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travish

New Project Thread

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Hey guys, I am building an automaticly fed resistance welding machine. We are going to make rebar mats that will have 5 longitudinal wires (spelling???) and 3 cross wires. The mats will be roughly 5 feet wide by 10 feet long. It will use 5 - 120kva transformers 480 primary to around 10 to 15volts secondary. Secondary voltage depends on the tap setting. So on the Supply side I am coming into the machine with 3 phase 500 mcm feeder thru a 400 amp breaker. Then need to break out the power to terminal blocks or a buss to tap the primary of the x-formers, and to feed 5VFD's (2hp largest) a 7 1/2 Ton Chiller. Don't have any Terminal blocks that large with that many wire terminals. Thought about using solid copper buss and just drilling holes and attaching like ground lug to the buss to make the connections, I really don't think I like this option. I guess I could use a panel board and use breakers to feed the devices. But I have never seen this done in a control panel. The panel is a 4 door approx 150" wide and 72" tall. Does anyone have any suggestions? Thanks Travis

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I have seen panel designs that have breakers in them, but only smaller homeline style distribution. I have yet to see anything that has the power capacity you are talking of. I was not really a fan of it, and am curious how putting something inside an enclosure gels with NEC or other listing standards. A few thoughts. Some breaker manufacturers have pre-fabbed jumpers to parallel feed breakers, then you only have to land your wires on the first one, no need for a distribution block for the xformers. Instead of an entire enclosed distribution breaker, you can buy just the guts and mount that to your sub panel. It will still serve the purpose without taking up as much room. They make insulated copper buss systems, you could run a horizontal run and tap off of that without leaving a bunch of exposed live surface in the panel. I think they even make tee shaped boots that would cover your connection point. There are distribution blocks that have the ability to break out into the number of points you need at that current rating. Point is you do have options. As far as feeling bad about the buss to lug connection, that is how it is done in switchgear, although I would use a burndy crimp log with two holes for somthing with that kind of current rating. Not a standard screw terminal ground lug.

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I use active links with 630amp in coming breakers all the time. I use Erico links and break away from the main MCCB with several 95sq. mm cables to the links. Then to the motor protection circuit breakers, circuit breakers and RCDs.

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Shiner, I like the idea of the buss bar with the crimp on connectors much better than with the ground lugs. BobB can you post a picture of what you are talking about I looked up the Erico links and saw what looked like hangers for the cable, How are ou terminating the cables? Travis

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Here is a link to the Erico distribution block catalogue. http://www.erico.com/public/library/Panelboard/Europe/LT0733.pdf I use the UD type - cable entry - available up to 500A.

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