Automatic voltageregulatortAVR^precision^ysteresis^utotransformer.comparator INTRODUCTION:
In our practical life voltage may be high or low for purpose of electricity supply system or for the weakness of supply system or for other causes. For that reason many important electric machine or for othercauses. For that reason, many important electric machine or electric equipment may destroy. In order to save these we need to us the voltage regulator.
The voltage regulator maybe manually or automatically controlled. The voltage can be regulated manually by tap-changing switches, a variable auto transformer and an inductionregulator.ln manual control, the output voltage is sensed with a voltmeter connected at the output; the decision and correcting operation is made by a human being. The manual control may not always be feasible due to various factors and the accuracy which can be obtained depending on the degree of instrument and giving much better performance so far as stability. In modern age large interconnected system manual regulation is not feasible and therefore automatic voltage regulation equipment is installed on each generator.
Power quality problems commonly faced by industrial operations include transients^ags^wellSjSurgeS/OutageS/harmonics and impulses that vary in quantity or
magnitude of the voltages.Of these voltages sags and extended under voltages have the largest
* -

Negative impact on industrial productivity and could be the most significant type of power quality variation for many industrial and commercial customers.AVR is a suitable choice to control the output voltage through field excitation in variable speed application.
SPECIFICATIONS:
I . • Input voltage:150Vto 273V
• Output voltage: 215V to 237V for all input lying
Based on the above initial design between 150V and 273V
decisions, the final • input and output frequency are the same
parameters/specifications: • High cut feature at 274V
• Low cut feature at 145V
• 8 relays are used.
• The auto transformer has a OV/neutral
tappings:315v,285v,257V,233V,212V/190V/172V/l
56V.
RELATED WORK DONE:
Design of traditional voltage regulator is discussed in these
C.S Hoong,S.Taib MIEEE, K.S Rao and I.Daut/'Development of automatic voltage regulator for synchronous generator",National Power & Energy conference proceedings ,Kuala L.KualaLumpur/Malaysia.
"Specifications and ratings of practical AVR",http://www.voltagestabilizer.com and http://www.voltagerefiufator.com.

"Configuration of automatic voltage regulator",Samsung,Venus,Microtech,Venstab and Siticon/http://www.vener7.com/servo-vottage-stabilizer/.
M.M.Hoque,"Design,implementation and performance study of programmable automatic voltage regufator",Electrfcaf systems 10-4,(2014),pp 472-483.
M.M.Hogue and A.I.Mahmod/'An improved automatic voltage regulator system with apposite hysteresis and immense precision",Chittagong university journal of sciences,vol 33,(2010),pp.21-33.
'Voltage regulator and power supply "/http://www.zen22142.zen.co.uk.
OVERVIEW OF THE PROPOSED DESIGN:
PRACTICAL CIRCUIT DESIGN 3>. C c/

1
CONCLUSION:
We will use a custom designed transformer and it 2ill be costly but other circuit component will be cheap enough. That the total system costs low or inexpensive.Although this regulating system is not wide-spreader in our country we hope if it becomes available ,the customers will appreciate it.So the proper steps should be taken to encourage the owner of industries to produce this type of regulator system and deliver to the customer at aresonableprice.Here this design ensures to regulate 150V-273V AC variation of input of the tolerable range of 215V-237 volt AC output.By adding many taps at the secondary side of the auto transformer and relays we can make a new automatic voltage regulator which can regulates inputb voltage range of 80V AC- 350V AC to a stable 220V AC output voltage.