Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Autotransformer shopping experience:
1. Compare - without doubt the biggest advantage that the Autotransformer offers shoppers today is the ability to compare thousands of Autotransformer at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Autotransformer? Wrong! If the Autotransformer is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Autotransformer then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Autotransformer? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Autotransformer and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Autotransformer wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Autotransformer then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Autotransformer site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Autotransformer, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Autotransformer, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
An
autotransformer is an electrical
transformer with only one coil#Electromagnetic. The winding has at least three electrical connection points called
Tap (transformer). The voltage source is applied to two taps and the External electric load is connected to two taps one of which is usually a
common connection that is also connected to the source. Each Tap (transformer) corresponds to a different source or load voltage. In an autotransformer a portion of the same winding effectively acts as part of both the primary and secondary winding.
Operation
The ratio of secondary to primary voltages is equal to the ratio of the number of turns of the winding they connect to. For example, connecting at the middle and bottom of the autotransformer will halve the voltage. Depending on the application, that portion of the winding used solely in the higher-voltage (lower current) portion may be wound with wire of a smaller gauge, though the entire winding is directly connected.
Limitations
A failure of the insulation or the windings of an autotransformer can result in full input
voltage to be applied to the output. This is an important safety consideration when deciding to use an autotransfomer in a given application.
Because it requires both fewer windings and a smaller core, an autotransformer for power applications is typically lighter and less costly than a two-winding transformer, up to a voltage ratio of about 3:1 - beyond that range a two-winding transformer is usually more economical.
In
three phase power transmission applications, autotransformers have the limitations of not suppressing
harmonic currents and as acting as another source of ground fault currents. A large three-phase autotransformer may have a "buried" delta winding, not connected to the outside of the tank, to absorb some harmonic currents.
A special form of autotransformer called a "zig zag" is used to provide grounding (earthing) on three-phase systems that otherwise have no connection to ground (earth). A
Zigzag transformer provides a path for current that is common to all three phases (so-called "zero sequence" current).
Like multiple-winding transformers, autotransformers operate on time-varying
magnetic fields and so are not used directly on DC.
Applications
Autotransformers are frequently used in
power transmission applications to interconnect systems operating at different voltage classes, for example 138 kV to 66 kV for transmission. Another application is in industry to adapt machinery built (for example) for 480 V supplies to operate on a 600 V supply. They are also often used for providing conversions between the two common domestic mains voltage bands in the world (100-130 and 200-250).
On long rural power distribution lines, special autotransformers with automatic tap-changing equipment are inserted as voltage regulators, so that customers at the far end of the line receive the same average voltage as those closer to the source. The variable ratio of the autotransformer compensates for the voltage drop along the line.
Variable autotransformers
As with two-winding transformers, autotransformers may be equipped with many taps and automatic switchgear to allow them to act as automatic voltage regulators, to maintain a steady voltage at the customers' service during a wide range of load conditions.
By exposing part of the winding coils and making the secondary connection through a sliding brush (electric), an almost continuously variable turns ratio can be obtained, allowing for very smooth control of voltage. Applicable only for relatively low voltage designs, this device is known as a variable AC transformer, or commonly by the trade name of
Variac.
From 1934 to 2002,
Variac was a U.S. trademark of General Radio for a variable autotransformer intended to conveniently vary the output voltage for a steady AC input voltage. In 2004, Instrument Service Equipment applied for the
Variac trademark for the same type of product. The term has acquired the status of a
genericized trademark and is often used to describe similar variable autotransformers made by other makers.
References
- Terrell Croft and Wilford Summers (ed), American Electricans' Handbook, Eleventh Edition, McGraw Hill, New York (1987) ISBN 0-07013932-6
- Donald G. Fink and H. Wayne Beaty, Standard Handbook for Electrical Engineers, Eleventh Edition,McGraw-Hill, New York, 1978, ISBN 0-07020974-X
An
autotransformer is an electrical
transformer with only one coil#Electromagnetic. The winding has at least three electrical connection points called Tap (transformer). The voltage source is applied to two taps and the External electric load is connected to two taps one of which is usually a
common connection that is also connected to the source. Each Tap (transformer) corresponds to a different source or load voltage. In an autotransformer a portion of the same winding effectively acts as part of both the primary and secondary winding.
Operation
The ratio of secondary to primary voltages is equal to the ratio of the number of turns of the winding they connect to. For example, connecting at the middle and bottom of the autotransformer will halve the voltage. Depending on the application, that portion of the winding used solely in the higher-voltage (lower current) portion may be wound with wire of a smaller gauge, though the entire winding is directly connected.
Limitations
A failure of the insulation or the windings of an autotransformer can result in full input
voltage to be applied to the output. This is an important safety consideration when deciding to use an autotransfomer in a given application.
Because it requires both fewer windings and a smaller core, an autotransformer for power applications is typically lighter and less costly than a two-winding transformer, up to a voltage ratio of about 3:1 - beyond that range a two-winding transformer is usually more economical.
In
three phase power transmission applications, autotransformers have the limitations of not suppressing harmonic currents and as acting as another source of ground fault currents. A large three-phase autotransformer may have a "buried" delta winding, not connected to the outside of the tank, to absorb some harmonic currents.
A special form of autotransformer called a "zig zag" is used to provide grounding (earthing) on three-phase systems that otherwise have no connection to ground (earth). A
Zigzag transformer provides a path for current that is common to all three phases (so-called "zero sequence" current).
Like multiple-winding
transformers, autotransformers operate on time-varying magnetic fields and so are not used directly on DC.
Applications
Autotransformers are frequently used in power transmission applications to interconnect systems operating at different voltage classes, for example 138 kV to 66 kV for transmission. Another application is in industry to adapt machinery built (for example) for 480 V supplies to operate on a 600 V supply. They are also often used for providing conversions between the two common domestic mains voltage bands in the world (100-130 and 200-250).
On long rural power distribution lines, special autotransformers with automatic tap-changing equipment are inserted as voltage regulators, so that customers at the far end of the line receive the same average voltage as those closer to the source. The variable ratio of the autotransformer compensates for the voltage drop along the line.
Variable autotransformers
As with two-winding transformers, autotransformers may be equipped with many taps and automatic switchgear to allow them to act as automatic voltage regulators, to maintain a steady voltage at the customers' service during a wide range of load conditions.
By exposing part of the winding coils and making the secondary connection through a sliding
brush (electric), an almost continuously variable turns ratio can be obtained, allowing for very smooth control of voltage. Applicable only for relatively low voltage designs, this device is known as a variable AC transformer, or commonly by the trade name of
Variac.
From 1934 to 2002,
Variac was a U.S. trademark of
General Radio for a variable autotransformer intended to conveniently vary the output voltage for a steady AC input voltage. In 2004, Instrument Service Equipment applied for the
Variac trademark for the same type of product. The term has acquired the status of a genericized trademark and is often used to describe similar variable autotransformers made by other makers.
References
- Terrell Croft and Wilford Summers (ed), American Electricans' Handbook, Eleventh Edition, McGraw Hill, New York (1987) ISBN 0-07013932-6
- Donald G. Fink and H. Wayne Beaty, Standard Handbook for Electrical Engineers, Eleventh Edition,McGraw-Hill, New York, 1978, ISBN 0-07020974-X
Autotransformer - Wikipedia, the free encyclopedia
An autotransformer (sometimes called autoformer) [1] is an electrical transformer with only one winding. The winding has at least three electrical connection points called taps.
Transformer - Wikipedia, the free encyclopedia
... wide variety of transformer designs are used for different applications, though they share several common features. Important common transformer types include: [edit] Autotransformer
autotransformer - Wiktionary
Definition from Wiktionary, a free dictionary
autotransformer - definition of autotransformer in the Medical ...
n a transformer with a single winding, having a large number of connections, or taps. Used to deliver a precise voltage to the high-tension primary circuit.
autotransformer - definition of autotransformer by the Free Online ...
An electrical transformer in which the primary and secondary coils have some or all windings in common.?
Variable Transformer, Variac Autotransformer, Variac Auto Transformers ...
Variable Voltage Auto Transformer, Variac Auto Transformers, Variable Transformer, Single Phase Transformer, Three Phase Transformer, Dimmer, India
autotransformer description - the Electricity Forum
autotransformer detailed description- Electricity Forum ... Autotransformer Description: Autotransformer On-line Directory; Autotransformer "Request For Quotation" Service
Autotransformer - Wikiversity
Please help improve this article by adding it to one or more categories, so it may be associated with related articles (how?). Please remove this tag after categorizing, but not ...
Autotransformer
500 MVA Single-phase autotransformers Mitsubishi Electric's Ako works facility specializes in producing large MVA, high voltage shell-form transformers and has vast experience ...
autotransformer - Definition at the #1 Online Dictionary
noun. Elec. a transformer with at least part of the windings common to both the primary and the secondary circuits
