Electricity in buildings part 1.pptx

1. Electrical Systems
Ar. Mansha Samreen

2. • A transformer can accept energy at one voltage and deliver it at
another voltage.
• This permits electrical energy to be generated at relatively low
voltages and transmitted at high voltages and low currents, thus
reducing line losses and voltage drop
Transformers
Location & Types of Transformer
• Location of the transformer is very important as far as distribution loss is concerned.
• Transformer receives HT voltage from the grid and steps it down to the required voltage.
• Transformers should be placed close to the load center, considering other features like optimization
needs for centralized control, operational flexibility etc.
• This will bring down the distribution loss in cables.
• Power transformers are used in transmission network of higher voltages, deployed for step-up and
step down transformer application (400 kV, 200 kV, 110 kV, 66 kV, 33kV)
• Distribution transformers are used for lower voltage distribution networks as a means to end user
connectivity. (11kV, 6.6 kV,3.3 kV, 440V, 230V)

3. • In Urban areas electrical cables
are Usually underground and
are brought up to entry point
at ground level or into
basement.
• Service cable cannot be bent to
small radii and this should be
borne in mind when
considering point of entry.
• In small buildings the cable run
is kept as short as possible,
terminating in a distribution
board at the first convenient
position.
Entry in the buildings

4. Intake to small scale buildings- Domestic supply
• Domestic electricity supply usually effected through distribution system and
describe as single and three phases.
• Normally small buildings are supplied with electricity by two wires, one phase
wire and the other neutral, known as single phase supply and gives a voltage for
the premises of 240 volts.
• In three phases, four wire bring 420/ 240 volts, 50 cycle per second. The
voltage.

5. Entry in the buildings • In these buildings the
distribution board
will be fitted with a
seal box to prevent
moisture from
entering the insulation
of the service cable, a
main fuse for the
premises in a box
sealed by the supply
authority and the
consumer unit or
other switch and fuse
gear belonging to the
building.

6. • A busbar is a metallic bar in a switchgear panel used to carry electric
power from incoming feeders and distributes to the outgoing feeders.
In simple terms, busbar is a electrical junction where incoming and
outgoing currents exchange.
• Electrical Busbar consists the number of lines electrically, which are
operating at the same voltage and frequencies. Generally, copper or
aluminum conducting material is used in the construction of bus bars.
• They are used either in the form of pipe or thin-walled tubes.
Bus Bar
Distribution Board
• A distribution board (also known
as panel-board or breaker panel)
is a component of an electricity
supply system which divides an
electrical power feed into subsidiary
circuits, while providing a protective
fuse or circuit breaker for each
circuit in a common enclosure

7. Meter
• An electricity meter, electric meter, electrical meter, energy meter, or kilowatt-
hour meter is a device that measures the amount of electric energy consumed by
a residence, a business, or an electrically powered device.
• Electric meter or energy meter measures the total power consumed over a time
interval.
• Electric utilities use electric meters installed at customers' premises for billing and
monitoring purposes. They are typically calibrated in billing units, the most common
one being the kilowatt hour (kWh). They are usually read once each billing period.

8. Distribution Circuits
• In most of the buildings electricity supply is divided into two types of sub circuit:
• Lighting Load sub-circuit and
• Power load Sub Circuit
• The sub circuit which gives supply to lighting load points is called lighting load sub
circuit. This circuit includes lamps, fans, tubes etc.
• As per Indian Electricity Rules. The following rating should be assumed
• Filament lamp 60W
• Ceiling fan 60W
• Socket for radio, table fan 60W
• Fluorescent tube 40W
• Mercury Vapor lamp 80W
• Power sub circuit-
• It includes water heater, AC, refrigerators etc. The maximum load for power sub
circuit should not exceed 3000 W.
The maximum load for power sub-circuit should not
exceed 3000 W. The number of outlets restricted to
two in each power subcircuit. If the power load
exceeds above 3000 W, a separate power circuit is
taken.

9. Isolator
• The isolator is a switch which
isolates the part of the circuit system
when it is required.
• Electrical isolators are the separate
part of the system that is created for
the safe maintenance.
• Isolators are generally used at the
end of the breaker to repair or to
replace.

10. RCCB (Residual Current Circuit Breaker)
• RCCB (Residual current circuit breaker) or RCD
(Residual-current device) are aimed to protect
people from the risk of electrocution and fire that
are generally caused due to the faulty wiring. An
RCCB is also very useful when a sudden earth
fault occurs in the circuit.
• RCCB is basically an electric wiring that trips or
disconnects when imbalance or mismatch in
electric current is detected. The best part about
RCCB is that it does not take much time to take
the control over the imbalanced electric current;
RCCB takes only about 20 milliseconds to trip.
• RCCB is essentially a current sensing equipment
that is used to control the low voltage circuit from
the fault. It comprises a switch device which is
used to turn off the circuit when there is a fault.

11. MCB (Miniature Circuit Breaker)
• MCB (Miniature Circuit Breaker)
• As we all know that, all fuses need to be replaced with the MCB for
safety and control purposes. MCBs are electromechanical devices
which are used to protect an electrical circuit from an
overcurrent.
• It can be reclosed without any hand-operated restoration. MCB is
used as an option to the fuse switch in most of the circuits.
• Unlike a fuse, MCB does not have to be replaced every time after a
failure as it can be reused.
• Advantage of MCBs- detection of a problem is easy.
• Whenever there is a fault in the circuit, the switch comes down
automatically and we are hereby informed that there was a fault.
• We can then manually go and put the MCB back up and the electricity
will start flowing again.

12. • The main difference between MCB, RCCB, and Isolators
• Isolators are generally used in power system while on the other
breaker. Isolators are manually-operated device, and on the
the automatically-operated device. Isolators cut the portion of the
occurs. The other devices like MCB and RCCB operate without any
breaker is the device of an Automatic circuit breaker or Miniature
the entire system and if any fault occurs, MCB is to protect the
Whereas, on the other hand, residual current device protects the
RCCB detects the leakage current and protects from the electric
• So, this is MCB, Isolators and RCCB and the difference between

13. Power Distribution in the buildings
General Layout of a consumer distribution board Meter and distribution boards in multi metering/ residents

14. Earthing System
• In electricity supply systems, an earthing system
or grounding system is circuitry which connects
parts of the electric circuit with the ground, thus
defining the electric potential of the conductors
relative to the Earth's conductive surface
• Used to protect the structures from lightning
strike, directing the lightning through the earthing
system and into the ground rod rather than
passing through the structure.