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bearfamily
Seeker
Joined: Oct 06, 2008
Posts: 64
Location: Shanghai
Status: Offline
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Oct 12, 2008 - 12:23 PM |
 
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| Post subject: Need a big voltage converter |
Just moved here:
1. We need to buy a more permanent type of voltage converter something that can be plugged in and used for 10-12 hours at a stretch (US 110 volts). The travel converter we brought is awkward (falls out of the outlet unsupported) and gets really hot after 2-3 hours of use. I've notice these rather large, heavy metal boxes (two three prong outlets, a toggle switch and light in front) that people here have in their flats that seem like more longer-use, heavy duty converters. What are they called (english and chinese?), how much are they and how does one get them?
2. We can you go to by a fire-extinguisher for home use? Our aiyi almost burned our kitchen down the first day she was here with a grease fire in the wok.
Thanks! |
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shiner
Seeker
Joined: May 28, 2004
Posts: 60
Location: Shanghai
Status: Offline
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Oct 12, 2008 - 06:58 PM |
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They are called transformers. You need to check your consumers about what power rating you need and then buy the appropriate transformer (e.g. 50W for a mobile phone, 500W for a PC/TV or 2kW for a vacuum cleaner or iron device). The simple/cheap type doesn't convert the frequency (50/60Hz), which can cause problems with devices with build in timers or motors can run at different speed and heating devices can overheat. |
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Mister_happy
Reacher
Joined: Oct 28, 2004
Posts: 349
Status: Offline
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Oct 12, 2008 - 07:13 PM |
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Another option is to have a look at the back of the appliance, sometimes there is a switch to convert between 220/110V. Another thing to do is replace the power transformer in the appliance itself. Sometimes that can be converted by changing the wire from serial to parallel, 2x110V or 110v+110v as there are two coils inside the AC/DC converter. |
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bearfamily
Seeker
Joined: Oct 06, 2008
Posts: 64
Location: Shanghai
Status: Offline
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Oct 12, 2008 - 08:37 PM |
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Shiner,
Thanks for the info. Any advice on where I could buy a transformer and about how much it would run? Would BestBuy have something like that?
Thanks  |
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CIA
LoopKicker
Joined: Mar 23, 2008
Posts: 890
Location: Least Expect
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Oct 13, 2008 - 09:05 AM |
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I've got five huge transformers (and some smaller ones) powering a healthy list of 'imported' AV stuff. In addition to the transformers, I've also got line conditioners and series of fused and breaker trips between the source and the end device. Obviously, I put all these safeguards in place because the stuff I'm running is in the thousands and thousands of dollars range and I don't want or need that kind of cash turning into a paperweight.
Couple things you need to understand, one is power (Watts) vs. voltage (V) or current (I). Power is expressed in watts, whereas voltage is expressed in volts and current in amps (usually). Something else you need to pay attention to is this formula: P=VI
What you'll need to do is this (simplified form), take the sum of the power you intend to run 'downstream' of the source (outlet). In addition, you will need to know the peak and the nominal draw of each individual device you plan on running. Determine if everything you want to run is reasonable from one source (this gets tricky as you need to know how your wiring is designed, outlets and circuits, some simple trial and error can tell you or you can call your buildings maintenance people).
Next you need to account for a 'safety factor' between the level of power you're drawing at the device end vs. how much that equipment costs or is worth to you.... basically if you have a lot of expensive stuff and you don't want to risk 'blowing it up' from a power spike or surge or other, then you're going to want to multiply the total power draw by a factor of at least 3 if not 5. This number will tell you how big (and / or how many) total transformers you're going to need to power your equipment safely. If you have a bunch of cheap stuff that you don't particularly care about, 1.5 to 3 is enough.
I've got two 3000 W, two 2000 W one 1000 W and several smaller ones taking care of a range of equipment. You'll need to devise a strategy for branching your equipment properly (balancing) and if you're really paranoid and want to make things nice and neat, look into conditioners and other methods of circuit breakers / fused disconnects / etc.
Also, remember that some equipment will run on a range of voltage (110 to 220) instead of just one or the other (110) or (220) exclusively. There are also 'timing' issues with the frequency (Hertz) that is supplied from the power source and the device design (50 or 60 Hz).
I've got things that run on 110 and the range 110 - 220 that I pump clean 110 into and I do this intentionally - every situation is different and up to the users preference / intended use / strategy. The primary reason I have my set-up designed the way I do is this: better safe than sorry.
Take a look at this website to get a feel for some of the technical stuff you don't understand or have familiarity with: www.howstuffworks.com
Last piece of advice: do your homework or find someone that understands this stuff in detail, the last thing you want to do is hear that infamous 'pop' and watch your investment go up in that little trail of white smoke.... i.e. don't just go plugging stuff in and throwing power switches, that's a good way to learn an expensive lesson. |
_________________
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| Every evening I died, and every evening I was born again, resurrected. |
Last edited by CIA on Oct 13, 2008 - 09:14 AM; edited 6 times in total |
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CIA
LoopKicker
Joined: Mar 23, 2008
Posts: 890
Location: Least Expect
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Oct 13, 2008 - 09:07 AM |
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Almost forgot: BB has a few transformers but nothing big (mostly all below 1000 W, if that).
I'll dig out the location I picked all my stuff up from, but I can tell you this, they are hard to find and even harder to find ones that are built well and that you can trust. |
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| Every evening I died, and every evening I was born again, resurrected. |
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verylatenight
Newbie
Joined: Oct 13, 2008
Posts: 4
Status: Offline
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Oct 13, 2008 - 09:34 AM |
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There are many web sites to point you in the right direction.
All devices have input voltage and frequency stated on the external transformer or equipment. Phones and shavers are usually no problem. Electronics that use an internal transformer can take the frequency change but need the correct voltage. Computers usually have a switch on the power supply. Anything with a motor such as vacuum cleaner, coffee grinder, or fan will not work or last long with the wrong frequency. Always check and may be best to put a big label on something that cannot be plugged into an outlet like a U.S. XBox.
Converting voltage is easy - buy a transformer. They come in small sizes by watts (amperage x voltage) up to big sizes to run a factory and measured in KVa. Small sizes are available at Carrefour and B&Q. You may need a small one in the bathroom for the hair trimmer and a larger one for some AV stuff. They get hot so bigger is better.
Converting frequency is difficult and pricey. Often too expensive for the house and cheaper to buy new appliances. There are motor drives and actual frequency converters. I have a contacts and experience for both. But like I said, price is high. |
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CIA
LoopKicker
Joined: Mar 23, 2008
Posts: 890
Location: Least Expect
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Oct 13, 2008 - 10:10 AM |
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Read this:
http://www.shanghaiexpat.com/MDForum-viewtopic-t-66414.phtml
Go to the store that ComputerSolutions describes in his long post - second or third stall on the right hand side as soon as you enter the building (down the right hall). |
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