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Application Note

VARIAC <> VARIABLE TRANSFORMER
Industrial Adjustable Variable Voltage Autotransformer
Motorized <> Manual Adjust
(Distributors of Staco and Power Design)

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The Variable Transformer, generically referred to as a "Variac", is widely used when adjustable voltages are required for quality control testing, electronic equipment burn-in, life-tests, low voltage performance evaluation, D.C. rectifier / regulator analysis or other engineering applications.

Autotransformer design permits configuring the output to achieve a voltage boost if required.  Typical designs provide voltage boost of 12 to 17%, although configurations that double input voltage are available. Output current generally must be limited when voltage boost exceeds 17%

Variac output voltage adjustment is normally accomplished manually, with a simple control knob. However, motorized variac control is also available for remote adjustment and for large units.

The Variable Transformer is also frequently used to adjust temperature, control lighting, hot wire cutting operation control, motor speed control and for testing equipment operation to simulate over-voltage or under-voltage conditions.

Audio enthusiasts report improved sound quality when line voltage to amplifiers is reduced to about 100 to 112 Volts ! !

Some audio devotees have installed a voltage regulator together with a Variable Transformer for constant lowered  voltage.

The Variable transformer is frequently combined with ferroresonant voltage regulators to provide a well regulated, wide range AC voltage source. Also, a variac coupled with an isolation transformer can "isolate" sensitive equipment from AC power Line electrical noise and interference.

In engineering and equipment service environments, the isolation transformer / variable transformer combo is  also utilized for personnel safety in addition to providing variable voltages for testing purposes.

A Variac combined with an isolation transformer can be used for any of the engineering, testing or control functions described above to provide interference or ground noise isolation.

A stepper motor controlled variable transformer, combined with a feedback controller, has been effectively employed to regulate output voltage to within 1 - 1.5%.  Effects of AC power input variations are effectively eliminated.

The 400 Hz Variac has found wide application in military and aeronautical engineering endeavors because of their small size and light weight. Because of these demanding applications, the 400 Hz variac is engineered to exhibit superior resistance to high temperature, humidity, altitude and shock / vibration. View available 400 Hz units.

Special Applications - Multiple Frequency Operation

Some Engineering, Test and Maintenance facilities require Variable Transformers capable of handling 50, 60 and 400 Hz power.  Link to Multi-Frequency Variable Transformers to check out available units.

Summary of Applications for The Variable Transformer / Variac

Please recommend this Application Note to an Associate

VARIAC <> VARIABLE TRANSFORMER
Industrial Adjustable Variable Voltage Autotransformer

Check Out
Our Variable Transformer
 Winter Sale Specials

	Precise, continuous voltage control 60 Hz and 50/60 Hz Models available Bench-Top and Panel-Mount Models Motorized Models can be factory ordered 120 Volt and 240 Volt Models Autotransformer design gives voltage boost Now Available !  400 Hz Variac ... See 'em Here Check Out ... 3-Phase Variable Transformers
Bench Top Models 120 Volt Models 240 Volt Models		Panel Mount Models 120 Volt Models 240 Volt Models

The Variable Transformer, often generically referred to as a "Variac", is widely used when adjustable voltages are required for quality control testing, electronic equipment burn-in, life-tests, low voltage performance evaluation, D.C. rectifier/regulator analysis or other industrial and engineering applications.

Bench Top units, employing a AC power line cord and electrical outlet, can be conveniently moved within the engineering laboratory or equipment service area to provide adjustable voltage.

Panel mount units are often incorporated into test equipment or permanent installations.

Printer Friendly Variable Transformer pages

 The Bench Top Variac / Variable Transformer is widely used in Service Shops, Industrial & Academic Laboratories, Engineering Design Facilities, Manufacturing Operations and Field Installation Teams.  Inherent portability makes these units valuable in instances where actual operational parameters need to be ascertained.

Pricing for Bench Top Variable Transformers

Panel Mount Variacs / Variable Transformers are utilized in permanent installations and equipment when operational or performance points need to be varied.  Panel Mount variacs are mounted both on external panels for operational accessibility and internally for system setup adjustments. 

Pricing for Panel Mount Variable Transformers

Check Out
Our Variable Transformer
 Winter Sale Specials

400 Hz Variacs - -
Contact Electronic Specialists to discuss requirements and availability
delivery time is usually 3 to 6 weeks After Receipt of Order
View details on available 400 Hz Variac models

Three-Phase Models - -

We have cataloged the most popular of our 3-Phase Variable Transformers . . See them Here

Contact Electronic Specialists to discuss requirements and availability
delivery time is usually 4 to 6 weeks After Receipt of Order and Payment
Payment in full required at time of order, as these are Specially Constructed

Motorized Models - -
Contact Electronic Specialists to discuss requirements and availability
delivery time is usually 4 to 6 weeks After Receipt of Order and Payment
Payment in full required at time of order, as these are Specially Constructed

Check Out Electronic Specialists Variac controlled voltage regulator and isolation transformer
Have a look at our Precision, Variac Voltage Regulator  packages
New ! Stepper Motor Variac Regulator Controller

FREE Variac / Variable Transformer Tutorial More Insight on Variable Transformers & Applications

View our 400 Hz Variac units

Special Applications - Multiple Frequency Operation

Some Engineering, Test and Maintenance facilities require Variable Transformers capable of handling 50, 60 and 400 Hz power.  Link to Multi-Frequency Variable Transformers to check out available units.

Variac is a Registered Trademark of Power Designs / Variac 

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Surges, Spikes and Interference Damage  
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Studies Show ...................

Winter Storms Cause More 
Wild Power, phone line outages, surges, spikes and interference
than Summer Storms

On the other hand, There are more Summer Storms

Winter Storm Spherics cause up to 50% as much damage as Summer Lightning Storms

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AC Power Line Protection  220-250 Volts ...... Commercial ... Industrial and .. Laboratory & Basic Grades  NEMA  6-15, 615, 6-20, 620	Direct Plug AC Power Protection with built in Modem Protector Dual Function - Direct Plug AC Power and Modem Protectors	Dual Function - Direct Plug AC Power and Network Protectors
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