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Infrastructure Supercharger V3 / TRANSFORMER
- Thread starter bestechno
- Start date
There is no specific rule for that. It depends on what the utility has available both in power and transformers. 387kW x #cabinets is the preferrable, and maximum that can be used.
For example a 12 stall site, 3 cabinets, will often have a 1000kW transformer. (~333kW/cabinet, or ~83kW/stall) But sometimes they will only get a 750kW transformer, other times they will get a 1500kW transformer, which is oversized and won't be able to be fully utilized, but it could be for planned future expansion.
Say in that 12 stall site, with the 1000kW transformer you, have four perfectly preconditioned vehicles all hook up to cabinet #1. It only has 387kW to split between the 4 stalls, so it asks the other 2 empty cabinets to send over ~290kW/each for cabinet #1 to combine with its own power to route to the four stalls. (So, all 4 stalls on cabinet #1 get almost 250kW, as long as the other 8 stalls are empty.)
RTPEV
Active Member
The grid input to the cabinet is UP TO 387 KVA (*7), but it doesn't need to be that much. Tesla probably has guidelines as to how much grid power they want to supply to the site based on statistics and the availability of on-site storage / solar. For example, for your 28 stall site (with no on-site supplemental power), it may be determined that the average draw across all 28 stalls might be 75kW (considering empty stalls and charge rate tapers), so rather than outfitting the site for the max 2700 KVA, the site might be outfit with only a 2100 KVA grid connection.
The shared DC bus is basically a way for cabinets (and on-site storage/solar) to share excess power and consume needed power. So as you can see from the nameplate, a given cabinet can pull 387kW from the grid + 580kW from the shared bus, for a total of 967kW that can be output to the up to 4 connected pedestals (so just barely under the 250kW that the 4 of them could supply). The 580kW on the DC bus would come from other cabinets on site that are not consuming all of their grid supplied power.
Basically what is happening under the covers is that each cabinet has AC/DC converters (rectifiers) in them that take the incoming AC power from the grid (up to 387 KVA for each cabinet) and convert it to DC at a voltage of 880-970V. If for example the DC bus is at 900V, ignoring losses, each cabinet that is supplied with 387 KVA should be able to pump out up to 430A of current (387K/900) (subject to whether or not there is a load (i.e. vehicles charging) connected to it). On-site storage & solar can also pump out current as well, up to a maximum of 640A altogether. The bus is just that: a giant beefy conductor connected to each cabinet, capable of operating at 1000V and 640A. Cabinets can sink or source power from that bus as needed. When sinking, they draw current from the bus and run it through a DC/DC converter to lower the voltage to the voltage requested by the vehicle (or limit the current to what's requested by the vehicle if it's in constant-current mode).
The shared DC bus is basically a way for cabinets (and on-site storage/solar) to share excess power and consume needed power. So as you can see from the nameplate, a given cabinet can pull 387kW from the grid + 580kW from the shared bus, for a total of 967kW that can be output to the up to 4 connected pedestals (so just barely under the 250kW that the 4 of them could supply). The 580kW on the DC bus would come from other cabinets on site that are not consuming all of their grid supplied power.
Basically what is happening under the covers is that each cabinet has AC/DC converters (rectifiers) in them that take the incoming AC power from the grid (up to 387 KVA for each cabinet) and convert it to DC at a voltage of 880-970V. If for example the DC bus is at 900V, ignoring losses, each cabinet that is supplied with 387 KVA should be able to pump out up to 430A of current (387K/900) (subject to whether or not there is a load (i.e. vehicles charging) connected to it). On-site storage & solar can also pump out current as well, up to a maximum of 640A altogether. The bus is just that: a giant beefy conductor connected to each cabinet, capable of operating at 1000V and 640A. Cabinets can sink or source power from that bus as needed. When sinking, they draw current from the bus and run it through a DC/DC converter to lower the voltage to the voltage requested by the vehicle (or limit the current to what's requested by the vehicle if it's in constant-current mode).
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