American Voltages & Htz in Aus with a transformer

First post, been lurking for years, great knowledgebase and great humour. But less of the praise and down to business.

I want to buy a Drill Doctor http://cgi.ebay.com.au/Drill-Doctor
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This DD750x model won’t be in 240volt production until next year, and the prices of the last models in Aus are just huge.
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I have a 240 to 110Volt transformer, but my question is what about the difference in Htz. In the <st1:country-region w:st="on"><st1>US</st1></st1:country-region> they work on 60 Htz, here in Aus we are 50 Htz.
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Should I buy it? or will it burn out, blow up etc. Or will it just be a bit slower?
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Technical advice would be appreciated.

So long as it doesn't have an onboard clock, you won't notice a difference.
(Clocks run at a slightly different speed - can be a problem for some.......;) )

It doesn't have a clock and 60Hz won't make much difference to the kind of motor in a drill sharpener.

I've heard that 60Hz may have a possible undesireable affect after hundreds of hours of use, where the rotor windings may loosen and thus lose efficiency and performance, i.e. it slows down. But I'm no expert on windings.

BTW I have an old sharpener which looks just like the Drill Doctor but it's driven from a normal electric drill. Works like a dream.

What? Your drill bit sharpener doesn't have a clock? When do you know it is time to sharpen?

;)

Thanks all for answering my question, I have just ordered the Drill Doctor, I will advice the Forum of my progress.

(I promise not to paste from MS Word in future, just learning!)

Quote:

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Originally Posted by Stuart.

What? Your drill bit sharpener doesn't have a clock? When do you know it is time to sharpen?

;)

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:D :D :D

Quote:

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Originally Posted by PPW

Thanks all for answering my question, I have just ordered the Drill Doctor, I will advice the Forum of my progress.

(I promise not to paste from MS Word in future, just learning!)

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(Fixed- thanks though - I have seen other threads like that in the past- wasn't sure what caused it- now I know!)

One thing concerns me here.

It says permanent magnet motor, which means it might already be running a small transformer in it.

If you grab it, see what makes it tick, might be fine with a transformer, maybe you just need to plug in the right power from a tranny to start with, making it even easier. :)

Ooh, I just asked this question in another thread,
PPL, how did it go? Did you blow up your drill doctor?
Thanks.
Hans.

I know this is an overdue reply, but it is important to correct some misinformation!!

Sorry Stuart & Knurl, but this is wrong. Any machinery with an induction motor designed to run from a 60hz system will have potential (and possibly catastrophic) problems if used at 50hz (The issues are not as dramatic taking 50hz systems and runing them at 60hz, mainly due to the voltage to frequency ratio decreasing - see below)

240 to 110Volt transformers are mainly sold to folk that want to use a TV, stereo, PC or other electronic appliance. Most of these appliances run their internal functions from DC voltage & the mains circuit feeds an AC to DC converter. Machinery motors are different!

The problems are due to the design of AC induction motors in general, and there are some additional issues with single phase induction motors. These issues include the following:

(a) Motor will turn 20&#37; slower. (b) Motor cooling will drop dramatically, resulting in windings heating up & causing premature motor failure. (c) The load's horsepower requirements will drop, possibly dramatically. (d) The voltage to frequency ratio will increase possibly causing a large increase in current draw & this coupled with the reduced cooling may cause rapid overheating.

Single phase motors have an assisted starting winding because single phase power does not have an inherent rotational aspect to it. This means an additional start winding is required to provide starting torque. A common method for controlling power to this temporary winding during starting is a centrifugal switch mounted on the motor's rotating shaft. This switch is normally closed during start up. Once the motor achieves a certain speed during start up the switch opens de-powering the start winding. If a single phase motor is moved from 60Hz to 50Hz it is turning 20% slower may not achieve a speed sufficient to open the centrifugal switch. This would likely result in an immediate burn out.

Some single phase motors have start or run capacitors and some both. If the motor is being shifted from 60 to 50Hz the capacitor will not work as effectively. This will result in possibly lower running and starting torques. This may mean the motor cannot successfully start its load or maintain running a load. A failure to start may result in a rapid burnout(in seconds) so this should be carefully monitored initially. Larger capacitors or additional ones may be needed - usually uneconomical for small appliances.

It is possible to buy frequency converting power supplies, but these a VERY expensive. Thousands of dollars.

Inverters designed for the US market may be a possibility, however the electronics in these devices usually are designed for runing other electronic equipment and do not produce a decent sine wave output. This can lead to motor problems & burn-out as well. Inverters also have (in the main) fairly low power (wattage) output.

Having said all that, there are motors designed for 50/60hz use. Any motor that has "brushes" is a so-called "universal moror" and these !should! work OK with a simple stepdown transformer.

Also, some appliances (but normally not machinery) use a transformer/rectifier and a DC motor, so will run fine from a "Dick Smith" style voltage converter.

As you can see, it is not simple and you really need to know the motor type & characteristics you are considering.

See http://www.epanorama.net/links/motorcontrol.html#ac for more info on motor types if interested