Sreerama Govt.

Polytechnic College Thriprayar

SREERAMA POLYTECHNIC COLLEGE THRIPRAYAR

DEPARTMENT OF ELECTRICAL ENGINEERING

4038: WORKSHOP MANUAL (Revision 2021)

Domestic Appliances Repair And Maintenance Workshop

SUBJECT CODE : 4038

Chembukkavu , Thrissur , Pin – 680020

Phone : 0487 2333290 Fax : 0487 2321753
Mail : info@mtithrissur.ac.in
electrical@mtithrissur.ac

Prepared by :
Neethu Raj P R

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

VISION

Mould socially responsible, ethically strong and technically competent electrical and

electronics engineers

MISSION

M1: To educate, inspire and mentor students to produce quality professionals in

the field of electrical and electronics engineering.

M2: To facilitate students to render services to the society through innovations

and entrepreneurial activities.

M3: To encourage students to become lifelong learners.

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

INSTRUCTIONS TO STUDENTS

1. Only enter the workshop(Lab) wearing proper workshop dress, shoes,

and IDcard
2. Use the tools and machines safely to avoid injuring yourself.
3. Never run inside the workshop.
4. Do your work with very attentive mind and carefulness.
5. Students must bring the rough record every day, with the experiment or
work of that day written and diagrams and table drawn.
6. The rough record of one day’s work should be completed and submitted
on next day.

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

SYLLABUS

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

EXPERIMENTS

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Sreerama Govt. Polytechnic College Thriprayar

Experiment No. 01
Date :
ELECTRIC IRON BOX

AIM : To study the construction and working of Electric iron box, dismantle the
given Electric iron box and identify the faults and suggest its remedies
and also prepare a maintenance chart .

TOOLS AND INSTRUMENTS REQUIRED

Sl.No. TOOLS AND INSTRUMENTS SPECIFICATION QUANTITY

1 Screw driver 200 mm 1 No.
2 Connector screw driver 150 mm 1 No.
3 Combination Plier 200mm 1 No.
4 Electricians Knife 100mm 1 No.
5 Neon tester 500V 1 No.

APPARATUS REQUIRED

Sl.No. APPARATUS SPECIFICATION QUANTITY

1 Electric Iron box 750W, 250 V, Non automatic 1 No.
2 Electric Iron box 750W, 250 V, Automatic 1 No.
3 Multimeter 0-100V dc/ac, 0-20Ω, 0-1A 1 No.

OBJECTIVES

1. Identifying parts of Electric Iron box.

2. Testing the given iron box.
3. Check for other possible faults.

1. Identifying parts of Electric Iron box.

An electric iron box is used to iron the cloths. Electric iron box can be classified into
two types as below
a. Ordinary (Non automatic) Electric Iron Box
b. Automatic Electric Iron Box

a. ORDINARY ELECTRIC IRON BOX

The temperature is not regulated in non automatic type iron box. The user has to
switch on or switch off the iron box according to heat requirement.

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It consists of Chromium plated base plate, Heating element, Pressure plate and Iron case with
Handle.

1. Sole Plate
It is made up of Cast iron. The transfer of heat from the heating element to
material to be ironed is done through sole plate

2. Heating Element
There are two types of heating elements. One is made of ribbon shaped nichrome
(resistance) wire wound around a sheet of mica. This type of element is placed on the top
of Sole plate. Other type is made up of round resistance wire coiled on ceramic form and
cast directly in to sole plate.
Its wattage varies 450, 500, 1000 etc.,

3. Pressure Plate
It is made up of Cast iron. Its shape as heating element. Its p u r p o s e i s t o k e e p
t h e heating element on sole plate with the help of two machine screws and nuts. The
pressure plate is insulated from the heating element by an asbestos sheet of the same
shape. Asbestos sheet prevent heat developed in heating element travelling upward due
to conduction and radiation.

4. Iron Case
It is used for covering the all above parts. In which an insulator terminal and
handle is provided. It is made up of iron sheet with Nickel plating.

5. Wooden or Ebonite Handle

It is used for holding the bar terminal with stand washers.

b.AUTOMATIC ELECTRIC IRON BOX

In addition to the above-mentioned iron box, the automatic iron box has a additional devices called
thermostat which regulate the temperature. It is connected in series with the heating element. This
thermostat controls the temperature. It Prevent over heating of iron and thus avoids damage to the

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heating element. The required temperature can be obtained with the help of thermostat.

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Bimetal thermostat switch: - It connected in series with heating element. It is a bimetal strip
(made of 2 strips of metal) with different thermal expansion rates contacted. At normal state i.e. at cool
time this switch contacts are closed. When current passes through this closed circuit one of the metal strip
expands and bends more compare to other and opens the circuit. The distance of expansion can be adjusted
by a screw and is attached to heat adjusting knob or regulating knob. At open circuit period iron cools,
then thermal switch contacts close again

Principle of Operation
An electric iron box works on the principle that when an AC current passed through a
resistive wire the electrical energy is transferred to heat energy. The Nichrome wire is heated up to
a certain temperature and gets a bright orange- red colour. The wire used in heating element
generally made by Nichrome wire whichis a combination of 15% Chromium 20% Iron and remains
Nickel.
Automatic irons are fitted with a thermostatic switch to regulate the heat to a specific
predetermined value the thermostatic switch disconnects the supply. When the predetermined
value is reached the supply is disconnected and reconnects the supply when iron cools down.

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2. Testing the given iron box.

Two tests are to be conducted on the iron box

a. Earth leakage test

Procedure
The earth leakage testing is done by connecting one lead to one terminal of
electric iron and other lead to metal parts of the element.

Conditions
• If the lamp give full light or dim light, there is a leakage in the iron.
• If the lamp does not glow , the iron box is in good condition.

b. Open and short circuit test

Procedure
Connect the two ends of test lamp leads in series to the terminals of Iron box
and give power supply.

Conditions
• If lamp glows dimly it means that element is in good condition.
• If the lamp does not glow it means that the heating element is broken or
thermostat contacts are disconnected or not clean due to carbon deposit.
• If the lamp glows brightly the both sides of the element touching the sole
plate or body.

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3. Check for other possible faults.

TROUBLES POSSIBLE CAUSES REMEDIES

No power at outlet. Check outlet for power.
Defective cord or plug. Repair or replace.
Loose terminal connections Check and tighten the terminals.
Broken lead in iron. Repair or replace lead.
No heat
Loose thermostat control knob. Clean and tighten.
Defective thermostat Replace thermostat.
Replace the element if separate OR
Defective heater element
replace sole-plate assembly.
Open terminal fuse Replace.
Low line voltage. Check voltage at outlet.
Insufficient heat
Incorrect thermostat setting. Adjust and recalibrate thermostat
Adjust and recalibrate thermostat or
Incorrect thermostat setting
Excessive heat replace.
Defective thermostat. Replace thermostat
First repair the thermostat control or
Blisters on sole- repair the sole-plate, depending on its
Excessive heat
plate condition.

Rough spot, nick, scratch, burn Remove these spots with fine emery and
Tears clothes
on sole-plate. polish the area with buff.
Iron cannot be Thermostat switch contacts are Check the thermostat switch contact and
turned off welded together. Open them by force.
Iron box not Power cord oose connection or Clean and tighten
turning on Broken wire. Repair or replace.
Dirty sole-plate. Clean.
Iron at a lower temperature. Use less
Excessive starch in clothes.
starch next time.
Sticks to clothes
Wrong setting of the
Set the knob to correct temperature.
thermostat knob.
Iron too hot for fabric being
Lower the thermostat setting.
ironed.
Check earth connection and connect
Disconnected earth connection.
Properly
Iron gives shock Weak insulation of heating Check insulation resistance of heating
element. element; if necessary replace element.
Earth continuity with common Check the main earth continuity and
earth not available. connect properly.
RESULT
TESTING OF IRON BOX

LAMP
Sl.No TEST FAULT
CONDITION
1 EARTH LEAKAGE TEST
2 OPEN/SHORT CIRCUIT TEST
Dismantled the Iron box and studied its parts. Tested for heating element faults and
checked other possible faults.

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

Experiment No: 2
Date :
ELECTRIC KETTLE
AIM : To study the construction and working of Electric Kettle, Dismantle the given Electric Kettle and identify
the faults and prepare troubleshooting chart.

TOOLS AND INSTRUMENTS REQUIRED

Sl.No. TOOLS AND INSTRUMENTS SPECIFIC ATION QUANTITY

1 Screw driver 200 mm 1 No.
2 Connector screw driver 150 mm 1 No.
3 Combination Plier 200mm 1 No.
4 Electricians Knife 100mm 1 No.
5 Neon tester 500V 1 No.

APPARATUS REQUIRED

Sl.No. APPARATUS SPECIFICATION QUANTITY

1 Electric Kettle 1000W, 250V 1 No.
2 Multimeter 0-100V dc/ac, 0-20Ω, 0-1A 1 No.
3 Test Lamp 230 V, 60 W 1 No.

OBJECTIVES

1. Identifying parts of Electric Kettle

2. Testing the given Kettle.
3. Check for other possible faults.

Identifying parts of Electric Kettle

Electric kettles offer a more convenient way to get boiling water when compared to a traditional stove
top kettle or pot. They’re not only more energy efficient than boiling water on the stove, but they
produce hot water much more quickly. On top of saving time and energy, most electric kettles also
offer an automatic shutoff, which saves additional energy and reduces risks related to stove top heat.

All electric kettles contain the same basic parts and setup, although certain elements may be different
depending on the make and model. The parts of an electric kettle include:

• Body: The reservoir for the water that is heated. This can be stainless steel, glass or ceramic,
and may have an outside layer or coating for aesthetic reasons. The kettle body includes a
pouring spout, a handle and a lid.
• Heating Element: The key to the electric kettle is its heating element, which is the structure
at the bottom of the kettle that produces the heat. The heating element is made of
Nichromwe ribbon resistance wire wound over flat mica sheet. This is placed between two
circular sheets, so that the Nichrome wire may not come in contact with any metallic part of
the kettle.

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• On/Off Switch: This switch turns the kettle on, which will start generating heat in the
heating element. Many kettles have an automatic shutoff, although there are still models
with a manual on/off switch.
• Thermostat: The thermostat connects the heating element, a temperature monitor and the
on/off switch. Once it detects the appropriate temperature, it sends a signal to the on/off
switch to stop flowing electricity through the heating element.
• Power Connection: The kettle will have either a direct cord, which connects to a standard
electrical plug, or a base with a cord to attach to a standard electrical outlet.

Options: The kettle may have an additional switch or selector to choose the temperature at which the kettle will
shut off.
How an Electric Kettle Works

An electric kettle works by using the heating element. This element is made of a resistive material that
produces heat when electricity flows through it. At the bottom of the electric kettle container, there is a
heating element, a metal, which is heated by converting electrical energy into heat. The thermostat
controls the flow of electricity and sends a shutoff signal when the desired temperature is reached.

Electric kettles come in two types of models: corded and cordless. In a corded model the cord is attached
to the electric kettle power base, which plugs into the wall. Cordless models actually still have a cord,
which connects to a base on which the kettle rests while heating. The advantage to a cordless model is
that the kettle detaches from the base, which makes it easier to pour or carry around. The mechanics of
both kettles remain the same.

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Testing the given Kettle.

1 Record the name-plate details of the appliance
2 Disconnect the power cord and check the power cord for continuity of the cable, soundness of the
terminal connection and insulation resistance between the line, neutral and earth terminals. If found
defective, either repair or replace the power cord.
3. Check the continuity of the kettle heating element either by using a test lamp or a Megger without
opening the kettle. If there is no continuity, the element is as considered to be open and it has to be
replaced
4. Check the insulation resistance between the appliance socket terminals and the body of the kettle, If the
insulation resistance is less than one Megohm, the kettle element needs to be replaced.
5.Read the assembly diagram in the instruction book of the kettle and dismantle the parts in the sequence
recommended by the manufacturer.
6 In the absence of the manufacturer’s recommended sequence diagram of the assembly, the following
parts may be removed observing the correct procedure as shown in the above figure..
Bottom cover
- Pressure plate-

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Sole-plate with asbestos insulation

- Element
7 Obtain a suitable element of the right shape, wattage and voltage and necessary mica and asbestos sheets
of the same type and quality.
8 Check the element for its continuity and ohmic value.
9 Replace the new element in position.
10 Assemble the parts in proper order and connect the appliance.
11.Measure the insulation resistance between the body of the appliance and its terminals before and after
connecting the power cord.
Switch ‘ON’ the kettle only after filling water in it.
12 Test the appliance with supply for its working

Two tests are to be conducted on the Electric Kettle

• Earth leakage test

Procedure
The earth leakage testing is done by connecting one lead to one terminal of Kettle and other
lead to metal parts of the element.

Conditions
If the lamp give full light or dim light, there is a leakage in the Kettle.
If the lamp does not glow , the Kettle is in good condition.

• Open and short circuit test

Procedure
Connect the two ends of test lamp leads in series to the terminals of kettle and give power supply.

Conditions
If lamp glows dimly it means that element is in good condition.

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If the lamp does not glow it means that the heating element is broken or thermostat contacts are
disconnected or not clean due to carbon deposit.
If the lamp glows brightly the both sides of the element touching the sole plate or body.

RESULT

TESTING OF ELECTRIC KETTLE

Insulation resistance between

appliances socket and body of
kettle

LAMP
Sl.No TEST FAULT
CONDITION
1 EARTH LEAKAGE TEST
2 OPEN/SHORT CIRCUIT TEST

Dismantled the Electric Kettle and studied its parts. Tested for heating element
faults and checked other possible faults.

Department of Electrical and Electronics Engineering

Sreerama Govt. Polytechnic College Thriprayar

Experiment No. 3
Date :

ELECTRIC MIXER
AIM : To study the construction and working of Electric mixer, dismantle thegiven Electric mixer and identify the
faults and remedies and also prepare a maintenance chart.

TOOLS AND INSTRUMENTS REQUIRED

Sl.No. TOOLS AND INSTRUMENTS SPECIFICATION QUANTITY

1 Screw driver 200 mm 1 No.
2 Connector screw driver 150 mm 1 No.
3 Combination Plier 200mm 1 No.
4 Electricians Knife 100mm 1 No.
5 Neon tester 0-500V 1 No.

APPARATUS REQUIRED

Sl.No. APPARATUS SPECIFICATION QUANTITY

1 Electric Mixer 500W, 250 V 1 No.
2 Multimeter 0-100V dc/ac, 0-20Ω, 0-1A 1 No.
3. Test lamp 230 V, 60W 1 No.

OBJECTIVES

Identifying parts of Electric mixer.

Testing the given Electric mixer.
Check for other possible faults.

Identifying parts of Electric mixer.

Motor
The motor used in Mixie is Universal motor, which is a series motor having both armature and field
windings. The special feature of this motor is that, it can be operated both in AC and DC supply. The
armature core is made of silicon steelalloy and laminated to avoid eddy current and hysteresis losses.
This motor provides a very good torque and its speed is regulated either by tapped field coils or tapped
resistance in series. The power rating of motor would be about 500 W, operates on 220/204 V, 50 Hz AC
supply. The no load speed would be about 18000rpm with a full load speed of about 10000 rpm. The motor
is housed in base of mixie body. Since the no load speed is very high, the mixie should not be operated
without load.

Blender and Grinder

Normally each mixie is associated with 3 kinds of jar of different capacity.

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Blades
Blades are made of good quality stainless steel and will therefore give high life. Each jar will have its own blades
according to its purpose. Jars are designed to grind dry or wet substances. So it is advisable not to interchange the
blades from one jar to other.

Speed control switch

For speed control purpose, the tapped field coils are normally employed in mixie motor. The tapped field coils
enable speed selection through a rotary switch provided in the Mixie. Normally 3 speed levels (1, 2 and 3) will be
provided in the Mixie motor. By turning rotary switch clockwise, we will get speeds 1, 2 or 3 as desired.
For inching purpose, it is required to turn rotary switch anti-clockwise for a few seconds and release for
momentary operation. (This is especially useful for wet grinding of chutneys, mincing meat, grating vegetables,
crushing ice, etc.).

PARTS OF ELECRTIC MIXER

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INTERNAL CONNECTION DIAGRAM OF MIXER GRINDER

Testing the given Electric mixer.

Two tests are to be conducted on the Electric mixer.

Earth leakage test

Procedure
The earth leakage testing is done by connecting one lead to one terminal of electric iron and other lead to
metal parts of the element.

Conditions
If the lamp give full light or dim light, there is a earth leakage in the mixer.
If the lamp does not glow, the mixer is in good condition.

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Open and short circuit test

Procedure
Connect the two ends of test lamp leads in series to the phase and neutralterminals of mixer and give power supply.
Conditions
If lamp glows dimly it means that mixer windings are in good condition.
If the lamp does not glow it means that the mixer winding is broken or looseconnection inside..
If the lamp glows brightly there is short circuit in the windings.

TESTING CONNECTION DIAGRAM OF MIXER GRINDER

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Check for other possible faults.
FAULTS CAUSES REMEDY
Overload Reduce the load.
Low or high supply Give proper supply
Mixer grinder is
voltage.
heating
Bearing and couple are too Lossen the dearing and couple and tight
tightened. appropriately
Supply does not exist Give proper supply
Couple is mechanically Check rotation, Dismantle if required and test.
block.
Coil are open circuited. Test the field coil for open circuit (test lamp)
and replace if necessary.
Complaint on over load Check switch with test lamp and replace if
Mixer motor switch. necessary..
does not rotate Defective the selection Check rotatory switch and replace ifnecessary..
switch.
No adequate pressure on
brush holder. Check brush holder and replace if necessary.

Short circuit on armature. Check the armature by growler to located

effective coil and replace if necessary..
Bearing problem. Check the bearing. Replace if necessary
Mixer makes Check the joining of couples and jar and put it
sound Improper coupling of jar. correctly

Short circuit on winding. Check winding using test lamp and replace if
necessary.
Speed can’tbe varied. Check rotary switch. Replace if necessary.

Low speed Decrease of sharpness of Check the blade and brush and replace if
blade or brush complaint. necessary

Short circuit in armature or Check commutator insulation.

commutator
Too tight to the working Check bearing and brushes.
motor.
Shock from Get shocks from body. Check water leakage inside of it. Clean it with
mixer hot air blower.
Get shock from cord wire Check insulation of cord wire. Replace it.

RESULT
Sl.No TEST LAMP CONDITION FAULT
1 EARTH LEAKAGE TEST
2 OPEN/SHORT CIRCUIT TEST

Dismantled the Electric mixer and studied its parts. Tested for winding faults and checked other possible
faults.
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Experiment o. 4
Date :

ELECTRIC GEYSER
AIM : To study the construction and working of Electric geyser, dismantle thegiven Electric geyser and
identify the faults and remedies and also prepare maintenance chart.

TOOLS AND INSTRUMENTS REQUIRED

Sl.No. TOOLS AND INSTRUMENTS SPECIFICATION QUANTITY

1 Screw driver 200 mm 1 No.
2 Connector screw driver 150 mm 1 No.
3 Combination Plier 200mm 1 No.
4 Electricians Knife 100mm 1 No.
5 Neon tester 0-500V 1 No.

APPARATUS REQUIRED

Sl.No. APPARATUS SPECIFICATION QUANTITY

1 Electric Geyser 1500W/240 V - 15 liters - 1 No. 1 No.
2 Multimeter 0-100V dc/ac, 0-20Ω, 0-1A 1 No.

OBJECTIVES

Identifying parts of Electric Geyser.

Testing the given Electric Geyser.
Check for other possible faults.

Geyser heater is used for large quantity of water. Generally, from 20 ltr to 90 ltr capacity geysers
are found in the market. In the storage tank, one or two heaters are fixed. For supplying of cold or
hot water, specific pipe lines are fitted with the storage tank. That means there are inlet cold water
and outlet hot water pipe. To control the flow of water, a valve is installed in the pipeline. To control
the heat one thermostat switch is there. The switch gets automatically OFF to avoid misuse of heat.
The entire body of the geyser is insulted. When the geyser storage tank is filled up, the water starts
flowing through an overflow pipe, and then the inlet valve gets automatically OFF. An anode rod
made of aluminum or magnesium is screwed in the storage tank to reduce corrosion of metal body
and metal parts of the water storage and supply system. This is because the metal of anode rod is
more sensitive to corrosive reactions than the metal of the body structure of the system. Body of the
storage tank is generally made of steel. As aluminum or magnesium is corroded faster, it makes the
water soften before it can corrode the steel.

Working of Geyser:

The electric geyser works on a simple principle that converts electric energy into heat energy.
When you turn on the geyser, the current gets converted into heat energy. The water then passes
through rods adsorbing the heat energy and becomes hot. The thermostat within the geyser helps in
keeping the water temperature below the set limit.

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Testing the given Electric Geyser.

Steps to be carried out

1. Open the inspection cover for the electric terminal connection and thermostat installation. In the geyser
after remaining power plug.
2. Conduct visual examination on the power cord and terminal at the apparatus.
3. Check the proper tightness and good electrical contact at the terminal Replace the plug pins if found
pitted.
4. Conduct the insulation test on the cord between leads, lead and earth.
5. Measure the insulation resistance between element and body. The minimum value of insulation resistance
should be .5 mega ohm.
6. Connect the geyser to the supply and switch on the apparatus keeping the bottom cover of the electrical
connection open.
7. The geyser should be switched on only with water in the container.
8. Observe the heating process in the cut off by the actuation the thermostat.
9. Replace the thermostat with new one if faulty.
10. Refit the inspection cover.

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Check for other possible faults.

FAULTS CAUSES REMEDY
a) No power a) check fuse
b) check availability of power
No hot water c) open the cover and check for the continuity
b) Defective thermostat Check the thermostat for the continuity between its
terminals at defective setting If the thermostat is
found defective, replace with new one
c) Thermostat out of calibration Adjust the thermostat for a high setting if the
thermostat is found to be good switch on the supply.
Observe the fuse
d) Defective heating element Check the element for its continuity and insulation
value between the terminals and the body.
Replace the defective heating element with good one
of same rating.
a) thermostat setting is i) Check the setting of the thermostat and
too high adjust it to a lower value. Switch on the
Water too hot geyser and wait for the thermostat to cut
b) defective thermostat off the supply for above 20 minute. Open
the inlet, collect the outlet and measure
the hot water temperature.
ii) If the water temperature is much higher
than the set values of the thermostat
replace the thermostat with a good one
a) Thermostat is too low i) Check the thermostat setting and adjust it to a
Water is not hot b) Incorrect heating element higher value. If the geyser produce hot water with the
enough c) Excessive lime in tank setting, then the earlier setting was wrong.
ii) Check and test the wattage of the heating element
if it shows a lower value. Replace it with a high
wattage element.
iii) Remove the heating element. Inspect the element
and the inner side the copper vessel for deposit of
excessive coating. In case the heating element of
correct wattage and the thermostat is properly set.
Remove lime coating
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RESULT

TESTING OF Geyser

Fault Remedies

Dismantled the Electric Geyser and studied its parts. Tested for heating element faults and checked other
possible faults.

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Experiment No. 5
Date :
TABLE FAN

AIM : To study the construction and working of table fan, dismantle the given table fan and identify
the faults and remedies, also prepare maintenance chart.

Identifying parts of Table fan

1.Rubber feet
2.Rgulator choke
3.Capacitor
4.Blade bush fixing screw
5.Spindle
6.Front cover
7.Stator
8.Oscillator knob
9.Back cover
10.Vertical Spindle
11.Gear box
12.Back cover fixing screw
13.Bush bearing
14.Link fixing screw
15.Switch
16.Pivot pin
17.Crank Lever
18.wire Guard
19.Bottom cover

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Parts of Table Fan:

1. Enclosure: The place where fan motor is mounted may be totally enclosed type or ventilated
type. The enclosure material is generally cast iron.
2. Body and Stand: The body of cast iron is made up 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.
3. Motor: The table fan motor is mostly of a single-phase capacitor start and run or rarely
shaded pole motor. This motor has two parts namely stator and rotor. The stator made of
laminated silicon steel, employs two windings called starting and running winding placed 90
degree apart. The windings are placed in slots of laminated iron core. The starting torque
depends on sine of angle between starting and running winding current. So capacitor is used
to produce required phase shift between these current and hence to produce high starting
torque and is connected in series with starting winding. Normally in table fan electrolytic
capacitor of 1.5 mF is used. Rotor employs single phase squirrel cage winding.
4. Blades: The blades 3 or 4 in number are fabricated from Aluminum sheet foil with light
weight. Modern table fans have moulded blades of plastic material. The blades are fully
balanced to ensure proper and smooth air delivery. The sweep of fan blades varies from 100
to 400 mm. The speed of fan is limited to less than 1000 rpm. The blade assembly is fitted to
the rotor shaft with a grub screw.
5. Guard: The guard is provided for protection against personal injury.
6. 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 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.
7. Supply cord: A 3 core flexible sheathed conductor of length about 2 m is used which has an
earthing conductor along with other two conductors. A cord grip is also inserted at the
entrance point of cord into the body
8. Fan regulator: It is built within the table fan. There are so many types of regulators i)
resistive wire type ii) choke or inductor type iii) capacitor type iv) electronic type. Generally
coiled resistance type regulator is used in table fan.

Working of Table Fan:

A table fan consists of a power button and a few buttons to control the speed of rotation of
the fan blades. When the fan’s main power supply button is turned on, the motor gets supplied with
electric current. The main purpose of the electric motor is to convert electric energy into mechanical
energy. The shaft of the motor is connected to the fan blade. This means that the rotatory motion of
the motor shaft gets transferred to the fan blades, thereby causing them to rotate along the axis.
Testing

Steps to be carried out

1. Note down the name plate details
2. Switch on the fan and check its function and vary speed and observe oscillation
3. Conduct visual inspection on the power cord, plug pin terminal for tightness for
good electrical connection
4. Open the bottom cover and verify the connection and clean the terminals
5. Conduct insulation test, continuity test in windings, capacitor
Identifying starting and running winding
1. By using test lamp method ( 200 w,240V lamp)
2. Starting winding has high resistance therefor the test lamp shows dim light
3. Running winding has low resistance so test lamp shows bright light
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Possible fault and remedies

Result:

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Experiment o. 6.
Date :
CEILING FAN

AIM : To study the construction and working of ceiling fan, dismantle the given
ceiling fan and identify the faults and repair.

TOOLS AND INSTRUMENTS REQUIRED

Sl.No. TOOLS AND INSTRUMENTS SPECIFICATION QUANTITY

1 Screw driver 200 mm 150 mm 1 No. 1 No.
2 Connector screw driver 200mm 100mm 1 No. 1 No.
3 Combination Plier 0-500V 1 No.
4 Electricians Knife
5 Neon tester

APPARATUS REQUIRED

Sl.No. APPARATUS SPECIFICATION QUANTITY

1 Ceiling fan 100W, 250 V 60 1 No. 1 No.
2 Test lamp 60W, 250 V 1 No.
3 Multimeter 0-100V dc/ac, 0-20Ω, 0-1A

OBJECTIVES
1. Identifying parts of ceiling fan.
2. Identifying winding terminals.
3. Testing the windings.
4. Check for other possible faults.

1. Identifying parts of ceiling fan

1. Electric motor:
Single phase capacitor start and run induction motor, rated at 230 V ± 10 % at a
frequency of 50 Hz, is normally used in ceiling fan. This motor has two parts namely
stator and rotor. The stator, made of laminated silicon steel, employs two windings
called as starting and running windings placed 90 degree electrical apart. The starting
torque depends on sine of the angle between starting winding and running winding
current. So Capacitor is used to 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 ceiling fan, an electrolytic capacitor of 2.5 mF±5% will
be used.
2. Blades:
The blades are made of sheet steel or aluminium sheets. Aluminium blades are lighter
than steel sheet plates and also improve the efficiency of the fan. The ceiling fans
normally have 3 or 4 angular blades. The four blade fan gives more air circulation
as compared to three blade fans. The blades are 120 o mechanically apart and may be
curved at an angle of 10o.

3. Blade flanges:
These are metal arms which connect the blades to the motor.

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4. Canopy/Switch Cup:
There are two canopies top and bottom, made of metal cylinder, placed along
suspension rod. Top canopy is mounted such that it covers the hook, nut, and bolt.
Bottom canopy is mounted below and in the centre of the fan’s motor. This is used
to conceal and protect various components, which can include wires, capacitors and
switches.
5. Ball bearing:
Friction free and noise free movements of rotating parts are ensured by providing ball
bearing between rotating and stationary parts. The ceiling fan may have single or
double ball bearings. The bearings made of high quality steel are regularly greased
with superior quality for its long life and noise free operation.
6. Suspension rod/Down rod:
It is made of rigid galvanized steel pipe of appropriate length and diameter. This
metal pipe is used to suspend the fan from the ceiling. One end of the pipe is bolted
or screwed at the place specially made on the motor body to receive the suspension
rod. The other end of the suspension rod is attached to two plates, to from a “U”
shaped joint, with the help of a nut and bolt (with additional lock nut).

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2. Identifying winding terminals

Procedure
Using multimeter measure the resistance between each of the three terminals.

Conditions
When two terminals shows maximum resistance the third terminal can be identified as the
common terminal of starting and running winding.
The resistance between common and starting winding terminals will be high.
The resistance between common and running winding will be low.

3. Testing the windings

There are two testing to be done for the windings.

a. Earth leakage test

Procedure
Connect the test lamp in series to the body of the ceiling fan and the common
terminal of starting and running winding.

Conditions
• If the lamp glows there is earth leakage fault.
• If the lamp is dark there is no earth leakage fault

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b. Open/short circuit test

Procedure
Connect the test lamp in series to the winding which is to be tested.

Conditions
• If the lamp glows dim the winding has no fault.
• If the lamp is dark the winding is open circuited, ie the winding is broken.
• If the lamp is bright the winding is short circuited and faulty.

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Check for other possible faults

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Experiment o. 7.
Date :
BLDC FAN

AIM : To study the construction and working of BLDC ceiling fan, dismantle the given ceiling fan and identify
the faults and repair.

TOOLS AND INSTRUMENTS REQUIRED

Sl.No. TOOLS AND INSTRUMENTS SPECIFICATION QUANTITY

1 Screw driver 200mm 150mm 1 No 1No
2 Connector screw driver 200mm 100mm
3 Combination Plier
4 Electricians Knife
5 Neon tester

APPARATUS REQUIRED

1 BLDC FAN 30W 1 No.

2 Test lamp 60W, 230V 1 No.
3. Multimeter 1 No.

OBJECTIVES
1. Identify the parts of BLDC Fan
2. Identifying winding terminals. 3.Testing the
windings.
4.Check for other possible faults.

Identify the parts of BLDC Fan:

Stator – The stationary object contains Copper windings, which produce magnetic flux when an
electric current is passed through it.
Rotor – The rotating object contains permanent magnets.
Shaft – The rod connecting a motor to the application
BLDC Drive– The drive contains control electronics to run the motor in a controlled manner.

Working of a Brushless DC Fan:

The basic construction of brushless-dc consists of a fan blade attached to a permanent magnet rotor that
surrounds the electromagnetic coils of the stator and associated control electronics.

The heart of the BLDC fan is the BLDC Drive. The working of the BLDC drive is as follows.

BLDC drive consists of the following equipment.

1. SMPS
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2. Micro Controller

1. SMPS: Switched-Mode Power Supply (SMPS)

The main purpose of an SMPS is to provide regulated, stable power to the BLDC drive. Switched Mode
Power Supply circuit which is designed for obtaining the regulated DC output voltage from an
unregulated AC voltage. Here SMPS is used to convert ac supply into dc supply.

2. Micro Controller

A microcontroller is used for receiving the input data from Remote control and giving output data
accordingly to drive circuit.

Fan blades are attached to a permanent magnet rotor of the motor to provide wind.

Working of Brushless DC Drive:

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BLDC fan working principle is when we turn on the fan the SMPS convert AC supply to DC supply
then after Microcontroller receives the input signal from the remote control and accordingly input
signal microcontroller sends the signal to the driver circuit, then after it drives the BLDC Motor.

Advantages of Brushless DC Fans:

A brushless direct-current (BLDC) motor is an advanced electric motor with an electronic commutator
system. Prominent advantages of BLDC motor fans over induction motor fans are

• BLDC motor fans do not run via regulators because of their distinct electrical design. They
operate on the remote control. Accurate Speed control, with the help of the remote control, can
set the speed, timer, and even sleep. This feature makes it convenient to use.

• BLDC motor fans consume low power, making them cost-saving machines.

• BLDC fans use less power than an induction motor fan. BLDC fans consume around 35 Watts,
unlike an ordinary fan that consumes about 80 Watts. That proves them the energy-efficient
fans.

• Although the cost of BLDC fans is high compared to ordinary fans a BLDC fan is a money
saver for the customers as it saves up to Rupees 1000-1500 per year.
• BLDC motor has a longer life span as they do not get heated because of the magnetic fields
around the fan, not in the center of the fan. A standard fan gets overheated.

• BLDC fans are silent as compared to a standard fan due to the absence of brushes on the rotor,
and the commutation is performed electronically.

Test the given Fan:

Steps to be carried out

• Note down the name plate details

• Switch on the fan and check its function and vary speed and observe air flow
• Conduct visual inspection
• Open the canopy and verify the connection and clean the terminals
• Conduct insulation test, continuity test in windings
• Check the value of constant DC voltage at output terminals using multimeter, if no output
voltage, then check each components in SMPS (output of rectifier, IGBT(switch) etc)
• Check IGBT using Multimeter in diode-check mode: The collector to emitter should give a
normal diode reading with positive on the emitter and negative on the collector. The multimeter
should read open or infinite with positive on the collector and negative on the emitter.

Other possible faults:

Fault/Troubles Possible causes remedies

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Noise • It is due to worn out bearings and • The bearing must be replace
absence of lubricating oil or if worn out, otherwise
grease lubricate with proper
lubricant

• Humming or induction noise due

to non uniform airgap owing to • Dismantle and reassemble
the displacement of rotor properly

Low Speed • Low voltage applied • Check the voltage and adjust
• Check power circuit and driver if possible
circuit (IGBT, rectifier) • Replace the IGBT, rectifier
• if damaged.
• Open in winding • Check the continuity in
winding, rewind

Not starting • Low voltage applied • Check the voltage and adjust
if possible
• Supply failure • Check the supply points at
switch, ceiling rose, fan
terminals
•
• Check the continuity in
• Open in winding winding, rewind

• Replace IGBT/rectifeir if
• Check power circuit and driver
damaged.
circuit (IGBT, rectifier)

• Replace the capacitor

• Bulging of capacitor

Result:

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Experiment No. 8.
Date :
WASHING MACHINE

AIM : To study the construction and working of washing machine, dismantle the given washing machine and
identify the faults and repair.
TOOLS AND INSTRUMENTS REQUIRED

Sl.No. TOOLS AND INSTRUMENTS SPECIFICATION QUANTITY

1 Screw driver 200mm 150mm 1 No 1No
2 Connector screw driver 200mm 100mm 1 No
3 Combination Plier
4 Electricians Knife
5 Neon tester

APPARATUS REQUIRED

1 Washing machine 30W 1 No.

2 Test lamp 60W, 230V 1 No.
3. Multimeter 1 No.

OBJECTIVES
1. Identify the parts of washing machine
2.Testing the given washing machine.
3.Check for other possible faults.

Identify the parts of washing machine:

The washing machine, also known as the laundry machine or clothes washer or washer, is a
machine that cleans out the dirty laundry without much manual effort.

Though different types of washing machines have their own design and features, with the parts varying
from machine to machine. But there are a few parts that you will find common among various types of
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Washing Machines in India. So, let’s have a look at these parts.

• Washing Machine Drum

The washing machine drum is the place where you load the clothes for washing. Some come with
two tubs (semi-automatic washing machines) for washing and spinning separately. Some come with
only one tub to perform washing and drying in the same tub.
• Agitator or Paddles
The agitator or paddles are placed inside the washing machine tub to perform the cleaning
operation. It actually removes the dirt and soil from the clothes by rotating and rubbing the clothes with
each other.
You will find the semi-automatic washing machines come with an agitator that rotates within the
machine to perform the cleaning. On the other side, most of the fully automatic washing machines come
with paddles in their inner drum that is controlled by a rotating disc.
• Washing Machine Motor
It is the most important part of the washing machine that ensures the operation of the appliance. It
combines the agitator or the disc to turn out the washing machine’s drum. Thus, it produces a rotator
motion for washing clothes.
• Water Pump
The water pump in a washing machine circulates the water throughout the machine by rotating in
two directions. This pump circulates water during the washing process and also drains out the water
while spinning (drying) clothes.
• Drain Pipe
The drain pipe expels out the dirty water while washing clothes in the machine.
• Heating Element
The heating element is present only in some advanced models of fully automatic washing
machines. It heats up the water at the desired temperature to remove the dirt from your clothes.
• Printed Circuit Board (PCB)
It is a very important component of the washing machine that lets you control the various operations
of the appliance. The Printed Circuit Board in a washing machine consists of the path or layout, as well
as the connections between various electronic components. Thus, you can easily control and automate
the operation of the washing machine.
• Timer
This function ensures to set the desired time for washing the clothes. In semi-automatic machines,
you have to set the timer manually. But in fully automatic washing machines, it can automatically set
the desired time as per the laundry load and dirt present in the clothes.

Operation to be carried out

1. Read the instruction manual
2. Connect the machine to the supply and switch on the machine, observe step
by step operation
3. Check inlet and outlet water flow
4. Isolating machine from the supply
5. Open inspection cover
6. Carried out visual inspection
7. Check the supply cord, pulley, motor, timer control switch
8. conduct insulation test to the motor by megger
9. Replace the faulty portion,
10. Assemble
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Possible fault and causes:

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Result:

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Experiment No: 9
Date:
ELECTRIC PUMP SET
Aim: To study the construction and working of pump set, dismantle the given pump set and identify the faults
and repair.
TOOLS & INSTRUMENTS REQUIRED:

Sl.No Tools & Instruments Specification Quantity

OBJECTIVES
1. Identify the parts of Electric Pump set
2.Testing the given Pump set
3.Check for other possible faults.

Identify the parts of Electric Pump set:

centrifugal pump is the simplest machine which is used in various industries as well as in many daily
applications to transfer fluid from lower head to higher head.
Most centrifugal pumps consist of a few basic components:

• Housing/casing - The outer shell of the pump which protects most of the components from
the outside elements. The casing of the pump should be of

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• materials suitable to withstand the environmental conditions of the application (e.g.

submersible pumps should be water and rust corrosion resistant
• Impeller - A rotating disk with a set of vanes coupled to a shaft. When the impeller
rotates, it imparts energy to the fluid to induce flow. Flow characteristics of the pump vary
widely based on the impeller design.
• Motor - The power source of the pump which drives the shaft. AC motors and DC motors
are the most common power sources for pumps, but internal combustion engines (ICEs),
hydraulic power, and steam power are other possibilities.
• Shaft - It is used to rotate the impeller. It is designed to transmit torque encountered while
starting and operating time of impellers and other rotating components.
• Volute - The inner casing that contains the impeller and collects, discharges, and
(sometimes) recirculates the fluid being pumped. The materials used to construct the lining
of the pump volute must be compatible with the handled media.

Other components:

• Bearing assembly - The mechanical support that allows continuous rotation of the
impeller and is continuously lubricated.
• Hub - Device attached to the bearing assembly which is the connecting point for the motor
or engine.
• Seal - Protects the bearing assembly from being contaminated by the pumped media.

Working of pump set:

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PRINCIPLE: This pump works on basic principle of change in angular momentum. It state that the
change in the angular momentum of a rotating particle is equal to the applied force. It means when
a certain amount of liquid is rotated with the help of external agency means turbines or electric
motor or external force, a centrifugal force acts on it which further turns into pressure. In addition
to, this as liquid passes through revolving wheel then there is change in angular momentum of
rotating wheel or impeller which generates more amount of pressure. In short, in a centrifugal pump
kinetic energy of impeller is converted into pressure energy of fluid which is used to raise up it to
certain height. Due to centrifugal force acting on water or fluid, it is lifted up to particular height.
So these pump is called as centrifugal pump.

Steps to be carried out:

1 Note the name plate details of the pumpset in separate Table.
2 Disconnect the supply from the pumpset
3 Dismantle the pumpset
4 Check the shaft for smooth running, carbon seal, motor, adaptor, Drive collar, impeller, casing
gasket, bearings
5.check the winding of the motor (whether any open in winding)
5 It every thing is satisfactory, assemble the pumpset
6 Connect the pumpset to the supply for its working .

Possible remedies and causes:

Result:

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Experiment No. 10

Date :

REPAIR & MAINTENANCE OF UPS

AIM :
To dismantle and assemble UPS and trace the wiring diagram.
To find the possible faults & suggest its remedies and to prepare a maintenance
chart
TOOLS AND INSTRUMENTS REQUIRED

Sl.No. TOOLS AND INSTRUMENTS SPECIFICATION QUANTITY

1 Screw driver 200 mm 1 No.
2 Connector screw driver 150 mm 1 No.
3 Combination Plier 200mm 1 No.
4 Electricians Knife 100mm 1 No.

5 Neon tester 0-500V 1 No.

APPARATUS REQUIRED

Sl.No. APPARATUS SPECIFICATION QUANTITY

1 UPS 1 No.

2 Multimeter 0-100V dc/ac, 0-20•, 0-1A 1 No.

3. Test lamp 230 V, 60W 1 No.

NAME PLATE DETAILS

(Complete Electrical Specifications)

OBJECTIVES

1) Identifying parts and working of UPS.

2) Check for other possible faults.
3) Prepare a maintenance chart

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1) Identifying parts and working of Inverter.

A UPS (Uninterruptible Power Supply) is an electrical device that provides

backup power to a load when the main power source fails. It is commonly used to
protect computers, servers, and other critical equipment from power surges,
voltage fluctuations, and power outages.
The basic components of a UPS are:
1. Battery: A UPS has a rechargeable battery that provides power to the load
when the main power source fails.
2. Charger: A UPS has a charger that charges the battery when the main
power source is available.
3. Inverter: An inverter converts the DC power from the battery to AC power
that the load can use.
4. Transfer switch: A transfer switch is used to switch the load from the main
power source to the battery power when there is a power outage.

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The working of a UPS can be explained as follows:

1. The UPS is connected to the main power source and the load.
2. When the main power source is available, the UPS charges the battery
using the charger.
3. The UPS monitors the voltage and frequency of the main power source. If
there is a power outage or voltage fluctuation, the UPS detects it and
switches the load to battery power using the transfer switch.
4. The inverter converts the DC power from the battery to AC power that the
load can use.
5. The UPS continues to supply power to the load until the main power source
is restored.
6. Once the main power source is restored, the UPS switches the load back to
the main power source and begins charging the battery again.
There are different types of UPS systems, such as online UPS, offline UPS, and
line-interactive UPS, with varying levels of protection and features. The
construction and working of a UPS may differ depending on the type of UPS

CIRCUIT DIAGRAM

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2) Check for other possible faults.

Troubleshooting chart for a UPS is shown below:

FAULT CAUSES REMEDIES

- Dead battery - Replace the battery

- Loose or faulty - Check and tighten all connections;

UPS does not turn
connections replace any faulty ones
on
- Faulty charger or - Check and replace the faulty
inverter component(s)

- Faulty charger or - Check and replace the faulty

charging circuit component(s)
Battery does not
- Remove some of the load to reduce
charge - Overloaded UPS
the load on the UPS

- Dead battery - Replace the battery

- Old or worn-out battery - Replace the battery

- Remove some of the load to reduce

Battery does not - Overloaded UPS
the load on the UPS
hold charge
- Move the UPS to a cooler location
- High temperature
or improve ventilation

- Remove some of the load to reduce

- Overloaded UPS
the load on the UPS

- Short circuit or
- Check the load for any faults; reduce
overload on the output
the load or repair any faults found
UPS shuts down side
unexpectedly - Faulty inverter or - Check and replace the faulty
transfer switch component(s)

- Charge the battery fully before using

- Low battery charge the UPS

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FAULT CAUSES REMEDIES

- Charge the battery fully before using
- Low battery charge
the UPS

- Remove some of the load to reduce

- Overloaded UPS
Alarm sounds the load on the UPS
continuously - Check and replace the faulty
- Faulty components
component(s)

- Move the UPS to a cooler location

- Overheating
or improve ventilation

- Charge the battery fully before using

- Low battery charge
the UPS

UPS output voltage - Faulty inverter or - Check and replace the faulty
is too low charger component(s)

- Remove some of the load to reduce

- Overloaded UPS
the load on the UPS

- Remove some of the load to reduce

- Overloaded UPS
the load on the UPS

- Faulty inverter or - Check and replace the faulty

UPS output voltage charger component(s)
is too high - Voltage regulator - Check and replace the faulty
failure component(s)

- Input voltage - Install a voltage stabilizer or surge

fluctuations or surges protector

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3) Maintenance Chart
The maintenance chart of an UPS is as follows

MAINTENANCE
FREQUENCY DESCRIPTION
TASK
Visually inspect the UPS for any signs of
Visual inspection Daily/Weekly physical damage, overheating, or loose
connections.

Replace the batteries in the UPS as per the

Battery replacement Every 2-5 years manufacturer’s recommended interval, or
when they show signs of wear.

Every 6-12 Test the UPS with a load to ensure it can

Load testing
months provide the required backup power.

Clean the UPS and its components, including

Every 6-12
Cleaning the fan, vents, and internal components, to
months
remove dust and debris.

Check the manufacturer’s website for

Firmware updates As required firmware updates, and install them as
required.

Calibrate any sensors, such as temperature or

Every 6-12
Calibration of sensors months humidity sensors, to ensure accurate
readings.

Replacement of Replace any faulty components, such as the

As required
faulty parts charger, inverter, or transfer switch.

Check the environment where the UPS is

Every 6-12
Environment check installed for proper temperature, humidity,
months
and ventilation.

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OBSERVATIONS

SL NO FAULT REMEDY REMARKS

RESULT

Dismantled the UPS and studied its parts. The circuit diagram is traced
and checked other possible faults. The maintenance chart is prepared

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Experiment No: 11

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