BUS BAR
EET414
SUBSTATION DESIGN
PPKSE
Ahmad Zaidi Bin Abdullah
Index
Info
MTE
Lab 2
DESIGN BUSBAR
INTRODUCTION
Commercial and industrial distribution systems use several methods
to transport electrical energy. These methods may include
heavy conductors run in trays or conduit. Once installed, cable and
conduit assemblies are difficult to change.
Intro
For moderate ratings on LV system, say, up to 600/ 800A,cables are
preferred,while for higher ratings (1000 A and above), the practice is to opt for
solid conductors (LV bus systems) because;
on the grounds of cost,
appearance,
safety,
ease of handling and maintenance.
For larger ratings, more cables in parallel may become unwieldy and difficult
to maintain and present problems in locating faults.
The busbar conductors may be of aluminium or copper. The use of copper
may be more appropriate at corrosive areas
STANDARD
IEE WIRING
REGULATION
JKR STANDARD
IEC 60059
WHAT is?
Busbar is a metallic
strip or bar from
copper or
aluminium that
conduct electricity
within sub-
switchboard to
switchboard
WHERE
Used for both distribution
and Final circuit of different
rating
In wide range of current
rating (thousand ampere)
location with high fault
economically in a high-rise
building
but depend on flexibility
ARRANGEMENT
Application include multi-
storey commercial or
domestic properties
Rising main busbar
trunking system are often
used to provide supplies to
individual floor within
building
WHY
A major advantage of busway is
the ease in which busway
sections are connected
together. Electrical power can
be supplied to any area of a
building by connecting standard
lengths of busway. It typically
takes fewer man-hours to
install or change a busway system
than cable and conduit
assemblies
EXAMPLE
SIZING BUSBAR
2 method
TEMPERATURE RISE
CURRENT DENSITY
SIZING BUS BAR
SIZE bus duct = Total Load Current (ib)
.. Current Density
current density copper = 1.5A/mm2
current density alluminium = 1.0/mm2
TABLE BUS BAR
Example Calculation
A building with 800A load need to install busbar .Find the size
complete with model .Refer Table.
SIZE bus duct = Total Load Current (ib)
..Copper Current Density
= 800A/ 1.5A/mm
= 533.3mm2
refer table = 6mm x100mm is suitable
cont
if Ib no given..
ib (three phase)=Total connected load / 610.9
ib (single phase)= Total connected load / 240
Sizing with Fault Current
Example with fault current
Other design Consideration
1. Size of enclosure
2. Voltage Drop
3. Skin Effect
Size of Enclosure
. The enclosure of the bus system
provides the cooling surface
for heat dissipation.
The ratio of the area of the
current-carrying conductors to
the area of the enclosure will
provide the basis to determine
the heat dissipation effect.
. dissipation factors that can be
considered as likely deratings
for a bus system under
different conditions
Voltage Drop
The voltage drop across a bus system should be as low as possible and
generally within 12% of the rated voltage.
This criterion will generally be applicable to a high current LV system.
affect the stability of the system as well as the performance of the
connected load.
VD BUSBAR
Voltage drop (Vd) = (3 ) x Ib x ( R cos +X sin )
where;
Ib = Current design
R & X = impedance in mikro Ohm from Table voltage drop Busduct
= refer to pf value (0.85)
Voltage drop allowable for busbar is only 1-2% from supply
voltage
example- try
given current design is 1000A, find suitable size of copper
bus duct and determine the voltage drop either meet the
requirement or not.
Busduct size = Ib/1.5mm
Voltage drop (Vd) = (3 ) x Ib x ( R cos +X sin )
answer= 0.05v meet the requirement
CABLE VD
4% from
supply only
allowed
READ
HERE
when no
trunking
& vertical
building
Iz
Iz
Table for Ca
Ca
Skin Effect
The phenomenon of uneven distribution of current within the same
conductor due to the inductive effect is known as the skin effect and
results in an increased effective resistance of the conductor.
A current-carrying conductor produces an electric field around it which
induces a back e.m.f. and causes an inductive effect. This e.m.f. is
produced in the conductor by its own electric field cutting the conductor.
The ratio of a.c. to d.c. resistance, Rac/Rdc, is the measure of the skin
effect and is known as the skin effect ratio.
Skin Effect
Skin Effect Analysis
Video Bus Duct Installation
Thanks.
