Page 278 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Blows fuse when a) Shorted power cord. a) Replace the cord.
switched on. b) As in ‘d’ above.
b) Locked shaft
c) Test the windings for short. If short is found,
c) Defective armature or field coils. rewind or replace.

d) Poor insulation resistance. d) Check, test and repair.

e) Low capacity fuse. e) Check the capacity of the fuse against the
mixer rating. Replace if required.
Mixer runs but a) Overloading of mixer. a) Bring down the load in the mixer or advise the
becomes hot. customer to go for a higher capacity mixer.
b) Time rating of mixer is exceeded.
b) Check the duration the mixer is switched on by
c) Bent shaft and rotor is rubbing the customer and compare with the mixer
the stator. c) Check, repair or replace if required.
d) Improper coupling. d) Check, repair or replace if required.
e) Shorted winding. e) Check, test and rewind if required.

Bad sparking at a) Struck or worn out or loose a) Check, reshape the brushes, replace the
motor brushes. brushes. springs or reposition the brushes for proper
b) Pittings or uneven commutator tension.
surface. b) Use sand paper or turn the commutator on a
lathe.
Mixer gives shock. a) Water leaking and coming in a) Check the drain hole in the coupler head
contact with live terminals. assembly for blockage. Check the jar examine
(Double insulated mixers with for leakage due to loose shaft or worn out
plastic body and two pin plug. bearing, ebonite washer breakage. Repair or
No earth connection). replace.
b) Vent hole in the mixer body b) Clean the vent hole.
c) Damaged power cord. c) Check and replace if required.
d) Absence of earth connection. d) Check the earth connection in the mixer motor,
power cord and at socket. Repair and re-do the
earth connection if required.
e) Live parts coming in contact with e) Check with a Megger and take corrective
metal body. action if required.

Wet grinder

Objectives: At the end of this lesson you shall be able to:
• explain the wet grinder
• state the different types of wet grinders
• explain the parts of a wet grinder
• explain the possible faults in wet grinders and their remedies.

Wet grinder
It is a domestic electrical appliance, which is used to grind the wet grains.
Types: There are three types of wet grinders
– Conventional (regular) wet grinder.

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CITS : Power - Electrician & Wireman - Lesson 101-103