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Correct way of wiring OpenEVSE in Europe for 3 phase 22kW

Discussion in 'Charging Standards and Infrastructure' started by emir-t, Jan 1, 2017.

  1. emir-t

    emir-t Member

    Oct 28, 2013
    Hello all;

    I'm about to purchase a few OpenEVSE's to install EVSEs at home, at work and build a mobile one like the Fivari charger to charge 3 phase, single phase in Europe. (whatever I have available) I believe I've looked at everything available online during research, however there's no one source to show how a 3 phase, Euro spec OpenEVSE could be done. Some people have done it but nothing is absolutely clear. In order to not lose any functionality I came up with this, what I believe would be the true way of wiring an open evse with a 3 phase power network.
    Some notes;

    • - Using the AC Relay side to power the 4 pole European contactor with 220VAC coil. I don't think there are any contactors with this much power handling, using 12V DC coils. I hope this is the correct way to wire. (some controllers have two outputs for both A1-A2 terminals on the contactor, I assume with OpenEVSE AC Relay H is to close contactor, AC Relay N is for neutral and A2 of the contactor is to energize, hence L1, I may be terribly wrong with this but it is what I came up with after seriously spending time looking at Viridian, Mainpine, SmartEVSE and OpenEVSE wiring cases)
    • - Using the OpenEVSE built in GFCI for GroundCheck success and also using an external RCD to protect for all three phases. Is there a way to connect the RCD to EVSE GFCI pins to get that check without the built in GFCI?
    • - To see energy consumption in the LCD, I am putting only a single phase through the current measuring CT, this will only show amperage per phase.
    • - AC test's both (L3-L2) goes to output of contactor so it would sense 220V AC on both test terminals (in ref. to ground of OpenEVSE board, otherwise 400VAC between both phases, I don't know how it is done) and auto sense Level 2. I hope I am correct with this logic.

    Besides the wiring, for this to function properly I believe I need to do firmware modification such that;

    • - Level 2 nominal voltage for energy calculation should be 220V instead of 240. Also I need to multiply measured L3 current through CT by 3. (for 3 phases)
    • - To plug the mobile version to single phase 220V schuko, I'll connect only L3 and leave L1-L2 empty. That won't change a thing on the functionality side as EVSE doesn't tell between a single or three phase but in terms of measuring it shouldn't be multiplied by 3. So, I am thinking because this will be Level 1 charging, Level 1 energy calc. formula shouldn't be x3 measured current. It would be great if I could change the names from Level 1, Level 2 to "Single Phase", "Three Phase"
    • - I also would like to change the language of the LCD menu.
    Do these make sense? Have I done my homework correctly? Could anyone direct me towards some links to edit the firmware properly? (I don't know much programming)

    Thanks in advance for your help.
  2. arg

    arg Supporting Member

    Aug 22, 2012
    Cambridge, UK
    I do not know the details of OpenEVSE, but from general principles:

    • If you want to use OpenEVSE's RCD (=GFCI) function, you must put all 4 wires - three phases and neutral - through the sense coil. If you only put one phase and neutral, it will look like a huge fault as soon as you connect a 3-phase load - the whole point of 3-phase is that most of the return current goes down the other phase wires rather than the neutral. The sense coil is measuring the net current through all the cores and expects it ro be zero- if not, some current has leaked out to earth, presumably due to a fault.
    • With 4 wires through the sense coil it will still work fine on single phase, as there will be no current in the two unused wires and it will behave as if they were not there.
    • There's in theory no need to have both an RCD and OpenEVSE's internal RCD function, as they are both doing the same job. However, if this is for permanent installation, the software RCD quite likely won't meet the requirements of your local regulations, so it's sensible to keep the external one. Given the hardware is already there, you might as well wire up the OpenEVSE one as belt-and-braces. If this is for a portable unit to connect to an existing commando socket, it might be more tempting to omit the separate RCD (as any regulatory requirement in respect of the fixed wiring is the responsibility of whoever put the socket in - quite often they will have provided an RCD already).
    • Doesn't OpenEVSE already measure the voltage rather than just assuming 240? In your case, measuring voltage and current on a single phase and multiplying by 3 should give a reasonable estimate of the total power (the actual voltage is likely to vary significantly from 220 or whatever the nominal is where you are, but the three phases will probably be roughly the same as each other, and for EV charging the currents will normally be very closely matched.
    • If the OpenEVSE you are using only has sense inputs to check the operation of a single phase contactor, there won't be enough for three phase. Arguably, welded contactor detection is less important for 32A than for 80A, and certainly many commercial designs of EVSE in Europe don't have it. If you are hacking the software, maybe you could re-purpose the sense inputs to detect the presence of L2 (and hence solve your problem of when to do *3 in the power calculation).
  3. swaltner

    swaltner Member

    Oct 13, 2012
    Kansas, USA

    No, while older OpenEVSE modules may have measured the line voltage, the current OpenEVSE v4 controller does not have that capability and simply has 120V and 240V hard-coded into the firmware for L1 and L2 operation. If you are running on a commercial site in the US (208V) or some other voltage, you would need to recompile the firmware with your local voltage to make sure the amperage -> kWh conversion calculation is accurate. Also, since voltage is rarely exactly at the nominal voltage of 240V on a residential setup, the kWh isn't necessarily accurate on the OpenEVSE display.

    I have three ways to monitor the electricity being consumed by my Nissan Leaf.

    - TED 5000 mounted in the breaker panel monitoring the current to/from the EVSE as well as the voltage. This seems to be most accurate.

    - Nissan Carwings website - This measures the power that the car consumes out of the battery. It doesn't include charging
    inefficiencies and is therefore slightly lower than the reading from the TED.

    - OpenEVSE display - This measures the same current that the TED sees (except for the couple watts consumed by the OpenEVSE controller and main
    contactor), but since it assumes 240V and I typically see a few volts lower than that under load, it records slightly higher than reality for its kWh readings.
  4. delage

    delage New Member

    Apr 14, 2017
    Thusis, Switzerland
    Hello emir-t

    I am a fellow european openEVSE user from Switzerland

    Just stumbled across your diagram on the forum here. You are right that there is not much documentation on European Version Tri-Phase open EVSE's around, so I am very interested on how you got on with your installation!

    I have tried to build an openEVSE myself and based some wiring on your diagram.

    It would be interesting for me to learn if your wiring actually worked in your installation. I am not sure if the power straight from the openEVSE is strong enough to activate the contactor. I read in other building instructions, that some other colleagues are putting in a 12V automotive relay in between, to activate the main contactor.

    After a first test today with your diagram (without the 12V relay) says: CONNECTED, 0 KWH but it doesn't seem to close the contactor. I am attaching a picture of my own installation (the 12V relay in the center is unused). Would you mind having a short look at it and comment please?
    In your diagram, it is not evident how the wiring to A2 on the connector is laid out exactly...

    Thank you very much and best regards,

    Attached Files:

  5. emir-t

    emir-t Member

    Oct 28, 2013
    Hello Delage! Sorry for the late response.

    I still haven't used to OpenEVSE. Kit has been lying down in the drawer for months. Now I'll get right to it and while checking out the old documentation I came across your message. I think in your setup AC relay "H" is going to A1 which is correct. But maybe AC relay "N" is supposed to go to A2. If the angle isn't deceiving me yours seems so to be going to Neutral and you bridged A2 with one of the phases? (#8?) I'm not an electrician but to the best of my knowledge A1 and A2 is connected. AC Relay H energizes A1 when conditions are met and car requests power, so that energy excites the contactor, closes it and the relay is connected through A2 going back to Neutral. What I'm not sure of is if we're supposed to take L2 to a Neutral source like regular contactors or if OpenEVSE AC Relay N provides that neutral within the PCB. So that could be wrong with my initial drawing but I'm not sure.

    I would love it if you could update me. I'll do my setup and post here soon.

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