Portable generator

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Post by photomac » Sun, 04 Aug 2013, 17:07

Is there reason not to use a portable generator (other than GHG emissions) to recharge a LEAF?
Yes,   we can.   Image
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Post by acmotor » Sun, 04 Aug 2013, 19:27

photomac wrote: Is there reason not to use a portable generator (other than GHG emissions) to recharge a LEAF?


None at all technically, if you do it right.
There are numerous threads on forums about this. Not all good advice. Even some here will be challenged by 'arguers of the point'Image.

To do it properly....IMHO

A few points real world tested on my iMiEV ....

Most generators, while having a 3 pin plug, do not earth the neutral pin. (connect earth pin and neutral pin)
To get the EVSE to accept generator power, the neutral and earth must be connected prior to the EVSE otherwise the power will not pass the 'is earth connected to neutral' test that an EVSE makes to ensure earth leakage detection can actually work. (you can't detect earth leakage without connecting to earth).
This can be done as a hard connection (correct method) or via a resistor. I've heard of values between 1k and 100k actually working .... but this is not the Electrical Standard way to do it.
This connection also applies to DC to AC inverters.

There are other topics including 'earth stake' for generator.
EV is considered an 'appliance' in Electrical Standards. It cannot be considered double insulated as clearly there are human contact metal/conductive surfaces. As such, the earth stake principle should be followed. There is more to this topic. Don't get hung up on earth vs ground words. Understand what is going on.

edit: Publications like this    p 47 may help. Notice the MEN connection has to occur somewhere.
edit: Earthing of the generator is also discussed earthing gens

The generator must have reasonably clean sine wave power without too many harmonics otherwise EVSE / EV will reject the power and flag a fault.
Keep in mind the EVs run extensive power factor correction circuits and these may potentially be damaged by say 'modified square wave'.

The generator power rating must be REAL !
If the EV draws 2.2kW for instance, this will be without any surges, smoothly ramped up by the charger and with power factor close to unity. (better than .97 most likely).
Just simply, with AC power, the current and voltage sine waves will not align in time (phase) when operating inductive or capacitive loads. (e.g. motors and power supplies as respective examples)
The degree of the misalignment and its effect on power is termed the power factor. Unity pf (1) is desired and appears with a resistive load, or a well engineered battery charger. Unity power factor produces the most efficient operation by reducing current for the same power.

Most generators are rated in kVA assuming pf 0.8 and thus their kW (actual power) rating will be kVA x 0.8   This does mean that you can not draw the kVA number in kW. e.g. a 3kVA generator may have 2.4kW power available. (this is typically the power of the ICE motor x alternator efficiency as an absolute maximum)
Further to that, most generators will have a standby or intermittent power rating that may be 30% more than their continuous kW rating.
Look for these details on the generator or handbook or net.

It is really hard work for a 2.4kW (continuous rated) generator with a healthy ICE motor, fresh fuel and good ventilation to charge an EV (like the leaf etc, using the portable EVSE at 2.2kW).
The load is continuous, for hours. Overheating may be the biggest risk.

50Hz vs 60Hz ..... EV chargers accept both.
In the case where generator kW is marginal...
It can be useful to run the generator at 60Hz as the ICE motor power is higher at 3600RPM (60Hz) than 3000RPM(50Hz) and that reduces the ICE motor load. This doesn't apply to inverter style generators that already change RPM depending on load.
A down side with an inverter generator is that the ICE may run at 5,000RPM + under heavy loading. This may limit life expectancy ?

Inverter generators are best in power quality and power to weight.
Traditional generators have ICE motor and 50 or 60Hz alternator. The motor RPM is locked and the iron core of the alternator weight is large, paricularly at 50Hz.
Inverter generators run the ICE motor at variable speeds and use a higher frequency alternator (400Hz ?) that has better power to weight than 50Hz alternator. AC is rectified to DC, put across capacitor bank, H bridge pure sine circuit produces 50Hz AC from this DC store.
The 50Hz is accurate and not ICE RPM dependent so ICE can relax RPM if there is lower kW loads.
Inverter generator can also start high surge devices like aircond motors using the capacitor bank storage. Traditional generators struggle with high start current loads. (EVs are not high start current though)


Having petrol fumes inside an EV while carrying a generator can be a down side.

Best choice...
A 'silenced' plastic case inverter generator with a couple of hours fuel tank. Electric start is useful though adds weight (battery).
e.g. ebay 4.4kVA inverter gen
This is a '4.4kVA' gen with 3kVA actual power so at 2.2kW would not be being thrashed.

My 2 bits worth. Image
Last edited by acmotor on Sun, 04 Aug 2013, 10:39, edited 1 time in total.
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Post by photomac » Tue, 06 Aug 2013, 21:53

acmotor, thank you very much for a detailed response. I was aware of just a few concerns that you pointed out, but to have it all together is very very useful! Thank you Image
Yes,   we can.   Image
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Post by acmotor » Sun, 18 Aug 2013, 08:23

Glad the info helped. Image

Just FYI here is an inverter gen charging an iMiEV.
The gen is rated at 3.7kVA in advertising and actually labelled 3.2kVA.
It will not supply 3.3kW in testing (max iMiEV or Leaf charge). It shuts the inverter off after nearly stalling the ICE.

Image

Image

The gen can supply 2.2kW (10A nominal charge rate) at less than max motor RPM. Actually seems comfortable at that continuously.

Image



Image
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Post by antiscab » Mon, 19 Aug 2013, 20:23

hey I have one of those gen sets sitting in my shed - inverter failed and won't start though.....
Matt
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Post by Richo » Mon, 19 Aug 2013, 21:24

acmotor wrote: Even some here will be challenged by 'arguers of the point'Image.
I hear ya Image
acmotor wrote:Most generators, while having a 3 pin plug, do not earth the neutral pin. (connect earth pin and neutral pin)
To get the EVSE to accept generator power, the neutral and earth must be connected prior to the EVSE otherwise the power will not pass the 'is earth connected to neutral' test that an EVSE makes to ensure earth leakage detection can actually work. (you can't detect earth leakage without connecting to earth).


I'm not disagreeing with your point.
But an RCD can measure the leakage(anywhere) current directly and doesn't require an earth for correct operation.
eg the current going into a circuit through the Live wire must return through the Neutral wire.
Any "leakage" will be seen as a differential.
Just remember this doesn't imply you should disconnect your earth Image
So the short answer is NO but the long answer is YES.
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Post by offgridQLD » Mon, 19 Aug 2013, 23:55

The other day I was thinking to myself from a cost point of view. How much Diesel I would consume if I charge my imiev from our 8.8kva kubota J108 diesel generator? Not that I plan to do this as my charging method.

I was doing the comparison between driving our Isuzu dmax diesel 4wd ute that consumes 8lt/100km and how much diesel I would burn to charge the I-miev from a diesel generator to drive 100km.

I only had rough numbers from the user manual of the generator but I will test and confirm consumption. From memory it worked out to 6.4lt/100km.

Going from the user manual the 37lt tank will last 11.5hr at full load (8kw true output) 37lt/11.5hrs = 3.2lt - hr x 2 hrs for 16kwh = 6.4lt to charge a Imiev battery from empty to full. I know more than 100km is possible from a full imiev battery but I just rounded down to 100km to cover for charging inefficiency.

I will need to try it for real but it just shows how efficient the i-miev is. This assumes you are able to charge at 8kw and I'm sure the efficiency of the generator would be less at 3.3kw load but I wouldn't be surprised if it was still less diesel burned than driving the Isuzu at 8lt/100km.

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Post by acmotor » Tue, 20 Aug 2013, 06:19

Richo,

Earthing and RCDs is all about a CIRCUIT.
Leakage current (and your ability to detect an earth fault) relies on a CIRCUIT to exist so there must be an earth and an earth current flow to operate an RCD. i.e. an unbalance betweeen the A and N current caused by a current flowing to earth from A and not all returning via N.

Without a circuit you can't measure leakage current. Well, there will be no leakage current for the first (fault) connection despite an unsafe condition being created.
I remember early days of EV discussion where folk imagined it was possible to measure earth leakage with a totally isolated battery pack.
Can't be done. You can detect the SECOND connection to earth having now formed a circuit, but the first connection you must make yourself with some form of earth reference.
This can be a hard connection or a resistive connection and is often the centre of the battery pack or the joining point of a resistor from each end of the pack that happens to equal the centre of pack voltage.

I don't want to open that old topic again. There was so much misunderstanding out there about the need for an electrical circuit to exist !
Domestic electrical wiring requires a hard earth connection. Enough to blow a fuse/trip CB. An earth leakage fault needs to flow a current in excess of 30mA to trip an RCD so a high resistance earth to neutral or a floating system would leave an earth leakage unable to be detected/tripped by a domestic RCD. That being part of this thread.



Kurt, that Kubota diesel gen is what 390g/kWh ? Diesel is close to the SG of 1 say. So 390ml/kWh. Not that low for a diesel gen ??
A good diesel gen should be under 300g/kWh and typical modern gens around 200g/kWh e.g. Perkins/Stamford GDP8 (8kW) 190g/kWh

That aside....

If the i is 135Wh/km then 100km is 13.5kWh so 13.5 x .390 litres = 5.2 litres. ( 5.2 litres/100km of diesel ) Not bad.

This assumes the gen runs at around 390g/kWh at 2.2/3.3kW load. Maybe 25% worse at part load. No problem, just get another iMiEV to charge at the same time. Image

On a 190g/kWh genset the i would be 13.5 x .19 = 2.6 litres/100km !!

This probably points out the efficiency of the little i as much as anything. Well, particularly wrt an 4x4 ute ! Image
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Post by offgridQLD » Tue, 20 Aug 2013, 13:50

Searching some more on the Kubota web page they rate it a 3.1 L/h at full load (8kw). So 387ml- kwh .Using 135wh/km as the imiev consumption works out to 5.2lt/100km.

Efficient home based generator + Imiev as basically a Separated hybrid. At 2.6lt / 100km It sure is a simple package. The consumption is always going to be better than dragging the generator around with you all the time.

That said if things could be tweaked so charging while driving was possible. I think with a tiny little motorbike style trailer in tow you could match or do better than some of the OEM hybrids fuel consumption numbers.

Kurt
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Post by acmotor » Tue, 20 Aug 2013, 17:57

Yes, there is much pondering.
A when occasionally required charge trailer is perhaps an option. I had thought that the trailer should drive its own wheels under towing vehicle control thus bypassing two further energy transfers (generator and emotor) and thus ensuring max efficiency.

Still, an improvement in battery capacity and charging that battery off renewables is a better focus.
Remember that (IMHO) a hybrid is neither a good EV nor a good ICE.
Towing a trailer in itself costs energy.    Image
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Post by Johny » Tue, 20 Aug 2013, 17:59

Does the iMiev have a towbar option?

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Post by acmotor » Tue, 20 Aug 2013, 18:10

No towbar option and one is not recommended by mitsi. (a bit like prius, leaf, volt)

There are folk in the US with aftermarket towbars fitted. imiev forum - trailer hitch
Technically there is no reason though. The big question would be the load capacity. Perhaps up to 300kg trailer is realistic.

Reduction in range would be a big concern for some.

Maybe a concern from mitsi would be that folk would expect a 1200kg capacity !

Clarification from mitsi and warranty situation should be sought.

edit: I'd want an aluminium tow bar with all up weight <10kg without a 1kg brass tow ball !
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Post by weber » Tue, 20 Aug 2013, 18:46

acmotor wrote: Richo,

Earthing and RCDs is all about a CIRCUIT.
Leakage current (and your ability to detect an earth fault) relies on a CIRCUIT to exist so there must be an earth and an earth current flow to operate an RCD. i.e. an unbalance betweeen the A and N current caused by a current flowing to earth from A and not all returning via N.

Without a circuit you can't measure leakage current. Well, there will be no leakage current for the first (fault) connection despite an unsafe condition being created.
I remember early days of EV discussion where folk imagined it was possible to measure earth leakage with a totally isolated battery pack.
Can't be done. You can detect the SECOND connection to earth having now formed a circuit, but the first connection you must make yourself with some form of earth reference.
This can be a hard connection or a resistive connection and is often the centre of the battery pack or the joining point of a resistor from each end of the pack that happens to equal the centre of pack voltage.

I don't want to open that old topic again. There was so much misunderstanding out there about the need for an electrical circuit to exist !
Domestic electrical wiring requires a hard earth connection. Enough to blow a fuse/trip CB. An earth leakage fault needs to flow a current in excess of 30mA to trip an RCD so a high resistance earth to neutral or a floating system would leave an earth leakage unable to be detected/tripped by a domestic RCD. That being part of this thread.

Sorry acmotor, but you can't make a false statement, and follow it with "I don't want to open that old topic again" and expect it to stop there. By making the false statement you have opened it again. I'm specifically referring to "there must be an earth and an earth current flow to operate an RCD".

We can distinguish two uses of "earth". There is the earth wire and there is the "general mass of earth". This statement is false for both. It is true that most realistic RCD tripping scenarios involve a current flowing in one or both of those earths, however it is quite possible for an RCD and generator in a completely floating system to be tripped by a person bridging from supply active to load neutral, or from load active to supply neutral. (Of course if the system was designed to be floating, they would not be called "active" and "neutral", just "line 1" and "line 2".) The fault current does not have to pass thru any earth. It merely has to bypass one side (and only one side) of the RCD. An RCD doesn't only measure "earth leakage", it measures residual current due to any cause.

I'm just saying what Richo said, but in different words.

If the system is floating then a person bridging from any part of it to earth will not cause any current to flow, there will be no danger and the RCD will not trip. If however, there has been an insulation failure that bridges from one line to some exposed conductive surface (which need not be earthed, it might be a floating car chassis for example), then if a person bridges from that conductive surface to the other line, a dangerous current will flow, but the RCD will only trip if the insulation failure is on the supply side of the RCD and the person is on the load side (or vice versa). That is why we don't use RCDs for shock protection in floating systems. Not because they can't trip without an earth. But because they only trip on "diagonal" faults.

In floating systems we don't need a special device to provide shock protection. The floating is the shock protection. But we need a device called an Insulation Monitor to keep checking that the system really is floating. Yes, the Insulation Monitor (IM) must have a connection to the exposed conductive surface (which may or may not be earthed), and so yes, when a person bridges from any line to the conductive surface there is a circuit, but I wouldn't call it a "CIRCUIT" Image because it is of significantly higher impedance than the human body. When there is no other insulation fault, a person bridging from either line to the exposed conductive surface will simply pull that line to nearly the same potential as the surface, possibly drawing a non-lethal few milliamps if the person is soaking wet and making a large area of contact. This will be detected by the Insulation Monitor which will raise an alarm.

You seem to be fixated on the term and idea of "earth leakage". What we'd really like to measure is "person leakage". Neither RCDs nor IMs measure only earth leakage. But neither can they measure all forms of "person leakage". There isn't much you can do if a person puts themselves directly in parallel with the load, bridging between load-side active and neutral, or line-side active and neutral, or line 1 and line 2.

But yes, gensets are not designed to be floating, so the earth wire and neutral wire should be connected together at the genset (except if the genset is connected to a switchboard which contains its own earth-neutral link). In either case, earth and neutral must be connected together on the supply side of the RCD, and not connected together on the load side of the RCD.
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Post by acmotor » Tue, 20 Aug 2013, 19:21

weber wrote:
acmotor wrote: Richo,

Earthing and RCDs is all about a CIRCUIT.
Leakage current (and your ability to detect an earth fault) relies on a CIRCUIT to exist so there must be an earth and an earth current flow to operate an RCD. i.e. an unbalance betweeen the A and N current caused by a current flowing to earth from A and not all returning via N.

Without a circuit you can't measure leakage current. Well, there will be no leakage current for the first (fault) connection despite an unsafe condition being created.
I remember early days of EV discussion where folk imagined it was possible to measure earth leakage with a totally isolated battery pack.
Can't be done. You can detect the SECOND connection to earth having now formed a circuit, but the first connection you must make yourself with some form of earth reference.
This can be a hard connection or a resistive connection and is often the centre of the battery pack or the joining point of a resistor from each end of the pack that happens to equal the centre of pack voltage.

I don't want to open that old topic again. There was so much misunderstanding out there about the need for an electrical circuit to exist !
Domestic electrical wiring requires a hard earth connection. Enough to blow a fuse/trip CB. An earth leakage fault needs to flow a current in excess of 30mA to trip an RCD so a high resistance earth to neutral or a floating system would leave an earth leakage unable to be detected/tripped by a domestic RCD. That being part of this thread.

Sorry acmotor, but you can't make a false statement, and follow it with "I don't want to open that old topic again" and expect it to stop there. By making the false statement you have opened it again. I'm specifically referring to "there must be an earth and an earth current flow to operate an RCD".

We can distinguish two uses of "earth". There is the earth wire and there is the "general mass of earth". This statement is false for both. It is true that most realistic RCD tripping scenarios involve a current flowing in one or both of those earths, however it is quite possible for an RCD and generator in a completely floating system to be tripped by a person bridging from supply active to load neutral, or from load active to supply neutral. (Of course if the system was designed to be floating, they would not be called "active" and "neutral", just "line 1" and "line 2".) The fault current does not have to pass thru any earth. It merely has to bypass one side (and only one side) of the RCD. An RCD doesn't only measure "earth leakage", it measures residual current due to any cause.

I'm just saying what Richo said, but in different words.

If the system is floating then a person bridging from any part of it to earth will not cause any current to flow, there will be no danger and the RCD will not trip. If however, there has been an insulation failure that bridges from one line to some exposed conductive surface (which need not be earthed, it might be a floating car chassis for example), then if a person bridges from that conductive surface to the other line, a dangerous current will flow, but the RCD will only trip if the insulation failure is on the supply side of the RCD and the person is on the load side (or vice versa). That is why we don't use RCDs for shock protection in floating systems. Not because they can't trip without an earth. But because they only trip on "diagonal" faults.

In floating systems we don't need a special device to provide shock protection. The floating is the shock protection. But we need a device called an Insulation Monitor to keep checking that the system really is floating. Yes, the Insulation Monitor (IM) must have a connection to the exposed conductive surface (which may or may not be earthed), and so yes, when a person bridges from any line to the conductive surface there is a circuit, but I wouldn't call it a "CIRCUIT" Image because it is of significantly higher impedance than the human body. When there is no other insulation fault, a person bridging from either line to the exposed conductive surface will simply pull that line to nearly the same potential as the surface, possibly drawing a non-lethal few milliamps if the person is soaking wet and making a large area of contact. This will be detected by the Insulation Monitor which will raise an alarm.

You seem to be fixated on the term and idea of "earth leakage". What we'd really like to measure is "person leakage". Neither RCDs nor IMs measure only earth leakage. But neither can they measure all forms of "person leakage". There isn't much you can do if a person puts themselves directly in parallel with the load, bridging between load-side active and neutral, or line-side active and neutral, or line 1 and line 2.

But yes, gensets are not designed to be floating, so the earth wire and neutral wire should be connected together at the genset (except if the genset is connected to a switchboard which contains its own earth-neutral link). In either case, earth and neutral must be connected together on the supply side of the RCD, and not connected together on the load side of the RCD.


Yep, told you so. Argue the point !! Image

Ponder a moment how an insulation monitor works. BY DETECTING FLOW OF CURRENT in a CIRCUIT.
OK you get hung up on the semantics of earth, ground, 'circuit'. I understand that. (and I only spotted one spelling mistake in your post ! Image )

At least in the light of this topic your last paragraph demonstrates that you do understand really.   Image
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Post by weber » Tue, 20 Aug 2013, 19:48

acmotor wrote:Ponder a moment how an insulation monitor works. BY DETECTING FLOW OF CURRENT in a CIRCUIT.
You apparently missed where I already agreed to that. I think it's obvious it works that way. But so what?
OK you get hung up on the semantics of earth, ground, 'circuit'.

I'm sure we both take a circuit to be a closed loop. I only wonder why you think the word needs to be "shouted" (in all caps) in this case?

I didn't say anything about "ground" at all. As far as I'm concerned it's a synonym for "earth". It's used in the US, but not in Australian electrical standards. I feel it is best not to use two different words for the same thing in a safety context, lest the novice reader think they refer to different things.

How exactly could we enlarge the meaning of "earth" so as to make your statement about RCD's become true?
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Post by offgridQLD » Tue, 20 Aug 2013, 20:44

Johny wrote: Does the I miev have a tow bar option?


Looking under the rear end the chassis sure looks more than adequate for mounting a tow bar.

I see it this way If your not going to tow anything heavier than the weight of 3 people and some luggage..300kg or so you wouldn't have a problem. The weight would be better off loading the trailers axle and wheels than the I miev's.

Insurance could be a issue though if you had a freak accident with a tow bar fitted when Mitsubishi recommend not to

I think I could build a trailer that is under 100kg and would have very little wind drag that could hold a 50 - 100kg generator & fuel.Profile would be no more than 800 high by 1000 wide with a aerodynamic shape.

I will most likely build and fit my own tow bar soon. Not for towing our trailers but the receiver hitch is very handy for our bike rack and our wheely bin (rubbish bin) carrier. Our bins need dropping off at the end of a 1.6km dirt road.

Kurt

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Post by acmotor » Tue, 20 Aug 2013, 21:27

An RCD is designed to and implemented in standards to detect earth leakage by measuring an unbalance in the Active and Neutral lines of comsumer equipment, typically by a flow of current (>30mA) to the earth system associated with the power circuit.
This function requires the Neutral and earth to be connected together prior to an RCD as it cannot function as intended without this connection. It may also trip if smashed with a hammer or heated with a blow torch. Image To operate an RCD without a MEN or earth connection is probably illegal not to mention stupid.
I think that about covers it.

iMiEV tow bar.   I'm just picturing the wheelie bin and its weekly journey !!

   
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Post by weber » Tue, 20 Aug 2013, 22:18

acmotor wrote: An RCD is designed to and implemented in standards to detect earth leakage by measuring an unbalance in the Active and Neutral lines of comsumer equipment, typically by a flow of current (>30mA) to the earth system associated with the power circuit.
This function requires the Neutral and earth to be connected together prior to an RCD as it cannot function as intended without this connection. It may also trip if smashed with a hammer or heated with a blow torch. Image To operate an RCD without a MEN or earth connection is probably illegal not to mention stupid.

I totally agree. But I was hoping you might also understand and acknowledge that what Richo said is true.
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Post by acmotor » Wed, 21 Aug 2013, 04:11

weber wrote:
acmotor wrote: An RCD is designed to and implemented in standards to detect earth leakage by measuring an unbalance in the Active and Neutral lines of comsumer equipment, typically by a flow of current (>30mA) to the earth system associated with the power circuit.
This function requires the Neutral and earth to be connected together prior to an RCD as it cannot function as intended without this connection. It may also trip if smashed with a hammer or heated with a blow torch. Image To operate an RCD without a MEN or earth connection is probably illegal not to mention stupid.

I totally agree. But I was hoping you might also understand and acknowledge that what Richo said is true.


??? but it isn't true ???
Did you actually read it ?

Richo is a big enough boy to speak for himself without you holding his hand. Hi Richo !
Perhaps if you hadn't jumped in to argue the point when you seemed to agree anyway, Richo's post would have got more attention.   Image My fault for taking your bait. Image
Richo wrote:.....
But an RCD can measure the leakage(anywhere) current directly and doesn't require an earth for correct operation.
eg the current going into a circuit through the Live wire must return through the Neutral wire.
Any "leakage" will be seen as a differential.
Just remember this doesn't imply you should disconnect your earth Image


OK, directly to you post Richo. Yes, a leakage will be seen as a differential. Now, a leakage to what ? What is the current path ? It can't be between A and N downstream of the RCD. That is balanced.
For the very purpose of this topic, the leakage current path is from active to earth. If the source is not also earthed (or earth referenced by resistors etc. to allow a current to flow) then there will be no current flow.... thus no earth leakage can be detected.

I can't be clearer than that.
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Post by acmotor » Wed, 21 Aug 2013, 04:22

Actually Richo, Lets see if we can set up a demonstration of RCDs at the next AEVA meeting. A chance for myth busting.
Hoops was working on a leakage detector for EVs a while back. Is that up and running ? We could get a demo of that too.
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Post by Richo » Wed, 21 Aug 2013, 21:14

Hey I said an RCD wasn't just limited to just Earth faults.
You are correct it does still need 2 connections to make a circuit (one of which is commonly Earth referenced).
Perhaps I shouldn't have said "correct operation" but "unusual alternative (but not recommended) operation"

http://www.powersafe.net.au/pdf/duosafety.pdf
So the short answer is NO but the long answer is YES.
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Post by markrmarkr » Thu, 29 Aug 2013, 14:29

Tuarn,

how do you think that 4.4KVA Inverter Generator would go with a 15 Amp load. I ask because a guy on another forum has sourced a portable 15 Amp J1772 charging station   for $500. Though you'ld need to swap the plug.

With that charging station and your generator the cost is less than $1000, for full speed charging
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Post by acmotor » Thu, 29 Aug 2013, 16:42

I'd say probably not.

The '3.7kVA' unit shown earlier couldn't manage 3.3kW and the '4.4kVA' is possibly just an up sales number on the same unit.
The specs on that '4.4kVA' gen only suggest 3kW cont. But beware the sales data is often fuzzy and swaps kW, kVA, peak, cont,and coffee temperature at will.

If you want to charge at the full 3.3kW (or whatever number) then the gen needs to state clearly it can do it in kW.... or be able to test it out.
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Post by offgridQLD » Thu, 29 Aug 2013, 20:54

Wouldn't it be a good idea to go for a generator that had some breathing space. Perhaps a 5kw output. I understand the aim is to load the generator reasonably well to get max kwh-lt fuel burned.

I don't know what the sweet spot is perhaps 2/3 load would be better. The generator wont be revving its guts out (noisy) or overloading its self.

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Post by acmotor » Fri, 30 Aug 2013, 05:11

Yes.
That was the logic behind the '3.7kVA' gen earlier in this topic running the 2.2kW EVSE.
It seems that a gen suitable for 3.3kW (maybe 5kVA+) is getting quite large and heavy for the back of the i ?
The longer charge of the 2.2kW EVSE may be the compromise with the likes of that '4.4kVA' inverter generator.
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