AC voltage adjustment

Single-Phase Variacs (Variable Transformers)

To vary an AC voltage from 0 to 100%: toroidal variable autotransformers from 160 VA to 11 kVA, manual with a graduated knob or motorised for remote control.

  • 160 VA → 11 kVA19 ratings
  • 0 → 100%of the input voltage (110% on request)
  • manual or motorisedlocal or remote adjustment
  • €131.90ex VAT, starting price
See the models Advice: +33 4 66 80 14 33
Single-phase variable transformer (variac)
Single-phase variable transformer (variac)
Single-phase variable transformer (variac)
Single-phase variable transformer (variac)
Single-phase variable transformer (variac)
Single-phase variable transformer (variac)
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The products

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Price excluding VAT for the lowest-priced version; the price of each version is shown on the product page.

How to choose: Voltage Controllers

Manual or motorised?

A graduated knob for on-the-spot setting; a geared motor for remote control or stabilisation.

Single-phase variac

No isolation

An autotransformer does not isolate from the mains: add an isolation transformer if needed.

Isolation transformers

What rating?

Choose a rating at least equal to the load: 2,000 VA = 8.69 A at 230 V.

Advice

Need advice before ordering?

Our technicians answer Monday to Friday, 8 am to 6 pm, by phone or e-mail.

+33 4 66 80 14 33Write to us

Good to know

Variac or variable transformer: the same device

A single-phase variac is a variable autotransformer: a brush moves along the winding and taps the voltage you need, from 0 to 100% of the input voltage (110% on request). “Variac” started life as a brand name and is now the usual term for a variable transformer. It is used for laboratory tests, test benches and adjusting resistive loads.

Our toroidal single-phase variac comes in 19 ratings, from 160 VA (0.7 A at 230 V) to 11 kVA (47.85 A), in two versions:

  • manual: adjusted with a knob and graduated scale;
  • motorised: a geared motor, operated by a switch, drives the brush, for remote adjustment or high ratings; on request, an electronic board stabilises the voltage to within 2%, controlled by potentiometer or 0–10 V signal.

Isolation and safety

Like any autotransformer, a variac does not isolate from the mains: its output remains connected to the mains. To work safely on a test bench, combine it with an isolation transformer. For a fixed voltage change (230 V to 120 V, for example), see our autotransformers. Need a three-phase or special model? Ask for a quote and we will reply within 48 hours.

Frequently asked questions

Is a variac the same as a variable transformer?

Yes: both names refer to a variable autotransformer that adjusts an AC voltage from 0 to 100%. Variac was originally a brand name.

Does a variac isolate from the mains?

No: it is an autotransformer, so its output stays connected to the mains. For isolation, add an isolation transformer.

Manual or motorised variac?

The manual version is set with a graduated knob. The motorised version is controlled remotely by a switch and can, on request, be stabilised to within 2% with potentiometer or 0–10 V control.

What rating do I need?

At least the power of the load. At 230 V, a 2,000 VA model delivers 8.69 A and an 11 kVA model 47.85 A.