Ten Uses for an Autotransformer, or Variac
- Testing a repaired electronic device. After performing a repair on a piece of electronic equipment, it is best to...
- Powering up an old radio or amplifier. When powering up an old radio or amplifier that has not been used for an...
- Roasting coffee beans or nuts. To obtain the freshest coffee possible, coffee...
What is a Variac and why use one?
What is a Variac? As the name suggests, it varies AC voltage. The descriptive term would be "variable AC transformer," but the trade name Variac was used by the General Radio company for many years, and eventually that became the generic name. Here are four variacs on my workbench: We'll look at each of them later in this article. Why Use a Variac?
Why choose a Variac transformer?
Their distortion free output is ideal for sensitive electronic applications, testing devices for agency approval, and numerous other applications where a variable AC voltage is required. Our VARIAC transformers are available that boost the output voltage in excess of twice the input voltage.
What is a varivariac used for?
Variacs can be used to gradually revive previously dormant electronic equipment. They can also be used to regulate servo motors and control the temperature of ovens and heaters. Voltage adjustment, when used with thermostatic control, provides more uniform heating.
What is a Variac power supply?
Affordable. As mentioned earlier, variacs are affordable AC power supplies that are capable of fulfilling voltage needs and operating at the same level of transformers or power sources that go for four times its price. This is why variacs are highly sought-after by casual hobbyists.
What do variacs do?
Variacs provide a voltage-adjustable source of alternating current (AC) electricity. Usually plugged into a wall outlet (120 volts AC at 60 Hertz in the USA), they have a knob-controlled output that can range from 0 volts AC (VAC) to about 140VAC, depending on how the winding is connected (see below).
What are auto transformer used for?
Autotransformers are frequently used in power applications to interconnect systems operating at different voltage classes, for example 132 kV to 66 kV for transmission. Another application in industry is to adapt machinery built (for example) for 480 V supplies to operate on a 600 V supply.
Do I need a variac?
A variac is an excellent tool for safely powering up an old radio or amplifier that has not been used for an extended period of time. Using this low-priced piece of equipment could save you time and money as well as enable you to bring that old piece of equipment back to life with very little effort.
What is a variac machine?
Variac® transformers are Variable AC Power Supplies that provide adjustable AC voltage. Their distortion free output is ideal for sensitive electronic applications, testing devices for agency approval, and numerous other applications where a variable AC voltage is required.
What is the advantage of an auto transformer?
The Autotransformer have many advantages over conventional double wound transformers. They are generally more efficient for the same VA rating, are smaller in size, and as they require less copper in their construction, their cost is less compared to double wound transformers of the same VA rating.
What is difference between transformer and auto transformer?
In an autotransformer, electrical power is transferred from primary to secondary partly by the process of transformation and partly by the direct current. The conventional transformer transfers the electrical power through the electric transformation due to which power loss occurs.
What is a variac?
Basically a variac is a variable transformer. They allow the user to vary the output voltage with some type of control. This is usually a knob attached to a wiper that makes contact with the transformer coil allowing the electricity to be “tapped” at any point along the winding for a specific voltage output.
How do you connect a variac?
1:324:27How to wire a Variac - YouTubeYouTubeStart of suggested clipEnd of suggested clipThat's where you put your line in now to get your line out. You share a common neutral. And you wantMoreThat's where you put your line in now to get your line out. You share a common neutral. And you want it the brush is your hot output. So share neutral and hot so that's all for the output.
Does a variac provide isolation?
0:5921:35Variac Isolation Transformer. Are Variacs Isolated? - YouTubeYouTubeStart of suggested clipEnd of suggested clipIt's clearly stated that it has an output of 0 to 130 volts ac at 60 hertz. And it is isolated. ThisMoreIt's clearly stated that it has an output of 0 to 130 volts ac at 60 hertz. And it is isolated. This is confirmed by variax literature for this model the schematic.
Is a variac a rheostat?
A rheostat is a variable resistor and a variac is an adjustable auto-transformer. Not likely to make one from the other though they both can vary a voltage but using very different principles.
Why autotransformer is used in substation?
Substation autotransformers transfer the incoming high voltage to the next lower voltage level. As an example, incoming high voltage of 400 kV would be transferred down to 220 kV. In general substation autotransformers are equipped with on-load tap-changers (OLTC).
What is the meaning of auto transformer?
Definition of autotransformer : a transformer in which the primary and secondary coils have part or all of their turns in common.
How does an auto transformer starter work?
When the motor picks up the speed (about 80 % of the rated speed), then the handle H is thrown to the RUN position. Consequently, the autotransformer is isolated from the circuit and the motor is now directly connected to the supply line and gets its rated voltage.
Why auto transformer is not used as a distribution transformer?
As the ratio on distribution side is too high from (11000 to 400v) therefore auto transformer is not used on distribution side.
Why use a metered variac during power up?
But a dead radio is something you can diagnose with your eyes and ears. The reason to use a metered variac during power-up is to watch for excessive current draw.
How many volts should a radio variac be?
The idea is to set the variac at a low level—say, 50 volts—and then gradually increase the voltage, carefully watching your set for any signs of trouble.
What is a variable AC transformer?
What is a Variac? As the name suggests, it varies AC voltage. The descriptive term would be "variable AC transformer," but the trade name Variac was used by the General Radio company for many years, and eventually that became the generic name.
Can you power a RCA CT-100 with a variac?
If you own a valuable restored set, such as my RCA CT-100 color television, you may always want to power it up using a variac. Gradually increasing the line voltage gives the set a softer start than suddenly turning it on a full power.
Do radio schematics have voltage readings?
If you restore vintage radios or TVs, you'll notice that schematic diagrams usually contain voltage readings. Often the key voltages are shown in the schematic itself, and some service manuals include a chart showing the correct voltage for every pin of every tube.
What is a variac?
For some reason, I have three of them in my shop, and yes, one is just a book end. But they do have a useful purpose. Variac is a generic trade name for a variable autotransformer.
What is the inside of a variac?
The inside of a variac looks like a giant rheostat. There is a single winding which is partially exposed so that the movable wiper can make an electrical connection. The primary connection of the transformer is made to both ends of this winding.
What is a variac?
Continue Reading. variac means a device which varies some quantities. like voltage , resistance, load etc. in electrical engineering variac is mostly used for resistor. it is a device which can gives you varying quantity of resistance. it can help you to perform tests and experiments. there is also a second name of variac.
What is variable autotransformer?
A variable autotransformer is a single-coil transformer in which two portions of the same coil are used as the primary and the secondary. Variable autotransformers are used for the same purposes as regular transformers, but handle lowe. Continue Reading.
Can a variac damage a load?
All variacs can adjust the output voltage from 0 Vac to match the voltage from the mains and beyond. This means that, if misused, a variac can damage the load. That is why variacs are mostly used in laboratories and shops where trained personnel operates them. 4.2K views. ·.
