SA, mSA & iSA Series
3 to over 800 Amps
Manually Operated & Motorised
Air & Oil Cooled Variable Transformers
Variable Transformers FAQ's
Here you’ll find answers to some of the more frequently asked questions when looking for a Variable Transformers.
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A Variable Transformer (frequently also referred to as a Variac) is a transformer that can produce a step-less, distortion-free adjustable output voltage from just one input voltage. The output voltage is typically adjustable from a few volts to over 100% of the input voltage.
Usually, single and three-phase models are offered as manually operated solutions (with a dial and control knob), but they are also available as motorised systems for larger ratings or OEM use.
While today there are many modern alternatives to the Variable Transformer, the load tolerant nature of the Variable Transformer ensures that it is still the best and most reliable method of voltage control for many applications.
Typical uses include quality control testing, electronic equipment burn-in, low voltage performance evaluation, DC rectifier/regulator analysis or other industrial and engineering applications.
A Variable Transformer consists of a copper winding on a toroidal core of laminated silicon steel. A carbon brush, connected to an output terminal, is rotated over the length of the commutator track to tap off voltage at any turn from zero volts to the maximum output voltage of the winding.
Typically variable transformers are designed to provide an infinitely variable step-less output voltage, being adjustable from 0 to 117% of the transformer’s input voltage. Where higher output voltages are required, models are available with extended windings.
It is recommended that to ensure a Variable Transformer’s performance and long service life, an annual general inspection, cleaning, and operational check is performed.
When a Variable Transformer is operated in accordance with the operating instructions, the only components that may require occasional replacement are the brushes. As the brushes are made of highly endurable carbon, and assuming they are in proper contact with the commutator at all times, the need for replacement is infrequent.