60A 3ø circuit for the vacuum table (which is consistent with two 10hp motors of conventional efficiency) and a 40A 240V
That would be 60A3+40A2=260 amps of capacity needed.
These are 120VAC legs. A 100A 3ph panel has up to 300A of phase current.
10A 3ø is 10A per leg, 3 legs, 30 amps.
40A 240V “single phase” is 40A capacity on two legs= 80A total
But that’s a wattage load, not amps, and we’re not 240VAC, we’re 208VAC, so 92.3A.
I get a potential 272.3A net total. And that’s just for the Swift, not the other one.
Say we have an entire empty 100A 3ph panel. 60A on W,X, and Y phases. The 40A 240VAC is actually 46A, not 40A, and it’s x2. At this point you’re technically over capacity for the 100A panel to put this on W and X. But you’d have to, nobody’s going to do yet another 100A panel for that. So that pretty much does it for W and X, and Y has 40A left.
There is a difference between nameplate capacity and actual use. Now, the Sawstop is technically rated at 7.5HP=46.6amps total (3 phases, 15.5A per phase). At startup, it briefly draws “a lot”, but just sitting there whirring with no load it’s probably drawing like 2 amps per phase. The 46.6A would only happen if loaded it fully- which would be insane. Like a wide dado through oak and pushing way too fast and actually pushed the motor to its limit.
This depends on the load type. A bandsaw and table saw could go on the same panel even if their max power draw is way over the capacity, because there’s basically zero chance someone will actually load either to the max ever, much less both at the same time. You can be ok loading up a panel with nameplate capacities of certain tools that run well past the panel’s capacity. On the other hand, if you have a shop vac that says it draws 12A, it’s gonna draw 12A at all times it’s on. Add a 3 amps of lights and popping a 15A breaker is guaranteed.
The regen blowers (vac pumps), while rated at 60A *3, I can’t tell what it will actually draw when running normally and what its starting profile does, but I would not be too surprised if they draw most of that 60A * 3 all the time. A 3hp spindle can actually load to 3hp, but you’d have to be an artist to load it just enough but not too much to not cause the VFD to shut down.
The 80V supply for the motors, on the other hand, is moving a gantry vastly heavier than the current CNC. I don’t know what but it will definitely draw high currents when accelerating, which is a lot of the time.
I only have a poor photo of their cabinet interior but it looks like those could be line freq transformers- this may have a power factor well off from unity, in which case we need the panel capacity to account for the real AND imaginary power components- it will draw more amps than the wattage alone comes out to.
The building’s got 3x 200A 3ph = 1800A potentially, if you somehow gamed everything in perfect balance. But our existing panels are sort of near capacity, and I don’t think anyone’s surveyed what phases are being loaded with what actual currents. I do know we really don’t want to blow a mains hard fuse on a phase, as that unbalances all non-VFD motors and can result in significant equipment damage. It also partially energizes the dead leg and that can damage even normal 120VAC appliances. That’s only if one of the mains hard fuses pops though- the mains are also protected by ganged breakers, which, if we’re going to overload something, that should pop and take down all 3 phases together which is far safer.
I don’t have all that data either, but at a glance we’ve been pretty cavalier about total loading, that much is clear. I truly don’t know how close we are to overloading a panel or a service entrance, and to my knowledge no one’s collected that data yet. The T-Flux added a lot of load and it’s concentrated on 2 phases. The vac bed CNC is definitely a massive addition, and also another high current CNC load, plus the fiber laser, that is “significant cause for concern” here.
