AVR for three winding transformer

I thought voltage regulation for transformers was usually accomplished with some kind of tap changer setup, but perhaps that is what you are talking about. I look forward to reading these posts.

I think you are looking for an on load tap changer, but it must be manufactured with transformer, or retrofitted.. To control both secondary windings independently on a three winding transformer will be a strange animal, and probably would need to be custom built by transformer vendor..

If you do not mind me asking what is the application that requires this arrangement??

You can install Servo-controlled Voltage Regulator which regulates voltage in either of the following ways :

1. U-V Phase Regulation within + 1% and V-W Phase Regulation within + 1% of the Phase to Phase Nominal Voltage

2. Independent Phase to Neutral Regulation within + 1% for all the three phases U,V,W w.r.t. Neutral

I have repaired a few times an automatic voltage regulator.

Input voltage 3 phase 50Hz 400V +/- 20%

Output voltage 3 phase 50Hz 400V +/- 1%

Output power 20 kVA

The system was build around a variable toroidual 3 phase transformer with servo control. A 3 phase main transformer and 3 one phase transformers mounted in de primairy circuit of the main transformer and feeding the toroidual transformer.

A small reference voltage was also available. When the input voltage was to low, the toroidual transformer adjusted the primairy voltage of the main transformer.

It was used to supply a CNC machine.

If you need more info, send me a mail.

As per my experience OLTC will be on HV windings only. By changing the Tap on primary, voltage on both secondaries will be regulated automatically. You can use any AVR relay. such as MR etc.

Regards

AHR