ET302

(POWER SYSTEM)

POLITEKNIK MERLIMAU,
KB NO. 1031 PEJABAT POS MERLIMAU,
77300 MERLIMAU,
MELAKA

5/29/2010 Jabatan Kejuruteraan Elektrik 1

• Substation provide services for distribution
electricity supply source in some area where
it housed.
• Substation’s main function was received
energy sent in high voltage of generator
station and make it low to certain value for
distribution local and this need suitable
switch gear.
• Some substation only function as easy
switching station where having different
connection between variety transmission line.
• Other than, it used to change AU supply to
AT or otherwise it also exchanged high
voltage frequency to low or otherwise.

• Substation definable as one group tools or

electric switch gear work to receive, change,
operate and divide electricity supply to near
consumer.
 Line Isolator
From the overhead
Transmission Line
(132kV or 275kV or
Towards the Main 500kV)
Busbar (MBB) or
Reserved Busbar
(RBB) through the
Circuit Breaker (CB)

Current Transformer

Capacitor Voltage Transformer

Figure 9: Typical arrangement of the HV equipments at a switchyard of a Pencawang Masuk Utama

(PMU) operated by TNB transmission.
SUBSTATION
EQUIPMENT
 TRANSFORMER TAP
CHANGING
• Long transmission line
system usually require
equipment that can control
transmission voltage.
Common equipment use was
regulator converter.
• Transformer tap changing
used to control voltage in
duplicate part or product.
Output voltage control can be
done with adjust
circumference number in
duplicate part.
• Output voltage in duplicate
part may be added or
minimized through
circumference adjustment in
duplicate part has been
provided in its design.
 CIRCUIT BREAKER
Circuit breaker assembled on high voltage delivery
system, it is fixed in transmission system
between divider and also transformer in
substation.
Circuit breaker can be divided into some types and
needs in substation is depends to electricity
capacity in kV range to be sent or distributed
in some area.
A circuit breaker is an automatically operated
electrical switch designed to protect an
electrical circuit from damage caused by
overload or short circuit.
Its basic function is to detect a fault condition and, by
interrupting continuity, to immediately
discontinue electrical flow.
Unlike a fuse, which operates once and then has to be
replaced, a circuit breaker can be reset
(either manually or automatically) to resume
normal operation.
Air Type Circuit Breaker
Circuit breakers are made in varying sizes, from small
devices that protect an individual household
appliance up to large switchgear designed to
protect high voltage circuits feeding an entire
city.
 OIL LINK UNIT
Divider is separatist switch used to
establish some part in power
circuit after load circuit in decide
by circuit breaker.
This divider may be possible from type
tendom or OLU. Divider
installation in substation is
depends to voltage value accorded
in one substation.
In transmission system or voltage
distribution which exceeded 11kV,
tendom type’s divider used while
in distribution system under 11
kV the OLU type's divider
frequently used.

Divider fitted between high voltage

power line and equipment in delivery
system. Divider in Substation
Hence divider prepared to prevent
voltage supplied to tools division busbar
fitted or other equipment parts are
installed.
GROUNDING
Grounding were the connection between
electric and ground equipment with
wire connection helps which had no
resistance.
Ground made as reference causes his
capacity considered empty, so anything
connected to him will be having empty
capacity also.
In substation system high voltage
instruments such as, OLU converter
and equipment other will grounded with
through grounding substation system.
 SURGE ARRESTER

• Surge arrester is tool used to

limit surplus current of enter
through converter and other
instruments in substation.
• This surplus current will flow
to grounding terminal.
• Apart from that it functions
as door (gate) which catch
current and bring it to
portion of the ground.
• With surge arrester would
rescue interface for electric
and electronic circuit within
one substation system.
 LIMIT CURRENT REACTOR
• Reactor is a coil which poss
large inductive stretching G1 G2 G3 Generator

as compared its ohm

resistance. Reactor Reactor
Busbar
• Reactor fixing in circuit
high voltage equipment Feeder
system to limit short-circuit A B C
current which flowed in
line. Figure 4.5 Schematic diagram of limiter current
reactor
• Current which flowed
would be curtailed by
reactor in safe position
before its flows to switch
gear occur in substation.
• So that, switch gear in
substation can be protected
from short circuit.
POTENTIAL TRANSFORMER
• Potential transformer operates in voltage
rate exceeding 380V and flow this voltage
in measurement equipment and relay
through coil intermediate potential
difference.
• This transformers installation enable low
voltage measurement equipment suitable
to gauge high voltage and separate this
equipment of high voltage.
• Primer coil of potential transformers
attaches to main busbar which
availability hardware installation
duplicate high voltage and coil usually
connect to measuring instrument and
relay.
INSTRUMENT TRANSFORMER
• Instrument transformers are used for measuring voltage and
current in electrical power systems, and for power system
protection and control.
• Where a voltage or current is too large to be conveniently used by
an instrument, it can be scaled down to a standardized, low
value.
• Instrument transformers isolate measurement, protection and
control circuitry from the high currents or voltages present on the
circuits being measured or controlled.

CURRENT TRANSFORMER
a transformer designed to provide a current in its secondary
coil proportional to the current flowing in its primary coil

VOLTAGE TRANSFORMER
• are designed to have an accurately known transformation ratio in both
magnitude and phase, over a range of measuring circuit impedances.
• A voltage transformer is intended to present a negligible load to the supply
being measured. The low secondary voltage allows protective relay equipment
and measuring instruments to be operated at a lower voltages.
 MAIN SUBSTATION 33K/11KV
• Main substation are also known as
transmission substation usually placed nearby
energy sources. Main substation operation can
understand with learn single line diagram.
• According to standards a main substation
fitted should at least has two 33/11kV
transformer, 33kV feeder, 11kV feeder and
other instruments.
• This instrument is special equipment designs to
handle in high voltage. Other equipment found
in main substation namely divider, circuit
breaker, voltage transformer, current
transformer, busbar etc.
MAIN SUBSTATION 33K/11KV SINGLE LINE DIAGRAM
 DISTRIBUTION SUBSTATION
11KV/415V
• 11kV/415V distribution substation is
another type of substation after it receive from
main substation.

• The standard installation, must minimally

have 11kVswitchgear, 11kV/415 stepdown
transformer, and fusegear or low voltage gear.
DISTRIBUTION SUBSTATION 11KV/415V SINGLE LINE DIAGRAM
INDOOR & OUTDOOR SUBSTATION
INDOOR OUTDOOR

This type also can be divided into two.

• 1000kVA limited ability value Usually namely as:
for each room transformer
• Fenced substation
located.
• Top pole- mounted substation.
• This substation usually
Fenced Substation usually placed in mine
placed in town, plants,
region, plants and far place from
building and others. town.
 ADVANTAGES & DISADVANTAGES
• The indoor’s comes with higher cost compared to the
outdoors. The need of building‐materials such as
enormous value of concrete and steel, overtaking land,
designing the building and others increases the cost of
INSTALLATION indoors compared to the outdoors. This cost can be even
COST higher when it’s come to the ability of the substation
needed by distribution system.
• In the other hand, the outdoors only need a minimal
space and just fenced to guard it. Concrete and steel are
the perfect material to be used, to locate high voltage
gears.
• Affected by the higher voltage equipment install indoor,
this will even more complicated the maintenance jobs
and increase the abilities of substation. Consequently
implementation cost will become greater compared to
the maintenance and renovation cost for the outdoors.
• Eventhough, another factor like temperature changing,
dusty, and rusty to the outdor, needs it to be designed
special, so it can do it best their job, means increasingly
the construction cost
 ADVANTAGES & DISADVANTAGES
• Indoors are more quiet than the outdoors. This
is due to the noisy from the transformer and
other gears didn’t spread around it’s parameter.
NOISINESS & The building itself act as soundproof room. As
INTERFERENCE an addition, all things inside building are
protected securely from any bad weather such
as lightning, rain, snow and hurricane.
• But for the outdoor, things go oppositely.
The noise spread around the substation and can
be heard if we’re closely to the area. More to
that, outdoors are more opens to bad weather,
dusty and dirty.
• As a conclusion, the indoors substation are
said more safe and secure rather than outdoors
substation.
 BUSBAR
• A busbar in electrical power TYPE OF BUSBAR
distribution refers to thick strips ARRANGEMENT
of copper or aluminium that
conduct electricity within a
switchboard, distribution board, SINGLE
substation, or other electrical BUSBAR
apparatus. DOUBLE
• Used as an intermediate device BUSBAR
connecting other electrical
appliances inside substation. RING
• The arrangement of busbar is BUSBAR
depends on electrical energy
distribution among the area
 SINGLE BUSBAR
• Each busbar are
connected to station
generator.
• Busbar are also connected
to generator, transformer
and feeder via circuit
breaker and isolator
switch.
• Pair isolator – To check if
there is inverting source
inside the system.
• Some problems occur in
maintenance process.
ADVANTAGES & DISADVANTAGES

ADVANTAGES
• Busbar arrangement – easy
• Maintenance cost – cheap
• Simple operational
• Hub system – easy

DISADVANTAGES
• If one of the busbar is
damage, all system is damage.
 DOUBLE BUSBAR

• Consist of 2 duplicate busbar that separated by circuit breaker and

isolator switch.
• If one of the busbar damage, power are still can be distribute to
consumer using the storage busbar.
• It done by opened the circuit breaker and isolator switch that
connected line to feeder with the damage busbar.
• Circuit breaker to feeder must be off.
• The changes of main busbar to storage busbar are done without
disturbing the power supply.
ADVANTAGES & DISADVANTAGES

ADVANTAGES
• Continuously energy supply
• Maintenance can be done without
interfearing supply to consumer
• Circuit breaker testing can be done
with the reserve line without
interfearing main line

DISADVANTAGES
Expensive installation and
construction cost
 RING BUSBAR
• Loads are
connected with
power supply.
• Each feeder gets
supply from two
different sources.
• When problems
occur, power
supply is not effect.
• Installation cost is
quite similar as
single busbar.
ADVANTAGES & DISADVANTAGES

ADVANTAGES
- Feeder can get supply from two different
sources.
- The failures of feeder are not disturb the
power supply.
- Maintenance can be done
without disturbing power supply.
DISADVANTAGES
• Open any circuit breaker will cause overload
because current is just only flow in one line
only.
• - Adding process of new cable is hard to do.