Marathwada Mitra Mandal’s College of Engineering, Pune
Name of the Student
Roll No
Experiment No.
Experiment Title
Study Safety Precautions while working on Electrical Systems
and Handling of Various Electrical Measuring Instruments.
Date of performance
Date of Completion
Signature of Faculty
Laboratory Continuous Assessment Rubric:
SCALE
DIMENSION
3
4
5
Did
not
Perform,
submitted in
time
Performed
and
submitted
later
than
scheduled
date
Performed on
schedule;
submitted two
weeks late
Performed
and
submitted as
per schedule
Neither shows
any
understanding
of
the
objective nor
can relate it
to theory.
Does not
participate in
experiment
States
objective
vaguely
Can only state
the objective
but shows poor
understanding
Performed
on schedule;
submitted
one
week
late
Understands
objective but
cannot place
it in context
of a theory
Performs the
experiment only
with the help
from
supervisor/others
and is confused
and untidy.
Performs the
experiment
with some
supervisory
help; but
forgets some
crucial reading
and is confused
and untidy.
Performs
experiment
on own
without
supervisory
help; records
all readings
properly but
untidy.
Cannot follow
the procedure
and do any
work
Follows procedure
half-heartedly
Follows right
procedure; but
cannot analyze
data and
interpret it
Follows right
procedure
and can
analyze data
and interpret
it
Performs
experiment
on his/her
own without
supervisory
help; records
all readings
properly.
Keeps the
setup clean
and tidy.
Follows right
procedure;
can analyze
data and
interpret it
with
justification
1
Regularity and
punctuality
Understanding
and
preparation
for Objective
Participation
in
performance
and
conduction of
experiment
Post
experiment
skills
SCORE
2
the
very
Understands
objective and
can relate it
to
an
appropriate
theory topic
Total
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
Title: STUDY OF SAFETY PRECAUTIONS AND HANDLING OF INSTRUMENTS
Aim:
i)
ii)
Study of Safety precautions while working on Electrical Systems
Study of various Electrical equipments such as Multimeter, Ammeters,
Voltmeters, Wattmeter’s, Resistors ,Inductors and Capacitors
Theory:
"Electrical Energy"
Electrical energy is widely used for domestic purposes. Even though it is
very convenient to use electrical energy, it is absolutely essential to observe certain
safety precautions while using this energy. Any negligence on the part of the user can
cause serious accidents and subsequent loss of property and human life. Some of the
safety precautions to be observed are listed below:
The precautions differ according to the probable hazard.
A) Precautions Against Bad Insulation: Insulation must be adequate and in good conditions since failure of insulation leads
to various types of faults giving rise to risks of shock, fires and equipment damage.
 In case of domestic insulations damaged wirings should be replaced as soon as the
insulating coating begins to harden and peel off due to ageing.
B) Precautions Against Improper Earthing:To assure adequate protection, the resistance of the earth path must be below.
If earthing is not effective there will be no isolation of the circuit (by blowing off the
fuse) during the earth fault and the fault will persist for a longer period. This may
damage the system and endanger human safety.
 Installation should have an efficient earthing electrode, which may have a form of a
well-buried metal plate or an arrangement of tubes or rods driven vertically into the
soil. Alternatively in city areas and underground water main system having metalto-metal joints forms a satisfactory earth.
 Earth connection should be always maintained in a satisfactory condition.
 Conduits or the metallic sheaths of wires should be electrically continuous and well
earthed.
 The metallic casing of portable apparatus should be connected to the third pin of a
three-pin plug, the corresponding socket being connected to earth. Use of two-pin
plugs and sockets should be strictly avoided.
C) General Precautions: The sockets should be fixed at a height beyond the reach of small children to ensure
their safety.
 Before bringing the wiring installation in to use for the first time, it’s essential to
ensure that all the fuses and switches are inserted in the phase (or live) wires only.
 For proper protection fuses with correct ratings must be used.
 The mains switch should be switched off before replacing any blown fuse.
 User must be equipped with rubber-soled footwear and should keep his/her hands
dry while using any electrical device.
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune



While cleaning any portable device such as table-fan, switch off the mains supply
and also remove the plug from the socket.
Plugs should never be removed by pulling the wires connected to them.
In case of a fire, Switch off the mains immediately. Never use water to extinguish
such a fire use fire extinguishers comprising of CO2(carbon-dioxide)
SHOCK
When in a state of shock, the patient may not have sufficient blood pumped through the body
and his tissues may not get enough oxygen. If not promptly treated, the victim's heart will get
weaker and begin to fail. If a person remains in shock too long, death could result even
though the injury suffered may not be fatal in it. This is especially true of the aged and the
weak.
Symptoms: Pale, cold, and clammy skin; shallow and irregular breathing; weak and rapid
pulse; dilated pupils; possibly beads of perspiration; a feeling of weakness and thirst; or none
of these.
Treatment:
 Have the patient lie down flat and Loosen any tight clothing, particularly about the
neck.
 If there are no head or chest injuries or any difficulty in breathing, then raise the lower
part of the body 8"-12". If the victim complains of pain over this, then discontinue
this.
 Keep the victim warm (to prevent loss of body heat) but avoid sweating.
 Speak soothingly and reassuringly to the patient. Give him a feeling of confidence in
you and in his own recovery. Speak calmly and matter-of-factly about what you are
doing as you begin to do it. This will help to orient him. But do not disturb the patient
with unnecessary questioning, movement, noise.
 Gentle stroking of the head (if it is not injured) or light, rhythmical massaging elsewhere is very soothing. Holding the hands or feet in a warm, reassuring way can help
to bring a person back.
 Do not give water if the victim is unconscious or nauseated. Also, do not give water if
medical care will arrive within 30 minutes. If medical care will be delayed longer than
this, then give only small sips and not enough to cause nausea.
 When you can safely touch the person, do CPR if the person is not breathing or does
not have a pulse. CPR stands for Cardiopulmonary Resuscitation.
1) Compressions
2)Airway
3)Breathing
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
B) Study of Electrical Equipments
The Knowledge of any parameters depends upon measurement. Measuring
Instruments are used to monitor a process or operation. In Electrical System the basic
quantities for any input/output of system are Voltage, Current, Power, Resistance. To
measure these quantities we require measuring instruments in Laboratory which are
as follows are
i) Multimeters ii) Ammeters iii) Voltmeters iv) Wattmeter’s
I ) Multimeters
A multimeter is an instrument that allows us to make multiple electrical
measurements using the same tool. We can use a multimeter as:
 A voltmeter to measure voltage
 An ammeter to measure current
 An ohmmeter to measure resistance
There are two basic types of multimeters: digital multimeters and analog multimeters.
Digital multimeters are superior to analog multimeters because of their better
accuracy in measurements, sensitivity to very small changes in input voltages, and
clear and easy-to-read displays. Multimeters can be used for testing batteries,
household wiring, electric motors and power supplies.
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
Functions of Multimeter
Hold Button: This button will "hold" whatever the meter reads after you have pressed it.
This is a great feature if you need to remember the exact reading of what you're measuring or
if you cannot see the multimeter whilst you're testing with the test lead or probes
AC Voltage. This will be your most common setting for testing voltages around the home or
work. Depending on where you live, you will typically measure between 100-240 volts AC.
SHIFT: Hertz:Used to measure the frequency of your circuit or equipment. Different
equipment and circuits are designed to operate at either fixed or variable frequency, so it's
important you know that before you undertake your test.
DC Voltage:The DC Voltage setting will enable you to test small electronic ciruits, indicator
lights and batteries. 99% of the time you come across DC Voltage, it will be below 30 volts
DC.
Continuity: The meter will emit an audible tone when continuity is detected between two
points. This is a fast and effective way for finding short circuits, or open circuits. Simply
place one probe on one point, and another probe on another point and and your meter will
give you a visual and audible signal.
Direct Current :The same as Alternating Current (Number 13), but with Direct.
Current Jack: Only to be used for measuring current amps with either a red test lead, or a
dedicated clamp attachment. If you use a dedicated clamp meter, you will most likely not
have this jack on your unit.
Common Jack :Used for all tests and is only to be used with the black test lead.
Range Button. Used to cycle between different ranges of your meter. Most meters have autoranging, but some have the option of selecting a specific range. For example, you may want
to know what your Ohms reading is in mega-ohms.
Brightness Button: Cycles the backlight of the display from dim, to bright.
AC Millivolts: If you're testing a small ciruit on the AC Voltage setting and the reading is
low, it's advised that you switch to the AC Millivolts setting to obtain a more accurate
reading.
SHIFT: DC Millivolts. If you're testing a small ciruit on the DC Voltage setting and the
reading is low, it's advised that you switch to the DC Millivolts setting to obtain a more
accurate reading.
Ohms. This setting is used to measure the resistance, which is measured in ohms. The
function on its own is called an ohmmeter. A great way to check the accuracy of your multi
meter is to get a resistor that you know the resistance of and use the ohms setting to test the
resistance. If it reads correctly, you can be sure that your DMM is accurate. The ohm setting
also a quick and easy way to test the condition of fuses - if the meter reads OL, the you can
be sure the fuse has blown. SAFETY NOTE: only test fuses with the ohms setting when they
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
are OUT of the circuit.
Diode Test. The diode test setting is the most reliable way to test if your diodes are good or
bad. The other way to test if a diode is functioning as it should involves using the Ohms
setting, however it isn't as accurate as using a dedicated diode test.
SHIFT: Capacitance. It is extremely important to note that some capacitors will have an
electric charged stored in them, even after power has been turned off. Please ensure you
safely discharge capacitors before measuring their capacitance.
Alternating Current. Normally performed with the addition of a clamp attachment, the
alternating current test is a must for tests such as how much load an appliance is drawing.
Red Jack. Used for all tests besides current, including: voltage, resistance, frequency,
diode, duty cycle, temperature, impedance and capacitance.
II) Ammeters
An ammeter (from Ampere Meter) is a measuring instrument used to measure the current in a
circuit. Electric currents are measured in amperes (A), hence the name. Instruments used to
measure smaller currents, in the milliampere or microampere range, are designated as
milliammeters or microammeters.



Selection of Ammeter depends upon the type of source (AC or DC). Select a proper
range of Ammeter. It has ranges from Micro Ampere, Milli Ampere and
Amperes.
Range depends on our application that where we are using it
When the ammeter resistance is low, almost all the current in the circuit is allowed
to pass through the ammeter. That is the reason ammeter is connected in series.
This allows the ammeter to accurately read the current in the circuit. If, on the other
hand, the ammeter resistance was more, the ammeter would read a value lesser than
the actual value flowing through the circuit. This is because, in this case, the
ammeter itself would oppose the flow of current.
III) Voltmeters
A voltmeter is an instrument used for measuring electrical potential difference between
two points in an electric circuit. The unit of potential difference is volts. In order to
measure the voltage, voltmeter should be connected in parallel.
Parallel connection is used because a voltmeter is constructed in such a way that it has a
very high value of resistance. So if that high resistance is connected in series than the
current flow will be almost zero which means the circuit has become open.
1V) Wattmeter
A wattmeter is an electrical instrument which is used to measure the electric power (in
watts) of any electrical circuit. It consists of two coils i.e. pressure coil (parallel) and
current coil (series).
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
As shown, The current coil is connected in series with the load so that the circuit current
flows through it. Similar to the voltmeter circuit, the voltage coil is connected in parallel with
the load. Both voltage and current coils will produce magnetic fields. These fields interact to
each other and produce a deflecting torque on the voltage coil. The interacting fields are
proportional to the circuit voltage(V) and current(I) respectively. So the produced deflecting
torque is proportional to the product of circuit voltage and current. i.e VI which is nothing but
circuit power.
The Multiplication Factor (MF) of the wattmeter is:
MF = (voltage range x current range)/(range of the wattmeter scale)
For example, if the the voltage range is 150 V, the current range is 10 A and the scale
range is 750 W, then the Multiplication Factor (MF) is (150 x 10)/750 = 2. Therefore, the
actual power measurement is the scale reading multiplied by the Multiplication Factor
(MF) which is 2 in this case.




Wattmeter on DC circuits:
For d.c. circuits, strictly speaking wattmeter is not necessary.
As power in dc circuit is P=VI watt , that can be measured separately by a multimeter.
Simply by multiplying V and I the power can then be calculated.
But in AC circuit, this simple technique will not be applicable as we need to consider the
power factor too ( P = VIcosΦ)
Connection Diagram for Ammeter, Voltmeter and Wattmeter in a circuit.
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
C) Study of Basic Electrical Components ( loads) {R,L,C}
Electronic elements that make up a circuit are connected together by conductors form
a complete circuit. If these connecting conductors are ideal conductors (i.e. they have
no resistance) then all parts of the circuit can be classified into two main categories
depending on whether they deliver or absorb energy from the circuit.
These are the active components and passive components.
 Active components: An active components supplies energy to an electric
circuit, and hence has the ability to electrically control the flow of charge.
Example: Voltage sources, Current sources, Generators

Passive Components: A passive component can only receive energy, which it
can either dissipate or absorb.
Example: Resistors, Capacitors, Inductors
A) Resistance: A resistor is an electronic component which is used to resist the flow of
current. When current flows through the resistor, the electrical energy is absorbed by
the resistor and dissipated in form of heat. Resistance is measured in Ohms ( Ω).
Symbol of Resistance is given below
Examples: Conventional Domestic Fans, Electrical Heaters, Electric Kettles and Iron, Fuses
,Resistors are used in laptop and mobile phones.
B) Capacitors: Capacitor is an electronic component that stores electric charge. The
capacitor is made of 2 close conductors (usually plates) that are separated by a
dielectric material. The plates accumulate electric charge when connected to power
source. The amount of voltage/charge that a capacitor can hold is referred to as its
capacitance. This is a value measured in Farads. Symbol of capacitor :
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
Examples: Audio and Radio circuits, Timing Circuits, Once charged a capacitor
has the ability to store a lot of energy and discharge it when needed. One of the
most familiar uses of this ability is in a camera flash, Filter Applications
C) Inductors: An inductor, also called a coil, choke, or reactor, is a passive two-terminal
electrical component that stores energy in a magnetic field when electric current flows
through it. As a result of the magnetic field associated with the current flow, inductors
generate an opposing voltage proportional to the rate of change in current in a
circuit.This property of an inductor is known as Inductance. Denoted By ‘L’ and
measured in Henry
.
An inductor typically consists of an insulated wire wound into a coil around a
core. Symbol of inductor is given by .
Example: Inductors are used in Tuning circuits, Transformers, Chokes, Relays,
Windings of motor.
Conclusion:
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
QUESTIONS:
1. What are the various treatments if a person gets electrical shock?
2. Explain the Use of Fire Extinguisher?
3. Give real life examples of Resistors, Inductors and Capacitors
4. Why is multi range use in Instruments?
Electrical Engineering Dept
BEE
Marathwada Mitra Mandal’s College of Engineering, Pune
Electrical Engineering Dept
BEE