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Cottonwood
Roadster#433, Model S#S37
I agree. The biggest benefit to the higher power will be for the two cars at once charging from one Supercharger cabinet. When I come up to a Supercharger, I am always careful to get a stall that is not being shared. Many do not notice the numbering, places like Hawthorne are not labeled, and as Superchargers are used more, there will not be a choice; these issues will all cause more sharing.
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Interesting! I will have to go down there and take a look. Besides, it's the only Colorado Supercharger that I have not tried!
I thought that was a 208V, delta connection. If that is true, with inefficiencies, they would need 400A service or better to get 135 kW out!
No such thing as a 208V delta.
However, even if it were a 240V delta arrangement, it would be pretty hefty - 400A 3ph service required for a single cabinet.You get 208V because in situations where you need a lot of 120V (L-N), you use a wye arrangement for 3 conductors of 120V, and you end up with 208V for L-L.
Delta configurations are usually used where you need a lot of 240V... to get 120V from it, one winding is center tapped and grounded. This gives you 120V from N-L on both sides. The "stinger" or "high-delta" leg (phase B) does become 208V, but you can't really use this for heavy loads because of the arrangement.
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Cottonwood
Roadster#433, Model S#S37
No such thing as a 208V delta.
You get 208V because in situations where you need a lot of 120V (L-N), you can deliver it from a 208V L-L wye arrangement.
Delta configurations are usually used where you need a lot of 240V... to get 120V from it, one winding is center tapped and grounded. This gives you 120V from N-L on both sides. The "stinger" or "high-delta" leg (phase C) does become 208V, but you can't really use this for heavy loads because of the arrangement.
Sorry for my confusion on terms. Thank you for your correction. Yes, I meant that I believe it is a 208V L-L wye connection in Lone Tree.
If I understand the way the existing "120kW" Superchargers work, they can get 120kW if they are connected with 277V L-N connections; note the Supercharger label requires the neutral with 480V service, but not with 208V service. These installs are used with 160A, electronic circuit breakers that are rated for 100% continuous load. 12 modular chargers with 4 on each phase use 160A per phase nicely. 160A * 277V * 3 = 133 kW. With 90% efficiency, that provides 120 kW out. In a 208V connection, each set of 4 modular chargers gets one of the 208V, L-L connections. This gives 208V * 160A * 3 = 100 kW draw. At 90% efficiency, that is 90kW out. BTW, the 208V connection needs to draw 160A*sqrt(3) or 277A continuous because of the L-L connections and 3-phase combining. See the label below that shows the need for 280A at 200-240V service and 160A at 480V service.
I think I got all that correct. Please check my math.
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Silverthorne, Glenwood Springs, and Grand Junction all have 480V, 3-phase transformers and provide 120kW per Supercharger cabinet. I believe that Lone Tree got the 208V, 3-phase connection because it is uses existing 208V service at the shopping center.
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Your math is correct.
I hadn't even considered that they would connect Superchargers to a 208 L-L wye configuration because of the current requirements (as you note you can't hit 120 kW with their specs @ 208V), but yeah, that would work too. However, the cables get too big and it just doesn't make sense to connect things in that way.
I suspect that the Supercharger is still capable of being connected to a 208 wye , but that would be 375A draw without any continuous load overhead considered. That would likely have to be delivered over 750 kcmil wire, which is 1" in diameter, qty 3, plus ground, for each cabinet. That's not going to be cheap if it has to be run any major distances.
I'm guessing they got an upgrade when they put in the new 135 kW units, along with a nearby transformer.
Cottonwood
Roadster#433, Model S#S37
Your math is correct.
I hadn't even considered that they would connect Superchargers to a 208 L-L wye configuration because of the current requirements (as you note you can't hit 120 kW with their specs @ 208V), but yeah, that would work too. However, the cables get too big and it just doesn't make sense to connect things in that way.
I suspect that the Supercharger is still capable of being connected to a 208 wye , but that would be 375A draw without any continuous load overhead considered. That would likely have to be delivered over 750 kcmil wire, which is 1" in diameter, qty 3, plus ground, for each cabinet. That's not going to be cheap if it has to be run any major distances.
I'm guessing they got an upgrade when they put in the new 135 kW units, along with a nearby transformer.
Yup, it's a lot of copper even with 480V connections; at 208V, it gets a little ridicules. I do think that the original 6 sites that were 90 kW were connected with 208V.
See page E-2, page 17 of the PDF from Madison, WI Supercharger Application. They are using 3/0 copper for the 160A connections from the Distribution Center to each Supercharger cabinet, and 4 parallel, 500 mcm coppers per phase for the connection from the 480V transformer to the Distribution Panel for a site that can have up to 4 Supercharger cabinets. It was from this document that I discovered the fancy electronic, Square-D breakers that can operate at 100% duty cycle and can be tripped and reset remotely.
The panels are rated for up to 2,000A per phase. Pretty heavy duty stuff! See my picture from Blanding below of the buss bars in those distribution centers.
Here is a picture from Farmington distribution center connection to the transformer where they connected 3 parallel, 500 mcm wires per phase for a 2 cabinet install with room to grow. Note the provisions for up to 6 parallel, 500 mcm cables per phase.
Read this thread and you will understand: Older Teslas limited to 90kW Supercharging
I was part of a group of A pack owners requesting a pack swap upgrade at a fair price....still waiting for details.
Cottonwood
Roadster#433, Model S#S37
It takes a lot of copper to carry 2,000 Amps! OTOH, 2,000 Amps at 480 Volts will support up to 12-120 kW or 11-135 kW Supercharger Cabinets at full power or a total of up to 24 Charging Stalls. I am very glad that Tesla is planning ahead for Supercharger capacity as they continue to sell more and more cars!
These are not your father's circuit breakers. Take a look at Square-D Mission Critical Circuit Breakers. Complete with remote computer control of the breakers, etc.
hans
P631
digitaltim
Sig737 VIN628
I heard they were delayed trying to decide if an attendant needed to plug the cable in for you... ;-)
Cottonwood
Roadster#433, Model S#S37
I'll take that bet on the side of "not in a decade" for Blanding, Utah where I took the picture. :wink:
HankLloydRight
No Roads
Cotton, Flasher and other gurus:
Well then, why should we be constrained to those 480V? Why not 1,000V? Or some juicy higher number?
That's a serious question: are there reasons other than "well, 480V is the normal max voltage hanging around in mere-mortal situations (ie, downstream of most substations)" not to consider higher voltages? In other words, if we're going to think outside the box....let's stay outside...the weather's fine!
At least three possible reasons.
1. At higher voltages the need for greater insulation makes the cables just as hard to manage, even if there's less metal.
2. The potential (pun intended) of arcing through the air is increased as the voltage goes up.
3. As the input voltage gets significantly higher above the battery's nominal voltage, it gets more difficult to shape it to provide the desired voltage and current to charge safely.
Well, at higher voltages, the space separation on circuit boards, terminals, and bus bars required to protect against arcing becomes greater, and the materials that must be used as insulators get far more expensive. Working on higher voltage equipment (>600V by NEC standards) requires special protective equipment (special gloves, boots, insulating mats, arc-flash prevention gear, etc.), additional crew members (because CONSTANT supervision is required in case of fault), and special training. Gear must be inspected and tested more often to ensure it doesn't allow arc-through.
At some point you have to step down anyway, as the battery pack needs 400V. Let's say you were to skip the intermediate transformer and just supply the distribution network's 7.2 kV or 14.4 kV to the cabinet... within the cabinet, the chargers would then have to do the voltage division or step-down, or would need a small transformer. Rather than sourcing special-purpose gear to do so, it's easier from a cost perspective to use common off-the-shelf capabilities, and one larger distribution transformer is more economical than several individual ~150 kVA transformers, one for each cabinet.
Right now, the answer seems to be that Tesla's use of the same chargers that are in the car has an economy of scale, they work quite nicely with the 277V L-N voltage provided on industrial 480VAC equipment. Finally, note that each cabinet doesn't have this huge need, they only need 135 kW each, and so as a result the best balance of all components seems to be standardized distribution transformers, standardized chargers, and a heavy-duty local distribution box.
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