VISHWAKARMA GOVERNMENT
ENGINEERING COLLEGE
COMBINED OVER-VOLTAGE & UNDER-VOLTAGE
PROTECTION SYSTEM
SUBMITTED BY
Dipak Chudasama.
Adarsh Chavda.
Dharmik Chauhan.
Harit Gajera.
Jenil Chaudhary.
170170109013
170170109011
170170109010
170170109020
170170109006
DEPARTMENT OF ELECTRICAL ENGINEERING
.
.
Guided by
Nilesh J. patel
INTRODUCTION
Here is an inexpensive auto cutoff circuit,
which is fabricated using contactor and
other discrete components.
 It can be used to protect loads such as
refrigerator, TV, and VCR from undesirable
over and under line voltages, as well as
surges caused due to sudden
failure/resumption of mains power supply
This circuit can be used directly as a
standalone circuit between the mains supply
and the load.
 The on-time delay circuit not only protects the
load from switching surges but also from quick
changeover (off and on) effect of over-/undervoltage relay, in case the mains voltage starts
fluctuating in the vicinity of under- or overvoltage preset points.
 When the mains supply goes out of preset (overor under-voltage) limits, the relay/load is turned
off immediately, and it is turned on only when
AC mains voltage settles within the preset limits
for a period equal to the on time delay period.
Major Components
 Auto Transformer
 Contactors
 Push Button
 Indiacator light
 Semaphore indicators
 Digital voltmeter & ameter
 Relays
 Hooters
CONTROL CIRCUIT OF COMBINED OVER
AND UNDER VOLTAGE PROTECTION
POWER CIRCUIT OF COMBINED OVER
AND UNDER VOLTAGE PROTECTION
NUMARICAL RELAY
FUNCTION OF RELAY
CONTACTOR
Advantages Of Combined Over and
Under Voltage Protection
 High reliability
 Low cost
 Over voltage protection
 Under boltage protection
 High performance
 It can be protect loads such as refrigerator,T.V. from undesirable over and
under voltages.
Future Work :
1. In the future we will try to improve our
design by high voltage
2. As well as we will try to minimize the
time delay
3. In future we will try to increase
performance and reliability
CONCLUSION
 It is an inexpensive auto cutoff circuit, which is
fabricated using transistors and other discrete
components. It can be used to protect loads
such as refrigerator, TV, and VCR from
undesirable over and under line voltages, as
well as surges caused due to sudden
failure/resumption of mains