High-wattage voltage converter

Ack!  I blew out the voltage converter I brought from the US the second time I used it, by leaving it plugged in for several days (this is what comes from not reading the instructions).

So now I can't use my wok, my rice cooker, or my sewing machine (the three items I decided were expensive and personalized enough that I would be willing to spend the money on a converter instead of buying new).

Does anyone know where I can get a UK to US voltage converter here?  I've looked at some similar threads, and saw that closet.hippie got one at Argos--but I'm confused as to whether that was just an adapter, or a converter.  And  my visit to the Argos website was a total failure.  I have no idea how to search or navigate that site.  All I found was a plug adapter.  I followed the link in that thread to Maplin, but all their converters were around 200 watts or less, and I need a 1600 watt one (the one I brought from the US had a switch that made it either be low wattage for things like phones, etc., and high wattage).

Thanks!

Ack!  I blew out the voltage converter I brought from the US the second time I used it, by leaving it plugged in for several days (this is what comes from not reading the instructions).

So now I can't use my wok, my rice cooker, or my sewing machine (the three items I decided were expensive and personalized enough that I would be willing to spend the money on a converter instead of buying new).

Does anyone know where I can get a UK to US voltage converter here?  I've looked at some similar threads, and saw that closet.hippie got one at Argos--but I'm confused as to whether that was just an adapter, or a converter.  And  my visit to the Argos website was a total failure.  I have no idea how to search or navigate that site.  All I found was a plug adapter.  I followed the link in that thread to Maplin, but all their converters were around 200 watts or less, and I need a 1600 watt one (the one I brought from the US had a switch that made it either be low wattage for things like phones, etc., and high wattage).

Thanks!

I don't know if they still sell such things...but I got all of my step-down converters from TeleAdapt.  I believe their UK online store is at:  http://www.shop.teleadapt.com/uk/

Sorry...I didn't have time to see if they still sell step-down converters.  But everything I've gotten from them has been first rate!

Good luck!

Janet

(lordcelery.blogspot.com)

Rather than semi-conductor switching technology it sounds like you might have to get a good old-fashioned step-down transformer. The RS organisation sell such things:-
http://rswww.com/cgi-bin/bv/rswww/subRangeAction.do?catoid=-1600754491&cacheID=uknetscape

(the one I brought from the US had a switch that made it either be low wattage for things like phones, etc., and high wattage).

Hmmm......   That's a very strange setup indeed.    It sounds like some sort of overly complex switched-mode supply or something of that nature, but to have a switch for output power (as opposed to selecting the output voltage) is rather weird.

I'd echo the previous comments:  You just need a good old-fashioned hefty transformer.  Here's another source (1, 2, and 3kVA types near the bottom of the page):

http://www.tlc-direct.co.uk/Main_Index/Transformer_Index/USA_110volt_Convertor_Transformer/index.html

So long as you install one of these where it has reasonably free circulation of air, there's no reason why you can't leave it plugged in continuously. 

Thanks everyone!  Wow, it is strange that the same item doesn't seem to be available here.

I found a whole bunch of items similar to what I had at the US amazon:



I think what I may do is order it and have it sent to my folks in the US, and pay them the $28 it costs to ship to me.  Even with that and VAT, it will be cheaper than the £110 or so it seems the wattage I need is available here.  And cheaper enough, I think, to risk blowing out another one.  If I do that again, maybe then I'd spring for the heavy-duty ones they have here.

A quick search on that Recoton model gives me some clues as to the design.  My best guess is that it incorporates a conventional transformer for the 50W setting and a switched-mode supply for up to 1600W which is most likely outputting a straight squarewave (normal AC power is a sinewave).     Squarewaves are bad news for
any appliance which has a motor or electronic control in it.

Judging by the size (or lack of) of that unit, I'd be willing to bet it gets pretty warm after a half-hour of running at 1000W too.

Sorry, but if I was asked for my honest opinion on this sort of unit, I'd have to say toss it in the trash and buy a decent transformer.   You get what you pay for, and $15 for 1600W is only going to get you junk.   

A quick search on that Recoton model gives me some clues as to the design.  My best guess is that it incorporates a conventional transformer for the 50W setting and a switched-mode supply for up to 1600W which is most likely outputting a straight squarewave (normal AC power is a sinewave).     Squarewaves are bad news for
any appliance which has a motor or electronic control in it.

Thanks for the electrical-knowledge info!  This makes things make much more sense. I now think that I will buy the 2000VA model.  I was just thinking the danger was wasting transformers, but if I could endanger my fuzzy-logic rice cooker I'm willing to shell out the money.  Plus, it has two plugs, which will enable me to plug in the rice cooker and wok at the same time! (A logical conundrum I encountered the first, and only, time I used the last one).

Just a thought,if you have a Machine Mart near you check them out.Or do a google and search on their site for transformers.


Dave

Just a thought,if you have a Machine Mart near you check them out.

Machine Mart stocks 110V building-site transformers.  These are intended for the 110-volt power tools which are used here on such sites.  They're bright yellow and look rather industrial, so you would probably want to hide one in a domestic environment.     

Instead of providing a grounded conductor and a hot conductor they also use a grounded center-tap on the secondary to provide a split 2 x 55V supply (intended to improve safety on sites), although for just running a few kitchen appliances that would not matter.   The output voltage is a fraction lower than the nominal U.S. supply, but well within tolerance.  (In fact I have an older site transformer which I have rewired to provide standard 110V power for some of my technical equipment.)

Assuming that you're not capable of modifying the unit for standard NEMA sockets (if you were you wouldn't be in this thread, right? ), you would have to provide a suitable extension/adapter cord though, as they are supplied with BS4343 industrial sockets.  A couple of heavy-duty American extension cords with the original plugs cut off and  BS4343 plugs wired on instead would work.

In the current catalog they show a 1500VA unit at £56.95, and a 2250VA at £62.95, both plus VAT (17.5%).    That's cheaper than the models sold specifically for U.S. appliances, but obviously without the appropriate sockets already fitted there would be more work involved to use one of these.

A couple of heavy-duty American extension cords with the original plugs cut off and  BS4343 plugs wired on instead would work.

Eek!  Too complicated for me.  But thank's for the pointer to a lower cost option, anyway

I got one of the heavy-duty ones from TLC.  Everything works fine except the rice cooker   I noticed a distinct difference in the wok from the old (cheap) converter--this time it cooked like it said it should, whereas before the temperature was way hotter than what I dialed (I burned dinner...).  I guess maybe that was due to the square wave?

I don't know what's up with the rice cooker, though.  It just doesn't seem to know it's plugged in.

If I've read your comments correctly, the rice-cooker has some sort of electronic control incorporated.  It's possible that it could have been damaged by the squarewave output of the old converter.

Is the wok just a simple heating element, with no fancy digital displays, keypad programming, or anything like that?   If so, then the fact that it was running hot before suggests that the old converter's squarewave was not properly regulated in voltage to deliver power equivalent to a proper sinewave. 

If I've read your comments correctly, the rice-cooker has some sort of electronic control incorporated.  It's possible that it could have been damaged by the squarewave output of the old converter.

Actually, I never got around to plugging the rice cooker into the old converter before I blew it out.  And yes, it has some sort of electronics.  I wonder if it's sensitive to the different Hz?

I wouldn't normally expect the frequency difference to prevent the unit from operating at all.    If the timer/clock derives its timing from the supply, then running on 50 instead of 60Hz can throw the timing out.  Such timers are relatively rare on modern units though.

If you've not actually used the unit since shipping it over here, I'd be more inclined to think that the jourrney has resulted in a loose connection or something like that. 

By the way, sorry to question what might seem the obvous, but if you've bought a transformer with two outlets, I take it you've used one of your known-working appliances to make sure that you have power on both receptacles?   

In the current catalog they show a 1500VA unit at £56.95, and a 2250VA at £62.95, both plus VAT (17.5%).    That's cheaper than the models sold specifically for U.S. appliances, but obviously without the appropriate sockets already fitted there would be more work involved to use one of these.

I bought 1 one of my transformers here in the UK from Newmarket Transformers (the other one I got in the States for a fair bit cheaper) and it has served me very well, we keep it near a socket but out of site in the kitchen.  All our American kitchen appliances (blenders, whisks, whaffle maker, George Forman Grill, etc) have worked a charm for a couple years now.
http://www.newmarket-transformers.co.uk/autos.asp

We have the uncased version as pictured in the top right picture.  If you pay about an extra £6 you can get one with a case which I think has the benefit of a handle.  We don't really move ours at all, we wouldn't want to, there's dense dark material inside them suckers - you can put your back out lifting them if you're not careful!

They also have Step-Up transformers if you move to the US and take your British stuff with you.  I've been warned by both Transformer companies that you should ideally have enough Wattage to cover double the amount required in case there is an electricity spike.  So you might want to consider a 3000 Watt Transformer for that 1600 Watt Wok.  Of course, you could go with a 2000 version and take the risk, it should work under normal conditions.

Matt

We have the uncased version as pictured in the top right picture. If you pay about an extra £6 you can get one with a case which I think has the benefit of a handle. We don't really move ours at all, we wouldn't want to, there's dense dark material inside them suckers - you can put your back out lifting them if you're not careful!

It's epoxy compound.  It help keep moisture out of the windings and evens out the heat dissipation.

I've been warned by both Transformer companies that you should ideally have enough Wattage to cover double the amount required in case there is an electricity spike.

Certain appliances do draw a momentary surge of power when you first switch them on.  Things with just basic heating elements, lights, etc. don't do that, but appliances with motors will.   (It's all to do with the way the magnetic fields interact in the motor as it starts.)

It becomes more of a problem as the motor gets larger.   You should have no problems with the relatively small switch-on surge from a coffee grinder, blender, etc. running on a reasonably sized transformer (500W or more).    When you come to starting the heavy-duty motors in a washer, dryer, or something like that though, the surge becomes much more significant.