Down under the price of stirrer/hotplate combos is very expensive. Some may even deem overpriced. However, the alternative that exists is buying a
hotplate/stirrer combo off an auction site and the question i have is in Australia we have 3-pin dual power point (socket). AS 3112 (Australian 10
A/240 V). By constrast US standard i believe is 115 V power cord.
[Edited on 21-5-2007 by gambler]not_important - 21-5-2007 at 04:29
The heating part pulls a fair amount of current, you'll want to over-rate a converter so you can run it for long periods.
The question of how compatible is the control portion, and perhaps motor, with 50 Hz power is something that would need to be answered by the
particular model. My oldest units don't care, bimetallic control on the heater and all, I just use a stepdown transformer. But that's no guarantee
that the unit you buy will be happy with 50 Hz power.
US is 110V, 60 Hz.Sauron - 21-5-2007 at 04:31
Forget about "power converters" as that nomenclature is used to describe small devices to power say, an electric shaver.
You need to power a US voltage stirrer-hotplate a rather serious stepdown transformer which should have a rating of at least double that of the
stirrer hot plate.
Standard Ozzie household outlets are indeed 240V 10A 50Hz and that works out to 2.5 KW. So buy a stepdown from 240 to 115 VAC of 3 KW, mine (for
220-110) cost me $250 US a few years ago new, it is a HEAVY sumbitch weighing a good 35 lbs.
Also you will need a universal type adapter so the US style plug can be used with the unique ANZ style socket which is not used anywhere else in the
world. A Taiwanese company makes such adapters, I have several and they are quite useful and rated for 250 V 10A.
All that being acquired, two things to consider. One, you will be using 60Hz motor and induction heater on 50 Hz so you'r going to lose 15% of your
top end on both speed and wattage output. Nothing you can do about that without a very expensive inverter, or a rather dangerous motor type phase
changer (NOT recommended.) All in all - grin and bear it.
The second is that you MUST drill into yourself and anyone else coming anywhere near this equipment that the power cord for the US device must NEVER
be plugged into the 240V wall outlet. If that happens and the hot plate/stirrer is turned ON, it will come to a sudden unhappy end. If you are very
lucky the inline fuse will catch it, but more likely the fuse will not be fast enough to prevent catastrophic damage to the stirrer/hot plate and it
will become a late instrument, passed over the loo, gone to its final reward and so on.
As I live in a 220V 50 Hz country and import a lot of second hand US-voltage lab equipment, believe me, I speak from hard experience. I have fried an
Ace temperature controller this way. Shit happens. Color code your power cords and pay attention to your setups. Don't be penny-wise on stepdown
transformers, buy the best you can get and do not overload them.unionised - 21-5-2007 at 10:59
Is buying from the UK less of a rip off than Australian stuff?
Stepdown transformers
gambler - 21-5-2007 at 13:56
Just a quick update before i head off to work. I will post a more complete version this afternoon.
Sauron:
Thankyou very much for the advice i do appreciate it. The cost of the stepdown transformer you purchased and the weight seem fairly different with
that which i could find.
Are any of these suitable for my purpose? Or will they be not what is required.
Thankyou again for your assistance.S.C. Wack - 21-5-2007 at 15:41
Here in the US we draw 120V from 240V lines all the time as standard practice for powering 120V add-ons to 240V appliances. Here it works by using the
ground wire and either one of the other wires for power. Waalaah, 120V. Does this sort of thing also work with Australian power lines? Is the
difference between 50 and 60 Hz going to matter much in this case?not_important - 21-5-2007 at 17:33
Quote:
...
Are any of these suitable for my purpose? Or will they be not what is required.
What matter is that
A) They match your mains frequence - 50 Hz in most of the world
B) They do the 2:1 stepdown
C) They can handle the full wattage of what you are plugging into them, plus a safety factor of 25% or so. For things that are going to be on for many
hours a little larger factor is a good idea. If the device has a large starting surge, as some motors do, again increase the excess capacity of the
transformer.
Can't tell you if any of those transformers will work, because you didn't give the specs on what it is you are powering.Sauron - 21-5-2007 at 17:40
@gambler
I haven't had time to look at that site yet, but I would recommend against the typical "household" stepdown as sold in hardware stores and
department-stire hardware sections, those are about 7" cubes weighing about 10-15 lbs and usually rated at 1.5 to 2 KW.
Those are not intended for heavy duty use and do not last very long. I know, I own one.
The one I am talking about is in a chassis about 8 x 12 x 18 inch and is bloody HEAVY, rated at 3 KW so it will handle a normal Aussie 250V 10A
circuit full load with 20% to spare. Remember V x A = W right?
In short you want a more industrial sort of bit of kit as I described, to power a resistance-heacter (hot plate). The motor for the stirrer will draw
little power, the resistance heater will draw a lot.
What is the power input of your US voltage hot plate stirrer in Amperes @ 115V?
The transformer I have (bigger one) has two outles for 110V and two for 100V and so using the first two you can power more than one US voltage device
at same time. I have used it to power a US-voltage rotavaper which draws a lot of power for waterbath, and a US voltage vacuum pump at same time. It
has two fuses and an on-off switch.
I just checked out that website,
Skip page 1. Page 2 has a variety of transformers from about 1 KW to 15 KW. If this is your chosen supplier (surely though you can find one down
under?) buy nothing smaller than 3 KW and 5 KW would not be a bad move. That is 2X more than your line will carry. Just remember never to load it
more than 40% or you might start blowing fuses or popping breakers at startup because of initial surge.
[Edited on 22-5-2007 by Sauron]bio2 - 22-5-2007 at 10:00
.......Here in the US we draw 120V from 240V lines all the time as standard practice for powering 120V add-ons to 240V appliances. Here it works by
using the ground wire and either one of the other wires for power. Waalaah, 120V. Does this sort of thing also work with Australian power lines? Is
the difference between 50 and 60 Hz going to matter much in this case?............
The 220 or 240V 50HZ single phase used in some countries is the line to Neutral voltage. Line to line voltage single or 3 phase would be 380 or 415V.
This derived from the square root of 3 times the neutral voltage.gambler - 23-5-2007 at 00:42
To be honest i hadn't picked a stirrer/hotplate it was merely a consideration due to the exorbitant prices of them down under.
I will do some more research in the coming days and provide some details in regards to the specs of what i am powering.
I will nevertheless have to find a better supplier for a step down adapter as sauron has advised as it will be useful for more than one purpose..
Thanks again everyone expect an update soon.Sauron - 23-5-2007 at 02:42
Wise move, gambler. You want something you can actually run an entire power strip off of, rather than just dedicating it to a single machine.
Minimum, 3 KW which will let you run a good 10 amps of 240 V while still leaving a 25% margin for safety. Yiu might want to stay below that because
that is what your Oz house circuits can carry and you might start tripping your breakers.
So maybe 8 amps is your practical maximum load. That's 2 KW (actually 1920 W) but don't make the mistake of dropping down to a 2 KW transformer. Yiu'd
fry it in no time. A good 3 KW stepdown autotransformer will handle 2 KW constantly without overheating. Obviously, use it in a cool place and out of
the direct sunlight.
