I bought a 10A 43kilo’s isolation transformer. I had a small one that I fried. Circuits Online member Ginny found this beast at Baco. She brought it per boat to a city nearby me and I collected it there.
43 kilos wood, steel and copper.
I made an operation panel for it. The big red switch is there to decouple the transformer from the mains (switch it off) The transformers in and outputs are connected to the back of the panel-cabinet.
The panel and 3 isolated outlets above it
For safety I can switch a series lightbulb between transformer output and DUT. Besides that I can switch a fast electronic adjustable fuse in series with the output. (1 to 7A).
The big orange lamp lets me know the transformer is on and a bright blue led shows me if the DUT is powered. The white “lamp” holder on the front is empty so I can see the series lamp if it lights up.
All worked well but there was 1 problem. The inrush current of the transformer sometimes tripped the mains fuse so I added an inrush limiter. See: https://www.circuitsonline.net/schakelingen/93/voedingen/inschakelvertraging.html
My relays needed more current so I increased the capacitor to 660 nF.
The guts of the panel
The transformer