The document discusses the differences between single-phase and three-phase power systems. Single-phase systems use a single alternating voltage while three-phase uses three alternating voltages offset by 120 degrees. Three-phase systems are commonly used for power transmission and to power electric motors as they allow for a more efficient power delivery with constant power output compared to single-phase. Some key advantages of three-phase include higher power ratings, smaller equipment size, lower transmission losses, and self-starting capability for motors.

1. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G

2. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
WHAT IS SINGLE PHASE? WHAT IS 3- PHASE?
Alternating current electric power
using a system in which all the
voltages of the supply vary in
unison
Common method of alternating
current electric power generation,
transmission and distribution

3. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
SINGLE PHASE 3- PHASE
• Used when loads are mostly
lighting and heating
• Power large motors and other
heavy loadsUSAGE
POWER
FACTO
R
• Instantaneous power
pulsating hence change over
the cycle
• Instantaneous power is
always constant over the
cycle
• Has only one sine wave
voltage
• Peaks in voltage at 90 and
270 degree with a complete
cycle at 360 degree
• Uses three, separate sine
wave that are offset 120
degree from each other
VOLTAGES

4. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
SINGLE PHASE 3- PHASE
• Only need 2 wires to
complete the circuit
• Need at least 3 wires
• One for each phase
• Simple • Complicated
• Established much before • Established later
COMPLICATI
ON
ESTABLISHM
ENT OF
SYSTEM
WIRES
NEEDED

5. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
SINGLE PHASE 3- PHASE
• Increase the conductor
needed by 50%
• Increase the power
delivered by about 73%
• Homes • Industries
• Costlier in long term • Economical in long term
INCREMENT
OF SYSTEM
PREFERENCE
S OF USAGE
COST

6. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
SINGLE PHASE 3- PHASE
• May not perform
better in motors
• Perform better in
motors
• One neutral wire and one
power wire with current
flowing between them and
power flows between them
• No neutral wire is being
used in delta configuration
• Neutral and ground wire is
being used in wye
configuration
QUALITY OF
PERFORMANCE
TYPES OF
WIRES USED

7. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
ADVANTAGES DISADVANTAGES
Lightweig
ht
Experiences more interruptions in
electrical flows
•High voltage of transmission, lesser
current going through the line.
•Due to low current, the size of
conductor is less so, weight of
conductor is also lesser.
•Thus, the supporting tower becomes
lighter.
Efficient Transmission
•Reduction of power losses due to
low current.
•Efficiency of the transmission
increases, the unit operates at its
optimum.
Not Uniform Torque
•Produces current unbalance and
voltage unbalance or power system.
•Torque obtained is not uniform
•Due to presence of frequency which
affects the operation quality.

8. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
ADVANTAGES DISADVANTAGES
Less Substation Required
•Voltage reduction, distance between
2 substation can be increased
•Fewer substation is required.
•Substations can be placed at the
high voltage grid to reduces the initial
cost
of transmission.
•Cannot handle much
overload compared to DC
models.
Cannot Handle Overload
High Insulation Cost
• Caused by high system voltage.
•Insulation depends on voltage.
•Size of wire depends on current.
Shorter lifespan
More prone to vibration
• Power transferred in motors is a
function of the instantaneous
current which is constantly varying.

9. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
ADVANTAGES DISADVANTAGES
Steady source of
power
Increased cost and
inconvenience of repairs•Power transferred is uniform
throughout the cycle, therefore the
vibrations are greatly reduced
•2 overhead wires are required. So
cost increases
Safety
•It is safer to use around combustible
materials since there is no sparking
when they start
High
efficiency•150 % more efficient than single
phase in the same power range
Defectiveness of one unit
•In three phase transformer, a
common core is shared for all three
units
• If one unit is defective, the core of
the defective unit would immediately
saturate because of the absence of
opposing magnetic field
• It must be shut down if any one
phase is defective

10. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
ADVANTAGES DISADVANTAGES
Can handle heavy load Greater cost of standby Units
•Takes more load than single phase
Available in larger horsepower
size•Three-phase motors are available in
larger horsepower sizes than single-
phase motors.
Less expensive in long term
•Less expensive and usually lighter
and smaller than single phase at the
same horsepower rating
Have uniform torque
•3 phase motor have uniform torque

11. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
ADVANTAGES DISADVANTAGES
Self starting
•produce a rotating magnetic field
• eliminates the needs for a separate
starting winding, centrifugal switch,
starting capacitor, or a system of
brushes
High power to weight ratio
•Power to weight ratio of 3-phase
transformer is high
•Means for same amount of Electric
Power, the size of 3-phase
transformer is small
•The overall cost of transformer is
reduced.
•Due to reduction in weight:-
•transportation and installation
of transformer become
convenient
•less space is required to
accommodate the transformer.

12. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
MOULDED CASE CIRCUIT
BREAKER• control electric energy in
distribution
• offer short circuit and over current
protection for circuits ranges from
63 Amps-3000 Amps.
• give a means to manually open a
circuit/automatically open a circuit
SINGLE PHASE ENERGY
METER• watt-hour meter
• monitoring the
consumption of
electrical energy
MINIATURE CIRCUIT BREAKER
• Guards an electrical circuit
from an over current and
overheating
• Rated current is not more
than 100 amperes
NEUTRAL LINK
• accessories in MCB
• isolation of electric
equipment & clearing faulty
downstream
• protecting electric circuit
from damage caused by
overload
COPPER BUS BAR
• A conductor
• Collect electric power from
the incoming feeders and
distributes them to the
outgoing feeders at one
location

13. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
MCCB
Connect to each MCB
from
energy meter

14. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
WHY 3-PHASE IS USUALLY USE COMPARED TO SINGLE PHASE
Constant power delivered
• In single phase circuit the power delivered is pulsating and objectionable
for many applications
High Rating
• Output of a three-phase machine is narly 1.5 times the rating of a single
phase machine
Size and Weight of
Alternator• Small in size and light weight for 3- phase machine
Long-term maintenance
• Lower long-term maintenance for 3-phase machine

15. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
WHY 3-PHASE IS USUALLY USE COMPARED TO SINGLE PHASE
Requirement of Copper and
Aluminium• 3-phased system requires less copper and aluminium for transmission
system
Frequency of Vibration
• Frequency of vibration in 3-phased is lower than single- phased
Torque
• Uniform and constant torque in 3-phased system
Self Starting
• 3-phased system are self-starting whereas single-phase motor is not self-
starting

16. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G
z
QUESTION: OPINION AS A QS IN TERM OF COSTING APPROACH?
Low Installation Cost
• Aluminum, Copper
Around 25% Less Conductor
Materials
Low Labor Handling Cost
Economical in Operation
• Efficient to run and have longer lifespan
• Require conductors with smaller cross-sectional area, saving copper = less
installation cost

17. CHAI JIA ERN 0324653 l CHEAH MAN YEE 0324743 l TAN KAI XUAN 0325066 l TEE WAN NEE 0325074 l NA YONG YI 0324458 l G