3 phase outlet, what is suitable for EV charging?

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T1 Terry
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3 phase outlet, what is suitable for EV charging?

Post by T1 Terry » Fri, 23 Aug 2019, 12:20

In my workshop I have multiple 5 pin 3 phase outlets marked as 10 amps on the cover. Groups of these a re protected by a 16amp circuit breaker. There is a 3 phase connection box with big cable running from it to a separate RCD marked C83. This circuit powered a monster hydraulic pump that drove a broaching machine, the machine had been sold and removed before I took possession of the workshop, but the cabling is still there isolated inside this connection box. What size 3 phase outlet could I connect to that for EV charging?
We have a huge transformer on the pole out front that the previous workshop owner had to pay for so he could get the power he needed to run his workshop, I doubt it is really being utilised because we use very little 3 phase power.

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Re: 3 phase outlet, what is suitable for EV charging?

Post by jonescg » Fri, 23 Aug 2019, 12:58

Not sure about the regs around running multiple 3-phase 10 A outlets on a single 16 A 3-pole breaker but the best you can manage is about 7 kW, assuming the vehicle was being charged from all three phases. Otherwise upgrade the wiring to 6 mm2 cable, install some 32 A 3-pole breakers and get the full welly.
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Re: 3 phase outlet, what is suitable for EV charging?

Post by antiscab » Fri, 23 Aug 2019, 13:08

16A breaker to multiple 10A points is fine as long as the wire in the wall is at least 2.5mm2

any ideas how heavy the wire from the transformer out the front is?
Got a pair of binoculars? see if there's a name plate on the transformer to work out how big it is.

If you're putting a new point in, I agree, use 6mm2 and put in a 32A 5 pin point. That allows you to draw up to 22kw.
at the moment only the zoe and the tesla s can actually draw that much

you could on the cheap just swap out one of the 10A units with a 16A, as long as the wire in the wall is at least 2.5mm2
That gets you 11kw, which would still max out model 3, hyundai kona and ioniq, cheap portable 10kw chademo, etc
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Re: 3 phase outlet, what is suitable for EV charging?

Post by T1 Terry » Sat, 24 Aug 2019, 12:32

I can't read anything on the transformer name plate, the markings are washed out, but I took some photos
Nameplate.jpg
Nameplate.jpg (72.48 KiB) Viewed 448 times
Transformer on pole.jpg
Transformer on pole.jpg (1.81 MiB) Viewed 448 times
The cables into the workshop go through that white plastic pipe and underground to the main fusebox.
The circuit breaker and cable I'd be most interested in using is a 3 phase switch with C63 and 6ka 415v and I'm guessing a part no. 4CB363/6
The cable from this circuit breaker out the top of the box and along the cable tray to the terminal box is big orange cable 20mm diameter.
No idea if any of that helps, but it does look like substantial cable compared to any of the other cable runs, including the cable to the overhead crane.

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Re: 3 phase outlet, what is suitable for EV charging?

Post by coulomb » Sat, 24 Aug 2019, 15:48

T1 Terry wrote:
Sat, 24 Aug 2019, 12:32
I can't read anything on the transformer name plate...
Wow. That looks (to my amateur eye) to be at least a 100 kVA transformer. Somewhat overkill, I think, but it's probably the smallest that the utility company deals with.
The circuit breaker and cable I'd be most interested in using is a 3 phase switch with C63 and 6ka 415v
So the C refers to the breaker's time and current curve; "C" is a general purpose curve; "D" is often used to start difficult loads (e.g. large motors under load). The 63 means the breaker is rated at 63 A per phase, so that's 230 x 3 x 63 = 43.5 kVA. That's enough for any sort of AC EVSE. Of course, AC charging is limited by the power rating of the on board charger; that could be 22 kW, 11 kW, 7 kW, or as low as 3.3 kW (as it is for my 2012 Leaf).

The 6 kA rating is the short circuit current that it is rated to not explode with. It depends on the impedance of the mains as to whether you need the common 6 kA rating, or the more expensive and less common 10 kA rated breakers. At a university where I worked, we had to use a few 10 kA rated breakers because they weren't far enough (electrically speaking) from an enormous transformer that fed several large buildings. After these few breakers, the remainder were electrically just far enough to get away with 6 kA breakers.
The cable from this circuit breaker out the top of the box and along the cable tray to the terminal box is big orange cable 20mm diameter.
I happen to have bought some 6 mm² 3 core plus earth round cable yesterday by mistake. It measures about 15 mm diameter (it's not perfectly round). It has no neutral, and your's almost certainly does, so I'd guess 4 core plus earth would be a bit more, call it 17 mm. I'd say yours would be the next size up, which is 10 mm², which is probably good for some 63 A, as it should be since it's protected by the 63 A breaker.
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Re: 3 phase outlet, what is suitable for EV charging?

Post by T1 Terry » Mon, 26 Aug 2019, 12:48

So, that would be the circuit to supply one or more 3 phase EV chargers? I never did get my head around how 3 phase converted to watts, 22kW appears to be the biggest expected demand, would this cabling and circuit breaker be sufficient to supply 2 units at the max expected 22kW output running simultaneously?

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Re: 3 phase outlet, what is suitable for EV charging?

Post by antiscab » Mon, 26 Aug 2019, 12:58

Maybe

The 63A breaker may be there simply to act as a switch, rather than be there for current protection
The utilities are a bit of a law unto themselves.
At my house I have my incoming mains has a 100A fuse on each phase. I was really excited when I bought the house as I thought the connection was huge, and the transformer for the whole block (a big 350kVA unit) was on the pole next door.
It was a bit of a let down when I saw the conductors were only 6mm2 (only good for 32A, or 40A under certain conditions)
I had 3 x 32A CB installed after that.


You will still need to find out how big the conductors/wires are running from the transformer to your workshop
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Re: 3 phase outlet, what is suitable for EV charging?

Post by coulomb » Mon, 26 Aug 2019, 19:23

T1 Terry wrote:
Mon, 26 Aug 2019, 12:48
So, that would be the circuit to supply one or more 3 phase EV chargers? I never did get my head around how 3 phase converted to watts, 22kW appears to be the biggest expected demand,
22 kW is 32 A per phase (230 x 3 x 32 = 22,080).
would this cabling and circuit breaker be sufficient to supply 2 units at the max expected 22kW output running simultaneously?
Presuming no silly buggers such as @antiscab found, then yes, your 63 A per phase supply should be able to run two 3-phase (type 2) EVSEs at maximum power. You could run the cable and breakers at a 64/63 - 1 = 1.6% overload for many hours before tripping, and the cable should just get a bit warm, and not melt (assuming that the breaker is a good match for the cable). [ Edit: and by then, at least one of the cars has probably stopped charging, or is charging at a lower current. ]

Most single phase house connections are 80 A or more these days, so I imagine that you'd have stout enough pole fuses and pole to house cable to run the EVSEs plus a typical house load.

Anstiscab, surely your pole or pit to house cable is at least 10 mm²? So you'd be able to get more than the 38 A per phase than 6 mm² cable can usually safely handle? But maybe they use thinner conductors for 3 phase houses, I don't know. It seems silly to limit three phase houses to just a little more than what a typical single phase house can use, otherwise, what's the point of 3-phase wiring with the more expensive breakers, meters, and so on? Just so you can run 3-phase induction motors?

Edit: Terry, I meant to add that the transformer seems to be powering other customers, not just you. It's hard to tell where the wires go from the photo, but there seems to be an above ground cable to somewhere (perhaps your original house wiring, possibly only single phase, and possibly not from the transformer near your house at all), and then two white conduits, presumably on the LV connection to the transformer. One is presumably your workshop, but what's the other one for? Another 3-phase customer perhaps? So the size of the transformer isn't the determining factor; it's really the size of the cable from the transformer to your workshop, and the pole fuses that protect that cable.
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Re: 3 phase outlet, what is suitable for EV charging?

Post by brunohill » Mon, 26 Aug 2019, 21:00

coulomb wrote:
Mon, 26 Aug 2019, 19:23
T1 Terry wrote:
Mon, 26 Aug 2019, 12:48
So, that would be the circuit to supply one or more 3 phase EV chargers? I never did get my head around how 3 phase converted to watts, 22kW appears to be the biggest expected demand,
22 kW is 32 A per phase (230 x 3 x 32 = 22,080).

And 240 volts X 1.732 (square root of 3 (phases) ) = 415 volts

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Re: 3 phase outlet, what is suitable for EV charging?

Post by coulomb » Mon, 26 Aug 2019, 22:08

brunohill wrote:
Mon, 26 Aug 2019, 21:00
coulomb wrote:
Mon, 26 Aug 2019, 19:23
22 kW is 32 A per phase (230 x 3 x 32 = 22,080).
And 240 volts X 1.732 (square root of 3 (phases) ) = 415 volts
Sure, 415 V phase to phase. But with 3-phase loads, either the voltage or current gets split such that the load only sees 1/√3 times that voltage or current. So either the 415 V is split down to 240 V again in each load (for star or Y connected loads), or the current gets split (so instead of 3 wires giving 3 times the current, you get 3/√3 = √3 times the current (delta loads). Either way, you end up with the total power being 240 x 3 x phase_current. I find it easier to think of the three 3-phase wires as three single phase wires (for the purpose of calculating the power only, of course). So then you have 240 x phase_current in each active wire, or 240 x phase_current x 3 total power.

I used 230 V because that's the international standard, and even most parts of Australia will be converting to 230 V nominal in the next year or two. I'll believe it when I see it; mains here is still often well over 240 V (244.6 right now, as measured by my solar energy system; 248 and higher is not uncommon). Also, 230 V makes the numbers come out right :)
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Re: 3 phase outlet, what is suitable for EV charging?

Post by antiscab » Tue, 27 Aug 2019, 09:35

coulomb wrote: Anstiscab, surely your pole or pit to house cable is at least 10 mm²? So you'd be able to get more than the 38 A per phase than 6 mm² cable can usually safely handle? But maybe they use thinner conductors for 3 phase houses, I don't know. It seems silly to limit three phase houses to just a little more than what a typical single phase house can use, otherwise, what's the point of 3-phase wiring with the more expensive breakers, meters, and so on? Just so you can run 3-phase induction motors?
My area is a late 60s early 70s development. Back then houses came with on demand electric hws as standard, which required 3-phase.

I suspect a bigger connection cost more, as if everyone did it, there's likely a regulation somewhere stating western power would have to put in a bigger or more transformers. No one wants to pay more for no more useful functionality, so no one did.
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Re: 3 phase outlet, what is suitable for EV charging?

Post by T1 Terry » Tue, 27 Aug 2019, 10:30

Thankyou all for your replies. That transformer does connect into the supply cables for the rest of the street, but all of those places were already supplied by the SA grid and transformers. Probably something to do with balancing the phases or what ever.
The other white conduit goes to the workshop next door, a carpentry house fitter/kitchen builder but the fuse box thing on the pole to that conduit is much smaller than the one going to our workshop. They ran a lot of 3 phase lathes as well as that big hydraulic pump for the broaching machine. That is the thing that monster cable powered and had its own circuit breakers dedicated to that supply in the main fusebox along side the circuit breakers for the sub board that supplied the rest of the workshop. The main switch 3 phase circuit breaker is marked as 80 amps on the lower section of the switch itself.
Now to convince my wife (the boss and workshop owner) that installing 2 x 22kW 3 phase charging outlets out front would be a good idea and could make money sometime in the future.

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Re: 3 phase outlet, what is suitable for EV charging?

Post by brunohill » Tue, 27 Aug 2019, 23:11

I used 230 V because that's the international standard, and even most parts of Australia will be converting to 230 V nominal in the next year or two. I'll believe it when I see it; mains here is still often well over 240 V (244.6 right now, as measured by my solar energy system; 248 and higher is not uncommon). Also, 230 V makes the numbers come out right :)

I used 240 volts because that makes the numbers right as to what is written on 3 phase boxes (in the "old " 240 volt days ). My mains voltage here is 260 volts when the sun gets on my neighbours solar panels , I can not export power and my hybrid inverter turns the mains off and I have to run off batteries . My wife said the opinion of the guy from the power company who came to inspect the problem was basically "what do you expect if you put in solar panels".

We have some politicians saying that we are paying too much for our unnecessary "gold plated "network and the media telling us there will be power shortages if we don't upgrade our coal generating capabilities. :?:

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Re: 3 phase outlet, what is suitable for EV charging?

Post by antiscab » Wed, 28 Aug 2019, 08:36

There is a solution to the high grid voltage problem:
lots of cheap UPS have a 230v to 24v transformer built in, for the purpose of stepping up, or stepping down the grid voltage when it is out of range.

you could easily harvest a few of these, put the 24v side in series with your incoming grid (effectively dropping the incoming down by 24v), and the 230v side in parrallel with your loads and solar inverter.
in fact given that this mode of operation is precisely how these UPS were designed to be used, you could likely use them as is, without dismantling.
how big is your hybrid inverter?

If you're able to push the grid voltage far enough out of spec, the grid operator will have to do something.
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Re: 3 phase outlet, what is suitable for EV charging?

Post by antiscab » Wed, 28 Aug 2019, 08:46

I actually saw this idea somewhere else, though for the life of me I can't find it. possibly silicon chip or autospeed
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Re: 3 phase outlet, what is suitable for EV charging?

Post by antiscab » Wed, 28 Aug 2019, 08:47

Matt
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Re: 3 phase outlet, what is suitable for EV charging?

Post by brunohill » Wed, 28 Aug 2019, 20:42

I think from memory that is an old technique called a bucking transformer. I am not sure the the power network would approve ( or the legality ) of me pushing the voltage in my neighbours houses over 260 volts deliberately ( even though they are allowed accidentally? ) I can use up to 10 kW in and allegedly allowed 3.5 kW out.

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