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Joined: Feb 2003
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RobbieD Offline OP
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Hello, I'm from Canada and working overseas for 6 Months. Every week I get a call to see what the problem is with someone's electrical appliance. When I get there I see that the appliance was plugged into a step down transformer 220/110 ,nameplate on appliance says 120V 60Hz, people always forget that we are overseas and that the frequency is different. They think that that little transformer changes the frequency for them. Silly people!
Usually if the appliance has electronics and it is not working anymore I tell them its because of the frequency and that they may have ruined it.If there were motors in it and they saw some smoke well I tell them to go buy a new one and make sure of the ratings. I don't even meter them anymore.
I have looked on the web about 60Hz appliances being plugged into 50Hz and the info I got was that it just slowed down motors and made digital clocks not work. Wouldn't the change in frequency affect the impedence of any circuit that is not purely resistive? Well I tell them to buy a new appliance good for 50/60 or just 50 if they are not taking it back to Canada.
Anyone have any thoughts on the effects of different Hz on equipment?

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C-H Offline
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Hi and welcome to ECN Robbie!

It will have an impact on 60Hz transformers: The lower frequency means the core saturates earlier, reducing the performance. At full load it will overheat.

Side note: The difference between a 50 Hz and 60 Hz transformer is small, but apparently significant. The difference between a 50Hz and a 400 Hz or 1000 Hz transformer is huge. There is a 1000Hz 120kVA 500V / 10V transformer laying around somewhere here. At 15 kg / 30 lbs. I can hold it it my hand. Lifting a 50Hz transformer with the same data is out of question.

Joined: Jun 2004
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I worked at a remote site with 240VAC 60Hz supply. Lights & heaters-no problems, anything that relied on the mains for syncronisation i.e. clocks in microwaves, alarm clocks, the clocks run 20% faster than 50 Hz. Some fridge compressors didn't like it either.

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C-H Offline
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Came to think of something that hasn't to do with frequency: Meter the voltage of the transformer. I recently got a 400 --> 230V transformer that in reality put out 250V @ 400V. If the step down transformer outputs the wrong voltage, it will smoke things.

Joined: Jul 2004
Posts: 145
C
Member
I have a couple of thoughts on this... one, the transformer saturation issue can be helped by using a lower voltage than the nameplate voltage, EG if you could tap the transformer at 110 rather than 120 volts.
Also, are you SURE it's 220 volts? if you have a transformer to produce 120v from 220, if it's plugged into 240 volts the output will be around 126 volts which may be over tolerance for many appliances, especially in conjunction with the lower frequency. (just a few ideas [Linked Image] )

Another thought, many manufacturers slightly overwind transformers, so if it's rated at say... 1 kva, 120volt, at no load it may well output 125-130 volts (the regulation on small transformers tends to be lousy)

[This message has been edited by chipmunk (edited 07-23-2004).]

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RobbieD Offline OP
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Here the voltage is 220V 50hz. The output of the step down transformers is 110V. The appliances that people are plugging in are 120V 60Hz. So the voltage has been reduced to keep the same frequency to voltage ratio.

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C-H Offline
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I just want to lift this thread up again. I feel Robbie didn't get a real answer and this isn't the first time people have reported problems with the frequency difference.

Joined: Jun 2004
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About 25-30 years ago, my father was selling 'Manitowoc' (?) brand ice makers in Australia (240VAC @ 50Hz). The units as shipped ex-USA were 110VAC @60 Hz. The units were fitted with 240-96 VAC stepdown transformers that were custom made to allow for the frequency difference.

Joined: Aug 2001
Posts: 7,520
P
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I agree with C-H in that we didn't seem to cover this well. It looks as though I missed this thread when it was posted as well [Linked Image] -- My apologies.
Quote
Wouldn't the change in frequency affect the impedence of any circuit that is not purely resistive?
It sure will.

Inductive reactance = 2 * pi * f * L
Capacitive reactance = 1 / (2 * pi * f * C)

So XL or Xc will be correspondingly 20% higher or lower. If the power factor of the circuit is fairly low, then that could have a considerable effect on the overall impedance.


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