Multiple Electric Car Chargers Demand Calculation

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Andrzej

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Is anybody aware of the demand factor in NEC, which can be used to calculate total demand for multiple electric vehicle chargers?
For example: if one level 3 charger is rated 400 kW and project requires 8 chargers per transformer, can 3200 kW demand be reduced per NEC?
 
Are you sure it is 400 kW? That is a lot of power. 1667 amps at 240 volts single phase.
 
There is none in the NEC and 625.41 requires these to be rated as continuous loads, however much of this hardware (Tesla or CHAdeMO systems) can limit/cap aggregate output (by way of communicating with the cars), and can be protected and wired at the programmed ampacity, which is also stipulated in 625.41.

So in a sense, you or the site engineer pick the capacity of total charging based off need/cost/POCO factors, and then wire it accordingly. If there are more cars than can be charged at “100% speed,” the software slows down charging. This often in practice works well for level 3 charging since maximum charging can only be done in the middle 50% of the battery capacity.
 
Andrzej said:
Is anybody aware of the demand factor in NEC, which can be used to calculate total demand for multiple electric vehicle chargers?
For example: if one level 3 charger is rated 400 kW and project requires 8 chargers per transformer, can 3200 kW demand be reduced per NEC?
Click to expand...

As has been said many times [in this forum] and elsewhere NEC is not a design manual. It's basically an installation instructional tool. That doesn't diminish its purpose however.

Your query is interesting because it runs the gamut of simple wiring to the modern intricate power distribution-- that involves application of high technology.

To focus on your question:

Can 3200 kW demand be reduced per NEC?

You could mathematically-- but you won't find a straight forward answer to that. . . not in NEC.
Electric car chargers are a different breed. I wish they are like electric ovens where kW demand is all you need to design a distribution infrastructure.

There are different types of chargers from different car makers. But most-- fall under level 3 type chargers. These differ from the high performance chargers for expensive high performance car models.

To determine your "exact" needs-- you need to apply DIVERSITY FACTOR since you wish to reduce the demand load calculation.

Load Management System-- along with diversity factors distribute the loads-- eliminating the need for oversized systems or having to upgrade the transformer.
As [most] batteries receive the charge--load demand begin to taper off.

Schneider Electric is a good source for the information you need.

Here is the link:


www.se.com

Country Selector | Schneider Electric Global

Country Selector Page
www.se.com www.se.com

Good luck and keep the distance.
 
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