PIP-4048MS and PIP-5048MS inverters

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Post by weber » Tue, 02 Dec 2014, 21:07

Jeff Owen wrote:Actually, I understand that the dimensions of the monolith are 1.25 x 5 x 11 feet. Yes, the highly evolved aliens with superior intelligence use a measurement system that matches our imperial feet and inches, not the metric system that you so strongly advocate.

I am sure you are already reaching for your copy of the book to check this.

Yes. Let's turn this into the black monolith thread. Image

Sadly I no longer seem to have a copy of the book "2001" although I have "2010", "2061" and "3001". In "2010" page 131 it states that someone "confirmed the famous 1:4:9 ratio to six decimal places". So if the book "2001" also says that TMA-1 is 1.25 x 5 x 11 feet, then clearly those are only approximate measurements. If it had instead claimed it was 1.25 x 5 x 11.25 feet then I would concede that feet and inches are clearly a superior system of measurement used by advanced aliens and I would give up on this SI rubbish immediately. Image

But now lets talk about the monoliths in the movie. The dawn-of-man, moon and death-bed monoliths are clearly the same box made of black-painted plywood. You only need the two images below with their convenient floor grid, and a ruler, to show that while the large face is close to 4:9. The smallest dimension is far less than 1 in relation to them. It is more like 0.65.

Image

Image

If we assume the floor is a 3 foot grid then I get:
8.5 +-0.5 inches (~0.7 feet)
51.5 +-0.5 inches (~4.3 feet)
119.5 +-1.5 inches (~10 feet)

And when you see the hands of the people in ape-suits against the small dimension of the monolith, and scale off a typical adult human hand, 8 to 9 inches is right.

That's approximately a 1:6:14 ratio (nowhere near 1:4:9).

So apparently I'm making a book monolith, not a movie monolith.

But there's another monolith! The "crystal monolith" that Kubrick had made, but decided not to use. It resurfaced some years later as a natty gift for the woman who has everything.
http://www.ianvisits.co.uk/blog/2012/07 ... er-bridge/

The plaque shown in the article claims it is 0.67 x 5.75 x 10.75 feet. But the plaque is clearly unreliable as it also claims the monolith used in the movies was made of "black basalt", which is complete nonsense.
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Post by weber » Wed, 03 Dec 2014, 04:37

Some progress on the DC side. A possible layout. The 3 Hager 2-pole MCBs are standing in for the Noarks which haven't arrived yet.

Image

Image
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Post by weber » Thu, 04 Dec 2014, 02:10

I still haven't produced a complete schematic. It's partly because there's a problem I still haven't solved, as described below.

BTW, I measured the coil current of the Pulset MT2/40/12 contactors. It's 300 mA at 12 V (3.6 W).

All the contactor coils, and the IMU that controls them, will be powered from a 48 V to 12 V DC-DC converter. I'm assuming this DC-DC will be connected on the _load_ (i.e. inverter) side of the EV200 battery-isolating contactor (not the battery side).

This has the advantage that if the EV200 is shut off there is no load at all on the battery. So it will not slowly bleed to death due to the quiescent current of the DC-DC if the humans are away for a week or two. This seems an essential requirement.

But it has the disadvantage that there is no power to pull in the EV200 to get things started.

The IMU would only drop out the battery contactor if it found that it couldn't protect the battery by the preferred means, firstly by serial comms to the inverter, secondly by turning off either the load contactor or the charging-source contactors. Battery contactor dropout is the third and final sanction. So it's OK that it should require human intervention to recover from.

I also haven't figured out how to best use the emergency stop switch. This has independent NO and NC contacts (one of each).

Pushing the emergency stop switch could interrupt the power to (or from) the DC-DC so that all contactors drop out.

It would be great if the user could recover from an IMU battery contactor dropout simply by pushing the emergency stop button in and then releasing it. You have to twist it to release it. You probably know the type.

But I can't figure out how to make this happen. Any ideas?
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Post by T1 Terry » Thu, 04 Dec 2014, 03:07

What about 48v from the solar panels somehow connected to the 48/12 converter so the next solar day everything is powered up again yet free to drop out if the system requires a shut down. A diode in the battery supply side to the 48/12 converter so the solar can not bypass the control system and feed directly into the battery.

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Post by weber » Thu, 04 Dec 2014, 05:43

Thanks T1 Terry. But I'm still planning a 6P3S array, so nominally 72 V rather than 48.

I have a suggestion from my friend David Chaplin, by email, to add a 12 V battery charged off the DC-DC.

How about, instead of a battery, a capacitor, like this?

Image
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Post by weber » Fri, 05 Dec 2014, 23:34

I spent a few hours today disassembling and reassembling the monolith with new, correct-length verticals. Here I've taped a black bed sheet to it as a mock-up. The things we do for art. Image

Image
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Post by T1 Terry » Sat, 06 Dec 2014, 00:08

weber wrote: Thanks T1 Terry. But I'm still planning a 6P3S array, so nominally 72 V rather than 48.

I have a suggestion from my friend David Chaplin, by email, to add a 12 V battery charged off the DC-DC.

How about, instead of a battery, a capacitor, like this?

Image

If the battery has discharged to the point the relay drops out, won't the capacitor have discharged as well?

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Post by weber » Sat, 06 Dec 2014, 01:24

T1 Terry wrote:If the battery has discharged to the point the relay drops out, won't the capacitor have discharged as well?

Thanks for asking. It sounds like there are (at least) two things I didn't explain very well.

1. The EV200 contactor doesn't have to wait for the battery to get really low before it drops out. The IMU is, in this case, the BMS master, and will actively turn off the contactor when the lowest cell has maybe 10% charge left.

2. It was misleading for me to compare the capacitor to a battery. In this circuit, the normal state of the capacitor is completely discharged. It only charges briefly, in between the e-stop being released and the EV200 contacts closing.

As it charges, the voltage across the DC-DC input drops. The capacitor has to be large enough that the DC-DC supplies power to the IMU which supplies it to the contactor which pulls in before the voltage to the DC-DC input drops below the minimum at which it can work, which is 18 V.

But after email discussions with Coulomb, I'm leaning back towards just connecting the DC-DC input to the battery side of the EV200 and thereby eliminating any need for bootstrapping.

This does mean that the battery can eventually be destroyed by the quiescent current drain of the DC-DC, but I figure it would allow at least 8 days for human intervention. Is that crazy?
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Post by T1 Terry » Sat, 06 Dec 2014, 02:10

Drop the inverter at say 10% SOC but leave the solar connected, bring the inverter back in at say 20% SOC say there is a bit of room between the on/off cycling. We found the easiest way to cut the inverter was a small solid state relay controlling the on/off switch. There still is a small parasitic draw from the inverter this way but far less than the losses through a heavy contactor controlling the main DC feeds.

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Post by weber » Sat, 06 Dec 2014, 03:50

T1 Terry wrote:Drop the inverter at say 10% SOC but leave the solar connected, bring the inverter back in at say 20% SOC say there is a bit of room between the on/off cycling. We found the easiest way to cut the inverter was a small solid state relay controlling the on/off switch. There still is a small parasitic draw from the inverter this way but far less than the losses through a heavy contactor controlling the main DC feeds.

Yes, hysteresis is necessary when switching contactors, but I was thinking of it as being more like 1% charge rather than 10%.

I remind you that I wrote, in viewtopic.php?title=pip4048ms-inverter& ... 332#p54604:
"The IMU would only drop out the battery contactor if it found that it couldn't protect the battery by the preferred means, firstly by serial comms to the inverter, secondly by turning off either the load contactor or the charging-source contactors. Battery contactor dropout is the third and final sanction."

And I remind you that the PIP-4048MS is an all-in-one unit with PV and genset charging as well as inverter, so it is not possible to turn off only the inverter part, hence there will be a contactor to disconnect the AC loads.

So, turning off the loads (while leaving the charge-sources) might happen at 20%, and in the unlikely event that this wasn't effective (say the load contactor has welded) then the battery contactor might be dropped out at 10%.

And I note that the EV200 battery contactor has an economiser circuit which means it only uses 1.6 watts after the initial pull-in.
Last edited by weber on Sat, 06 Dec 2014, 15:03, edited 1 time in total.
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Post by weber » Sun, 07 Dec 2014, 07:39

David Chaplin came over today, and pretty much designed the layout you can see below, for all of the 35 mm² cabling, from the battery, through the DIN-rail double-pole fuse-switch (100 A, 22 x 58 mm fuses), the shunt and the EV200 contactor, to the inverter, and still left room for the DC-DC converter and the IMU in the same Hager 12 way enclosure. Thanks David.

The only way we could fit all that stuff in a 12 way box, given the bending radius limitations of 35 mm² cable, was to move the PV array circuit breakers and Minitactor to the 8 way box you can see above the 12 way.

Image

I note that the monolith has 3 battery shelves, each capable of taking 12 cells. So it can take double the capacity it has now, either as buddy-pairs or as two strings of 16.

Image
Last edited by weber on Sat, 06 Dec 2014, 20:54, edited 1 time in total.
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Post by T1 Terry » Sun, 07 Dec 2014, 11:50

weber wrote:
T1 Terry wrote:Drop the inverter at say 10% SOC but leave the solar connected, bring the inverter back in at say 20% SOC say there is a bit of room between the on/off cycling. We found the easiest way to cut the inverter was a small solid state relay controlling the on/off switch. There still is a small parasitic draw from the inverter this way but far less than the losses through a heavy contactor controlling the main DC feeds.

Yes, hysteresis is necessary when switching contactors, but I was thinking of it as being more like 1% charge rather than 10%.

I remind you that I wrote, in viewtopic.php?title=pip4048ms-inverter& ... 332#p54604:
"The IMU would only drop out the battery contactor if it found that it couldn't protect the battery by the preferred means, firstly by serial comms to the inverter, secondly by turning off either the load contactor or the charging-source contactors. Battery contactor dropout is the third and final sanction."

And I remind you that the PIP-4048MS is an all-in-one unit with PV and genset charging as well as inverter, so it is not possible to turn off only the inverter part, hence there will be a contactor to disconnect the AC loads.

So, turning off the loads (while leaving the charge-sources) might happen at 20%, and in the unlikely event that this wasn't effective (say the load contactor has welded) then the battery contactor might be dropped out at 10%.

And I note that the EV200 battery contactor has an economiser circuit which means it only uses 1.6 watts after the initial pull-in.

Please don't take offence if I question the system, just looking from the outside in to offer ideas that being to close to the build side can be overlooked.
What is the back up plan should either the inverter or IMU should fail? At the moment, if the IMU fails is all control lost? It may fail to safe as part of it's design but does that leaves the house without power? If the inverter fails is the house also without power or a charging system until a replacement inverter is installed?

My thoughts were along the lines of a fail safe to a secondary separate system, like the Victron BMV, and use the relay contacts to switch the inverter itself off by what ever means possible but leaving the charging circuit intact. The idea behind the 20% was enough capacity remaining to run refrigeration and emergency lighting via a separate back up inverter.

As a charging back up system, a simple cell voltage control circuit can act as both a secondary back up charging system and a cell protection system should the IMU fail, a second inverter can act as an emergency power supply for essential loads should there be a system failure.

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Post by weber » Sun, 07 Dec 2014, 15:34

T1 Terry wrote:Please don't take offence if I question the system, just looking from the outside in to offer ideas that being to close to the build side can be overlooked.
No offence whatsoever. I welcome your suggestions. I just wanted you to know (a) that the design was already, in effect, dropping the inverter but leaving the solar connected, and (b) why the specific method you suggested, (solid state relay controlling the on/off switch) while good in general, would not work in this case.
What is the back up plan should either the inverter or IMU should fail?
The backup plan is the standard one for off-grid power systems -- an internal combustion generating set. In this case, manual start.
At the moment, if the IMU fails is all control lost?
Yes. If it fails while leaving loads on, the user will eventually be alerted by the beepers on the top of all 16 cells.

Just a reminder to please consider trimming quotes back to the minimum required to identify what you are responding to, to avoid boring or annoying readers. For example, in the previous case, I suspect you could have left my quote out entirely.
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Post by offgridQLD » Tue, 09 Dec 2014, 17:09

"This does mean that the battery can eventually be destroyed by the quiescent current drain of the DC-DC, but I figure it would allow at least 8 days for human intervention. Is that crazy? "

Yes to me its crazy.... 8 days I'm sure a 8 day + absence from ones home isn't something out of the ordinary.

I know you have to draw the line at some point as you can never cover for every possible unforeseen chain of events. Though I think this ones isn't unforeseen. It's more or less a guarantee that if you have a LVD event you have a 8 day expiry date on you expensive cells if your not home.

The component layout looks nice and simple, tidy. How much heat will that dc/dc give off. Is it ok in the closed box?

Like the black sheet cover. Perhaps you can put that to use in the unveiling to the customer Black sheet drops away dramatic sound follow by a few gasps. Then a moment of silence befor the unit springs to lifeImage.

Kurt
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Post by weber » Sat, 20 Dec 2014, 23:35

offgridQLD wrote:Yes to me its crazy.... 8 days I'm sure a 8 day + absence from ones home isn't something out of the ordinary.

I know you have to draw the line at some point as you can never cover for every possible unforeseen chain of events. Though I think this ones isn't unforeseen. It's more or less a guarantee that if you have a LVD event you have a 8 day expiry date on you expensive cells if your not home.
OK. You and Coulomb have convinced me not to connect the DC-DC on the battery side of the battery contactor, despite the fact that measurement of the quiescent current when the new one arrived, showed that it would actually take more like 30 days for the DC-DC to discharge the last 10% of the battery capacity.

So I'll either be using the previously-posted capacitive bootstrap circuit, or Coulomb's suggestion of a green momentary push-button in addition to the latching red emergency stop button. The green button would simply replace the capacitor in the aforementioned circuit.
The component layout looks nice and simple, tidy. How much heat will that dc/dc give off. Is it ok in the closed box?
Good question. With the cover off, its surface temp is 25 degrees above ambient. This appears to be nearly independent of load, which is consistent with it being nearly all switching losses, due to switching at hundreds of kilohertz to minimise its physical size. The losses are only about 4 watts, so I think it will be OK.

An update on progress. I've had hands-on help from both Coulomb and BladeCar which is much appreciated. Thanks guys.

The monolith is currently powering my house, hoorah, with the mains fed in where the genset would go, and a 1.5 kW PV array.

It's all working fine. But so far it's all manually configured and the contactors manually controlled, not yet operating under BMS control. But Coulomb has translated the PIP CRC code to MSP430 assembler, and an optic fibre input has been added to the PIP, and the BMS has successfully sent a command to change the float voltage.

The float-at-76%-SoC idea seems to be working. With the PIP set for both bulk and float voltage of 53.1 V, yellow LEDs dance across the top of the cells as they bypass at 3.322 V per cell.

When they were around 80% to 95% SoC I could have sworn they were near-perfectly balanced, as they were all at 3.33x V. But it's just that this is an extremely flat plateau in the voltage vs. SoC curve. But when I let the SoC drop below that I saw a much greater spread open up between the cell voltages. Their "rested" or float voltages ranged from 3.30x to 3.32x V. And now the voltages are all together again at 3.28x V under light load, which corresponds to the 3.29 V (rested) lower plateau between about 45% and 65% SoC, as shown in this document:

http://www.cse.anl.gov/us-china-worksho ... %20BMS.pdf

So that little step at around 76% really is there, at least for my blue Sky Energy cells. It remains to be seen for the grey CALBs. Who knows, some new dopant might completely spoil this convenient float point.

I use 3.32 V and 76% SoC, not because it's midway between the two plateaux -- that would be about 3.31 V and 73% -- but because it's the point where the slope is steepest, and because it gives us more usable capacity. But it certainly does require the +- 3 mV accuracy that our BMS gives us.
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Post by offgridQLD » Sun, 21 Dec 2014, 01:17

That's great news that the PIP is powering your house for testing. This should give you some idea of what the AC side of the package is like to live with. I assume some load testing or at least to the extent it will be loaded in the customers home is in order.

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Post by weber » Tue, 06 Jan 2015, 06:03

A lot has happened with the Monolith since the installation of the "sanity-savers" in the PIP (the quiet fans blowing upward). Coulomb has been giving me lots of help. But I can't afford to take much time to write about it, as the poor customer is still waiting.

Here's a photo of the two switchboards to the right of the PIP, which are finally complete. They are both DC switchboards. The upper one is at PV array voltage (MPPT-range 60 to 115 V, 6P3S x 72-cell modules x 195 W) and the lower one is at battery voltage (nominally 48 V, 16 x LiFePO4 cells x 180 Ah).

Image

The lower switchboard also contains the BMS master in the upper left. It's a modified version of the current and insulation monitoring unit (IMU) used in the MX-5, which is itself a modified cell monitoring unit (CMU). Its two reed relays, that were used for insulation testing, have been replaced by two large MOSFETs that are used to control two sets of contactors having 12 volt coils.

The two sets are "source" and "load". In fact there is a third set "battery" which doesn't need its own MOSFET since it is diode-ORed from the other two. So it is on whenever either of them are on. Or putting it another way, you have to drop out both sources and loads before the single battery contactor (a Kilovac EV200, middle left of Battery switchboard) will drop out.

Of course the point of all these contactors is to be able to protect the battery under conditions of over-charge and over-discharge.

The source contactor set consists of the genset contactor (Pulset 40 A 2-pole) in the AC switchboard to the left of the PIP (not shown) and the PV array contactor (a Gigavac MiniTactor) on the right of the PV array switchboard (shown).

The load contactor set is entirely in the AC switchboard and consists of a changeover relay feeding 12 V to the coil of one or the other of two Pulset 40 A 2-pole contactors, making a virtual 40 A 2-pole changeover that powers the household AC load from either the inverter or the (manual start) genset (if it's going).

The battery fuses (22x58 mm, 100 A) are on the right, and you can see, alongside the negative battery cable below them (35 mm^2), an optic fibre goes from the right side of the IMU to CMU #1. Alongside the positive battery cable a fibre comes back from CMU #16 to the left side of the IMU. You can't see it in the photo but there are two fibre outputs on the right of the IMU. The other one goes to the PIP in between the two PV array cables (13.3 mm^2, 6 AWG).

The IMU senses the voltage across the current shunt (fine twisted pair) and it senses the open-circuit array voltage, between battery positive (from the left side of the shunt) and PV array negative (from the lower right of the MiniTactor). This is so it can protect the PIP from array open circuit voltages above 145 V which are possible in winter at dawn, before the panels have had a chance to warm up.

The IMU, and through it, the coils of all the contactors, are powered from the DC-DC converter in the middle of the battery switchboard (48 V to 12 V, 30 W). This uses 13 watts continuously to power all the contactors. It only needs its full power briefly while pulling in the EV200 battery contactor.

The circuit board at the bottom left of the battery switchboard was built by Coulomb on Sunday. It contains the 48 V bootstrap circuitry that allows even the DC-DC to be disconnected from the battery in an emergency shutdown, whether triggered by a human via the emergency stop switch, or by the IMU. In order to start up again (which requires a human to release, or push and release, the e-stop switch) the DC-DC needs to be briefly powered directly from the battery, for long enough for it to power the IMU, and through it the battery contactor, thereby latching itself on.

It uses essentially the capacitor/diode bootstrap circuit shown a few messages back, with some rearrangement and the addition of two 1.25 A 100 Vdc fuses to protect the 3-wire cable going (upward) to the e-stop switch.

So from now on, it's all about implementing, in the IMU software, all the required battery protections.

For a week now we've had PI control of the PIP by the IMU, in response to individual cell stresses, while charging from either AC-in or the PV array. That was by far the hardest part of the IMU software. Thanks for all your help with that, Coulomb, both writing and debugging.

Second in difficulty was a bug that cost me a whole day recently. It had apparently been lurking for years in the code written for the MX-5, just waiting for someone to decide they needed to lower the BMS "heartbeat" to 2 Hz. It is currently 15 Hz in the MX-5 and has never been lower than 4 Hz. There is a single timer which is used for both serial comms timing and the cell-status heartbeat, so there is some interaction between the two. I have no time to get to the bottom of why it didn't work with the original start-bit setup-time formula, but adding one to it fixed the problem.

Ah well. That's (software-engineering) life.

[Edit: Improved grammar and punctuation. Added link to battery-contactor bootstrap schematic.]
Last edited by weber on Wed, 07 Jan 2015, 08:35, edited 1 time in total.
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Post by weber » Fri, 09 Jan 2015, 23:20

Here's the AC switchboard that sits to the left of the PIP inside the monolith. It isn't quite finished yet. There are two more items that need to go into it. One is a kilowatt-hour meter. The other will be left as an exercise for the reader, after I explain the problem. Image

Image

The orange circular cables at the bottom are AC to and from the PIP inverter/charger. The two on the top are from the genset and to the main AC switchboard. All are 4 mm^2. The black cable on the bottom right carries +12 V and 0 V and two switched 0 V signals from the IMU, to control source (genset) and load contactors if necessary for battery protection.

From the left: The 25 A MCB protects and isolates the outgoing cable to the main switchboard. The next 3 items are 40 A 2-pole normally open contactors (Pulset MT40s). They switch both active and neutral since they are switching alternative sources of supply. The leftmost switches the genset to the inverter/charger's AC input.

The two rightmost contactors form a pseudo-changeover contactor that chooses whether the loads are powered from the inverter output or the genset. Only one of them is operated at a time thanks to their coils being fed 12 V from the single-pole changeover relay on the far right (a Hager EN145). I did this because I couldn't find a real 40 A changeover contactor with a 12 V dc coil.

That problem I mentioned: When you hit the big red stop button, neither of those contactors gets any 12 V, because the battery is disconnected and so the DC-DC that produces the 12 volts is un-powered, and my pseudo normally-closed contacts from the genset are a very poor pseudo indeed. This means the customer can't run their house off the genset as intended, when the monolith is shut down (whether for maintenance or due to a fault).

I have a solution, but I thought I'd let you think about it for bit before I reveal it. Image Maybe someone will come up with a better one.

BTW, in the above photograph you can also see the black optic-fibre connector at the bottom of the PIP, with its black fibre going off to the right and curving down. It was easy to connect this photo-transistor as the PIP already had an input optocoupler there. We only had to solder our fibre photo-transistor in parallel with that of the opto, and hold it in place with some silicone.
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Post by weber » Sat, 10 Jan 2015, 05:07

Here's a scruffy looking wiring diagram for the Monolith's AC switchboard, as shown in the photo in my previous post.

Image

I forgot to point out that there's a barrier made of 1 mm clear Polycarbonate (difficult to see in the photo) that separates the 12 Vdc wiring from the 240 Vac wiring.
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Post by neilg » Sun, 11 Jan 2015, 00:58

"That problem I mentioned: When you hit the big red stop button ..."

Can I suggest a simple solution: A 12v plugpack running directly off the genset output - battery connected or genset running = 12v!

Neil

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Post by weber » Sun, 11 Jan 2015, 01:05

I needed to put that wiring diagram up so my electrician friend had something to keep his mind occupied. Image

He soon made me realise that "INV AC IN" and "INV AC OUT" are rather ambiguous terms. They are intended to refer to the terminals as named on the inverter. So INV (AC IN) rather than (INV AC) IN. The arrows (for direction of power flow) help disambiguate.

He was understandably concerned about the possibility of live exposed pins on the 15 A caravan-style inlet for the genset. But now agrees that the only way that could occur is by contact welding. I did some reading on that and it seems there are only two ways contact welding can occur:

1. when the contacts close between a low impedance source and a capacitive load (or other load with a high inrush current such as a DOL Induction motor, or another source which is out of phase, or a short-circuit), i.e. an extreme current occurring before full contact pressure can be established, and

2. when they open and immediately reclose, while powering an inductive load, i.e. reclosing while arcing.

Regarding case 1: The two sources (genset and inverter) are output current limited to less than the 40 A contact rating.

Regarding case 2: I will ensure, in software, that the contactors cannot change state more often than once every 2 seconds (or maybe 5 seconds).

He also pointed out that it needs a 16 A breaker for the genset inlet, so a more powerful genset cannot be used.

Thanks David.

In regard to the problem I mentioned earlier, where the Normally Closed contacts of my pseudo double-pole changeover contactor are not really normally closed, but annoyingly go open when the battery is disconnected, and thereby prevent the genset from powering the loads:

My dirty deed of a solution is to use one of these AC/DC modules, done dirt cheap at $11.50 for 5 watts.Image And power it from the genset input, to provide an alternative source of 12 volts to the changeover relay contacts, with a diode in the negative leg of each 12 V source ("GND" on the wiring diagram, not to be confused with Earth).
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Post by weber » Sun, 11 Jan 2015, 01:11

neilg wrote:Can I suggest a simple solution: A 12v plugpack running directly off the genset output - battery connected or genset running = 12v!

I'm glad someone posted a solution before I posted mine. Image

And yes, that's essentially what I'll do. Thanks Neil.
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Post by coulomb » Sun, 11 Jan 2015, 02:34

Or, of course, use an actual changeover contactor [ edit: actually, this is a relay ], like this one:

Image

From Ali Express.

Of course, I'll be the first one to admit that finding something on Ali Express or similar is not the same as being able to actually buy just one.

Plus, of course, it's most convenient to have a DIN rail mountable contactor that looks as though it might last.

It might have been wise (in hindsight) to design what is now the 12 V section to be 24 V. Industrial gear tends to be much more available at 24 V.
Last edited by coulomb on Sun, 21 Jun 2015, 04:41, edited 1 time in total.
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Post by weber » Wed, 14 Jan 2015, 21:34

Well found Coulomb. And yes, I think the next monolith will have 24 V contactor coil drive. The only annoyance is, the MOSFET drivers will still need a 12 V supply.
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Post by coulomb » Wed, 14 Jan 2015, 21:54

weber wrote: The only annoyance is, the MOSFET drivers will still need a 12 V supply.

I use TC4431 drivers on a project at work. 24 V drivers, max 30 V.

These are the DIP equivalent, inverting:

http://au.element14.com/microchip/tc443 ... dp/1852208
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

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