Specifications

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Enclosure: The place where the fan motor is
mounted may be totally enclosed type or
ventilated type. The enclosure material is
generally cast iron.
Body and stand: The body of the table fan is
usually made of die cast iron or aluminum alloy.
The body is fitted or mounted to the heavy base
stand, made of die cast iron or aluminum.
Fig.13.5 - External parts of table fan
Motor: The table fan motor is mostly of a single phase capacitor start and run or rarely shaded
pole type motor. The operating voltage of the motor will be 230 V ± 10 % at a frequency of 50 Hz.
This motor has two parts namely stator and rotor. The stator, made op laminated silicon steel,
employs two windings called as starting and running windings placed 90 degree electrical apart.
The windings are placed in slots of laminated iron core. The starting torque depends on sine of
angle between starting winding and running winding current. So Capacitor is used produce
required phase shift between these current and hence to produce high starting torque and will
be connected in series with starting winding. Normally in table fan, an electrolytic capacitor of
1.5 mF. Rotor employs 1-phase squirrel cage winding.
Blades: The blades, 3 or 4 in number, are fabricated from Aluminum sheet foe light weight.
Modern table fans have molded blades of plastic material. The blades are fully balanced to
ensure proper and smooth air delivery. The sweep of the blade varies from 100 to 400 rpm. The
speed of the fan is limited to less than 1000 rpm. The blade assembly is fitted to the rotor shaft
with a grub screw.
Guard: The guard is provided for adequate protection against personal injury. The front and rear
of the fan guards are made out of wire mesh which covers the blade. It prevents the external
objects coming in contact with the blade thus preventing an accident. The front guard is normally
detachable and rear one will be permanently fixed to the body of the fan. The diameter of the
guard wire is normally not less than 1.6 mm and not more than 10 mm.
Bearing: Most of the fan motors use phosphor bronze sleeve bearings mounted in the bell
housings and use felt wick to supply oil to a small hole drilled through the bearing wall. The felt
wick receives oil from a hole in the bell housing. Most of the fan motors use an integral ball
bearing to locate the rotor. It is held in place by spring clips in the bell housing and is self-aligned.
Mounting: It means attaching the fan system (motor and blades) to its base. The mounting
may be rigid (change of direction is by turning the entire fan body) or semi-rigid (the direction of
draught can be altered without changing the direction of the base).
Oscillating mechanism: The oscillating unit mechanism consists of a worm gear or a motor
shaft that engages a gear on a short jack with the gear on the vertical shaft. A disc attached to
the lower end of the vertical shaft rotates at a very slow speed and by means of a strong crank
lever attached to the disk at one end and the motor at the other end, the fan is caused to
oscillate. This principle is employed in most oscillating units built into the gear mechanism with