Guru
Joined: 21/06/2018
Location: AustraliaPosts: 1206
| Posted: 07:23am 17 Jul 2024 |
Edit : not sure if you edited your post before I posted but either it changed or my reading skills let me down because now it looks correct.
KeepIS if you carefully read my first post on page 13 of your thread, I explained (or tried to) how to soft start the second transformer from the first transformers 240V output when it was already running normal mains.
I used the example of a globe as an initial current limiter to try to help visualise how we get the second transformer fluxed up with idling current just before we apply the opto/primary excitation for the second power board, so in effect a soft start.
Now I have progressed on from that and plan to use some NTCs to flux up the second transformer with a max worst case single cycle peak current of ~ 11A and reducing each cycle after that.
I am well advanced with a complete design for the second stage auto start, which turns on for greater than 5kW and will stay that way until the load drops to less than 5KW.
It uses an AC current sensor, a HEF4538 dual monostable an LM393 and a few other ancillary bits. I expect that it will have teething problems but pretty sure I can beat it into submission.
Edited 2024-07-17 17:25 by wiseguy