Variable Transformers, Their Working Principle and Different Parts

Variable transformers are characterized by giving out varying amounts of voltage from the same input voltage. These transformers are available in trademark versions and simple versions as variable transformers that can be customized. They are widely used in industrial and home applications and are among the most commonly used components in these sectors. Variable transformers are also known as autotransformers and consist of the single-coil design like in a 415V 3 phase variable transformer. 

The increase and decrease of voltage are sometimes adjusted by a dial-in of these transformers. Such as dimming lights or increasing their brightness and other similar applications where precise control is required over the amount of voltage that a load receives.

You might get confused between the variable and standard transformers. Even though they operate on the same principles, they are different from each other. in standard transformers; dual coils create a separation between the voltage line and the load. There is no such physical separation in variable transformers because they have a single core. Variacs like 415V 3 phase 50 Hz are designed for low-voltage applications, while the standard transformers can be used for high voltage applications. 

Physical Principle

Variacs are autotransformers, and they work in the same way as other flexible devices due to their design, like a 415V 3 phase transformer. Variable transformers have a single coil but many taps situated along with the coil. The load of the variac is attached to the load and source of the voltage. The load is then connected to the taps located on the secondary side of the transformer, which helps in varying the voltage received by the load. 

You can determine how much voltage the load can receive from the number of windings in the transformer. There are many different taps situated around the coils, and this helps to utilize the different windings and quickly bring variations in the voltage. 

We previously mentioned the main difference between single and dual-coil transformers. There is a physical separation between the load and the voltage source in the dual coil transformer. Whereas in the single-coil or autotransformers, there is no such separation. 

In an autotransformer, the device can fail when the entire voltage is put into the transformer to be given out to the load. This failure is hazardous for any equipment. 

Functioning of Variable Transformer

When you spin the dial knob, the surface area that is touching the coil changes; the more the brush touches the coil, the more it will give out the voltage to the load. The function that makes variable transformers like 415V 3 phase 4 wire transformers stand out from the rest is that they can alter the voltage so much that it can go from zero to a voltage higher than the input voltage itself. These various perform this function very smoothly and efficiently.

Unlike other autotransformers that provide specific voltage over fixed taps, variable transformers can carry amounts of voltage as needed for the application. A variable transformer is manufactured to work with different voltages ranging from very low to high. They are also helpful for testing purposes in the industrial sector. 

Variac Brushes

Variac brushes are components of variable transformers that are in contact with the windings. The contact between the brushes and the coil can be reduced or increased by turning the knob. The variac can’t function without the brush, and the design is most suited for low-voltage Variacs.

The brushes with the variable transformers are detachable and can be examined. The basic design of the variable transformer is considered to be very basic and easy, with the brush, coil, and container housing all the components within being the main components in a 415V 3 phase breaker

Variable Connectors

The connectors of variable transformers help them connect to other equipment. The connectors are primarily designed for testing, but there are multiple designs. These connectors are available separately from the various because they have a long lifespan. Variable connectors are also known by the name of variac autotransformer connectors. 

Connectors also come as input connectors that match the standard connectors used to get line voltage into any electrical appliance. In comparison, some connectors are designed to be directly wired in the circuit. 

Variable Dial Knobs

The knob looks like a rotating button that gives the operator access to control the voltage. They are made of insulating material so that the operator is not affected by the voltage going through the transformer.  They come in different designs, from small to large. The small ones are used in situations where the variac needs to be a part of some minor or fixed system. The large ones are used more for minor adjustments. 

You can purchase high-quality variable transformers either online or from a nearby store. However, it is better to purchase online because of the variety and information searching.

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