Yes it makes sense to use the same sensor for AC and DC.
ISTR reading somewhere that current standards dictate that the EVSE shouldn't (maybe even must not ?) do the AC RCD function, but instructions should specify that they are connected to a type A RCD at source. Not sure how accurate this is, or where it is specified, but apparently at least one EVSE manufacturer (Anderson) has removed the AC RCD functionality from its unit.
Thanks, thats interesting. In fact, i have only recently found out that EV wall box's should not have a Type A RCD function, because it would be blinded by a DC current level at 6mA or greater.
An EV wall box needs to have a type B RCD, which trips out on 30mA of AC imbalance, but doesnt get blinded by even 100mA of DC level in the mains.
So an EV wall box needs a type B RCD and a DC level sensor which can sense up to greater than 200mA DC.
This is quite a spec...do you know of off-the-shelf devices that can do this?
Does it mean only fluxgate sensors, or Hall sensors can be used?...since any "Normal" CT would be blinded by the DC.
Just got out of my yearly training for refreshments of knowledge here in germany regarding EVSE. Focus on the checks for electrical safety in operation here in germany and german regulations. (VDE is used here)
In short: RCD type B is not always necessary. There has to be a RCD present with max 30 mA for person protection, AND there has to be some way in a 3-phase setup to detect DC currents, because above 6mA a RCD type A (which might be in the main distribution) will go "blind".
In a brand wallbox we had available for testing, a standard RCM module was used for this in combination with a standard RCD type A you could get at every corner.
OR one could use one of those quite new RCD type A-EV, which combine a traditional RCD type A and DC 6mA sensing.
Of course, the more highend way would be to use an RCD type B, which might be better available. And depending on the testing equipment (here in germany regulations say that once a year in commercial enviroment a wallbox etc. has to be tested) a RCD type B might be easier to test because of preprogrammed values in testing equipment.
In fact, many wallboxes in germany use only an inbuilt RCD type A and a DC recognition of 6mA.
Word of warning: It is not allowed to mount a RCD type B behind a RCD type A- simply because the type B would tolerate much more DC current than type A can handle- and what would affect some possible other circuits that might reside on the same RCD.