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Posted by Johnny B Good on May 26, 2018, 3:24 pm
Seeing as how quiet this news group is of late, I thought I'd post a
copy of the above titled thread originally posted in uk.d-i-y on the off
chance that there may be UK based subscribers still monitoring
However, since Lidl have expanded their operations into the USA in
recent years, this may prove of interest to the wider US centric group
monitoring from the sidelines so, if nothing else, here's my take on the
'Latest Offering' in inverter gensets from Lidl in the hope that it will
help relieve the boredom of monitoring this NG, an "activity" that's
perhaps best described as the business of "Watching Paint *Peel*". :-(
The XYL returned from a quick shopping foray this afternoon with the
latest magazine showing next week's offers which included a "Golden Oldie"
first seen two years back. Said Golden Oldie (the PGI 1200 A1), presumably
being priced for nostalgic reasons, is on 'offer' at the original 129 quid
price (their version of "Rollback Pricing" I'm guessing).
Although remarkably cheap for an inverter genset even at the 30 quid
higher asking price than the later PGI 1200 B2 "Suitcase" generators they
were selling in the 2nd week of April this year, it has even more going
against it than the 99 quid B2 model which I'd assumed to be its
replacement and thus rendering the A1 model totally obsolete.
After checking out this video review on youtube:
and taken another look at this one on the B2 model:
which is worth checking out simply for the extremely informative
comments made by dean handley from ten months ago which would have saved
me so many return trips to finally track down a working PGI 1200 B2 some
seven weeks back, I have come to the conclusion that unless you want to
strip out the guts of the A1 and transplant them into a properly designed
enclosure of your own (whether portable "suitcase" or just a small brick
outhouse), or you simply want to use it for spares, I wouldn't bother
unless you're really desperate to get hold of a 1KVA pure sine wave
inverter generator having just missed out on April's bargain of the decade
in cheap inverter genset technology.
Having said that, it's still superior to a cheap open frame genset. Yes,
it may be almost as noisy but at least its 1KW of pure sine wave power can
be safely used with electronic kit and even old fashioned sine wave UPSes,
unlike normal generators using 'sophisticated' AVR control which will
grossly over-volt at the drop of a hat (leading current loads from a few
microfarad's worth of capacitance generally being all that's needed ime to
send a 2.8KVA 230vac generator going north of the 270vac mark!).
If you're looking for a cheap alternative to buying a few hundred quid's
worth of SLAs to boost the autonomy of a 1.5KVA or higher rated UPS by a
couple of hours, this could prove a more cost effective alternative,
especially as you can get a good 3 to 5 hours worth out of each gallon of
unleaded petroleum/gasoline you care to pour into its tank (5 to 7 hours
in the case of the PGI 1200 B2).
The only downside, of course, being the noise pollution if you don't
already have a suitable brick outhouse to minimise this and both secure
and run it safe from the CO poisoning and fire hazard risks presented by
such generators. In this regard, it's very little different to the 99 quid
PGI 1200 B2 Lidl were selling just a mere 7 weeks ago. For static use, the
only downside is that extra 30 quid hit on your bank balance.
Even so, it's a remarkably cheap way to buy into a 1KW standby source of
pure sine wave 50Hz 230vac power. Now that I've replaced all the GLS lamps
(bar the set of four 35W 12v halogen downlighters in the shower room) with
LED lamps, I can keep all the lights on along with the fridge,
the freezer, the 4K smart TV, my IT kit and the CH with a mere 1KW of
standby power. Admittedly, only at a pinch and by careful power management
but if ever the need for sustained emergency power ever arises, this is
just exactly what anyone running off emergency power would be having to do
I'd have preferred a 2KW inverter genset but not only are the cheapest
alternatives some four or five times as pricey, they'll burn through
emergency fuel reserves faster as well even when only providing the same
amount of power as the smaller genset. Limited emergency power is better
than no emergency power at all and even if I do push the boat out on a
quieter 2KVA inverter genset at a later date, at just 99 quid, I can
afford hang onto the Lidl genset as an emergency backup to the 2KVA
emergency backup genset. You can never have too many emergency gensets
when the price is *so* right.
TBH, I'm quite amazed at the cheek of Lidl in trying to sell an inferior
version of the PGI 1200 B2 less than two months later and at an extra 30
quid to boot! Perhaps they're thinking that its "Retro Chic" cheap two
stroke portable genset looks are deserving of the extra 50 or 40 quid over
a more appropriate (IMHO) 80 or 90 quid price point.
Major points of difference between the A1 and the B2 models are:
The A1 uses a top mounted 4.2l pressed steel gravity feed tank prone to
leaking fuel during transportation. Fuel consumption rating at 2/3 power
output is 0.88l/hour from its 2.85hp 53.5cc engine (4.77 hours run time on
a tank of fuel). Considering the use of a gravity feed fuel system,
there's a surprising absence of a carburettor float bowl priming plunger
to assist cold starting.
The B2 uses a plastic (presumably shatter-proof) 4.5l side tank (which
reduces sloshing of its contents) feeding an engine vacuum powered fuel
lift pump. Fuel consumption rating at 2/3 power output is 0.68l/hour
from its 2.04hp 53.5cc engine (6 1/2 hours run time on a tank of fuel).
The A1 is 200g lighter than the B2 (13Kg). Both produce the same total
sound power of 95dBW but the B2 claims to be 1.3dB quieter at the 1 metre
SPL test distance (80.2dBA).
Now that I have an actual class 2 SPL meter to test with, I'll be able
to confirm just how optimistic a claim this is for myself (give or take
1.5dB of metering error along with other environmental factors that make
such tests so less than 'scientific'). At least I'll be able to get base
line figures by which to gauge any attempts to quieten it.
 Afaict from pictures - unlike the potted inverter module in the B2,
two cermet trimmers do actually poke up out of the hard and shiny black
potting compound in the one used by the A1 making it amenable to adjusting
for manufacturer's calibration errors, assuming they haven't switched
over to using the same inverter part used by the B2 (probably not since
the A1 shown still only uses two LEDs to show status using blink codes for
normal/slight overload/full overload condition and "Goodnight Vienna"
whilst the B2 uses three LEDs).
 The only downside of using a fuel lift pump, aside from the extra
complexity over that of a simple gravity feed setup, is the need to spin
the engine over several times on the starter cord just to prime the fuel
line and the carburettor float bowl when starting from "Dry" (initial
commissioning run or else after a long lay up after letting the carb run
dry to minimise the risk of fuel gumming up the carburettor's jets during
periods of protracted storage).
In this case, it's best to crank the engine over leisurely 4 or 5 times
after turning the fuel feed on with the ignition still off and closing the
choke for the penultimate pull before turning the ignition on for a full
on pull of the cord to actually fire it up without needlessly wasting
energy on premature attempts to fire it up before there's even any fuel in
the carburettor float chamber.
Where more regular use (say every weekend) precludes any need to run the
carb float bowl dry, this won't be an issue. A single priming yank before
turning the ignition on and setting the choke should get it running on the
next pull of the starter cord.
 I discovered when testing with a 900W toaster and a bunch of 150W
incandescent lamps and a few other ses lamps of various wattages that the
inverter signals overloading at the 980W mark according to my digital watt
meter. I was a little disappointed at discovering this, especially in view
of the fact that it would cheerfully run a 1200W test load not for the
mere 5 seconds claimed but a full half minute every time before shutting
the inverter down.
I realise it's just possible that it's been calibrated to detect
overload at exactly 1001 watts and my watt meter is merely under reading
by 2% of the +/-3% allowance of its rated measurement tolerance. Still,
I'd have hoped they would have erred a little more on the positive side of
the tolerance range with their overload setting point, say 1050W before
sensing an overloaded state.
This is how I came to discover the complete absence of any means to
adjust the output voltage setting or the current overload point to correct
such a parsimonious setting. I guess I'll have to do some cross checking
with my other "Kill-A-Watt" meter and the analogue watt meter before
deciding whether to buy another PGI 1200 B2 the next time they're on offer
from Lidl to do a "Pick 'n' Mix" swap out to get the inverter genset I so
For the benefit of American readers, here in the UK we rarely experience
summertime heatwaves longer than a week so very few homes are equipped
with AC - it's simply not worth the investment unless it's part of a heat
pump based heating package. Most urban UK homes rely upon NG powered
central heating and domestic hot water systems which require less than 50
or 60 watts to maintain the controller panel, a zone valve or two, a
circulating pump and perhaps a small boiler flue purging fan.
The biggest compressor motor load in a UK home is likely to be a chest
freezer or fridge/freezer, typically less than 800W peak load, well
within the 1200W max (5 or 30 seconds) rating of the Parkside inverter
gensets mentioned above.
Also worth noting is the fact that urban mains voltage supplies which
serve over 80% of the UK's population, are largely laid underground and
have annual 'up times' in excess of 99.99%. The rest of the population in
the UK countryside (farmers and well paid city workers who commute or
otherwise telecommute or simply work from home) do have to endure the
problems of mains power carried over rural lines and so are generally a
little better prepared for outages typically measured in hours rather
than days. As per usual, some are better prepared than others.
Interest in backup emergency power is now increasing in proportion to
the increasing levels of Government incompetence in the provision of
winter time energy supply security, largely as a result of the folly of
'Green Power' investments made as a sop to those idiot 'Greens' who
believe that a few windmills and solar cells will provide all the energy
we'll need in preference to the only sane (and truly green) nuclear power
All that and the fact that Honda no longer have a monopoly in inverter
genset technology means that we are seeing competitively priced inverter
gensets appearing in the market to serve the modest needs of homes with
electricity demands largely centred on sensitive electronic devices which
are not only susceptible to the poor quality of standard genset supplies
to begin with but which will also trigger such gensets into producing
destructive overvolting events. IOW, there's already an existing market
for mass produced cheap inverter gensets right here and right now.
I can only see those 2 and 3 KVA gensets with their "fancy" AVR going
the way of the Dodo as they prove themselves deadly to the task they were
designed for (they were never a good idea - the simple induction motor
converted to a "Poor Man's generator" with a dozen or so microfarad's
worth of run caps across the output were a safer bet for this application
I can already see a situation where using such a conventional generator
won't even be a safe option just to literally keep the lights on in a
modern home full of cheap LED GLS lamps using simple capacitive dropper
ballasts for fear of over-volting to the capacitive load of the lighting
circuits alone! :-)
Even if for no other reason than this, the future for emergency gensets
depends on the use of inverter technology. It might be a relatively
expensive solution right now but, given the manufacturing cost reductions
of mass produced electronic hardware, it won't be too long before it
becomes cheaper to make an inverter genset than a 'standard' conventional
Not only that but I can foresee the day when the recoil pull starter
will be relegated to backup emergency use only in favour of electric
start courtesy of a small 12v 7AH SLA (or more likely its more compact
and lighter Li-ion equivalent) and a brushless motor drive module
(ideally, a function built into the inverter module) to run the PM
alternator as a starter motor (no need for the extra weight and
mechanical complexity of a seperate starter motor when you can apply the
"Dynastart" principle in modern day brushless motor form).
From this, I can also foresee an integrated battery/inverter genset UPS
module to optimise the whole UPS with standby genset backup power
paradigm (the presence of battery backup would allow for improved stall-
free "eco-throttle" performance as an additional bonus). Since the PM
three phase alternators generate either a nominal 200vdc for 120vac or
400vdc for 230/240vac inverter gensets, you'd either use 200 or 400 volt
battery packs in the genset/UPS combo or else use 12/24/36/48 volt
battery packs with a high efficiency DC-DC converter to provide the two
or four hundred volts required and accept the additional 1 or 2 percent
loss this would involve.
 Essentially a PM multi-pole rotor three phase high voltage version of
an automobile/truck alternator where the magnets are mounted on an outer
rotor which allows the alternator to be keyed onto the engine shaft to do
double duty as the engine's flywheel, thus neatly saving unnecessary
weight and space. It's the reason why they can be made so lightweight and
compact. The inverter module is effectively a pair of back to back class
D power amplifiers, designed to be powered off a 200 or 400 volt DC rail,
driven from a 50 or 60 Hz pure sine tone reference and using the much
lower sampling rate of circa 5KHz to improve efficiency beyond the
typical Hi-Fi sampling rate of 48KHz used in standard class D audio amps.
The 200/400 dc voltage from the alternator is controlled by engine speed
alone via stepper motor control of the carburettor throttle mediated by
the microprocessor in the inverter module which compensates for varying
electrical demand on the inverter's output terminals both for volt drop
due to resistance in the alternator windings and to vary the throttle to
control engine torque according to the current demanded by the electrical
load. All that's required by way of alternator voltage control is that it
stays within the relatively wide range of 350 to 420vdc in the case of a
240vac inverter output (or half of those voltages for a 120vac inverter
Given enough time between now and Armageddon, I've no doubt we'll see
water cooled fuel injected engine modules being used in the later more
compact, quieter and even more fuel efficient portable inverter gensets
with built in Li-ion battery backup and automatic electric start. :-)
Johnny B Good
Posted by Johnny B Good on June 1, 2018, 9:59 pm
Well, did anyone here in the UK check these out at their local Lidl
Johnny B Good
Posted by dolmen on June 2, 2018, 9:32 am
On Saturday, May 26, 2018 at 4:24:17 PM UTC+1, Johnny B Good wrote:
Hi there I watched the vids, thanks for the links and decided against the A1 and am waiting in the chance that the B2 option will come up again. It certainly seems like a much better option all things considered.
Posted by Johnny B Good on June 3, 2018, 2:32 am
On Sat, 02 Jun 2018 02:32:51 -0700, dolmen wrote:
=====snippage of my take on the merits of inverter gensets====
Thanks for the follow up. I was beginning to think I was the only UK
citizen still subbed to this NG. :-)
The only problem with doing that is you could be left waiting for quite
a long time before the B2 gets put back "On Offer" (or it might reappear
next month - who can tell with Lidl's (and, for that matter, Aldi's)
kakamaimee retailing strategy?) so you might start regretting that
decision some six months down the line.
It's worth keeping in mind just how much more expensive the alternatives
available in this segment of the UK inverter genset market are. A quick
search using duckduckgo located this open frame HortiPower 1800/2000W
inverter genset at Amazon, currently on sale for a mere £249.00
That's an unusually cheap price for a 1.8KW rated inverter generator but
I've no idea what their quality is like. They quote the 7 metre SPL
rating which makes it around 16dB quieter compared to the 1 metre SPL
figure quoted by Parkside inverter gensets. Once you've added that
missing 16 dB this gets you an 81dBA SPL@1mtr to directly compare the
two. Considering the absence of cosmetic panels, this rather highlights
what the reviewer was saying about the A1.
If you're looking for a less marginally specified output power genset,
this could be a better alternative (but you'd be spending an extra 120
quid on a machine that burns a litre of fuel an hour when loaded to 70%
(1260W) versus 0.88 litre per hour at 75% of load (750W) for the A1 or
0.68 litre an hour in the case of the B2) and you'd be dealing with a
company based out of Peterborough in Cambridgeshire run by a person of,
it would appear, Polish extraction.
That's just fine and dandy if you happen to live in and around
Peterborough but a bit of a pain for the rest of us who have to wait on
delivery by Amazon or, worse still, deal with returning faulty goods,
guarantee or no guarantee.
I only mentioned that HortiPower unit because it's the first time I've
seen an alternative 1 to 2 KVA rated inverter genset in the UK below the
300 quid mark. The prices for inverter gensets available from walk in
stores such as MachineMart, Toolstation and Screwfix typically start at
£190 for a 700/780W rated inverter genset <https://tinyurl.com/ycfm8vjo>
and carry on upwards of 280 quid for a 1.2/1.5KW Impax and 400 quid for
the 2.2/2.5KW Impax inverter gensets (Screwfix prices). What the extra
money might buy you in this case is maybe a 2dB reduction in noise
pollution levels (Oh, and a 12v charging lead and shorter run times on a
tank of petroleum/gasoline).
My derogatory remarks about the A1 were made from a position of great
strength. I'd already acquired the slightly superior version at the
bargain of the decade price of 99 quid. :-) It won't matter so much to me
if the B2 models never reappear but if and when they do, I'll get my
chance to compare the overload set points and swap out the inverter
module if the second unit is on a more generous overload trip point
With the exception of the B2 model, compared to every other 1000/1200W
inverter genset model currently available in the UK, there's nothing
anywhere near as cheap, even at that elevated £129.00 price point.
There's a massive price premium on truly quiet suitcase inverter gensets
(12 to 18dB quieter) suitable for use on camp sites. The Honda units
typically adding an extra 800 quid onto the price of the Parkside units.
Those other Impax models mentioned above are, at best, just another 2 or
3dB quieter and this is typical of most of the competing models in the
two to four hundred quid price bracket.
BTW, talking about SPL figures, I took the opportunity yesterday
afternoon to run another test of mine using a 240v 900W toaster as a 780W
(230v) test load to get some SPL readings. This time I took the trouble
to mentally take note of the actual readings at the 1 metre mark for idle
at eco and normal settings as well as on a 780W load.
I'd stood the generator on a hard concrete surface alongside of the
patio table (so no benefit from soft grassy soil to knock a dB or two off
the 'hard standing' readings) where I had the toaster and a couple of
plug-in energy monitors plugged into a short 4 way mains extension
lead set up to toast a couple of slices for my 7 year old twin
granddaughters to sample the delights of "Generator Toast".
From the starboard side panel, I got readings of 79 and 88 dBA
respectively for eco idle and 780W loaded (whether in eco-idle mode or
not) whilst the figures for the exhaust (stern) end were, as expected,
about another 2 or 3 dB higher. I didn't bother stepping back another 20
feet to get 7 metre SPL figures since there was too much 'clutter' to get
any meaningful 'free space' readings.
I was a little surprised that the 780W load didn't boost the non eco-
idle speed since earlier tests with 960 to 1200 watt loads had
demonstrated a slight but definite speed increase. I guess the 780W load
wasn't quite enough to justify any further speed increase, merely a wider
(and louder) throttle setting to increase the engine torque required to
balance the alternator drag. I'd expect the SPL to go up another dB on
the 780W load figure when generating the full 1KW's worth of maximum
sustainable output (in my case, 980W just before it starts the 30
second timer to 'overload shutdown')
Since the Parkside generator specs included a tolerance error (K factor)
of 1.2dB for their claimed 1 metre SPL dBA figures and my class 2 SPL
meter could be out by +/- another 1.5dB anyway, those readings seem an
entirely reasonable match to the specifications which I had naturally
assumed to have been determined with the generator running in its
quietest mode, unloaded eco-idle enabled.
The dBA SPL claims for all these gensets will always be for the quietest
mode of operation and you can likewise expect a similar 10dB boost when
running at maximum sustainable output (but don't forget the 16dB
difference between 1 metre and 7 metre (23 feet) referenced SPL figures).
Don't assign too much meaning to the expression "quiet" in the
manufacturers' description copy, written by PR types educated in the fine
art of "Lying by omission" where the justification for such a statement
can be as slight as the product being a mere 1 or 2 dB quieter than a
standard open frame generator of comparable output. Ignore such wishy
washy statements as "Quiet", "Quieter", "Quietest yet" and take care of
the 1 and 7 metre SPL standards' 16dB difference when looking at any
actual numbers they may offer in their "Specification" sheet.
Except for notably quiet exceptions from Honda (and a few other brands -
Honda no longer hold a monopoly in "Very Quiet"), you can assume a 'ball
park' 1 metre SPL figure of 96dBA safe in the knowledge that you're
unlikely to be more than 2 or 3 dB out on the actual SPL figures.
 I was using one to monitor voltage and the other the load wattage.
 According to one of my plug-in energy monitors, the one that matches
very closely my trusty Metrawatt analogue watt meter as opposed to the
230vac version of a Kill-A-Watt meter which under-reads by comparison
(and which I'd relegated to monitoring the voltage during this test).
 The specifications for both the A1 and the B2 models mention a 5
seconds limit on the 1200W surge rating. However, it turns out that the B2
model will sustain such an overload for a whole 30 seconds before
tripping the inverter out, necessitating a reset which, unconscionably
requires the engine to be stopped rather than by a reset button which
would allow the engine to keep running to save the ritual of another pull
Mind you, this is probably for the best since in practice this means the
inverter will get a chance to cool down any thermally stressed parts
before the user gets another chance to abuse it. This can be a pain if
you're running close to the limit without a UPS in line to protect more
critical loads such as desktop PCs and NAS boxes which don't take kindly
to having the rug pulled out from under them.
Even with a UPS, there's still some pain since you have to nip out to
attend the generator. However, that said, restarting is a doddle since it
will be warm and primed ready to go on the first confident pull of the
starter cord. even if you've left it half an hour it will still be nice
and warm since the engine carries on running, leaving you to manually
switch it off when you're ready to restart it (see note)
 Unless they stand ready to switch the engine off and then switch it
back on just before it comes to a complete standstill which, if timed
exactly right (it's quite critical is the timing!), will reduce the
alternator output voltage sufficiently to initiate an inverter reset
whilst there is still enough inertial energy to let the engine pick back
up on turning the engine switch back on. No need to ask me how I know
this, I'll tell you - I simply tried this trick a few times before I
succeeded in resetting the inverter module without the engine stalling
It's a useful trick since it saves needless wear and tear on the starter
cord and you can still give the inverter module time to recover by simply
waiting a minute or two before cycling the engine switch. Incidentally,
there's no need to unplug the load before firing it up unless you have
loads with heavy startup current demands that can take it well beyond its
1200W limit (or over its 1000W - 980W in my case) limit for more than 30
The only item that didn't like the resulting soft start being the 230vac
Kill-A-Watt meter which requires a more rapid voltage increase to reset
itself - i.e being plugged into an already live socket or the socket
switch turned from off to on. Apropos of which, other things that might
not take kindly to a soft start could be fridge and freezer compressor
The freezer you'd only plug in once a day when the load will be
minimised or even totally shed so as to chill the cabinet on the "Rapid
Freeze" button to prepare it for its next round of doing without
electricity for a bit. Freezers can keep their contents safely frozen
during 24/48 hour power cuts if they aren't being accessed every half
hour of the day so using the "Rapid Freeze" button to reduce the
temperature below normal is an effective way to timeshare the generator's
energy output to minimise overloading events.
Modern fridge compressors, I believe, only use 35 to 60 watts when
running although they may demand 3 to 6 times that for a few seconds when
starting up. However, I haven't tested this with our own fridge so I
can't verify this from actual experience.
If you happen to have a really modern fridge/freezer using a linear
compressor, you won't suffer the 'compressor startup surge' effect which
simplifies the issue of running it from inverter generator power somewhat.
Johnny B Good
Posted by Johnny B Good on June 9, 2018, 3:40 am
On Sun, 03 Jun 2018 02:32:40 +0000, Johnny B Good wrote:
Following up on what I wrote above, I've since run a test with our under
the counter larder fridge using the 2000MU-UK (the 230v version of the
Kill-A-Watt, btw, both manufactured by Prodigit Electronics Co Ltd) and
my Metrawatt analogue wattmeter for measuring the watts and volt amps
consumption, both running, averaged and peak values.
It's actually been several days since I ran the tests (I was hoping to
use another follow response as a chance to include these test results,
hence the delay). The on and off cycle times turned out to be hours
rather than tens of minutes so on the 2nd day of monitoring, I set a
camera up on a small tripod to video the meter readings so I could
capture and replay the startup surge event.
It turns out that my 3 to 6 times running wattage startup surge estimate
was a little on the optimistic side. It peaked at a 1000 watts on the
analogue meter (660W was the 2000MU-UK's best shot at registering this
peak) which turns out to be some 14 times greater than the 65 to 72 watt
steady state consumption of the compressor motor after it has been
running for more than a minute, way higher than I was expecting. :-(
The 2000MU-UK was showing a VA figure of around 135VA and a wattage
reading some 7W higher than the more credible Metrawatt reading. The
averaged over a 34 hour period power consumption, after correcting for
the 7 watt over-read, proved to be 37 watts (324KWH per annum). The
power factor figure btw, was 0.55 (55%) just about what you might expect
of a domestic fridge compressor motor. The power factor at peak startup
current will be a lot higher since most of the power under such an
extreme surge condition will be resistive losses taking the PF somewhere
around the 80% mark as a best guess.
The only consolation of that assessment is that the 1KW peak isn't going
to translate into a 1.8KVA (at 55% PF) load on the generator when
attempting to power the fridge as the only load, more likely a 1250VA
peak (which may still be enough to cause the generator to immediately
Although the UPS's 2KVA 1500W rating will allow it to start the fridge
compressor without tripping out, this relies upon the generator shutting
down to effect the transfer to battery power and the UPS's much beefier
inverter, so a far from ideal 'solution' since you'd have to reset/
restart the generator within a few minutes each time to avoid unnecessary
depletion of the battery. You'd also have to limit the other loads to
500W or less to avoid tripping out the UPS itself.
The most practical way to make use of a 2KVA 1500W rated UPS in this
circumstance would be to insert an automatic load shedding switch with
a reclosure time of ten seconds between the generator and the UPS set to
immediately disconnect the generator before its own protection can
respond with an immediate overload shutdown. You'd still need to limit
the other loads to no more than 500W but at least you'd only lose
generator power for a ten to fifteen second period each time once every 5
hours or so.
I haven't yet tested the chest freezer's load characteristics. The
results from the fridge tests rather put a dent in my enthusiasm for
trying to persuade such a weedy inverter genset to run it even with
careful load management since I suspect its demands will be higher.
However, now that I can see a way around this problem using the higher
surge capacity of the UPS, I'm thinking that perhaps it's worth testing
after all. It might not turn out to be as bad as I thought. In any case,
it's always best to have some actual test results to work from rather
than rely upon assumption alone. At least I'll know exactly where I stand
in regard of my emergency power options.
 I hadn't been able to locate the model number rating plate when I
first took a cursory look inside the fridge several days ago assuming it
must have been stuck to the back of the fridge. It was only when I
extricated it from its under the worktop location, just a few hours ago,
that I discovered its absence from the back of the fridge, motivating me
to get on my hands and knees to do a more thorough search of the interior
which finally solved the mystery. I'd had to extract the 'crisper trays'
from the bottom before it was revealed to be stuck to the right hand side
just below the bottom shelf - a hands and knees job indeed, no wonder the
cursory search had come up dry!
This got me a model number (ART 417/G) and the electrical specification
which, as is typical of most electrical specifications, a seeming work of
fiction, apart from the voltage (220-240 V~) and frequency (50Hz - vital
info in the case of induction motor driven appliances), leaving the
fictional information that it had a consumption of 100W and that it was
fused at 13A (this last was no doubt true despite the fact that a 5A fuse
would have entirely adequate).
The 100W is obviously intended to indicate the running wattage after the
initial 1KW startup surge. It certainly would have passed through this
wattage level a second or so after starting up but wouldn't have stayed
within even +/-10% of that figure for more than another second or two
before swiftly settling down to 75W from where it would eventually drop
to 65W over the next two or three hours.
Also included on the label was its energy rating in the form of
0.6KWH/24h, corresponding to an annualised figure of just 219KWH which is
how it's been more normally expressed for domestic fridges and freezers
for at least a decade now. That was a bonus which proved useful since I
couldn't find a free download of the owner's manual in English and the
Dutch language version I perused showed no mention of this energy rating
I can only surmise that my higher estimated 324KWH per annum figure was
due to the summer like temperatures we had been enjoying when I had been
running my tests, along with the fact that the back of the fridge had
been long overdue a spring cleaning which I completed when I'd been
searching for the rating plate information. Considering its age (some 15
years or so, afaicr), it still seems to be doing well and as the door
seals are still in good condition there's no urgent need to replace it
 I could homebrew such a switch using a current transformer with a
transistor driven relay that can detect precisely when the current
exceeds the 4.3A limit to operate the relay to interrupt the line
current for a ten seconds timeout interval, pre-empting the inverter
genset's built in overload protection. This would allow the more robust
UPS's inverter to deal with such brief overloads automatically without
having to rely on the generator tripping out to effect the transfer to
battery power and all that that entails.
It's a work around solution to a problem most would consider best fixed
with a simple generator upgrade. However, as 'obvious' a solution as that
appears, it does rather overlook the expense, both capital and running
costs, of providing excess capacity just to deal with a 4 or 5 second
event once every 4 or 5 hours of run time.
If it had been merely a choice between spending 280 quid on a 1.5KW
genset and 400 quid on a 2.5KW one, spending the extra 43% choosing the
higher output one (or even 143% if upgrading an existing 1.5KW genset)
would have been the obvious choice. However, since for me, it amounts to
spending an extra 400% to double up on my existing genset rating, such a
work around solution has a very strong cost advantage.
Admittedly, this work around solution does rather depend on my already
having a 1500W/2KVA rated UPS conveniently to hand and one that I know
from experience can handle such extreme surge loadings - the degaussing
surge of a 19 inch colour monitor in point of fact.
 I want to disconnect by *operating* a relay rather than the more
common release of a cut out relay typical of the more usual overload
protection circuits. The rationale in this case being that when the
generator is coping with the load. I don't want to be drawing any
additional power holding a relay in its operated state to pass the power
through to the UPS.
It doesn't matter if the the circuit 'fails unsafe' (leaving the genset
output connected) if the genset does trip out anyway since the end result
remains the same - no power to the UPS in either event. When the overload
shedding relay module successfully pre-empts the genset's built in
overload protection, I'll have more genset power to spare than I'd know
what to do with, which makes the few volt amps or watts of power needed
to operate the relay to open its normally closed contacts a non-issue. :-)