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lincomatic / open_evse

Firmware for Open EVSE
GNU General Public License v3.0
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Three-phase energy calculation option #84

Closed glynhudson closed 6 years ago

glynhudson commented 6 years ago

My notes on three-phase calculation: 

- P(3ph) = V(LN) * I * 3
- V(VL) = 230V (line to neutral voltage)
- V(LL) = V(LN) * √3 = 230 * 1.75 = 400V
lincomatic commented 6 years ago

thanks for the PR. Next time, please squash your PR's into one commit.

beikeland commented 6 years ago

Seems it got merged as 3 instead of sqrt(3) (or * 1.732 )

lincomatic commented 6 years ago

We have to keep the math as integer. Any comments, @glynhudson ?

glynhudson commented 6 years ago

Sqrt(3) is only required when calculating power using Line-to-line voltage (usually 400V) when using Line-to-neutral voltage (usually 240V) multiplying the current by three is all that's required. See my notes on calculation in the PR above.

beikeland commented 6 years ago

But in a IT network the line to line voltage is 240, most TN networks the line voltage is indeed 400, and some TN networks (i forget if its TN-C or TN-S, the line to line voltage is still 240); so some clarification on some level is probably a good idea. More to the point a Type1 car will still only charge off single phase 240V regardless of the line to line voltage.

On Thu, Jun 28, 2018, 17:54 Glyn Hudson notifications@github.com wrote:

Sqrt(3) is only required when calculating power using Line-to-line voltage (usually 400V) when using Line-to-neutral voltage (usually 240V) multiplying the current by three is all that's required. See my notes on calculation in the PR above.

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