identify on the electrical power sources in case of emergency. for more details https://www.youtube.com/watch?v=-gYV8G7DJSs&t=127s

2.  The Need For Electrical Emergency Power Source.
 Common Types Of Emergency Power Sources:
 The Diesel Generator.
 The Uninterruptible Power Supply (UPS).
 Central Battery System.

3.  There is a need for emergency power source because there
is a probability for the normal power source to fail in case
of faults or bad weather conditions. In the same time there
are some types of loads which requires continuous service
of electrical energy. (some examples on these loads are mentioned
in the following slides).
 The emergency loads are usually a percentage of the total
load of the building but in some cases the whole building
may be connected to the emergency power source
according to the importance of the building.

4.  The most common two types of emergency power sources
are: Diesel Generators and UPS.
 Also Central Battery System can be used in some Types of
buildings.
 The nature of the loads determines the suitable type of the
emergency power source which the load need.

5.  The diesel generator is actually a set consists of a diesel engine
coupled mechanically with an electrical generator.
 If the normal power source failed, the Diesel generator receives a
signal to start and it can produce the required power after some time.
So the loads fed from the generator will be shut down for some time
depending on the specifications of the generator.
 The main advantage of the diesel generator is the ability to supply
large loads by electric energy for long times.
 The main disadvantage of the diesel generator is the high levels of
noise which requires special
specifications for the room
which contains the
generator.

6.  There is a control panel called automatic transfer switch (ATS) which
connects between the diesel generator and the rest of the distribution
system. If the normal power source failed, the ATS sends an order to the
diesel generator to operate.
 The typical loads which are usually connected to the diesel generator
are: lighting loads with a percentage according to the project type,
some ventilating loads related to life safety, some low current loads
such as door controllers and some mechanical loads such as fire pump.

7.  The uninterruptible power supply is an electronic circuit consists of a
rectifier which converts the AC voltage of the main power supply to DC
voltage, batteries to store electrical energy and an inverter to convert
the DC voltage to AC voltage.
 Its principle of operation depends on energy storage through the built-
in batteries to feed the loads in case of normal power source failure.
 It is suitable for feeding loads which requires a continuous electrical
service without any failure even if for one second.These loads are like
data centers, main computers of banks, servers, IT racks and some
important equipment of hospitals especially operation rooms.
 Main advantage: operation without very low level of sound.
 Main disadvantage: using batteries which have relatively short lifetime.

8.  The UPS can be divided into three types according to the principle of
operation:
 1. Offline (Stand By) Type:
 2. line interactive Type:

9.  3. Online (Double Conversion) Type:

10.  1. Normal Mode: By taking the electric power from supply and rectified
then converted again to AC through the inverter without extracting
power from battery.
 2. By-pass Mode: it is used when there is an overload on the inverter or
when the internal temperature exceeds the max. limit .
 3. Battery Mode: used when the AC supply fails, the power is extracted
from battery and converted to AC via the inverter.

11.  Central Battery System is an integrated system which contains battery
bank and conversion systems (charger& inverter).
 The principle of operation of central battery system is similar to UPS
but there are some differences.
 It is suitable for feeding and monitoring the emergency lighting
fixtures.
Central Battery UPS
Typical Loads Emergency lighting Other loads
Monitoring Yes No
Size Relatively small Bulky equipment
Power loss Low high

12.  Emergency Lighting is the necessary lighting which must be existing
in case of normal power outage even if the emergency power source
( Diesel Generator ) became no longer working.
 It is necessary to provide vision for the people inside the building to
move towards the exit doors in case of fire.
 The emergency lighting should have a specific lux values according to
the international codes ( approximately 10.8 lux ).
 The emergency lighting can be achieved by a percentage of the normal
lighting fixtures with special locations to achieve the required lux level
plus exit signs.

13.  Every Emergency Lighting fixture usually should be equipped by a
built-in battery to ensure working after the power outage for a specific
time so these luminaires are called “ Self Contained luminaires”.
 The alternative solution instead of the built-in battery is the Central
Battery System .
 The central battery system enable us to feed, monitor and control all
the emergency lighting fixtures inside the building.
 It prevents us from using the built in batteries which need continuous
maintenance and have short long time.
 The central battery system is useful in many applications such as hotels,
hospitals and office buildings.