60hz Vs 50hz

[Richardgr]

I have a US Knight amp from 1959 and a Japanese Panasonic amp from 1964. They require 117VAC and 110VAC respectively.

I have been testing them on a Variac, but then it occurred to me they'll be getting the right volts, but 50hz supplies, whereas their transformers are specified for 60 hz. I did some reading, and this could be an issue, reducing the current handling of the transformer in the unit being tested - by 17% in fact.

Is a Variac an option here? I have an autotransformer, but I don't think that is any better, so a step down transformer is going to be required, I suppose.

[emeritus]

Is 60Hz actually specified? Japan has both 50Hz and 60Hz mains supplies according to region.

[Skywave]

Provided that you feed those items with the correct magnitude of voltage (110, 115 or 117), type of transformer you use is not really important. What could be a problem is the frequency: 60 Hz transformers will run hot on 50 Hz.

Al.

[Dave Moll]

Given that this is the the record players section, I was going to say that turntable speed would be a problem, but of course that's not an issue if they're just amplifiers.

[Richardgr]

Ok, thanks for the replies. I have just noticed Japan has 50hz and 60 hz supplies, so hopefully it will not be an issue on that unit. I have a 150 VA step down transformer for the Knight, which is just a 20W mono amp, so hopefully ok there too.

The lesson I'll take away is to check the running temperature of the transformers. If that is ok, then all is fine and dandy

[analogadikt]

Originally Posted by Richardgr

step down transformer for the Knight, which is just a 20W mono amp, so hopefully ok there too.

Are you sure about that 20 watts figure? Seems very frugal to me if it is a valve amp.

Regards,

Anwesh

[Richardgr]

Hi Aneesh, the 20watts is just the output power, but the transformer is rated to 120watts, so contingency even if the amp is only 25% efficient.
Richard

[Neutrino]

Originally Posted by Richardgr

Ok, thanks for the replies. I have just noticed Japan has 50hz and 60 hz supplies, so hopefully it will not be an issue on that unit.

The nameplate ratings of 117VAC and 110VAC suggest that these were not designed for the Japanese market because the supply voltage there is 100 V a.c. In principle, if running a transformer at reduced frequency the supply voltage should be reduced correspondingly but the equipment may not work well if the voltage is reduced by about 16.6%. The aim is to find middle ground where the transformer is happy and the equipment works as intended.

David

[Richard_FM]

I did wonder why Japan ended up with such an odd electrical supply.

I've been told originally the American system was supposed to be 100V, but at the time the equipment could only produce it with a 10% tolerance so 110V was a nominal figure.

Maybe the Japanese followed the same steps but managed to get the supply closer to 100V.

I've heard the frequency differences was due to having two power grids, one of which started supplying Tokyo & the other Osaka, before each of them spread out to cover a half of the country.

[broadgage]

In the VERY early days the USA used various voltages including 100 volts, this gradualy became 100 volts at the lamp socket and 110 volts at the very local power plant.
By the 1930s the present voltage of 120 volts nominal was well established and was a requirement for new electrification schemes.
Appliances were often rated at 117 volts, 117.5 volts or 118 volts, this being to allow for a nominal 120 volt supply into the premises, and a few percent voltage drop in the consumers installation.

Present day American practice is to rate appliances at 120 volts nominal, with the supply into the premises being called 120 volts, but in fact averaging about 124 volts at the meter and about 120 volts at the point of use.

Historically the USA used many frequencies, but 60 cycles has been the standard for decades. There was a lot of 25 cycles, and some may still exist for industry.

I have always thought that Japan had 50 and 60Hz because each end was taken over by different forces after WWII.

[Sideband]

Originally Posted by Richardgr

Ok, thanks for the replies. I have just noticed Japan has 50hz and 60 hz supplies, so hopefully it will not be an issue on that unit.

I wouldn't worry. At the test house where I work, we often get amplifiers with dual voltage/frequency. If it's designed for use in Japan (which incidentally is 100V 50 or 60Hz depending where you are) then it will be fine. Yes it will run slightly warmer on 50Hz than 60Hz but it will only be a couple of degrees and probably less than ten.

The chances are that American amp will also be OK. We test such amplifiers over the voltage range 108 - 132V (for + or - 10% mains tolerance...120V being the nominal voltage). Again the transformer might run a little hotter but not enough to worry about.

[Synchrodyne]

Originally Posted by merlinmaxwell

I have always thought that Japan had 50 and 60Hz because each end was taken over by different forces after WWII.

No, the origin of that Japanese duality goes back much further. To quote from the IEEE article “The Origins of 60-Hz as a Power Frequency”, by Edward L, Owen:

“In 1895, AEG sold a 50-Hz generator to the power company in Tokyo and the eastern half of Japan was put on the 50-Hz path. A little over a year later, GE sold a 60-Hz generator to the power company in Osaka, and the Western half of Japan was put on the 60-Hz path (see Fig. 3).”

That article quoted was an IEEE history item from 1977 December.

Also pertinent is this IEEE history article from 2011 July-August:

“50-Hz Frequency - How the standard emerged from a European jumble”, by Gerhard Neidhöfer.

There are other IEEE history articles on the same general subject, such as 25 Hz, 40 Hz, frequency conversion, two-phase and so on.

All of those IEEE articles are available at the IEEE site for a fee, but with some searching the above-mentioned may be found as free downloads. They appear to be well-researched and have probably been subject to some peer review, so are probably reliable sources, better perhaps than some others that are derived from secondary sources only, errors included.


Cheers,

That's much more fun than invasions, thank you.