Variacs or variable auto transformer is a Continuously variable voltage transformer, having a single layer winding on a toroidal core of high grade Steel.
In an variable voltage autotransformer portions of the same winding act as both the primary and secondary winding. the winding has at least three taps where electrical connections are made. One end of the winding is usually connected in common to both the voltage source and the electrical load. The other end of the source and load are connected to taps along the winding. Different taps on the winding correspond to different voltages, measured from the common end.
On one face of the copped winding, along the periphery, a special durable contact surface is made. A specially designed carbon brush slides smoothly on the surface. A contact arm holding the contact brush is fitted to the central shaft and as the control knob is rotated, the carbon brush slides over the winding and taps off a portion of voltage across the winding.
Any desired voltage within the maximum range can be obtained by adjusting the position of the brush. The calibrated dial reads approximately the output voltage at no-load, when the input is at its rated value. Rotation of the brush arm by manual of motor drive delivers an output voltage from zero to or above line voltage.
Variable Voltage auto Transformer, manufactured by Purevolt is the most useful and effective device for step less, break less and continuous control of A.C voltage and therefore, for control of various other parameters, dependent on A.C voltage. It is ideal controlling device for numerous applications in laboratories and in industrial & commercial fields.
The basic Variable Voltage auto Transformer is meant for operation off a nominal voltage of 240 V A.C & can give output voltage anywhere between 0 – 240 V or upto 290 V, by a simple transformer action. Three such Variable Auto transformer when connected electrically in star & mechanically in tandem, became suitable for operations of 415 V 3 Phase A.C. supply & to give output of 0 – 415 V or upto 470 V.
We can also provide you DC & AC Variable Auto Transformers Variacs with option of DC and AC output. We also provide additional features like MCCB, Motorized Operation, Remote Extension etc.
Rating Available: 2 Amp to 1800 Amp
Air / Oil Cooled and Single / Three Phase