I want to know if there's a way to operate a normal (250 VAC primary rating) transformer at higher primary voltage levels, as I have an AC voltmeter project using a microcontroller (currently using Arduino Uno), with over voltage detection.
The controller will perform a specific task for undervoltage case, a specific task for normal voltage case, and a specific task for high voltage case (>250 VAC rms).
I have accomplished the voltage detection using a simple circuit shown below, in which, the output DC voltage has a certain mathematical relation with the input AC voltage.
But my only concern is whether the 250 VAC (rms) primary rated transformer will survive high voltages (upto 400 VAC rms). If not, what are the ways that can help increase the primary voltage rating. For example, combining 2 transformers, or anything?