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Author Topic: Inverters and freezer/fridges.  (Read 12239 times)
jonesy
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« Reply #15 on: August 08, 2012, 11:49:48 AM »

It sounds like you are on a TT supply.  These are quite common in the UK.  My last house, 1970s build, in the suburbs of Oxford was TT.  You can usually tell by the lack of earth provided by the electricity board.  UK electrical safety could be improved by the use of dual pole MCBs.
Single phase, AC appliances couldn't care less which way you wire them up.  This is why 2 pin plugs are prevalent on a lot of (double insulated) French appliances.  The French regulations (NF15-100) do stipulate the distinction between phase and neutral.  As you look at the socket, earth pin at the top, live is on the right, same as a UK socket. I never quite understood why the UK moved away from 5A, 2 pin plugs.  Incidentally, fridges and freezers don't need a separate feed.  There is a recommendation to feed freezers off a dedicated (and extremely expensive) type HPi, RCD.   However, wire is cheap and French regs on kitchen appliance wiring is a definite and massive safety improvement over the UK.

I think I understand what you're doing.  You have already got the inverter wired in to several appliances, which you switch out when your batteries are discharged.  And it's the fridge that wont run on the inverter.  It's a good idea to change-over with a 3 pole switch, centre off.  Less chance of an accident.  I'd suggest keeping the inverter earth connected, though, to provide a discharge path for the inverter filter capacitors. 

The inverter terminals should be marked L/N, so keep this consistent L to red (or whatever other colour you've got), N to blue.

You must have some substantial loads, or 3 phase motors, to want a 3 phase supply.  They're a pain for small domestic.
AB
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clockmanFR
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« Reply #16 on: August 08, 2012, 09:39:52 PM »

Hi, artful...
I will have to check the Inverter Earth arrangements, and see whats happening, but will do it in daylight as the Inverter runs the house at night. But i have a suspicion that the inverter may not be earthed to the house system anyway.! So i will let you know what i find.

In the UK a 90a supply is standard, here a 90a supply single phase costs about 38 standing charge per month. Most folk have a 30a supply to their house with several friends in flats with just a 15a supply. For us we have 40a per phase, (costs us 20 standing charge per month) and i split the phases around the different buildings we have, Gite, my workshops with lathes, milling machines, welders etc etc.

Other-power, I have taken note of your comment, but for me running a 1kw motor along side the fridge does seem a little bizarre.?



 
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Other-Power
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« Reply #17 on: August 08, 2012, 10:44:48 PM »


Other-power, I have taken note of your comment, but for me running a 1kw motor along side the fridge does seem a little bizarre.?



The APC UPS and some other brands do not deliver much reactive power and as such the motors in the fridges wont start up as they stall and overload.

The induction motor gives you some spining reserve of reactive power to give the fridge motor a bit of a kit up the ass.

some sort of time conficoration to get the induction motor spinning up before the fridge turns on and then the motor kicks off afterwards.

Cheers

Jon
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clockmanFR
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« Reply #18 on: August 09, 2012, 07:13:54 PM »

Thanks jon, that now makes sense to my small brain.
But will need to investgate further what is required for a good kick up the arse/fridge.         

Artful_....  Inverter is earthed to the house earthing system which in turn is attached to a pole in the cellar that goes a meter into the ground.
Sad news, tried your trick, connected the N to Earth on the power coming from the inverter, no, nope, no difference, sorry, but thanks for the suggestions.

However, did put my multimeter (its not a AVO, but pretty good) set on KHz, when Inverter it shows .220 and wanders about, on the mains it shows .050 stable. err!.
Really could do with a oscilly, i have frequency counters but they like square waves.

So my inverter will run all telly's, satellite systems, satellite Internet, all other stuff around the house but not the fridge and freezer,  agghh.   
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spencer1885
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« Reply #19 on: August 09, 2012, 08:06:51 PM »

You could add one of these capacitors to your fridge/freezers compressor,http://www.kickstartoem.com/about_us/about_us.html or any other motor needing a kick to start it from a weak generator or inverter.
Cheers
Matthew
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jonesy
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« Reply #20 on: August 10, 2012, 02:51:46 PM »

That's a real shame clockman.  It looks like Jon is probably on the money.  I'd never thought of the reactive side.  My 3kva MGE is a 4 quadrant ups, so that must have a way of  dealing with the reactive power, and my smaller APC 1400 isnt man enough to drive my 'proper' motor loads - only tidlers like power drills.  I like the Jon's idea of spining reserve, just a bit tricky to implement.  As a real 'try anything' idea, try putting a traditional 100w light bulb on the ups, and nothing else.  Anything else connected might distort the waveform (CFLs really kill the waveform) and a small resistive load might help.  You could also try some caps out of an old ups -  some nice big 1uF 250VAC rated, across the l/n.  Might give a reserve, but the current is in the opposite quadrant, so probably not.

I'm not sure if a different starter would help, but I guess a bigger kick might help, if the ups will source the current.  What probably would work is to start the fridge on grid and then drop to ups.  The fridge can't stop spinning in the 40-50ms a power relay would take.  Down side is that you might end up with twice mains on the motor if you switch at the bottom of one cycle and onto the top of another.  Power engineers have a name for this which escapes me.  Doesnt sound like a good idea.
AB
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clockmanFR
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« Reply #21 on: August 10, 2012, 07:00:42 PM »

Thanks Mathew for the link. I will have a look at these but will try other things first, as connecting in a starter just on the Inverter/UPS might complicate my circuitry a bit.

AB, Thanks i do appreciate your help.
As i said some where back, I now have a spare APC 5000 (3.7Kw), (came from the Police HQ) which is same model but not old. I have to add power in and power out cables, and a couple of small cables for remote switching on and off. So i will install the new one and see if things improve.

I would be nice to run the Fridge and freezer, but being honest its the underfloor heating we have designed into the house and Gite's that will be the main use, lights, office sockets, water heater and others will all be switchable.

Andy the Inverter Man, (on this forum) got me an adaptable APC1500 for just the Fridge and freezer, just in case we loose our main supply, normally in the winter for several days at a time.
Its 24v and i will have to drag a couple of 36kg batteries around with it. BUT must check it and see if it works Okay.  Huh 

Anyway if you do come across a fridge that will work on my present system, i would be forever gratefull.
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spencer1885
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« Reply #22 on: August 10, 2012, 08:55:11 PM »

Hi clockman,
You seem to be having a problem with your APC UPS, as we had no problem with running the whole house, inc a oil fired boiler,fridge/freezer,hoover and so on.
I can't remember the exact model but I think it was a 2200 rack mounted model, so smaller than your 5000va model.
It maybe that it's faulty as you should have no problems with running your fridge/freezer from a UPS of that type and size.
Cheers
Matthew
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clockmanFR
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« Reply #23 on: August 11, 2012, 10:34:39 AM »

Thanks Mathew for your encouragement.

In that case I will hasten changing over the APC 5000 with the newer version.

So maybe there will be a happy ending.  Smiley
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jonesy
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« Reply #24 on: August 11, 2012, 02:54:54 PM »

At the risk of asking a silly question (normally the ones that have people in stitches ) why dont you run your underfloor heating straight off batteries.  I'm assuming that you mean electric u/f and not the pump that drives hot water for them!

BTW, I used to run my lights (CFL) off 216V DC (18 x 12V nom), although it wouldnt matter with most types.  You could get away with 192V (16off) but they were a little bit dimmer.  I used 7ah batteries and charged them weekly as the draw is tiny per CFL say 20mA. (but that's for 2 people - soon adds up) And you don't need to leave the inverter running drawing its battery draining 1A (every ups I've ever owned, irrespective of operating voltage draws 1A!)  The bulk of modern equipment ie with switch mode PSUs will also run straight off batteries - most motors excluded  - but some will.
Fingers crossed for the APC 5000.  And the 1500.

AB
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clockmanFR
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« Reply #25 on: August 13, 2012, 07:45:53 PM »

Hi AB,

Originally our system was a 48v wind turbine, Hugh Piggotts design, and i wound the coils accordingly. The APC 48v input 5000 UPS was part of the plan along with 600ah of batteries.

Since then the system has grown as we slowly come off grid. I am a horologist so i hate magnetic fields, its in my nature to convert DC to AC.

In general we just switch over chunks of circuits accordingly, so having 230AC is a little easier than separating circuits out for DC use.
Also we will advertise our Eco Gite with Eco electric supply 3.7kw, but as ordinary folk will be using it they will need some training and explanation so its better keeping it at 230AC.

Regards UPS using power, yes mine uses 128watts continuously when on with no load, but that's mostly the cooling Fan.
Will install other UPS next week, as starting another wind turbine tomorrow. Grin

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ilovethesun
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« Reply #26 on: January 27, 2015, 08:11:42 PM »

I don't know if my apc ups would run this fridge freezer as the ups exploded shortly after the lister died.
Any idea what caused the UPS to explode? I've got one of them (been sitting gathering dust for donkey's years) and I suddenly got worried, lol
PS OP, did you get to the bottom of your fridge problem or find one that worked?
« Last Edit: January 27, 2015, 08:23:32 PM by ilovethesun » Logged
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