German Clock in the USA 230V 50Hz to 120V 60Hz

[Palmbay]

My first suggestion to these fine people, was to replace the motor to a 230V 60 Hz motor. I have talked with a few people I do business with and could not find a reputable clock man in our area. The clock owners have come to the same conclusions. The next step for me was to investigate what it will take to make the current configuration work in or country. I am not going to work on the mans clock. I am far from that realm of meticulous craftsmanship.

I'm doing good to keep my finger prints off the wall, and not track mud in.

Hell if it works the first time I hit the switch, I'll dance a jig.

This seems to be a simple problem, with some not so simple solutions.

Everyones opinions are appreciated.

However I have not come up with the solution yet.

I will get a picture of the clock to post, that might give you a better idea of what I am talking about.

 

[winnie]

I've been giving this more thought.

As you say, modifying the clock itself is out of the question, making the only option to somehow get 230V 50Hz. The 50Hz is critical to the time keeping of the clock, and as others have mentioned, using a dimmer to reduce the voltage won't help.

So the real question is: what is the most appropriate way to get the 230V 50Hz in question?

The VSD answer has already been put out. As I mentioned above, I would be very cautious with this approach. The output of a VSD will not be a nice clean 50Hz sine wave, but rather a much higher frequency switching voltage that can be filtered to produce the desired sine wave. Normally the inductance of the motor itself is what acts as the filter, so you end up with an ugly high frequency _voltage_ being applied to the motor, but a relatively clean _current_ flowing through the motor. The high frequency switching can put severe stress on the motor insulation.

A variation on this theme is to use an 'inverter'. These use similar switching techniques to generate output, however they are designed to operate at fixed frequency and have built in output filtering. You can buy 230V 50Hz inverters for under $40, although these have what is called 'modified sinewave output'. Spend $150 and you get 'pure sine wave output'. I do not know if the voltage distortion in the cheaper inverters will make any sort of difference in your application. The benefit of using an inverter is that you get a _listed_ device designed specifically to drive 230V 50Hz single phase loads. Run the thing using a battery and a charger, and now the clock is on a UPS for not too much money.

The big down side is that these cheap inverters are not very accurate. The 50% is specified as being +-1%, meaning that the clock could be off by 10 or 15 minutes per day.

The most 'esthetic' approach would be to use a synchronous rotary converter. This is a synchronous motor driven by the 60Hz supply, mechanically driving a synchronous generator with suitable gearing or pole count difference. The output is 50Hz, tied to the frequency of the electric grid; I consider this the most esthetic approach because it uses the same sort of time base that the clock was originally designed to use. This approach will not be particularly cheap, and the motor/generator system running 24x7 will have its own issues.

Beyond these approaches, a custom inverter system could easily produce the desired voltage at the desired frequency, using any number of time sources, including the AC mains, a crystal time base, even GPS or WWV radio. I don't know how much it would cost to farm this sort of job out.

-Jon

 

[Palmbay]

A guy that helps me with my old car sometimes, he made a home made phase converter for a 3 phase machine he has. I was trully impressed with his ingenuity, considering he works on flat head ford motors for a living. These converters have worked in his shop for years with out problems. I was entertaining the idea of creating the same set up he has for this application. Just in a smaller scale. A 240V 60Hz motor wired to house wiring, shafts mated to 230V 50Hz motor wired to clock outlet. Install a time delay on the load side so it does not load the motor untill up to speed.

What is the manufacture of these $50 to $150 inverters.

 

[rattus]

Maybe:

Maybe:

Maybe, just maybe, the pinion on the clock motor could be changed.

 

[winnie]

A 240V 60Hz motor wired to house wiring, shafts mated to 230V 50Hz motor wired to clock outlet. Install a time delay on the load side so it does not load the motor untill up to speed.

This is exactly the 'esthetic' approach that I was speaking of. However you will find that 60Hz motors and 50Hz motors generally have different rated speeds. So you will probably need to couple the shafts using some gearing. The clock is probably such a small load that the time delay would be unnecessary. Getting the proper voltage regulation will be an issue. You will need to use synchronous motors if you want proper frequency regulation.

What is the manufacture of these $50 to $150 inverters.

I don't know. I simply did a google search for 50Hz sine inverter and got tons of hits.

-Jon

 

[Limey Pete]

German Clock in the USA 230V 50Hz to 120V 60Hz

I have been doing some research and it looks like the clock is going to run fast with the Higher AC frequency.

Question:

1. 230V to 120V from Germany to USA. Will this require a 120 to 230 transformer or will a USA 230V work? Rephrase, is Germany 230V to ground or is it 230V Phase to Phase?

2. Once the correct voltage is achieved, I am thinking a dimmer on one leg can compensate for the faster clock movement created by our AC frequency.

All your input is appreciated.

Mike.
I couldn't sleep tonight, I've been up doing a little research and think I have found an inexpensive answer for you.

You could use a UK spec'd 12v TO 230v INVERTER. (50 Hz)
Then just supply it with a US spec'd 12VDC power supply.These are available on Ebay UK, for a few dollars as very little power is required to run this motor, probabley just 10 watts or so.

If you check them out on Ebay-UK they seem to have a freq. accuracy of plus or minus 2%, not great but a lot better than 50/60hz ratio and I presume the fact that the clock will more or less work is more important than accurate time keeping.

Make sure the seller is specifing 50Hz and accuracy, as I suspect the cheaper models will be somerwhere in between so that the inverter parts can be more easily modified for differebt markets.

Good luck!.

ps. As the output current is going to be constant you could probably get a more accurate frequency output by adjusting the DC input within the spec'd range ( 11 to 14V).

pps. LOL! I know this is going to work now; As soon as I posted this reply my status changed from Junior Member to Member!.

 

[Limey Pete]

OK still can't sleep, nearly time for work now anyway! A little more nocturnal thought tells me:
The three most likely causes of frequency drift will be; input voltage,output current, and inverter temperature changes, but in this case input V is very stable, output Amps is totally stable, and this would in itself stabilize the temperature but you could make it even more stable by placing it in a small cupboard or something away from air thermals.
Also as well as adjusing the freq.by changing the input V you could also try doing it by adding additional parallel output load, which should change the V across the freq. generator circuit, maybe a small lamp or better yet a reostat until you have a freq. very close to correct.

 

[dbuckley]

The good folks at Viscom Industries do a 1KVA 50Hz converter, which although hundreds of times oversized for a clock(!) will probably do the job, and you can hire them as well so you can test it out. It does output a sine wave, which is essential for synchronous motors.

However, I, as others, am also of the opinion that swapping motors would be a better approach. All the synchronous motor clocks I've ever seen look about the same inside, using the same sort of motor that Lauren Hammond (as I've noted before, he of Hammond Organ fame) brought to the marketplace at the start of the 20th century. It must be worth a look.