Variable Auto Transformer (Variacs/Dimmerstat)

PACT Variacs or variable auto-transformer is a continuously variable voltage transformer, having a single layer winding on a toroidal core of high grade Cold Rolled Grain Oriented Steel.

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.

APPLICATIONS:

Supply voltage adjustment, boosting of low lines and line voltage stabilization, either manually or automatically in automatic voltage stabilizers. Voltage and current control in development and experimental work.

• Over and under voltage testing of electrical and electronic equipment.
• Heat control of ovens, furnaces, infra-red heaters etc…
• Testing and calibration of voltmeters, ammeters, watt meters etc…
• Built in as an integral control element in electrical, electronic and automatic control and process equipment.
• Lighting control in theatres, auditoriums, hotels.
• Restaurants, photographic studios and darkrooms etc...
• Motor speed control either direct or through suitable circuits.
• Control of DC voltage and current through rectifiers.
• Control of rectifiers in electroplating etc…

Various Models available are:

• Single Phase Open Type Model
• Single Phase Motorized Model
• Single Phase Portable Model
• Three Phase Open Type Model
• Three Phase Enclosed Model
• Three Phase Oil Cooled Model

Features:

Rugged construction:
Our variacs are designed for heavy duty trouble free operations. All components are designed to give maximum life to the unit under extreme operating conditions.

Excellent regulation:
The drop in voltage from ‘no load’ to ‘full load’ is minimal in our variacs.

High efficacy:
Careful copper core selection and design assures the user of low watt loss as compared to other types of controllers.

No wave form distortion:
Our variacs provide an output voltage wave from which is a faithful and distortion less replica of the input voltage wave form.

Overload capacity:
Because of its careful designing, our variacs can withstand many overloads.

Low operating torque:
A glass smooth commutator, special sintered bushings for the shaft and perfect assembling of the coils, result in low operating torque for our auto-transformers.

Smooth and linear output:
As voltage between turns is small and as the bush arm is in constant contact with more than one turn, harmful sparkling is avoided and output can be set very easily to a fraction of a volt from zero onwards by rotation of the knob.

Low magnetic current:
By using an adequate section of the high quality grain oriented silicon steel, the iron losses are controlled to the minimum. The no load current is invariably less than 1% of the rated current.

Negligible maintenance and trouble free long life:
PACT variacs have been designed to guarantee performance. Therefore no special care needs to be taken in normal working conditions. Timely replacement of carbon tips and cleaning of the commutator surface of foreign particles and accumulated dust will ensure a considerably long, maintenance free and interrupted life to the unit.