Kisaki dispensary is found in Morogoro Region which is within the Morogoro Rural District, Kisaki ward and is located in Tanzania about 250km South-East of Dar es salaam, the country’s capital.Kisaki dispensary is intended to provide health service like tests and diagnosis of different diseases and their treatments. This dispensary serves several villages that are kichangani, gomero, tini, Kisaki station,and nyarutanga, so Kisaki dispensary depends electric power from TANESCO.
PROBLEM STATEMENT
Problem facing the hospital is during the night hours after the power from TANESCO is cut-off, the process of providing health service during the night shifts is provided in a hard way forcing the doctors and nurses to use torch as a source of light . The situation causes the patients to lack good health service and It makes the doctors and nurses to work in a crucial environment during night hours. So due to this problem I propose an innovative system of designing an automatic emergency power supply system as alternative source of light when the TANESCO power is cut-off.
MAIN OBJECTIVES
To end up the problem of cutting power when the mains power supply fails by design an automatic emergency power supply system at Kisaki Dispensary.
SIGNFICANT OF THE PROJECT
Automatic switching of system when the main system fails.
It will Power saving.
Low running cost .
Pollution free.
Easy to install anywhere.
LITERATURE REVIEW
Literature review include existing system and proposed system.
EXISTING SYSTEM
The existing system depend on electric power from TANESCO.
DISADVANTAGES OF EXISTING
Power cut-off during the night shifts the health services given is poor.
PROPOSED SYSTEM
So the proposed system will include battery charger, automatic change-over switch, battery, TANESCO supply, circuit breaker, Distribution board, AC loads, and Critical loads.
ADVANTAGES OF PROPOSED SYSTEM
Many systems which need electrical power for its operations will be employed , so the health services will be improved .
DATA ANALYSIS PROPOSED CIRCUIT DIAGRAM
LOAD SELECTION
So, Power output = current × voltage supply
Then, current = power output /voltage supplied
= 1962/ 230
= 8.5A.
Therefore,
Total load AC Wh/day =1962 from the table above
Total watt-hours per day needed for the supply =AC load per day × 1.3(energy loss in the system)
= 1962× 1.3
=2550.6Wh/day in DC
AUTOMATIC CHANGE OVER SWITCH
Switch specification.
NPN-BC547, BC548, BC549.
PNP – BC557, BC558, BC559.
Then, I propose BC547 its available.
IC ≤ 200mA
IB ≥ 1µA
ß = 120-150
Then, the proposed value is 140.
VCC max ≤ 24
Resistor-400Ω, 300Ω.
Proposed value is 300Ω.
Therefore, from the above valuations the proposed value of IC is 40mA.
Then,
IC = ß/IB
IB= IC /ß
= 40mA/140
IB= 2885µA.
But
IB≥1µA
VB= IB × Rb
therefore,
RB= VB / IB
= 12 / 28.6mA
RB = 42,000Ω
RB = 42kΩ
RELAY SELECTION
Therefore selection depends on the load ratings
coil voltage =12Vdc
contact current (Ir) = 40mA
then coil resistance (Rc) will be
VCC =IC × RC
IC = IR
RC =12 ∕ 40
Hence, the relay resistance is 300Ω
INVERTER SELECTION
Convert DC power to AC power
Therefore, sizing of inverter is given by
= safety factor (1.25)× total load in AC Wh/day divided by power factor of pure sine wave inverter (0.9)
=(1.25 × 1962) / (0.9)
=2725 VA approximate to 3kVA
This is available inverter in the market 3 kVA .
CONCLUSION
This project has partially successfully taken an idea of designing of emergency power supply system as alternative source of energy. All the potential data needed for the design of the emergency power supply system were successfully because data was well collected and analyzed. The designed system met my expectations reasonably well. Therefore, it can be concluded that the project objective and its designing consideration have been met.
RECOMMENDATION
Emergency power supply system must be implemented to the societies, It provides the sustainable energy and ensure the presence of power when the main supply fails.