Alternate voltage variators variable-ratio autotransformers

Alternate voltage variators are basically autotransformers wound on a toroidal magnetic core, with a constantly variable ratio that allows an extremely fine variation and regulation of the output voltage. They are an advantageous and economical replacement for rheostats, transformers and autotransformers with multiple outlets. Thanks to their characteristics and flexibility of use, voltage variators may be used within a range of alternate frequencies between 50 and 400 Hz, therefore increasing their actual power. (E.g.: MI 150 VA: 50 Hz. 150 VA - 400 Hz. 500 VA)


  • Output voltage variation from zero to the rated voltage value under load, with no circuit interruption;
  • Output voltage variation from zero to voltages higher than the supply voltage (step-up winding types);
  • Virtually zero leakage flux;
  • Maximum operation security thanks to the high quality of the used materials and to the thorough checks carried out on each component; they are tested under extended overload and under dielectric insulation tests at 2500 VA.
Ci-Effe-Gi variators have a compact footprint as they are built using high-quality, tape-wound grain-oriented toroidal cores. The insulated copper wire winding is placed as a single layer on the core and perfectly fixed by means of the exclusive "LITOBLOK" system, which allows complete aeration of the most part of the winding and thereby reduces its heating while in service. Thanks to the winding's low resistance, the output voltage variations from unloaded to full load are reduced to a minimum.


They are available as back-of-board (unprotected or protected) or bench models. Unprotected models with power up to 1500 VA are connected using fastons, while higher power models are connected with steel poles.
Bench models are power-supplied by means of cable and relevant plug, while the output is connected with insulated fiberglass finger-protecting bushings ( as per EEC regulations).


The power of voltage variators decreases the higher is the difference between the supply voltage and the maximum output voltage.
To make sure the correct current (Au) is used, it is advisable to perform the following calculation:
Example: 3300 VA - Vin, 220V - Vout. 0 - : 260V