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Forum Index : Electronics : Nano Power Inverter - Roll Your Own Style

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wiseguy

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Joined: 21/06/2018
Location: Australia
Posts: 474
Posted: 08:22am 31 May 2020
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  Warpspeed said  One thing to consider when connecting L1, L2, and L3 in parallel is that all of the combined return current then flows back through the same common neutral.

You have three twenty amp phases, plus a twenty amp rated neutral.
So the total power must be limited to twenty amps total, or you could potentially burn up the neutral.

The neutral has no fuse or circuit breaker over current protection, so its a potential hazard to be aware of.


You are quite correct Tony, when I had the extra 3 Phase outlet fitted I was thinking unidirectional (feed  only) and 10+KW for bench testing stuff seemed more than adequate.

But my thoughts began to wander "what if the power goes out tonight, how could I easily utilise the inverter power for the house" ? - I know, I'll use my new 3 phase connection along with gee I wish I had put in 32+A cable  .

I'm contemplating installing a contactor in the main switchboard to accomplish an automatic changeover.  I can use the nano phase compare to keep in step with the mains so it minimises any upset when this occurs.  Maybe I could just run a suitable rated single phase cable back to the switchboard if the inverter stays in my workshop and common up the phases at the contactor.

The last detail to be worked out is how to ensure the 3PH solar inverter never tries to feed my inverter and always has the mains supply (if its available) to dump power to.
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
wiseguy

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Joined: 21/06/2018
Location: Australia
Posts: 474
Posted: 07:21am 01 Jun 2020
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  noneyabussiness said  fuse holder

Proper dc rated fuse holder..

fuses

Fuses...


  renewableMark said  
Re the start up procedure, it's no big deal having to pre charge. I have the same setup on my house and van  units. The house one obviously just runs 24/7 and never gets turned off.
The van one I just leave going on stand by. All it's doing is keeping the caps charged, which is bugger all energy requirement. When the unit is required, just a quick press of the momentary button starts up the control board and it's going in a couple of seconds.
That saves mucking around with the pre charge.

Re the phases, would it be possible to wire all the house requirements onto one phase? and then have an Auto changeover switch between the grid power and your inverter.


Noneya, thanks for the fuse & fuse-holder info. Are the fuses rated for DC - they looked to have a ~ next to their current.  Not being picky but I have seen first hand the results of a >50V DC ARC and it was scary, they appear to be ceramic which would be a plus.

Mark, yes I agree that once powered up the pre-charge is not an issue but in this testing phase where it is on and off multiple times, you need to keep well focused on what sequence you need to meet.  Re-Wiring the house would work but I want to try to avoid that and work with what is - a contactor that links all phases after disconnection from mains should work ok.
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
noneyabussiness
Senior Member

Joined: 31/07/2017
Location: Australia
Posts: 265
Posted: 11:37am 01 Jun 2020
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Unsure of where the ~ is, however i have been assured by a reputable friend these are more than needed. And have worked twice now with accidental shorts with no bang / flash personally.
I think it works !!
 
wiseguy

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Joined: 21/06/2018
Location: Australia
Posts: 474
Posted: 12:29pm 01 Jun 2020
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The ~ is the little mark next to the 500V ~ & 600V ~ with their associated fault current interruption ratings (120kA & 50kA ?) .  The Main current rating ie 150A does not appear to indicate AC or DC.  I do accept that they have worked ok with DC without disaster.
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
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