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Author Topic: Grid Hopping  (Read 87833 times)
jonesy
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« Reply #30 on: September 16, 2015, 11:19:31 AM »

Well, I looked at the manual and the default NE relay setting is off.  I suppose you could install another transfer relay before your own transfer relay and put the NE link there.
The RCD thing is to do with how RCDs operate.  The AC/A type use a coil with L & N threaded through and any current difference will be detected by another winding. If your high frequency/transformerless inverter puts a bit of DC onto the AC supply, which can be under normal operation, this DC interferes with the RCD coil and generally they won't trip if they detect an AC fault. A type B RCD typically has a hall effect device to detect/ignore the DC and will carry on working ok. Manufacturers of HF inverters try, by design, to prevent DC appearing on the AC terminals.  SMA  do this (it's in the manual IIRC), so a normal type A/AC RCD is fine.  I've never looked, but I'd think type B are bit pricey, just like 100mA time delay for TT systems. I did a word search for RCD in the mastervolt manual, but they don't give guidance on the RCD.  Probably worth an email.
The 6 odd transformers you have will probably be HF converting the 48V to 400V, amongst other things.
I had a squint at the rs232 and re-read your post.  You need to connect the 0v/Vcc on the max chip, otherwise it won't work.  The easiest way to test the max232 is as I posted before.  Give it some juice, plug into the pc, and link the rx/tx that would have gone to the mastervolt.  Find the com port on the pc (device manager) and use realterm or putty to open a rs232 session on that port.  Type a bit and the characters should appear on the screen.  Remove the link and the characters stop.  Job done, close realterm and plug into the mastervolt and use their software. If their software can't detect the inverter, swap tx/rx on the inverter.
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1.1kWp PV & SB1700. 7kW log burner.
Nickel2
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« Reply #31 on: September 16, 2015, 01:27:25 PM »

Hi Jonesy.
 Purely as a matter of curiosity; I know RCDs rely on a L/N current balance/imbalance to trip, how does injected/unwanted DC stop them working properly? I can understand that a wave-shape difference between the positive half of the waveform and the negative half could cause a residual DC effect, but would that be enough to cause a problem? Core saturation or something like that?
 Smiley The more I know, the happier I am! Smiley
N2
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1.140kW mono south-facing at 49*
EpEver 4210A at 24v
New (Old) 8S7P LiFe battery, 105Ah @ 26.4V
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
jonesy
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« Reply #32 on: September 16, 2015, 04:15:06 PM »

Yes. Saturation.  There is a nice description here http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=59058 , copied below
ALL RCDs will trip with a normal resistive fault between L and E, but the more common ones use a current transfomer, which can become magnetically saturated and locked out if there is DC present.
So a fault in a system with rectifiers with a fault between the wiring after the rectifier and ground, may inject only a single sided fault current, and as real transformers don't do DC, the fault will not cause a trip if is a well smoothed DC, and the fault came on gently, and worse, this DC may also saturate the iron core, and reduce sensitivity or even prevent it responding at all to a normal fault.

So now, to combat this we add a hall effect sensor to the design, instead of the secondary winding of the current transformer core, now the trip can be made to respond to any uni-polar magnetisation of the core in the RCD, as well as just changing 50Hz component. Then there are various degrees of either friskiness or delay to the responses of the DC and AC parts to accomodate high frequency pulses, and either ignore or respond to switching transients as desired.

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Nickel2
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« Reply #33 on: September 16, 2015, 07:29:41 PM »

Cheers Jonesy, more Nollij.
I had never really considered a DC component in an AC imbalance trip.
Article read and understood, ta. (scratches head and tries to remember 40 years ago college stuff on magnetism. Exams passed, stuff forgotten.)
N2.
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1.140kW mono south-facing at 49*
EpEver 4210A at 24v
New (Old) 8S7P LiFe battery, 105Ah @ 26.4V
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
jonesy
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« Reply #34 on: September 29, 2015, 09:56:02 AM »

...if you want to install an RCD on the shortbreak output you should not make a fixed connection between N and PE
Well, that's correct, as a fixed link at the output would/could change the shore earthing scheme. As PME isn't permitted to supply a boat, you'd be creating a dangerous situation and in any event, IIRC PME only permits E & N link at the supply/source.

The house is always earthed, so the main risk if the NE relay link fails to make on inverter supply is that the output side RCD fails to operate under fault. ie you want TN-C-S (PME), but the system degrades to (floating) IT without warning. RCDs can fail to operate correctly without a path to earth. A RCD is inadequate to protect IT systems.
I experienced something close to this when I was on a TT supply. It was a hot summer & I lived on granite, about 200m from the supply transformer.  The leccy board had replaced some overhead lines. The day after I was installing a new socket when I realised N was live WRT earth. I rang and suggested they had a problem. They were there in minutes and confirmed the fault. L & N had been reversed. Then the guy decided to trip my incomer. The supply L became live again. A check showed I had a full L/E fault, but the RCD didn't trip as there was no earth path ie there was no earth return through my earth rod to the transformer due to the dry conditions, basically giving me an IT system. The L/E fault was swarf on a pattress box screw head piercing the L insulation.
You'll need to draw this out to check it, and ask mastervolt another question.  You must state you are in a house! If you link the incoming and outgoing N and disable the NE relay, that will mean the house earthing scheme is reflected to the inverter side?  I'm pretty sure that's what APC do.
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Nickel2
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« Reply #35 on: April 29, 2016, 06:47:26 PM »

Your 'Ah' meter sounds like a register of disappointment, as in - (looks at solar production) 'Ah'... Grin
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1.140kW mono south-facing at 49*
EpEver 4210A at 24v
New (Old) 8S7P LiFe battery, 105Ah @ 26.4V
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
Nickel2
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« Reply #36 on: April 30, 2016, 07:39:16 PM »

I've just forked out for an 'Epever' 4210A Tracer unit plus MT50 box-thing. It has a RJ45 coms port with software that allows you to monitor most of it on your PC.
(Mods please remove if not liked  fight ) I have been planning for a long time, it all may happen before I snuff it. No panels or battery bank yet, I'm still watching flea-buy for suitably affordable stuff. I've just run 60+ feet of cat5e out of the kitchen door to the shed to try it out on a pair of old sealed batts.



Hopefully I'll get some panels soon!
« Last Edit: April 30, 2016, 08:07:42 PM by Nickel2 » Logged

1.140kW mono south-facing at 49*
EpEver 4210A at 24v
New (Old) 8S7P LiFe battery, 105Ah @ 26.4V
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
Nickel2
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« Reply #37 on: May 01, 2016, 01:26:41 PM »

At the moment I'm still playing learning how to set it up. In the battery options it has Sealed, gel, flooded and user specified. I assume ( whistlie) that it has the SOC/voltage/temperature curves programmed in for the various type of battery. You can manually alter the other charge-conditions if required. The batt-temp shown defaults to 25c when there is no temp-probe connected. The batteries were at about 11c when that screenshot was taken.
The monitor indicates about 0.05V low compared to my Fluke 75 DVM, so I have reasonable confidence in the device's measuring accuracy. I have still to find out if my confidence is justified. The 4210A is the low-volt, indoor spec model of the tougher 'shed' model.
These units appear to be new this year (or late last year), internet reviews seem favourable.
Edit time:
Further play investigation shows that the 25.3 volts in the field shows that I have entered a maximum DOD for my system of ??%, and that 25.37 is the voltage for that DOD according to which type of battery and what temperature etc. The actual real-time volts and current read across the window in the battery bit, unlike down the window in the PV panel bit. Something to do down Chinese inscrutability?
« Last Edit: May 01, 2016, 02:31:59 PM by Nickel2 » Logged

1.140kW mono south-facing at 49*
EpEver 4210A at 24v
New (Old) 8S7P LiFe battery, 105Ah @ 26.4V
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
Mostie
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« Reply #38 on: August 21, 2016, 02:48:12 PM »

its good to find stuff thats allegedly broken.... but actually isn't   Grin
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2x Solis PV = 1.875 kW, Mitsubishi inverter heat pump. Yorkshire Boiler Stove.
biff
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« Reply #39 on: August 22, 2016, 12:49:18 AM »

all very strange,
           you can buy a brand new c40 xantrex for less than 120 euros.
               why would you bother with that
                           biff
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camillitech
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« Reply #40 on: August 22, 2016, 06:55:35 AM »

Nice find Scruff,

I bought one off Clockman a couple of years ago and swapped it out for a TS45. Normally I wouldn't have bothered for myself but it was as a gift for a mate who let us stay in his house. His 'off grid' PV was maxed out and he'd no more room for panels. The MPPT certainly was an improvement over the PWM, which I kept and used in 'diversion mode', have 5 of them, great bits of kit.

Paul
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'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 9kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
Tombo
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« Reply #41 on: February 20, 2017, 05:05:47 AM »

Neat. I only learned you could you a regular led as a photo sensor the other day.  Nice to see a practical application so soon.
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camillitech
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« Reply #42 on: February 20, 2017, 06:54:24 AM »

Yes, nice work indeed Scruff, is the TriStar using anything much when it's singing? Can you use another cell to actually switch it off when it's dark?

Cheers, Paul
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 9kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
camillitech
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« Reply #43 on: February 21, 2017, 06:39:48 AM »

Nice find the wee Studer Scruff  Cool
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SMA SI6.OH, 800ah Rolls, 9kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
biff
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« Reply #44 on: February 21, 2017, 11:03:39 AM »

Great posts Scruff,
               Addictive to say the least.
 Best wishes with your man cave. I see old traces of fume leaks in the stack. Would hardly matter if you were just popping up to store something up there but if you were actually working up there for prolonged periods of time, you might start getting headaches and maybe worse, especially if you clad the ceiling and down to the purloins. You would not have to have a fire on your own side but the fumes could leak through the stack from the other side. A little investment in a carbon monoxide alarm would be very worthwhile. (even if you fit a velux.).
 I see 4 flues in that stack. It is not the original one but more than likely repaired after WW2 by that famous company called Bodgitt and Legitt.
                                                                   Biff
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