This project’s goal is to create a low-voltage and high-voltage tripping mechanism to safeguard the load against harm. In houses and businesses, the AC mains supply fluctuates often. In these circumstances, delicate electrical equipment is readily harmed. To safeguard the load, it is better to include a tripping mechanism. If the input voltage drops below or rises above a certain level, the suggested system will trip the load. One quad comparator IC is converted into a window comparator using two comparators. If the input voltage to them exceeds the voltage window, this produces an error output. The load is then turned off using a relay for safety purposes.
MAIN OBJECTIVES
To protect electric devices from damages due to the rise and falling of voltage beyond the require value, by designing an over voltage and under voltage detection system.
SPECIFIC OBJECTIVES
Determining the electric devices at Tanzania-China Friendship Textile Company Limited (FTC).
Determine and specify components and tools for the circuit.
Design the circuit for the detection system.
Build the prototype.
Test the prototype.
SIGNIFICANCE OF THE PROJECT
To protect the electric devices from damage due to overvoltage or under voltage
Increase the production at the company
Remove disturbances of daily maintenance
LITERATURE REVIEW
Literature review includes existing system and its problem and the proposed system.
EXISTING SYSTEM
The existing system has some downs in protecting the electric devices from overvoltage and under voltage.
DISADVANTAGES OF EXISTING SYSTEM
It leads to the damage of electric devices due to the failure in controlling the rise and falling of voltage.
PROPOSED SYSTEM
A step down transformer is used to decrease the air conditioning supply down to 12 V. Through a scaffold rectifier, the AC power is converted to a DC supply. The supply is subsequently reduced in volume by capacitors connected crosswise across the rectifier. The voltage controller is then supplied the unregulated supply after which the yield is delivered to the comparators IC LM324 and transferred as supply. The connect rectifier’s unregulated supply is set to sets 1 and 2 for information. Potentiometers ckt.1 and ckt.2 from sets 1 and 2 are separately linked to comparators IC LM324 as information.
The comparators and load are also connected to hand-off. When there is an overvoltage or undervoltage, the comparators examine the predetermined circumstances and signal the hand-off and hand-off exits, turning off the pile. With the intention of protecting the electrical equipment
ADVANTAGES OF PROPOSED SYSTEM
The proposed system will protect the electric devices from being damaged due to over and under voltage
Reduce the disturbances of daily maintenance to the electricians
Increase the production at the company
Over Voltage Protection
Operational speaker IC LM324 is utilized here as a comparator as shown in fig.
16. IC LM324 comprises of four operational enhancers, out of which just two
operational intensifiers (N1 and N2) are utilized as a part of the circuit.
The unregulated power supply is associated with the arrangement association of
resistors R1 and R2 and potentiometer VR1. A similar supply is likewise
associated with an arrangement association of 6.8V Zener diode (ZD1) and
resistor R3. Set VR1 is balanced with the end goal that for ordinary supply of 180V – 240V,
the voltage at the non-rearranging terminal (stick 3) of operational speaker N1 is
under 6.8V. Subsequently the yield of the operational intensifier is zero and
transistor T1 stays in off state. The transfer, which is associated with the authority of transistor T1, additionally
remains not stimulated. At the point when the AC supply is given through the
ordinarily shut (N/C) terminal of the relayto the electrical apparatuses, the
supply isn’t segregated amid ordinary task. When the AC voltage increments over 240V, at that point the voltage at the non transforming terminal (stick 3) of operational enhancer N1 increments and the
voltage at the upsetting terminal is still6.8V due to the Zener diode.
Under Voltage Protection:
When the line voltage is lower than 180V, the voltage at the upsetting terminal
(stick 6) of operational enhancer N2 is beneath the voltage at the nonmodifying terminal (6V) as shown in fig. 16. Subsequently the yield of
operational speaker N2 goes high and it empowers the hand-off through
transistor T1. The AC supply is separated from the framework and electrical
apparatuses kill.
• Subsequently the machines are secured against under-voltage. IC1 is wired for
a directed 12V supply.
• The transfer invigorates in two conditions: in the first place, if the voltage at
stick 3 of IC2 is past 6.8V, and second, if the voltage at stick 6 of IC2 is lower
than 6V.
• Over-voltage and under-voltage levels can be adjusted utilizing sets VR1 and
VR2, individually. 3.5 Hardware Implementation
• It includes the points of interest of the arrangement of outline details. The
equipment plan comprises of, the choice of framework segments according to
the prerequisite, the points of interest of subsystems that are required for the
total usage of the framework has been completed. It includes the part
determination, segment portrayal and equipment subtle elements of the
framework outlined.
Motor damage
There is an average of 1-3 motors that are damaged per month
due to overvoltage and under voltage that are caused by ac
mains supply fluctuation.
Lamp ratings
Voltage rating 230-240V
Current 0.167A so,
Lamp type fluorescent lamp
Manufacture Philips
Rated power 40W
Luminous flux 770lm
Load selection
power = 1.5 KW
voltage = 380-415 V
power = voltage × current
but current = power / voltage
= 1500W /415V
= 3.61 A
Relay selection
Relay selection depends on the load ratings
so contact current (Ir) = 7.2A
but in market there is no relay with contact current =7.2A but there is of 10A with coil
resistance (Rc) = 400Ω so relay coil current will be Ic, then
so Ic = Vdc/Rc
12V/400Ω
I30mA
Therefore relay contact current (Ir) = 30mA
Existing protection scheme for the loads
Miniature circuit breaker (MCB)
Cartridge fuses
Motor ratings
but power 1.5KW
rated voltage 380-415V
so Current =3.4A
Motor speed 1430rpm
Motor type Three phase induction motor
Manufacture siemens
Power factor 0.82
Frequency 50Hz
Connection direct online
CONCLUSION
The project has successfully taken the idea of designing an over voltage and under voltage detection system because All potential data needed for the design of an overvoltage and under voltage system where successfully collected and analyzed hence the set goals where reached.
The designed system met the expectations reasonably well. Therefore, it can be concluded that the project objectives and its designing consideration have been reached.
RECOMMENDATION
Since the circuit will be capable of just protecting not more than two devices, then I recommend that the circuit should be modified so that it can protect many devices at once.