Hi,
Try this place.
http://www.voltageconversion.co.uk/store/home.php?cat=260
HTH,
David,
London,UK
So how can I get this thing power up, the transformers in the uk electronic shop maplin go about 70 dollars that is £50, as much as the Item itself, surley they is another way anyone?
I wouldn't worry about inrush current, a transformer should be able to handle many times its rating for a very short period of time and double it's conterminous rating for a bit longer.
What normally kills a transformer?
Overheating which causes the insulation to fail between neighbouring windings to fail causing them to short and overheat more until it starts a fire unless some thermal protection kicks in.
The good thing is, because a transformer is a huge lump of iron it takes awhile for it to overheat, even if it's short circuit for a second or so. The inside of a motor has something in common with a transformer: it's lots of wire wound round an iron core. If the motor's windind can withstand the inrush current drawn when it's started, then a transformer of the same power rating certainly will.
Underrating for low duty is also very common - you'll often see 3kW for 15 minutes or 1.5kW continuous printed on the nameplates of transformers. Of course you can get away with overloading larger transformers more for longer simply because they have a higher thermal time constant. I wouldn't expect you to connect a 300W load to a 150W transformer for more than a minute without it overheating.
In this case the fuse might be a problem. You might only use your blender for a couple of minutes at a time so you decide that a 150VA transformer will do but if the transformer is fitted with a 1.5A fuse it's almost certain to blow within a couple of minutes of just over 2A being drawn.
So how can I get this thing power up, the transformers in the uk electronic shop maplin go about 70 dollars that is £50, as much as the Item itself, surley they is another way anyone?That's the problem, transformers aren't cheap.
I found one in Maplin for £30.
http://www.maplin.co.uk/Module.aspx?ModuleNo=265288
How long does the blender normally operate for?
If it's only for a few miniutes at a time with as long a rest in-between then you will probably be able to get away with using a slightly lower power transformer, as 150W which will cost you less but it is a risk.
http://cgi.ebay.co.uk/K-E-R-T-POWER-TRANSFORMER-EURO-UK-230V-USA-110V_W0QQitemZ320476667026QQcmdZViewItemQQptZLH_DefaultDomain_3?hash=item4a9de5dc92
the other is fully electronic or magnetic with electronic voltage regulation built in.
Neither type is very fond of heavy inrush currents.
The regulated ones are designed for use with delicate electronic devices that can't handle a wide variation in voltage.
thats a very bad idea, particularly as a recomendation, if you choose to take that risk yourself fair enough, don't suggest it to someone that may not understand the implications
the other is fully electronic or magnetic with electronic voltage regulation built in.I've never seen an electronic transformer, apart from the type used to power halogen lamps and in that case the output is normally a high frequency square wave, not a 50Hz sine wave.
Could you please post a link to one?
I imagine an electronic transformer would be very complicated. First the AC needs to be rectified to DC, then an inverter is required to convert it to a different AC voltage, The inverter won't be simple, to get a good sine-wave, a class D amplifier would have to be used.
I would imagine that an electronic transformer would already have built-in over-current protection so overloading it shouldn't do any damage, the chances are it would just shut down, then try to restart after a certain period of time.
QuoteNeither type is very fond of heavy inrush currents.I don't know about an electronic transformer but I know a magnetic transformer won't be damaged, just look at any audio amplfier power supply schematic and you'll see a huge electrolytic capacitor immediately after the rectifier which will short circuit the transformer when the power is first applied. So much so that a large audio amplifier will have inrush protection, but not to protect the transformer but to prevent the fuse from blowing every time it's powered up.QuoteThe regulated ones are designed for use with delicate electronic devices that can't handle a wide variation in voltage.I don't see why you'd ever need a tightly regulated mains supply?
Most delicate electronic devices are powered from a switched mode supply which can accept a wide range of mains voltages. Those pesky SMPSes also tend to draw a large inrush current because they have a capacitor connected to the output of a rectifier.
I'd rather educate someone so they can make up their own mind up rather than be a nanny and say don't do it.
http://www.voltageconversion.co.uk/store/product.php?productid=16214&cat=260&page=1
It's nothing more in theory than a common wall wart, only it'll output AC.
Because some of the voltage converters have a much wider voltage output range (especially in the unloaded state) than some electronics are designed to handle. You can hook a drill or heater up to 140 or 150 V and it'll be fine. Some electronic products won't. The unregulated step down transformers can have that high of a voltage when no load is applied. It will fry some delicate stuff.
If your electronics have a switched mode supply that can handle 90-230V, you probably don't need the step down transformer in the first place, right?
You've already suggested that he use a 150VA transformer to run a 250W motor load a few times. That's just wrong. You could power a 150W incandescent light bulb, since it's a linear load with near 1.0 power factor and the watts are more or less equal to the VA, but a motor doesn't have a perfect power factor. He will need a minimum of 300VA and likely more.
Might be cheaper to replace the motor?
You must get a transformer that's rated for more than your motor is rated. Motors can have an inrush current many times that of their operating current (in your case about 2.1A on US voltage). So when you start the machine, it will be using way more than 150W, more like 800W for a short time. You also need to make sure that you get a converter rated for appliances. They will have a magnetic transformer rather than an electronic one. The voltage will not be exact (possibly about 130-140V) but it will handle the motor load. Another thing to be aware of is the frequency difference. Your appliance will run slower on 50Hz than it would in the US on 60Hz, and will have a little less power.
Thank you everyone for the information, im not going
to buy a transformer as it is expensive and im
not going to make one either as its not a
breadboard and my partner would be using the blender in the kitchen