7mX3.3m to 3mX3m 1050MM
2.4mX2.7m to 2.4mX2.4m 900MM
For larger size two or more fans
will be required.
SELECTION OF SIZE/SWEEP OF
CEILING FAN FOR YOUR ROOM
Important: - To optimize air-delivery, your fan should be approximately
3metres from the ground

Table Fans
Table fans are ideal for any situation where 'spot flow' is required.
Pedestal Fans
These are used in lawns and commercial establishments etc. where it is not
possible to hang the fan from the ceiling.
Wall Fans
As the name implies, Wall fans are used wherever spot cooling is required e.g.
restaurants, cabins, kitchens, etc.

55
Exhaust Fans
These are used for blowing the air in/out of the room. In order to decide upon
the exhaust fan/s to be fitted certain ventilation planning is necessary. The
decision would be based on the following:

56
The number of Air changes required. The recommended Air changes
are as under:
Situation Air changes per hour
Assembly Halls 8-12
Banks 4-8
Boiler Houses 40-60
Canteens/Restaurants 12-20
Cinemas/Theatres 20-30
Factories/Workshops 12-20
Foundries 40-60
Hospitals (General Ward) 8-12
Kitchens (Domestic) 20-30
Laboratories 8-12
Offices 8-12
Photographic Darkroom 20-30
Note: The above air changes up to eight per hour provide for removing contamination normally
caused by human occupants. The higher rates of air changes provide for removing heat and
steam in a temperate zone. Twice the number of air changes must be allowed where smoke
occurs.

57
The following calculation would serve to illustrate the selection of an
exhaust fan:-
Situation Size Volume Air Changes/hr Air Movement
Office 10mX10mX4m = 400m3 10 400X10:4000m3/h
Factory 30mX20mX8m = 480m3 20 480X20:9600m3/h
Restaurant 20mX10mX8m = 1600m3 15 1600X15:2400m3/h
Once the Air movement required is determined the air movement should be
divided by the rated air delivery. This would determine the sweep/model/No. of
fans to be used for the required situation.

58
Sound level – The level of sound that emanates from an exhaust fan is very
important factor while selecting a fan for designing a ventilation system. This is
because a high sound level can cause mental exhaustion.
e.g. In the calculations as above in case an office requires air movement of
4000CMH, our 18" 900 RPM Exhaust fan would be able to provide the
necessary ventilation as it has air delivery of 3900 CMH. Two fans would be
required for the factory.

Sound level in db Grade Fan Types (single / three phase)
50-55 Very quiet 300mm dia 900rpm
380mm dia 900rpm
56-60 Fairly quiet 300mm dia 1400rpm
450mm dia 900rpm
600mm dia 700rpm
61-63 Tolerable whirl 380mm dia 1400rpm
64-65 Fairly noisy 450mm dia 1400rpm
600mm dia 900rpm
The recommended sound levels for various sizes are:-

60
Personal Fans
In several places space constraints precludes the usage of T/fan or C/fan. The
option is a small 'personal' fan in the shape. It can be used in places like Paan
shops, kitchens, bathrooms, etc. This is an all purpose fan.

61
BUREAU OF ENERGY EFFICIENCY (BEE)
lBEE is a statutory body under Ministry of Power, Govt. of India.
lTo save power ‘ Star Rating Project’ initiated by BEE for all consumer
appliances
Star Rating Service Value
(CMM/W)
  4.00 – 4.50
  4.50 – 5.00
  5.00 – 5.50
  5.50 – 6.00
  6.00
lService value = Air delivery / Wattage (CMM/Watt)
lAs per BEE the minimum Air Delivery should be 210 CMM
STAR RATING - FANS

lSee detailed instructions provided on the motor box supplied with the Fan for
method of installation and connecting to the supply line.
lEnsure that Fan down-rod is freely suspended and not obstructed by false
ceiling or defective hook. Fan down-rod when freely suspended should be
vertical.
lMinimum distance of Fan blades plane from the Ceiling of the room must be
12" (30 cms) or more.
lCeiling Fan blade plane should be around 8 feet to 10 feet from floor to get
adequate breeze.
lHandle blades carefully while mounting or handling. Do not allow mixing-up
of one set of blades with other set of blades. Each set of blade is provided in a
cardboard carton.
INSTALLATION OF CEILING FANS

S.No. Nature of
complaint
Probable cause Remedies (Follow the sequence)
1 Fan fails to start or
has reverse rotation
a)Regulator open circuit
a)Fan motor winding open circuit
or burnt
a)Capacitor faulty
a)Wrong connection at the
terminal block of the fan motor
a)Check the regulator as per
instructions
a)Check continuity of fan motor and
connections by multimeter
a)Check capacitor circuit, if found
defective, replace.
a)Check colour code at the terminal
block as per instruction provided.
Even after checking if it rotates in the
reverse direction then the motor is
confirmed to be defective.
COMPLAINTS, CAUSES & REMEDIES –
CEILING FANS

S.No Nature of
complaint
2 Inadequate breeze
or improper
regulation
a)Low voltage at the supply point
a)Low speed
a)Due to faulty regulator
a)Sweep may not be suitable for
the room
b)Fan may be too close to the
ceiling
c)Fan may be too high from the
floor
a)Check the voltage for 220/230V at the
fans terminal block when regulator is on
‘ON’ position. If it is low, nothing can
be done. If voltage is found OK, change
the capacitor.
b)Loss of capacitance; change the
capacitor with a new one
c)Check the resistance:
Terminals soldering must be checked
for continuity.
Rotary switch for continuity.
-- Replace accordingly.
(d) Check suitability of sweep as per
chart provided
(e) Minimum distance of plane of blade
must be from 10”-12” from the ceiling.
(f) Fan should be around 3 meter from
the floor.

S.No Nature of
complaint
3 Noisy Fan (a) Bottom canopy touching
(b) Blades are not fixed or
tightened properly to the
motor.
© Stator may be touching the
rotor
(d) Due to lack of lubrication
in bearing
a)Fix it at a proper distance from bottom
cover, so that it will not touch.
(b) Check whether blade fixing screws
on the motor are with spring washers, if
not, put the spring washers.
© Rotate the motor with hand very slowly
and check whether there is a slight jerk.
Also check whether there is a rubbing
noise in the motor, if so, touch is
confirmed.
(d) Switch the fan ‘ON’. After the fan
reaches full speed switch it ‘OFF’ and
observe the sound. If the sound persists
then clean and grease the bearings.

S.No Nature of
complaint
4 Fan swing /
Wobbling
a)Uneven blade height or angle
(b) Hexagonal nut and bolt is not
tightened firmly at both the ends
Of the suspension tube.
a)Please contact service centre / nearby
dealer.

We are continuously putting our efforts to perfect a range to suit every
customer and in doing this have developed product features unique to
Polycab.
SHAFTS
Polycab uses fine ground table fan shafts which do not wear out fast and
therefore our fans do not have problem of starting sound etc. which
necessitates change of shafts.
GENERAL FEATURES

INSULATION
Insulation of our motor is E.
ROTOR FINS
Fins are additional part of the fan provided on to the rotor. The movement of
these fins circulates the air inside the motor thus keeping the motor
temperature Low and resulting in higher efficiency. We at Polycab can claim
to be one of the few having "a fan within a fan".

INTEGRAL GEAR BOX
The integral gear box in fan ensures oscillation in tilted position as well as non
misalignment of gear box mechanism in transit.
BLADE DESIGN
Polycab blades are made of PP (Polypropylene) with dynamic balancing to
avoid vibration.

MOTOR CHARACTERSTICS
The quality of motor components and the fabrication process as in ceiling fans
is of the highest standards to ensure best motor performance.
PAINTING
The guards are painted by the process of electrostatic powder painting to
produce smooth and uniform paint with high gloss.

THE GEAR BOX
The oscillation of a table fan differs from the motor shaft movement in three
aspects.
lSpeed of movement
lAxis of rotation
lSemi-rotary movement in oscillation as compared to rotation of shaft.
The gear box serves the purpose of making motor shaft motion compatible
with oscillation. Additionally there is a mechanism for starting and stopping the
oscillation.

SPEED OF MOVEMENT
The rotor shaft movement is in excess of 1300 RPM which has to be reduced
to 20-30. This is obtained by the use of a worm gear. The worm gear meshes
with the thread on the portion of the shaft which connects the shaft to the gear
box.
AXIS OF ROTATION
Circular motion on an axis perpendicular to the shaft is obtained by use of a
‘Delrin’ Gear which is linked to the worm.

OSCILLATION
The ' Delrin' gear moves the pinion shaft in locked position which in turn
moves the spur gear shaft. It moves the revolving pivot which is actually a part
of a cam arrangement. This revolving pivot is connected through a link to the
oscillating pivot which is the second half of the cam system. The oscillation
now takes place as described in the IGB and non-IGB systems, while the
movement is the same.

INTEGRAL GEAR BOX
As the name implies the gear box is an 'integral part of the motor back cover.
The major advantage of this system is the extremely low probability of
misalignment of motor shaft with the gear box mechanism. The oscillation is
operated by means of a flick type knob providing ease in usage.

NON-INTEGRAL GEAR BOX
The gear box is die cast separately and fixed by screws to the motor back
cover. Since these processes are separately done there is a higher probability
of misalignment. The locking mechanism is the push pull type. Another
problem in this system is the wearing out of steel balls.

COMPLAINTS, CAUSES & REMEDIES –
TABLE / PEDETAL / WALL FANS
S.No. Nature of
complaint
1 Fan does not start a)No supply to fan terminal.
(b) Loose or wrong connection
at the terminal block.
© Defective capacitor
(d) Regulator Resistor burnt or
open circuit
(e) Fault developed in winding
(f) Starting switch defective.
a)Check the supply voltage
a)Check connection at terminal block of
motor.
© Replace capacitor.
(d) Replace Resistor.
(e) Replace motor.
(f) Replace Switch

S.No. Nature of
complaint
2
3
4
Fan gives shock
Fan does not
oscillate or there is
oscillation defect
Jerky operation
a)Some wire or a strand of the
wire may be loose and touching
the body.
(b) Stator insulation might have
failed
(a) Weak spindle spring
(b) Damage to Delrin worm gear.
(c) Worm threads of shaft worn
out
(a) Body pin loose in end shield.
(b) Back false cover touching
oscillating knob.
a) Check all wiring from the motor to
the base sheet and remove wire.
a) Check the red wires coming from the
motor stator body connected to the
switch with the body of the fan. If the
insulation has failed replace stator / fan.
(a) Replace spring
(b) Replace Delrin gear
(c) Replace rotor
(a) Tighten the body pin.
(b) Adjust back false cover

79
S.No. Nature of
complaint
5
6
Vibration
Noise
a)Blades not fixed properly
(b) Blades distorted / unbalanced
(a) Rotor touching the stator.
(b) Noise due to washer rubbing.
© Blade loose
(d) Guard loose
(e) Decorative plate loose
(f) Bush noise
a)Fit the blades properly by tightening
the blade fixing screws.
b) Replace blade set.
a) Check for damage in transit. Replace
motor.
a)Check for damage in transit.
Reassemble the motor.
b)Tighten blades.
c)Tighten guards.
d)Tighten screw fixing decorative plate
f) Lubricate bush bearings.

S.No. Nature of
complaint
7
8
9
10
Cable damaged
Fan not working on
2 & 3
Fan rotating reverse
Switch buttons
coming out
a) Excess movement of cable.
a) Faulty cable
(a) Wires may not be in contact
with the switch
(b) Switch may be defective
(a) Wrong connections of
capacitor.
a)Adjust cable to have minimum
movement.
(b) Replace Cable
(a) Check the wires and re-solder the
same.
(b) Repair / replace the switch.
(a) Interchange two of the leads.
(a) Replace / stick the buttons with
araldite before fixing clean the switch
portion properly.

81
S.No. Nature of
complaint
11 Oscillation defect
on wall fans
a)Lifter pin bent.
a)Oscillation lever touching back
false Cover.
© Clutch wire clamp loose.
(d) Wear out of the delrin gear.
a)Adjust lifter pin..
a)Adjust lever and false back cover.
a)Tighten clutch wire clamp.
a)Replace the delrin gear.

lSufficient open space should be available on inlet and outlet side of the fan
lExhaust fan should never be mounted near windows or doors.
lAvoid mounting directly over heat source.
Some layouts of good and poor systems are:-
LOCATION OF EXHAUST FAN
POOR LAYOUT GOOD LAYOUT

INSTALLATION OF EXHAUST FANS
INSTALLATION DETAILS
Diameter of opening on the wall should be 25mm more than the sweep.
Area around the opening should be completely closed.
It is recommended to use the motor horizontally.
IDEAL EXAMPLES OF INSTALLATION
In ordinary kitchen and bathrooms install in the upper part of the wall
nearest to the working area. (Fig A)
In large restaurants, conference rooms,
auditoriums and the like, install multiple units
on both sides (Fig. B)
Installation in the bedroom as in (Fig. C)

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