A variable auto transformer provides continuously adjustable AC voltage. In it’s Auto transformer form it is an efficient, reliable method of controlling AC voltage from zero to line voltage by amplitude modulation of the AC waveform. Since the current, power, heat, light and motor speed are further functions of the voltage, the Dimmer Dot Variable Transformer finds its varied use, but is not designed to provide AC mains isolation.
Air cooled – single and three phase:
Air cooled units are a cost effective, trouble free device to provide continuously adjustable voltage for AC supply equipment. Air cooled units are light weight and easily transported. When used correctly they give many years of reliable service.
The Variable Transformer, consists of a single-layer winding on a toroidial silicon-steel core. As the control knob is rotated, a carbon brush traverses the winding, tapping off a portion of the total voltage across the winding. The brush is in continuous contact with the winding, and the voltage between turns is always less than 1 volt even in the largest model. In the smallest model it is only about 0.3 volt. The discrete voltage increments obtained as the knob is rotated are always less than the voltage between turns. Since the brush spans more than one turn, the change in voltage is practically continuous. The brush is so designed that excessive heating cannot occur in the turns that it spans. Dimmer Dot has many operating advantages over any other manually operated voltage control devices for alternating current use
Air cooled versions are available in either:
Portable / Bench top (P) which are designed to sit on a bench or floor.
They are enclosed in a protective square casing with convenient carry handles for easy transport. New square shape design enables easy mounting of external equipment, such as mounting blocks for GPO’s, etc. Single Phase units have Rubber feet while Three Phase units have ball transfer units or steel feet. Single Phase units can be rear mounted in an electrical enclosure, simply by removing the rubber feet. Single Phase units up to 15 Amp have an AC flexible cord only, fitted. Open back / Panel mount (OB) which are designed to be mounted behind a panel for easy installation into electrical enclosures, where only the support bolts and control knob are protruding. Single Phase units can be rear mounted in an electrical enclosure, simply by removing the rubber feet. Single Phase units up to 15 Amp have an AC flexible cord only, fitted.
Open back / Panel mount (OB) which are designed to be mounted behind a panel for easy installation into electrical enclosures, where only the support bolts and control knob are protruding.
Good Regulation Output voltage is substantially independent of load.
Smooth Control The Dimmer Dot can be set very closely to any output voltage within its range.
High Efficiency Very low losses under all load conditions. Greater than 96% efficient.
Long Life With the exclusive Dura Dot contact surfaces, the life of the Variable Auto Transformer is essentially the same as that of any standard fixed-ratio power transformer.
Linear Output Voltage Output voltage is continuously adjustable from 0-112% of line Voltage by approximately 340 degreee dial movement. The dial reads directly in no-load output voltage at rated line voltage or some dials are calibrated for percentage of the full range control.
Mechanical Design Rugged construction and robust parts. Two or more units can be ganged on same shaft. Shaft is also reversible for simple conversion from front to back of panel mounting.
Temperature High ambient temperature tolerance. Current rating up to 45c
Sine Wave Purity Virtually no radio interference, wave shape distortion or harmonics created, unlike SCR-Thyristor and Triac AC power controls.
Lower Input Current Input power consumption is proportional to output unlike electronic Thyristor controllers which still maintain high input RMS currents.
Special Voltage Range Available in standard Single phase 240V and Three Phase 415V 50Hz. Other special input voltages can be supplied.
Two phase models are also available.
Technical Assistance Our engineers are well qualified to advise and assist you with the selection and applications on the Variable Transformers.
Warranty 12 months from date of purchase.
Tortech | Transformers and Electrical Equipment
Established in 1987, Tortech a privately owned Australian business focuses on the design and manufacture of a wide range of transformers.
We manufacturer transformers, inverters, power supplies, single ...