Superior Electric Powerstat variable transformer 1296DU

The most common use of the term "autotransformer" is for a transformer where the primary and secondary are both just taps on the same winding.

The 1296DU is a variable transformer (often a Variac in the UK).

From your question I suspect that you want to adjust it automatically. This is possible but has problems and is much less common now than it might have been 50 years ago.

Mostly people use electronics to achieve the same result - you can buy adjustable AC regulators capable of handling power from a few watts to mega-watts.

The problems with a motorised variable transformer are its slow response and short life (due to wear on the brushes)

Can you explain what you want it for - it may be that there is a better solution.

They are obtainable ready made but you could fairly easily modify a manually operated variable transformer for a one-off.

https://www.ravistat.com/variable-auto-transformer-motorized-variac.php

MK

The most common use of the term "autotransformer" is for a transformer where the primary and secondary are both just taps on the same winding.

The 1296DU is a variable transformer (often a Variac in the UK).

From your question I suspect that you want to adjust it automatically. This is possible but has problems and is much less common now than it might have been 50 years ago.

Mostly people use electronics to achieve the same result - you can buy adjustable AC regulators capable of handling power from a few watts to mega-watts.

The problems with a motorised variable transformer are its slow response and short life (due to wear on the brushes)

Can you explain what you want it for - it may be that there is a better solution.

They are obtainable ready made but you could fairly easily modify a manually operated variable transformer for a one-off.

https://www.ravistat.com/variable-auto-transformer-motorized-variac.php

MK

Thank you very much. This is very helpful

we use them for product development and certification testing in a laboratory environment and have voltage regulation requirements. We make commercial refrigerated display cases and heated display cases. We also have an accredited lab.

must maintain individual measurements +- 4% of rated voltage for DUT average over the test period and +- 2% of the rated voltage

What you need is a powerline conditioner.  They are designed to do what you state and come in all sorts of sizes.