Note: this article is only relevant if you have a delta grid topology, which is only found in some parts of Belgium, Norway and France. If this is not applicable, you can skip this article.
When an EV Wall is installed in a residential installation with a 3P (3 x 230 V) Delta grid connection, some additional requirements need to be taken into account. You can verify whether you have this topology by checking the grid connection to see if the following are true:
- There is no neutral wire.
- The voltage between two phases is approximately 230 V.
- The voltage between a phase and earth is approximately 130 V.
Some EVs are not compatible with this type of grid connection due to a built-in security in the EV. Contact your EV manufacturer for more information.
The security feature that some EVs have is a voltage check between the phase that is connected as neutral and the ground. If this is not 0 volts, the car won’t charge. The presence of this security feature may vary for each manufacturer and for each model.
As there is no neutral wire available in this topology, the L3 will be used as neutral. In this case, some EVs will be able to charge dual phase (using both L1 and L2) and some will only charge single phase. In practice, this may limit the maximum charging power. This again varies for each EV manufacturer and each model.
If your EV is not compatible with this grid topology, or if you would like to achieve higher charging power than what is possible on a delta grid topology, you can install a transformer. This transformer will convert the 3 x 230 V delta topology to a standard 3 x 400 V star topology.
Special Installation Instruction
Please see the relevant section of the installation manuals. Note especially that the L3 will be used as neutral.
Tip: if the EV won't charge on two phases, try to disconnect the L2 of the charging cable/socket to force the EV to charge single-phase.
Changes to overload protection
There are two significant differences between a 3 x 230 V network and a standard 3 x 400 V network:
- All current on one phase must return on a different phase.
- We only measure 2 of the 3 phases.
These differences have an impact on how the overload protection works because we have to calculate the current on L3. This means that an EV's charging current will sometimes be limited by our overload protection, even though L1 and L2 aren't near their current limit. For example, let's say an EV can charge dual phase 16 A. On L1 and L2 there will be a current of 16 A but on L3 there will be a current of 28 A. If the breaker is only rated for 25 A, this means we will need to reduce the charging current to less than 16 A.