# 240 volt fans



## JockandRita (Jun 1, 2005)

Hi all,

We have just bought ourselves, 2 x 240v clip on fans to use in the MH.

They are only 20 watt, but are very good on mains power.  However, when used through the 300 watt inverter, their performance is very much lacking.   

Please, can anyone explain why this is so, as the Sky box and LCD TV operate fine on the inverter, whilst pulling about 80 watts between them.

J & R.


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## 96088 (Aug 22, 2005)

I think I will just ask if it is a pure sine wave inverter or a modified sine wave inverter.

And watch the thread develop :wink:


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## Scotjimland (May 23, 2005)

Oldskool said:


> I think I will just ask if it is a pure sine wave inverter or a modified sine wave inverter.
> 
> And watch the thread develop :wink:


 :lol: :lol: :lol: nice one .. :wink:

I rather think it's low voltage, can you check the output while it's running Jock ?


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## JockandRita (Jun 1, 2005)

Hi Pete,

Whilst waiting for a reply, Rita dragged me away as the washing machine was trying to flood the kitchen out.    

That's all sorted now, and I am back at the puter. It is a modefied sine wave (I think) as there is a small fan that operates within the inverter.

However, that little cooling fan doesn't operate when using the 240v fans as they don't pull much power.

Jock


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## JockandRita (Jun 1, 2005)

Hello Jim,

Just got your reply after my last post.

Would that require me to strap a meter across the output socket, whilst the fan was plugged in and swithced on, and if so, what would be the safest method to adopt?

I am very respectful of things that hurt. :lol: :lol: :lol: 

Jock


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## Scotjimland (May 23, 2005)

JockandRita said:


> Would that require me to strap a meter across the output socket, whilst the fan was plugged in and swithced on, and if so, what would be the safest method to adopt?
> I am very respectful of things that hurt. :lol: :lol: :lol:


Hi Jock

Get someone else to do it ? .. :lol: :lol: I'm reluctant to advise as it might get you hurt and be 'illegal'  maybe Pete has a safe method .. ???

Have you checked the input with the fans running ? maybe the 12v is low..


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## JockandRita (Jun 1, 2005)

Jim,

I'll suss it out after tea and get back to you. Kievs are calling. :lol: :lol: :lol: 

Jock.


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## 96088 (Aug 22, 2005)

ScotJimland said:


> Hi Jock Get someone else to do it ? .. :lol: :lol: I'm reluctant to advise as it might get you hurt and be 'illegal'  maybe Pete has a safe method .. ???
> Have you checked the input with the fans running ? maybe the 12v is low..


Jim

It's easy to check the input on my inverter due to the way it is connected to the battery. (Accessible screwed terminals, great for sticking probes down)

I'm not sure it would be on a 300W as it might be a sealed unit (or something like that)

I'm not sure how to do it on the output.

Jock and Rita

I'm sure the cavalry will be along soon with some solutions

*Health Warning*

The random sticking of probes into live lekky bits requires a certain amount of caution


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## JockandRita (Jun 1, 2005)

Kievs now devoured, although it did take Rita an age to catch, pluck and cook them. :wink: :wink: :wink: 

Right, having erred on the side of safety, and heeded Petes health warning, here are the results.

Reading at the inverter input terminals = 13.65 volts (charger on)

Reading at the inverter output socket = 183/4 volts  

you were right about the low voltage Jim, but what I cannot understand is why the TV and Sky box work just fine if the voltage is low.

Does this mean that the inverter is duff?   

Jock.


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## Scotjimland (May 23, 2005)

JockandRita said:


> you were right about the low voltage Jim, but what I cannot understand is why the TV and Sky box work just fine if the voltage is low.
> 
> Does this mean that the inverter is duff?


Looks that way Jock, unless another bright spark can illuminate us :?

PS, can you tell us how you tested the 240v safely ?? 8O


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## spykal (May 9, 2005)

Hi
I wonder if the load is too low for a 300 watt invertor ( to low to get it kick started)....if you can do it safely :roll: try* adding a further load of say a 60 watt light bulb along with the fan and check again. Rubber boots, goggles and hard hat to be worn :lol:

mike

*Disclaimer :roll: 
I do not endorse any of the advice. I provide it to you as a service. I can neither guarantee the soundness of the advice, nor make any claims as to the outcome of following this advice. I provide it for your entertainment only. Should you choose to follow any of the advice, it is solely at your own risk. This is not intended to substitute for obtaining advice from appropriate sources and/or professional counseling. I recommend you consult an appropriate professional, counselor, and/or a trusted advisor before taking any action based on this advice. :lol: :lol: :lol:


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## 96088 (Aug 22, 2005)

ScotJimland said:


> PS, can you tell us how you tested the 240v safely ?? 8O


Please :shockingzap:


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## JockandRita (Jun 1, 2005)

Oldskool said:


> ScotJimland said:
> 
> 
> > PS, can you tell us how you tested the 240v safely ?? 8O
> ...


I am not prepared to divulge such information, as I would not like to think that someone else may wrongly act upon it, thereby causing themselves, or others an injury, fatal or otherwise. :roll: :roll: :roll: :lol: :lol: :lol:

Right, I am off to load the socket. Watch out for the *flash* an *bang*.

Jock


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## JockandRita (Jun 1, 2005)

Righty ho,

I plugged a table lamp into the inverter and switched it on.
It made no difference to the 240v fan's performance, but it did cause the unit's cooling fan to operate.

Glad to say, no *flashes *or *bangs*. :lol: :lol: :lol:

Jock.


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## Scotjimland (May 23, 2005)

JockandRita said:


> I plugged a table lamp into the inverter and switched it on.
> It made no difference to the 240v fan's performance, but it did cause the unit's cooling fan to operate.
> 
> Glad to say, no *flashes *or *bangs*. :lol: :lol: :lol:
> ...


Guess it's back to the drawing board..or down to Maplins :lol: :lol: 
don't worry Jock, 10 pints will buy a new one ... :lol: :lol: :lol:


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## JockandRita (Jun 1, 2005)

> Guess it's back to the drawing board..or down to Maplins
> don't worry Jock, 10 pints will buy a new one ...


Hopefully not Jim, as it is not a year old yet. Now where did I put that bl##dy receipt? :lol: :lol:

Jock.

P.s. Thanks to all for the help and advice.


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## geraldandannie (Jun 4, 2006)

Whoa - hang on there. I'm thinking .....

I would think it's something to do with the inductive loading you're putting on the inverter, which is upsetting it.

Jock - can you do the same thing as before - fan, and lamp. THEN unplug the fan, and measure the voltage. Does it go up again? If it doesn't, switch off, and then switch on the inverter + lamp again. Voltage up?

The fan is a motor, and it may be something to do with the power factor, inductive load, blahdy blahdy blah. It could be that it's just not suitable for driving motors e.g. fans. It's all very clearly explained 
>> HERE << - in particular, take notice of the graph of the frequency spectrum of line-line voltage, where your problem is all too obvious. :?

Maybe. As far as I can remember, low-cost inverters and low-cost motors do not a happy coupling make. Each has difficulty working with the other's shortcomings. If I'd paid more attention at university, I'd be able to tell you exactly. As it is, all I can do is post links to sites which look like they might contain the answer hidden in its depths.

Gerald


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## sallytrafic (Jan 17, 2006)

gerannpasa just beat me to it 

modified sine wave is basically a square wave with lots of missing bits and it cant come close to powering a purely inductive load like a fan. Put lots of resistive loads such as light bulbs on as well and it might work. 

Frank


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## JockandRita (Jun 1, 2005)

Frank/Gerald,

Thanks guys. I was just about to e-mail Maplins. No need to now.

So really, we shoulld either have bought, a pure sine wave inverter, or 12 volt fans. Yes?

Gerald, that link took some reading, whilst emptying the Asprin bottle. Cheers mate. :lol: :lol: 

Jock.


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## geraldandannie (Jun 4, 2006)

JockandRita said:


> Gerald, that link took some reading, whilst emptying the Asprin bottle. Cheers mate. :lol: :lol: .


Wot, you READ it??? :lol: :lol: :lol: Some of the squiggles brought back unpleasant memories.  

So, try what Frank said, although that might be impractical for normal use. I was going to write that pure sine wave inverters were expensive, but not that much by the look of >> THIS <<

If you're too hot, why don't you just open a window? :wink:

Gerald


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## JockandRita (Jun 1, 2005)

gerannpasa said:


> JockandRita said:
> 
> 
> > Gerald, that link took some reading, whilst emptying the Asprin bottle. Cheers mate. :lol: :lol: .
> ...


I would try what Frank suggested, but I only have a couple of table lamps. :lol: :lol: :lol:

Gerald, if someone is prepared to provide assistance by way of a link, then the least I can do is to take a look, and read it. :wink: :wink:

Jock.


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## Scotjimland (May 23, 2005)

gerannpasa said:


> Whoa - hang on there. I'm thinking .....


Hi Jock, I told you a bright spark would be along soon enough ... :lol:

Two choices, buy another two table lamps then plug the fan in to keep you cool.. or head for the pub :wink:


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## JockandRita (Jun 1, 2005)

> Hi Jock, I told you a bright spark would be along soon enough ...
> 
> Two choices, buy another two table lamps then plug the fan in to keep you cool.. or head for the pub


I don't need to be told twice, I am off there right now. :lol: :lol: :lol:

Jock.


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## geraldandannie (Jun 4, 2006)

ScotJimland said:


> .. or head for the pub :wink:


I think this should be our standard advice from now on.

Leaking roof? I'd head down the pub if I were you.

Bad service? Down the pub you go.

Problems with your electrics? There's no problems down the pub. Away with you.

This, of course, has the added advantage that the significance of any and all problems reduces as the quantity of beer increases. So if you drink enough beer, the problem goes away. I'm sure I can find an equation somewhere ...

Gerald


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## spykal (May 9, 2005)

Hi

sorry to have missed the phun we just got back in, ....from...yes you got it "the pub" and could not reshist a look in ere..... we halve a fan which came fom a crapboot slaale .....it is a hexpelair and wash hexpensive wen knew, it runs perfic on my maplin invertisher using 30 whats..and it is very quite.

night night

mike


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## JockandRita (Jun 1, 2005)

Mike,

It is interesting to learn, that your fan works normally from your inverter.

Would that be a pure sine wave, or modified sine wave inverter?

Jock.


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## sallytrafic (Jan 17, 2006)

You may not be surprised to learn that there are modified sinewave inverters and there are modified sinewave inverters. There are two areas where problems may arise the first is with the purity of the sine waves the closer the output resembles a sinewave the more power that will be available at 50Hz and the less that will be wasted at other frequencies.

The next concerns the switching and is more complicated to explain.

One way of making an output that resembles a sine wave is to have several voltages available which you quickly switch to the output at the correct moment. This gives a square edged wave that steps up and down. The switching devices commonly used have a property that they are switched on by a small electronic signal but can't be switched off until the output current falls to zero. In a 50Hz ac circuit this happens every 10ms. However in an inductive circuit the current gets out of phase with the voltage and the devices don't switch off at the right moment. The effect of this is that the more inductance a circuit has the more the load actually affects the output waveform of the inverter.

The more expensive the inverter the more sphisticated its waveform control will be until its output will be as good as a mains supply

Anyone who know 'owt about electronics will recognise the above is a very simplistic explanation. A more detailed explanation is in this

PDF File

Regards Frank


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## spykal (May 9, 2005)

JockandRita said:


> Mike,
> It is interesting to learn, that your fan works normally from your inverter.
> Would that be a pure sine wave, or modified sine wave inverter?
> Jock.


Hello Jock

The invertor is a 300 watt Nikkai from Maplin, a modified sine wave output. The fan is an Expelair Taurus 9" desk fan...I guess quite expensive when new but I got it cheap seconhand...just a lucky buy, it seems to have turned out to be. It is very quiet and no noisier on the invertor than it is on mains.

This subject of fans being noisy ( humming ) when used on an invertor has come up before in other threads about invertors & fans:-

Link 1

Link 2

Mike


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## JockandRita (Jun 1, 2005)

*Frank*,

Many thanks for the info. It's that old saying, that you only get what you pay for, but I did think that the inverter, which is the same model as Mike's (Spykal) would siffice for the low wattage items that we would be likely to use.

I will look at all 54 pages of the PDF file, (honest).....when Rita comes back from the chemist with some more Asprin. :lol: :lol: :lol:

*Mike,*

Being a larger, and older fan, I am assuming that the wattage will be greater than a smaller fan. As I am using the same inverter as yourself, with lesser results, I can't help thinking that it is not functioning correctly, especially as the reading without any loading is still only 183/4 volts AC.

Thanks again gents,

Jock.


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## sallytrafic (Jan 17, 2006)

JockandRita said:


> as the reading without any loading is still only 183/4 volts AC.
> 
> Thanks again gents,
> 
> Jock.


Alas not all meters are equal. The ordinary digital or analogue meter measures the peak to peak voltage of the waveform and assumes that it is seeing a sign wave and applies a suitable correction to give an RMS (root mean square) value of 230V. When the waveform is not a sinewave the ordinary meter applies the same correction but because the form of the wave is different comes up with the wrong answer.

Frank


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## JockandRita (Jun 1, 2005)

Aaaaah,

Thaaaaaat explains the low reading.

Cheers Frank.

Jock


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## spykal (May 9, 2005)

JockandRita said:


> Aaaaah, Thaaaaaat explains the low reading.


Hi Jock and Frank

It certainly does! and to confirm your findings Jock I have just been out and tested my invertor with the fan running.

Measuring with a digital multimeter
The voltage output from the invertor is reading 189 volts
Fan speed 1 measuring the input to the invertor = 1.3 amps (12.5v*1.3a=16.25 watts)
Fan speed 2 measuring the input to the invertor = 2.7 amps (12.5v*2.7a= 33.75 watts)

We live and learn :roll:

mike


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## JockandRita (Jun 1, 2005)

Hi all,

I recently sent an e-mail to Maplins techie department, reference the fans on the inverter. Here is their reply.

*Thank you for your enquiry

The invertor provides a Modified Sign Wave and most motors do not like this
type of power hence it is running slow, a multi meter is not suitable for
checking a modified sign wave voltage and the 180 volt reading is normal on
a multi meter.*

Thanks to those that answered my query, and to the more knowledgeable than myself, whose reply was the same or similiar to that of Maplins.

Jock.


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