3 Phase 28A Green Dot Variac

A variac is a variable auto-transformer. They are used extensively to regulate the voltage for tool testing, laboratories and universities. Variac’s usually have a toroidal auto transformer winding and a moving arm that gives the required voltage at different points along the surface of the toroid. The moving arm can either be manual or motorised. Variac’s are usually air-cooled or oil cooled. Oil cooled variac’s can operate close to their maximum current rating for prolonged periods of time without over-heating.

Usage

• Units are designed to be used to a maximum current, not VA rating, so maximum current rating must not be exceeded at any point of operation.
• The adjustment dial should be varied (increased or decreased) gradually, not fast or in jerky movements, rapid or rough dial movement may damage or break the carbon brush, necessitating replacement.
• This will ensure long life of the variac, and reduce wear on the carbon control brush.
• The unit is designed for regular movement of the adjustment dial, if being used continuously in one output position (no dial movement) the output current rating must be reduced or de rated approx. 10% as outlined in the specifications.
• The output dial includes a scale of voltage that provides general indication of voltage, it is not precise, for precise measurement, use an appropriate multimeter to measure the output voltage. Alternatively, some models are provided with output voltage and/or current meters for more accurate readings.
• Loads such as LED lights, switch mode power supplies may have a lot of harmonics in them therefore it is recommended to use a Variac that is double the load rating. (E.g. A 9 AMP load requires a 18 AMP Variac)