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Bronson ++ Isolation transformers-Any good?
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electr_peter:
I think you could reuse it with relatively low cost improvements and testing. My recommendations:
* make proper schematic of transformer and make sure it is correct. If you change something, update schematic. Default mode should be PE carried through and L/N floating w.r.t. PE
* check grounding connections, make sure they are all up to standand, remove paint where necessary
* Check all cables and fuses for size, test wire and connection resistance (cables maybe not be from real copper, but from CCA!). Consider ceramic fuses
* add input socket with double fuses (as in medical transformers teardown-and-modification-of-noratel-imed-e-150-isolation-transformer)
* add double pole AC switch which lights up if energized
* test isolation between primary/secondary/ground (POT testing or similar)
* test leakage currents/stray capacitance (data sheet on medical transformer leakage test, noted in page 15 https://www.noratel.com/fileadmin/content/downloads/medico/en/IMED2014_en.pdf)
* check thermal performance. Add more fans/holes in the case if necessary
* investigate soft start circuit (inrush current limiting)If above checks out, then you will have a very usable item.
djsb:
Thanks. Please excuse my ignorance, but in your first bullet point what does PE mean? And also in your third point what is CCA?
Thanks for the link in point 4 and I'll look into what you suggest.






PS. Just bought myself a UNI-T UT210D Digital clamp meter as I'm going to need it. Require one anyway for non-intrusive current measuring.
electr_peter:
PE - protective earth (or ground) in mains socket.
CCA - copper clad aluminum i.e. aluminum strands coated in copper. It may look like copper, but it is a bad choice as cable conductor for many reasons.
Also, run with a strong magnet over the wires. Wires should not be magnetic, but who nows what you will find at this quality level.
Double fuse idea is for potential line/neutral reversal or unusual situations, just in case.
Alti:

--- Quote from: djsb on November 24, 2021, 07:38:36 am ---There is mains potential between the Chassis and the LIVE OR NEUTRAL(..)
PS There was a thin piece of wire bridging the terminals on the ON/OFF switch. I removed this piece of wire and now the ON/OFF switch works. There appears to be very little quality control on these units.
--- End quote ---
Do you think the transformer itself is made to a higher standard? I wonder what you are going to find under this plastic foil wrap. Maybe you could reuse some of its components to build a decent unit but I'd be cautious about its "isolation" properties at this stage. It must either include double isolation between pri-sec (class II) or must be pri-sec separated by PE (class I). So I wonder which path they took. Most likely it is class II and does not include any PE or shielding.
threephase:
I note that the OP is from the UK. Independent fusing of the neutral is prohibited in the UK and can lead to dangerous scenarios, especially for class 1 appliances.

You either have a single fuse in the live only or you can have a double pole trip unit that walloped both the live and neutral simultaneously.

I am almost tempted to buy one myself to do a full inspection on and see if it has similar issues, or the OP is unlucky.
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