The document describes a mains supply sensed over and under voltage trip switch designed to protect sensitive electronic devices from damage due to voltage fluctuations. It outlines the hardware components used, such as comparators and transformers, and explains the working principles of the system, which operates by tripping the load when voltage exceeds set limits. Future enhancements include integrating a GSM modem for alert notifications.

1. Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Introduction
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch
 Over Voltage Under Voltage Trip Switch to protect the load from
damage. The fluctuation in AC mains supply is frequent in homes and
industries. The sensitive electronic devices in these conditions can get
easily damaged. It is preferable to have a tripping mechanism to
protect the load.

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Block Diagram
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Hardware Components
 LM 339 quad comparator
 LED
 Voltage Regulator
 Resistors
 Potentiometer
 Capacitors
 Diodes
 Relay
 Lamp
 Transformer
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Transforme
r  Transformer is an electrical device.
 It transfers electrical energy between two or more circuits
through electromagnetic induction.
 A varying current in one coil of the transformer produces a varying magnetic
field, which in turn induces a voltage in a second coil.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Capacitor
 Capacitors store and release electrical charge.
 They are used for filtering power supply lines, tuning resonant circuits.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Over Voltage
 When the voltage in a circuit or part of it is raised above its upper design
limit, this is known as overvoltage.
 The conditions may be hazardous.
 Depending on its duration, the overvoltage event can be transient - a
voltage spike - or permanent, leading to a power surge.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Low Voltage
 Under Voltage condition occurs when a load is suddenly connected to a
power supply.
 The load will start to draw current, this causes the voltage to temporarily
drop.
 Multimeter is set to measure voltage Instruments for measuring voltages
including the voltmeter, the potentiometer, and the oscilloscope.
 The voltmeter works by measuring the current through a fixed resistor,
which, according to Ohm's Law, is proportional to the voltage across the
resistor.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Description
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch
 The tripping mechanism is to protect the load from damage.
 The fluctuation in AC mains supply is frequent in homes and
industries.
 The sensitive electronic devices in these conditions can get
easily damaged.
 The proposed system will trip the load in the event of the input
voltage falling below/above a set value.

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Description
 Two 555 timers are used as window comparator.
 This delivers an error output if the input voltage to them crosses the
range beyond the voltage window.
 A relay is then operated to cut-off the load for safety reasons. A lamp is
used as load in this project.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Working Principle
 A 220 volts ac is given as a input to the transformer.
 A step down transformer is used, as it serves to reduce the pressure
remaining 12 volts, through a D1-D4 connected to Direct rectifier bridge
circuit.
 This rectifier converts ac to dc but the obtained dc is not pure dc it is a
pulsating dc, to obtain pure dc we are using regulator so that we can
obtain pure dc.
 And the capacitors are used for filtering.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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 In the regulator the voltage across the pins 1 and 2 will be the input and
output will be from the pins 2and 3.
 Here we are using another IC which as 14 pins.
 The 4th pin in this IC act as V cc and the 11th pin will be grounded.
 Here we are using two zener diodes of 6.8v and 6v.
 The 6.8 volts zener diode is connected to the 2nd pin of IC2/1 and 6 volts
zener diode is connected to the 5th pin of IC2/2.
Working Principle
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Working Principle
 The voltage coming from the diodes D2 and D4 goes to 3rd pin of IC2/1
and 6th pin of IC2/2.
 Here IC2/1 act as high voltage detector and IC2/2 act as low voltage
detector.
 When the voltage obtained across the 3rd pin is greater than the voltage
at the 3rd pin then IC2/1(high voltage detector) will function and the
switch will be closed and load will be and LED glows.
 This is the indication of high voltage.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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 High reliability
 High performance
Advantages
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Disadvantages
 In this project, relay is used as it is making of sound. So some noise
pollution occurs.
 It is specified of minimum range of the higher voltage and lower
voltage.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Future Scope
 This system can also be enhanced in future by interfacing it with a GSM
modem to convey alert message to the user via SMS to take appropriate
action.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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Conclusion
 Mains supply sensed over voltage under voltage trip switch will
indicate the high voltage and low voltage. Due to this we can safe
guard our home appliances without damaging the equipments.
Mains Supply Sensed Over Voltage
Under Voltage Trip Switch

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