I am working on a project to safely combine separate power circuits into one. Its to do with using available power instead of renting mobile generators. The problem is that the 'magic box' has various safety devises that are being hampered by backfeed- as when one supply is cut the eg. contactors remain fed through bacfeed from the other circuits. If it was DC we would , i think be talking diodes, but its ac 230v. I have looked at SSR relays but it seems although no back-feed current will flow there is still a potential voltage present and this is enough to keep the relays/contactors open. I have also looked at using RCD devices to detect some kind of in-balance but the back-feed seems to be balanced through it's own neutral. I have used DP double pole MCB's to provide overcurrent protection but also to offer a higher degree of isolation. I did try running two lives through the DP MCB's and using one feed for the coil. This worked, in that the O.C. devices in the magic box would activate the contactors. But I still have the problem that one of the supplies can be cut outside the magic box with no activation of a contactor.
My Objective is that if one supply is cut off - all supplies will separate.
:Please edit your question to explain your requirements. (1) Are multiple supplies on and connected at the same time? (2) Do you want just one supply on at any time? (3) What is your intended sequence of operation? (4) Is it to be fully automatic?
- YES multiple supplies are on and connected at the same time.
- NO I do not want just one supply on at any time.
- Sequence of operation: 1. Plug in 3 x trailing leads from magic box to 3 x 13amp supply 1ph. Flip trip switches in the magic box to energise 1x 32amp 1ph supply trailing lead from magic box.
- Yes once energised the safety should be fully automatic.