Automatic Voltage Controllers

In spite of best efforts, no state electricity board can ensure constant voltage to the customer because of long and inadequate distribution lines and irregular load pattern on distribution transformers. Generally Voltage is low during day time and high during night hours. Moreover on holidays , peak hours , rainy days and when agricultural and Industrial load is switched off, the voltage rises sharply which is more dangerous.

In spite of best efforts, no state electricity board can ensure constant voltage to the customer because of long and inadequate distribution lines and irregular load pattern on distribution transformers. Generally Voltage is low during day time and high during night hours. Moreover on holidays, peak hours, rainy days and when agricultural and Industrial load is switched off, the voltage rises sharply which is more dangerous.

This higher current affects the electrical motors (particularly smaller capacity motors upto 7.5 H.P.) in three ways:

1. Higher current produces higher losses in electrical motors which causes premature failure of winding.

2. These higher losses of electric motors also increase the losses of cables, switches, transformers & other associated equipments.

3. For smooth continuous operation of motors, over load relays are usually set at 20% higher setting.

With the installation of the Servo Controlled Voltage Stabilizer and maintaining 390/400 volts, the motor will operate smoothly drawing 15 - 20% lesser current.

The table below compares the behavior of 5 H.P. motor at different voltage:

Input Voltage	Current	KVA	PF
400	7.5 A	5.2	0.8
425	11% More	18% More	0.7
435	19% More	28% More	0.61
445	26% More	38% More	0.57

The table below compares the behavior of 60 watt lamp at different voltage:

Voltage	Current	Watts	Luminous Intensity	Life in Hours
220	0.25	54 W	690	2000
230	0.26	60 W	710	1000
240	0.27	65 W - 8.3% More	820	575
250	0.28	70.6 - 17.6% More	943	338
260	0.29	75.4 - 25.6% More	1073	200
270	0.31	83.4 - 39% More	1213	100

and correspondingly the relay setting can be reduced by 15 - 20 %. In case single phasing occurs, the relay will trip in 40-50 seconds. The motor can withstand the high current for this period and will be safe. Also, the relays, contactors, switchgears, etc. incorporated with the motor, will be safe.

Loss Comparison of Make Regulator & Conventional make Regulator

Loss Comparison of Make Regulator & Conventional make Regulator

Capacity	make Roller type regulator losses	Conventional make Carbon brush type Dimmerstat losses
60 A	575 W	1050 W
75 A	730 W	2055 W
100 A	900 W	3105 W

Table below gives approximate quantitative advantages of automatic voltage controller at various fluctuation levels:

Input Voltage
Variation

% Reduction in Breakdown Possible
Motor Load Below 10 HP.	Lighting Load

Approx. Power Saving Possible
Motor Load Below 10 HP.	Lighting Load

380-400 volts

Nil

Nil	Nil & Servo Stabilizer Required

380-420 volts

10%

380-440 volts

10%

20%

10%

360-460 volts

40%

20%

360-480 volts

60%

10%

30%

340-500 volts

80%

15%

37%

Description of Controlled AVC:

Stabilizer is manufactured as per IS : 9815 and primarily consists of the following:

1. Liner Plus / Minus Type Vertical Rolling Contact Voltage Regulator

In our regulator we are using heavy section of electrolytic grade rectangular copper strip instead of copper wire to minimize the losses & increase the efficiency of equipment. We are also using self lubricating Carbon Roller Assemblies instead of ordinary Carbon Brushes which offers more reliability and trouble free performance of the equipment.

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