Superior Electric Powerstat variable transformer 1296DU

jmurray32168 In almost 40 years of working with electrical devices, I have not personally seen anything like what you are looking for.  It could be made, but I haven't seen a commercial product.  Good luck in your search. 

no. I mean one that can digitally maintain a given input commanded voltage. If for any reason the input supply drift we have to manually adjust the wheel. I want to take us to the next level. I thought i had seen a mechanical device that can be added to these can automatically adjust the wheel based on any input drift/variation

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

There appear to be versions of the 1296DU that already have motors attached for digital  control.

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