Converting enlargers from USA to Australia mains?

AgX · Jun 12, 2021

Some time ago I asked if there are any electronics in our field that actually need true sine waveform. None came up so far.

The wafevorm my solid state DC to AC converter yields is called "modified sine wave" or so, likely a staggered sine wave (my oscilloscope is broken).

AgX · Jun 12, 2021

mgb74 said:
The transformer will convert the 220v 50hz to 110v 50hz which will charge the UPS batteries. The UPS will output 110v 60hz as long as power to it is not being fed power. I believe that to correctly power electronics, it needs to output a pure sine wave so the really cheap UPS models won't work.

My understanding of your idea was to feed the UPS behind its batteries with the respective low DC.
I am not sure your approach of feeding the UPS with AC will result in the intended AC frequency change.

The UPS likely just feeds through the incoming AC as is to its outlet, and use part of the incoming AC transformed to low DC for charging its batteries. The 60Hz out of own creation likely only is availabe if the UPS is running on its batteries (or an alternative DC source as I thought of).

Maybe someone with USP expertise might shed some light on this.

beemermark · Jun 12, 2021

mshchem said:
An ordinary 23c no color head enlarger is a simple matter of proper bulb or a dimmer to reduce voltage. Anything with a motor is another problem. Before the USA had a national electric grid, the West was on 50 Hz, rest of the country on 60 Hz. People with fancy electric clocks, paid to have them converted, the rest of them went to the trash or in some cases dumped into the Pacific Ocean. You will need to check. I would want a timer designed for 50Hz, shouldn't be hard to find outside North America 220 50 cycle power is the norm.

Electricity generation from hydro generating plants were typically 50 hz, steam driven generators were always 60 hz. Hz is directly related to generator speed.

mshchem · Jun 12, 2021

beemermark said:
Electricity generation from hydro generating plants were typically 50 hz, steam driven generators were always 60 hz. Hz is directly related to generator speed.

Yep

MattKing · Jun 13, 2021

beemermark said:
Electricity generation from hydro generating plants were typically 50 hz, steam driven generators were always 60 hz. Hz is directly related to generator speed.

Almost all of our electricity in British Columbia is hydro driven - 60 Hz everywhere.

AgX · Jun 13, 2021

beemermark said:
Electricity generation from hydro generating plants were typically 50 hz, steam driven generators were always 60 hz. Hz is directly related to generator speed.

The frequency should be as high as possible concerning the size of transformers, the same time with higher frequency selfinduction rises and thus loss of electrical energy. For physiologic reason (flicker of discharge lamps) the frequency must not be too low either. Also the number of poles and the feasable max. rotational speed of the generators limited the frequency within a certain range
I do not see any relation to the kind power source. By means of drives, design of turbines etc. the standard rotational speed of the generator could be set.
The standardisation of 50 resp. 60Hz is purely arbitrarily. It was set by the decision of major manufacturers of power plants. With the spread of their plants these frequencies became standards.

The commercially applied mains frequency in history reached from 25Hz to 133Hz.

spark · Jun 13, 2021

Speaking here as a career EE with experience adapting equipment for different countries. Frequency and voltage converters do exist for industrial use, look up “georator”. Once these were motor-generator combinations, now they’re solid state electronics. They’re somewhat overdoing it for an enlarger. Step down the voltage and the power supply for the electronics should handle the frequency change with no problem. Some OEM power supply modules have taps to select 100-120 or 200-240 operation. If there are AC powered cooling fans, replace them with modern DC brushless types for quieter and more reliable operation (some rewiring needed) Or shop locally for 50 Hz fans that fit the same form factor, fan sizes are standardized.

mgb74 · Jun 13, 2021

AgX said:
My understanding of your idea was to feed the UPS behind its batteries with the respective low DC.
I am not sure your approach of feeding the UPS with AC will result in the intended AC frequency change.

The UPS likely just feeds through the incoming AC as is to its outlet, and use part of the incoming AC transformed to low DC for charging its batteries. The 60Hz out of own creation likely only is availabe if the UPS is running on its batteries (or an alternative DC source as I thought of).

Maybe someone with USP expertise might shed some light on this.

My understanding is that a UPS, when plugged into power, will do just that - feed through the incoming AC. That's why I said that the UPS had to be disconnected and operating from battery for the conversion.

AgX · Jun 13, 2021

So again we are at my initial question: "Why use a UPS for a routine operation?" Unless you got such UPS at hand with battery capacity enough to cover your darkroom session, maybe with the enlarger taking intermediately off from the UPS and let it charge for that time.
Again, the solution would be to skip the UPS and instead use a transformer with DC output and feed this into a DC to AC converter with apt frequency.
Or use a AC to AC solid state frequency converter, the hasslefree solution.

Maybe though I have been underestimating the battery capacity of the UPS you got on mind.

MattKing · Jun 13, 2021

The biggest reason to use a UPS is because a lot of UPS's also function as voltage stabilizers when the power is up and running.

AgX · Jun 13, 2021

Over here voltage is most constant and a stabilizer not needed. It might be different in a industrial zone.

Mick Fagan · Jun 13, 2021

AgX said:
Over here voltage is most constant and a stabilizer not needed. It might be different in a industrial zone.

That may be the case in Europe and in particular in Germany, but in sunny Australia our voltage situation is all over the place. The main culprit is the unbelievable amount of rooftop solar panel uptake in suburbia and elsewhere in the country, which is making life very difficult for the power companies to maintain our nominal 230V supply.

I myself am part of that as we have had rooftop solar for nearly 10 years and a couple of years ago upgraded with more solar panels and house batteries. Essentially, our house is run completely through batteries, which means we have stable 230V 50Hz all of the time.

As for stabilised darkroom voltage, yep did that around 30 years ago with a stabilised power supply for my colour enlarger. Certainly one of the better things I did for colour control back then. These days the house batteries supply power to the house via the inverters and it is very closely controlled.

Mick.

Converting enlargers from USA to Australia mains?

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