# 3-phase rectification using individual step down transformers for each phase

I'm looking make a simple low-voltage DC power supply from a 3-phase supply.

Looking into 3-phase rectifiers I came across the below articles https://www.gprectifier.com/news/rectifier-11261763.html and https://www.electronics-tutorials.ws/power/three-phase-rectification.html

So I decided to make an uncontrolled rectifier and got myself a 3-phase rectifier locally. (this one to be specific https://www.rectron.com/public/product_datasheets/skbpc3504-skbpc3516.pdf)

With that connected to 3 phases I got a no-load Vout of roughly 570Vdc on the multimeter. Since I didn't have any load rated for such high voltages I assumed it was working since that's what the article shows.

I then decided to get 3x 220v to 24v 1A transformers (1 for each phase) and hook it up to the bridge.

Doing this got me no-load Vdc of around 90V. I decided to sacrifice a 24V LED strip being aware that the load voltage could not be so much going by the formula in the referred article.

To my surprise the LEDs barely lit up. Hooking it to the multimeter I got a voltage of ~14V.

I don't quite understand what is exactly happening here so any help would be much appreciated.

• Show how you wired the three transformers and state what the input supply voltage was. – Andy aka Jul 30 at 11:19
• A schematic is better than words. You can add one in using the CircuitLab button on the editor toolbar. Double-click a component to edit its properties. 'R' = rotate, 'H' = horizontal flip. 'V' = vertical flip. Note that when you use the CircuitLab button on the editor toolbar an editable schematic is saved in your post. That makes it easy for us to copy and edit in our answers. You don't need a CircuitLab account, no screengrabs, no image uploads, no background grid. – Transistor Jul 30 at 11:28
• Hello Sai. A diode bridge outputs (pulsating) DC. A transformer requires AC input. Attempting to power a transformer from (pulsating) DC will destroy it. 3-phase 408v is very dangerous, have you considered an existing product? There are 3-phase supplies specifically geared towards LED lighting with dimming control, waterproof, etc. – rdtsc Jul 30 at 14:06
• It's unclear what exactly you are trying to do, but the overall project sounds quite unwise. This is really not something that should be attempted without a much more thorough background. – Chris Stratton Jul 30 at 19:04
• Transformer coils having a single connection accomplish nothing - they are bad antennas, not paths for useful current. – Chris Stratton Aug 1 at 10:52