design a energy back up for a hospital.

To design a Energy Back-up for a Hospital using Batteries
1. Introduction

The electricity demand of a hospital is always higher than most other building types.
This is because the hospitals have many types of equipment which require very large
power as well as highest reliability such as magnetic resonance imaging (MRIs),
computer tomography (CT) scanners, and other imaging equipment.

Also hospitals require many types of equipment common to different buildings as well
as in same building.

The load of air-conditioning and ventilation systems are also very high in hospitals as
compare to other buildings of same type due to the height of the building which always
equired fast air change rate subsequently more stringent temperature requirements.

As per NFPA 70 and NFPA 99, the electricity requirement in a hospital can be
categorized as 3 locations –
1. General Care
2. Critical Care
3. Wet Locations

The emergency power supply systems in hospitals are required to ensure backup power
availability in Critical Care for sure and for some of the appliances of "General Care"
and "Wet Locations."

Below is the list of patient care areas which are falling under "Critical Care" areas as per
NFPA 70 guideline-

o Operating rooms.
o Delivery rooms..
o Cystoscope rooms.
o Oral Surgery
o Perodontics, and Endodontics
o Maxillofacial surgery
o surgery and labor recovery beds
o Patient bedrooms of Coronary care units.
o Intensive care unit including patient bedrooms
o Emergency care units including rooms and cubicles for treatment, trauma
and urgent care..
o Labor rooms
o Stress test and preparation room for Labor rooms.
o Intensive care nursery
o Isolation care nursery.
o Cardiac catherization.
o Rooms of Angiographic exposure
o Facility of hemodialysis.
o Surgery suites including roomsof preparation and hold.
o Hype
aric chamber.
o Radiation Therapy
o Simulator room of radiator therapy
o Nuclear medicine
o Camera room for nuclear medicine.

The patient care areas, exposed to wet conditions are considered as Wet Conditions.
The other patient care areas which are not falling under above two category are known
as "General Care."


2. Single line Diagram

Below can be a single line diagram for a typical hospital power system.



Alternate Electricity source design requirement is also based on NFPA 70 and NFPA 99
guideline. The alternate source of power can be a generator, battery system, or internal
energy source available within the equipment. The alternate Power source should have
the capacity to supply its full connected load for at least an hour at rated voltage. The
alternate power generating system should have mechanism to connect within 10
seconds. The another important dimension of NFPA 70 and NFPA 99 is that alternative
power should designed to provide electrical power for hospital plus 20% future load
growth at 100% demand. In a typical hospital, electrical system load is less than 150
KVA.

Alternative Electric Energy can be generated by Generator set, batteries or the
combination of both, however parallel Generator set operation can provide a valid
picture regarding operation of alternate Energy sources. Initially first generator
energizes and connects with the emergency buses. A pre program device is placed in
the power system which facilitates the transfer of emergency system loads from the
normal bus to emergency bus as per requirement on faster pace. It makes sure that
transfer should happen within 10 seconds. Once second generator becomes online
emaining instrument load will also get connect with the emergency bus and both the
generator will work in parallel.

If any one of the generator unit fails due to any fault during the normal operation, the
emaining unit will immediately supply to emergency system loads including highest
priority equipments loads. Below line diagram will explain the process further.

Similar to the parallel operation of generator, the alternative electric source made of
atteries should also have two parallel battery backups. One will back up the
emergency load as well as highest priority equipments loads while other will manage
other important loads. In case of fault in any of the battery unit the other will start
supplying the emergency loads. In the above figure, the Generator G1 and G2 can be
eplaced by batteries panel as well as inverters / UPS.

Once normal power supply becomes stable, emergency system loads and equipment
system loads both will be again transfe
ed to the normal power source. This transfer
should be automatic using transfer devices and should happen after Thirty minutes to
make sure the normal supply is stable,.

The essential electrical system for a typical hospital consists of two parts:
 Emergency system
 Equipment system

The emergency system is further divided two
anches:
 Life safety
anch
 Critical care
anch
The life safety
anch should connect with loads identified in NFPA-70 and 99 as critical
loads. No other load should be connected to life safety
anch. As per NFPA-99,
Reliability of supply in critical areas can be considerably high in case of combination of
normal, critical and equipment
anch power supplying to critical areas. The equipment
system includes all the essential equipment listed in NFPA-70 and 99. To improve the
operation of hospital further, additional loads can also be connected to the critical
anch.: A symmetric diagram is showing below the power system set up in the
hospitals




As per guideline, the power and lighting loads for the following areas can be connected
to the critical
anch


2.1 Essential Loads.

Critical Care Loads as stated above in the report, total estimated load = 100 kVA.

As per guideline, the following configuration of lighting, equipment limitations and
eceptacle are defined below:
a. 25% of co
idor area illumination and 50% of stairway illumination.
Additionally 25% of assembly areas can be considered as essential loads.
Considering a 10 floor hospital with area in each floor around 20k square feet.
Typically 15W power required to illuminate 10 sq feet area. The estimated
load is equal to 15 kVA
. Exit signs and smoke conditions. The estimated load could be 1 kVA

c. The areas in hospital where patient evacuation is difficult, Fire alarm and piped
medical gas alarm systems should be the part of essential load. The estimated
load could be 1 kVA

d. Emergency communications including telephone, power and lighting for
communication closets. It should also include centers for crisis control and
associated equipment. The estimated load could be 1 kVA
e. Elevator lighting, communication, elevator control devices including signals
and systems. The estimated load could be 1 kVA




2.2 Critical Branch Loads-

o Nurse calling device, telephone equipments for communication and
selected computer equipments including selected data hub based on
equirements..
o Equipments supplying Oxygen and medical gases
o Vacuum pumps and compressed air system used in medical surgeries.
o Patient rooms.
o All the essential instruments in patient service
o All...