Whoa, nice. I like the empty consumer units which can be populated with double pole breakers. I'd put a 63, 100 or 125 amp type D main MCB with 16, 20, 32 and 40 amp type C branch MCBs. Only thing I dislike is the limited wire bending room and gutter space compared to US equipment. I like long flowing sweeps of wire.
In parts of France and Belgium they still have (or had) 3x230 pas neutre which is my favorite system of all time- particularly when its of the TN-S but without the neutral distributed flavor. I am personally not a fan of TT earthing though it has many, many legit merits such as neutral to earth voltage mitigation on farms where the supply network is TN-C-S or MEN. Older installations in Norway are IT, but they screwed it up in 2 ways:
1) They only had a local earth rod for the grounding system. There was no 4th wire to provide a low impedance bond between the earthing system of each structure. So A phase might fault in one structure (making the network fundamentally TT) and B phase latter in another structure. Due to the high earth soil resistance diazed fuses would not always blow resulting in two separate structures energized at 230 volts opposing potential between them. Overtime this resulted in many fires and is now being mitigated via RCDs.
2) Many pole mounted units were/are wired wye ungrounded primary - wye ungrounded secondary but with one catch. The secondary neutral point is brought out of the can and run through an isolating nullpunktsikring before being connected to ground:
https://www.el-tjeneste.no/download/2851777/Bruksanvisning-Nullpunktsikring-01-A3596.pdf
This worked until the nullpunktsiring became permanently shorted to ground for various environmental reasons while there was already an existing phase to earth fault out on the LV network. (Most IT networks serving residential customers have protracted or standing ground faults- who knocks on their neighbors doors to deliver the message 'hey you have an electrical earth fault somewhere on premise'.) With the neutral isolater shorted this was electrically equivalent to taking one secondary of an LV phase and directly connecting it to the secondary (X0) neutral terminal of the transformer. Because zero sequence current from the ungrounded wye primary has no place to go the entire voltage vector of the 3 phase connection shifts upward resulting in 400 volts between each LV phase and turn subjecting 230 volt customer loads to 400 volts line to line.
The IT system in Norway was a brilliant idea begotten from the heart but unfortunately due to poor implementation (stemming from past ignorance about the theory behind grounding and bonding that was present in every corner of the planet) became one of the most dangerous systems in the world resulting in many fires.
Personally I would have grounded the HV/MV transformer's secondary neutral at the substation, run an MV multi grounded neutral and grounded the primary neutral point (H0) on the pole mounted transformer (not always possible because Norway wants to operate its MV distribution system as IT ie ungrounded or resonant grounded) or used a delta primary on the pole transformer; permanently bypassed the nullpunktsikring; run a 4th wire out with the LV secondaries at not less than half the equivalent cross sectional area of the phase conductors; calculated I2R short circuit heating not exceeding a final conductor temp of 250*C to blow an LV network Lucy fuse or MV cutout; required that each structure take in a 3rd or 4th PE wire connected to the main earthing terminal; and stipulated all the following be met at the consumer's building 1) a maximum external earth fault loop impedance not exceeding 0.8 ohms, 2) a perspective fault current of not less than 250 ampers L-PE at the point of any incoming supply, 3) a perspective earth fault current not less than 5 times the non residual trip current rating of the main disconnect as measured or calculated at the main disconnect enclosure, 4) A L-L and L-L-L perspective fault current of not less than 4 times the trip rating of the main disconnect as measured or as calculated at the main disconnect enclosure, 5) Residual current protection shall not be used as the sole or primary means to achieve required disconnection times of mains supply exceeding 55 volts AC between conductors in any part of a consumer installation when supplied by an externally operated public network.
133/230Y or better yet 145/250Y (I wish LOL), TN-S but without the neutral distributed.
This system is the best system and a win win for power providers in that by connecting all loads phase to phase load current will not be placed to the primary neutral of a 3 phase wye gorunded - wye grounded transformer bank. This means that the issue of ferroresonance in single phase switching of cutouts can be mitigated allowing for distribution voltages of up to 34.5kv, not having to deal with neutral to earth voltages which present themselves in connecting customer loads line to neutral in conjunction with a wye-wye bank, and being able to set 50/51/67/32N feeder ground pickups at a lower value without having to account for load current on the multi grounded neutral.
Which, speaking of 34.5kv, running a distribution system at 33kv can allow for a utility to bypass the entire 11kv system and its associated intermediate substations. Higher feeder coverage exposure and more customers per circuit compared to 11kv can be mitgated via recloser auto-loops, distribution automation, tree wire and spacer cable.
Ie, 3 radial 11kv feeders serving 1,250 customers operating at 300 amps (500 amps rated emergency switching) supplying 5.7 MVA of load can be consolidated into a single 33kv feeder at 300 amps 3,750 customers. The larger load size per feeder mitigated by dividing each feeder into 3 parts via 3 reclosers- feeder, midpoint and tie such that a fault in any section results in no more than 1,250 customers being effected as originally. Each segment or 1,250 customers at 33kv pulls 100 amps of load. A worse case fault in the first zone A of line between the bulk HV/LV substation and feeder recloser drops 1,250 customers at lockout, the remaining 2,500 customers in healthy zones B and C being a total of 200 amps transfer to a neighboring feeder also running at 300 amps but rated 500 emergency by opening the feeder recloser and closing the tie into the neighboring feeder. 2,500 customers are restored, and 300 + 200 = 500 amps the rating of the neighboring feeder. Voltage drop taken into consideration of course but typically a much larger deviation is permitted during contingency switching.
Although an interesting note- at 230/400Y you can supply many more customers with a single MV/LV trafo- larger units and having dampening load can actually mitigate ferroresonance too. Interesting to think about.
Which speaking of bypassing intermediate stations that is what is being done where possible at many utilities. 10kv distrbution and 30kv sub-transmission is being phased out for 20, 22 or 23kv distribution across the globe.
