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EV CHARGING EQUIPMENT

I am hearing from my network of contractors, that have actually read the new 722, that they have been asking charging equipment manufactures for documentary proof to comply with Note 5 of 722.411.4.


They are getting knocked back for asking or in one case a Declaration that says the particular device complies with BS 7671. I think that is wrong to declare that as BS 7671 is an installation safety standard and not a product standard. I believe that as a minimum the equipment must comply with the Low Voltage Directive and be CE marked. I also believe that manufacturers have to issue a Declaration of Conformity. 


BS 7671 722 has numerous references to the various standards required such as BS EN 61851 that the equipment must comply with. I am thinking it may be illegal to offer the sale of equipment that does not comply with the Low Voltage Directive and is not CE marked?


I am hoping the countries top man of equipment safety standards, Paul Skyrme , sees this post and will come on and give us his expert view?


Has any forum member asked for a Declaration of Conformity from EV charging equipment manufacturers and received one?

  • davezawadi:

    I am not disagreeing with you Graham, just trying to air the subject as fully as possible.


    The next question may be slightly painful to some, and that is: Who in a suitable position to understand the problem signed up to accepting standards which are basically faulty in concept? There appears to be no suitable way in an urban environment where an electric vehicle can be guaranteed to be free of the PME system, even if the supply is "TTed" with a local electrode. So quite simply the now common problem of a lost N connection can make a car significantly dangerous however many RCDs of whatever type are in place. The answer is that we now need to monitor electrode to neutral voltage and disconnect the vehicle completely, including the Earth and control wires, should this voltage exceed some value, say 55V RMS for discussions sake. This disconnection needs to be permanent needing a reset back to the no fault condition and substantially instant. Such a device is fairly simple and cheap to manufacture, but we don't have a requirement to fit one. Instead we have all kinds of very expensive RCDs which do not provide anything like the same level of protection. So lets make a new standard, to incorporate such a device in every charge point, which fixes the problem for good.




    Only the UK seem to have a serious problem with the lost Neutral ... other countries seem to be getting on with it with little or no fuss.


    Some other countries banned the use of Type A RCDs many years ago, so they will only need an RDC-DD (or that built into the charger).


    To a certain extent, the RCD issue has nothing directly to do with EV's - it's a problem generally, that will increase with the increasing use of embedded generation, and certain electronic devices (some of which are not so modern but were perhaps preventing Type AC RCDs from operating all along).


  • Chris Pearson:




    gkenyon:

    BS 7671 does have another solution in Annex 722 for separation of the vehicle from the installation, if pockets are deep enough.




    And still this thread rumbles on.


    Graham if you had a PME supply (could be single or three phase) and deep pockets (deep enough to have bought an EV in the first place) which method would you choose please?


    Average semi with single-phase supply, I'd rather connect to the PME earth if at all possible, so I'd choose 722.411.4.1 (iii), (iv) or (v), with the following commentary:

    • My first choice would be a (iii) device, but for a single-phase supply a measurement earth electrode would be required. This may not always be practicable, as there has to be at least 2 m separation from this electrode buried metalwork connected to the PME system (see Annex I of 4th Ed CoP).

    • Following that, I would choose either (iv) or (v) device.


    With either option, of course, the first time I used the product I'd want to do some due diligence on the product.


    But overall in a small curtilage single-phase property, I think it's better to connect to PME using one of these devices, than try and make a separate TT system, given all the attendant issues of separation and the risk of striking buried services ... and the problems in future maintaining the separation.


    If I was going to install V2G system, then that's a different story, as the 722.411 (iv) and (v) devices are not available - but again in this case I'd prefer to use 722.411.4.1 (iii) device with earth electrode than a separate TT system.



    Please also clear up what may seem to be an elementary question. I understand the need to separate the earthing arrangements of different systems, which could lead to difficulty placing either a TT earthing rod or a reference electrode. So does the separation have to be from a PME electrode (in my case, I assume that would be a street lamp by the corner of my property) to an installation electrode; or does it have to be from a service cable to an installation electrode?


     




    The separation has to be between the separate TT installation earth electrode, and any buried uninsulated metalwork connected to the PME earthing system. If the PME (or public supply TN-S) service cable is PILC (paper insulated lead covered) then sure that's included as it's at PME earth potential.

  • I am not disagreeing with you Graham, just trying to air the subject as fully as possible.


    The next question may be slightly painful to some, and that is: Who in a suitable position to understand the problem signed up to accepting standards which are basically faulty in concept? There appears to be no suitable way in an urban environment where an electric vehicle can be guaranteed to be free of the PME system, even if the supply is "TTed" with a local electrode. So quite simply the now common problem of a lost N connection can make a car significantly dangerous however many RCDs of whatever type are in place. The answer is that we now need to monitor electrode to neutral voltage and disconnect the vehicle completely, including the Earth and control wires, should this voltage exceed some value, say 55V RMS for discussions sake. This disconnection needs to be permanent needing a reset back to the no fault condition and substantially instant. Such a device is fairly simple and cheap to manufacture, but we don't have a requirement to fit one. Instead we have all kinds of very expensive RCDs which do not provide anything like the same level of protection. So lets make a new standard, to incorporate such a device in every charge point, which fixes the problem for good.

  • gkenyon:

    BS 7671 does have another solution in Annex 722 for separation of the vehicle from the installation, if pockets are deep enough.




    And still this thread rumbles on.


    Graham if you had a PME supply (could be single or three phase) and deep pockets (deep enough to have bought an EV in the first place) which method would you choose please?


    Please also clear up what may seem to be an elementary question. I understand the need to separate the earthing arrangements of different systems, which could lead to difficulty placing either a TT earthing rod or a reference electrode. So does the separation have to be from a PME electrode (in my case, I assume that would be a street lamp by the corner of my property) to an installation electrode; or does it have to be from a service cable to an installation electrode?


  • davezawadi:

    OK you say what if a N-E fault occurs on the cable or elsewhere in car or charger. This will trip any RCD as a large current (compared to 30mA) will be diverted to the earth conductor, bypassing the N side of the RCD. The small DC signal (lets say 12 mA or whatever) will not prevent this trip. I




    DC core saturation may occur with Type AC RCDs, preventing the trip. IET Article explains.



    In any case to be dangerous we need a second fault, say a lost N elsewhere and a person effectively connected to ground touching exposed conductive parts of the car.


    ...


    The danger will be a bit more if the car has finished charging but is still connected, but under this condition we still need a fault and a person well connected to ground, whatever the RCD does.





    Disagree, the N-E fault also potentially causes "blinding" of other RCDs upstream in the same circuit. It also causes circuit current to be shared down the cpc indefinitely which is not really considered "safe" in the UK - we're not allowed TN-C in the consumer installation.



    Under the same conditions I can see that a large number of consumers will be exposed to exactly the same danger in many other situations.



    Agreed, I personally would prefer Type AC RCDs to be scrubbed, for a number of reasons all related to the nature of present-day loads, and the increasing prevalence of embedded generation and storage systems.



    It seems to me that this is getting out of proportion as it is not possible to avoid any risk without making cars class 2 which seems to be unacceptable to "the powers that be". The supposed solution is not available to be risk free, RCD or not. Because the car body cannot be isolated from the supply system (even if the supply is TT, and that is a severe problem in urban environments) we have some level of risk from faults. Such faults are very unusual (when did you last find an appliance with a N-E fault in the connecting cable?) and it is probably folk law that RCD tripping in the presence of a high fault current is prevented by 12mA of DC, although the 30mA value may be somewhat increased. It seems to me that the RCD reliability is probably less good than the cable fault scenario, and so we are not making any difference with increased complexity.





    I won't repeat my other posts regarding the likelihood of moving to Class II vehicles. However, BS 7671 does have another solution in Annex 722 for separation of the vehicle from the installation, if pockets are deep enough.


    "Probably folk-lore" is, I think, going a bit far, and certainly not a statement to base standards on. The issue of which RCDs are suitable for the kinds of residual fault currents that are anticipated is now well-documented in the product standards for RCDs (BS EN 62423 has been in place wince 2013). Therefore, we are now in a position that we can't "un-know" the problem with Type AC RCDs and certain types of fault current - regardless of whether it's each and every Type AC RCD, or only a few. To consider ignoring this in BS 7671 (and its international counterparts HD 60364 / IEC 60364) is really nonsensical. An argument with substantial technical evidence would be required to change this, and would probably have to start with the product standards first.

  • OK you say what if a N-E fault occurs on the cable or elsewhere in car or charger. This will trip any RCD as a large current (compared to 30mA) will be diverted to the earth conductor, bypassing the N side of the RCD. The small DC signal (lets say 12 mA or whatever) will not prevent this trip. In any case to be dangerous we need a second fault, say a lost N elsewhere and a person effectively connected to ground touching exposed conductive parts of the car. Under the same conditions I can see that a large number of consumers will be exposed to exactly the same danger in many other situations. The danger will be a bit more if the car has finished charging but is still connected, but under this condition we still need a fault and a person well connected to ground, whatever the RCD does.


    It seems to me that this is getting out of proportion as it is not possible to avoid any risk without making cars class 2 which seems to be unacceptable to "the powers that be". The supposed solution is not available to be risk free, RCD or not. Because the car body cannot be isolated from the supply system (even if the supply is TT, and that is a severe problem in urban environments) we have some level of risk from faults. Such faults are very unusual (when did you last find an appliance with a N-E fault in the connecting cable?) and it is probably folk law that RCD tripping in the presence of a high fault current is prevented by 12mA of DC, although the 30mA value may be somewhat increased. It seems to me that the RCD reliability is probably less good than the cable fault scenario, and so we are not making any difference with increased complexity.


    I cannot find a type B RCD in my odds box to evaluate it properly. A loan of one would be much appreciated if anyone near Bristol has one hanging about (working condition!) or would post it to me.

    Thanks
  • OK, but:


    1. The charging cable is Mode 2 not Mode 3 or 4. The two can't be 100 % compared. This is why the requirement for Type B (or Type A or F + RDC-DD) is where the vehicle connector is used, for tehthered cables or Mode 3 / 4 charging station. With Mode 3, there are additional options available for the pilot. Where you have Mode 2 cable, a Type A RCD is sufficient.


    2. When the vehicle is not connected, or if there is a problem in the monitoring circuitry on the vehicle, the source is 12 V. Therefore with a tethered cable on Mode 3 (or EVSE where the cable is left plugged in), we still have the situation that an N-E fault on the cable, which can happen at any time, provides 12 V DC. And the cable is connected at all times.




    I would recommend, if you want to look into this further, to have a look at BS EN 61851-1 (or IEC 61851-1). Quite a lot of areas' library subscriptions will permit you to have a look at the standard on line, although I'm sure the resourceful individual could perhaps find a way to access on the internet in any case.


    I've also seen a number of articles on web-sites about the vehicle charging interface, where the diagrams and info in BS EN 61851-1 (IEC 61851-1) are reproduced.

  • gkenyon:




    davezawadi:

    Yes Andy, but that will put the short circuit ability  (which may be an amp if its a good battery) through the RCD and we are working on milli-amps of DC! A 1k resistor also in the battery circuit will give 9mA etc.




    Agreed - that's effectively what we have with EV charging equipment pilot, but the source is 12 V not 9 V.


    How much is shared with the Neutral depends on the resistances of the conductors upstream back to the point of common coupling.


    Therefore in a TT system, the risk is less than a TN system, and TN-S lower DC current is likely to be shared than in a TN-C-S (PME) installation.


     



     Hi Graham. I thought I would share the reply I got from Mitsubishi regarding the "granny lead" that came with the car which I mentioned earlier in this thread;


    Good morning,

    Here’s a brief explanation of what the CCID box does and how it controls the charging. We have no information as to what type of RCD is fitted to the CCID.

    The box on the cable is not the charger, it is a control and interruption device that switches the current to the on board charger (OBC) which is mounted in the car, on and off. The CCID initially outputs a 12VDC supply via a switch onto pin 3 of the EVSE (Electric Vehicle Supply Equipment) Connector whenever the charge lead is  plugged in to a 240VAC power supply. This indicates the EVSE is ready, but not connected to a vehicle.

    When the EVSE connector is connected to a vehicle, a resistor in the OBC pulls the voltage on pin 3 down to 9V. This indicates to the CCID that it is connected to a vehicle. At this point, the CCID activates a switch to start sending the PWM Pilot signal out on Pin 3. The pilot signal tells the OBC how much current it can draw. In the UK this will be 10A.

    Once the OBC registers the Pilot signal, it switches on another switch. This connects a resistor into the circuit which pulls the voltage down to 6V. This tells the CCID to commence charging and the CCID will then switch on the RCD to allow mains supply to the charge lead.

    When the battery has reached full charge the OBC will turn off the relevant switches which puts the pilot signal back up to 9v which tells the CCID to switch off the RCD.

    I hope this helps.

    Kind regards,



    We have no information about the RCD in the CCID, but if it is double pole, then from the above the neutral would only be connected when 6V were showing in the DC circuit. Regardless of whether the RCD was DP or not, the whole of the time the vehicle is charging, only 6V would be on the circuit. 

     


  • davezawadi:

    Yes Andy, but that will put the short circuit ability  (which may be an amp if its a good battery) through the RCD and we are working on milli-amps of DC! A 1k resistor also in the battery circuit will give 9mA etc.




    Agreed - that's effectively what we have with EV charging equipment pilot, but the source is 12 V not 9 V.


    How much is shared with the Neutral depends on the resistances of the conductors upstream back to the point of common coupling.


    Therefore in a TT system, the risk is less than a TN system, and TN-S lower DC current is likely to be shared than in a TN-C-S (PME) installation.

  • Yes Andy, but that will put the short circuit ability  (which may be an amp if its a good battery) through the RCD and we are working on milli-amps of DC! A 1k resistor also in the battery circuit will give 9mA etc.