Page 273 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

TASK 5:

1 Dismantle the pedestal fan
2 Specify parts of the fan
3 Draw the sketch of the fan
4 Draw the circuit diagram

5 Check the windings of the fan with multimeter.
6 Measure the resistance of the windings.
7 Identify the starting and running winding.
The starting winding is having comparatively higher resistance.
8 Study the internal connections of pedestal fan.
Fan is noisy

• Collect the history and nature of the noise of the fan from the user.
• Run the fan and observe the noise.
• Identify whether the noise is due to one or a combination of the following.
a Slack canopy/cover - touching the rotating body.

b Worn out/partly out shackle.
c Loose element of the blade.
d Loose or missing screws.
e Capacitor housing slack.
f Broken or worn-out split pin at the top and bottom.

g Lack of lubrication, or dirt in bearing.
h. Worn out bearing/bush.
i Blade distortion/breakage.
j Alignment of blades.

Fan wobbles excessively
• Check to be sure that the screws which attach the fan blade flanges to the motor hub are tight.
• Check to be sure that the fan blade flanges seat firmly and uniformly to the surface of the motor hub.
• Tighten the hanger bracket screws to the junction box, secure the hook.
• Interchange the adjacent (side by side) pair of blades.
Motor runs hot

• Check for partial short circuit in winding. If defective, send it for rewinding
• Check for tight bearing, if it is defective, replace it with good bearing
9 Rectify the fault of the fan, if any.
10 Reassemble the fan.

11 Check the working of fan.

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CITS : Power - Electrician & Wireman - Exercise 101