How might electronics be different if AC voltage was 72V at 45 Hz?

[AlexB23]

Hey guys. I have a question related to electricity and alternating current. Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz. How would appliances be designed, and what impact would the lower frequency and voltage have on transformers, wiring, TVs, computers, LEDs, motors, and heating, assuming the laws of physics and technology are the same as on Earth?

 

[Baluncore]

Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz.

Instead of 115V 60Hz or 230V 50Hz ?

For the same power, currents would be higher, wires would need to be significantly heavier. Buy shares in the copper industry on Earth. Their home planet would need to have plenty of conductive metals on the surface.

Power poles would not be needed for voltage isolation, the heavy cables used for distribution would be buried underground in a suburb.

Insulation could be thinner, but not by much. Switches would be heavier since they carry more current, but have less voltage to sustain an arc when turning that current off. More switches would have mercury wetted contacts.

Transformers would be inefficient and heavy, with more core and windings. Motors would run slower.

 

[AlexB23]

Instead of 115V 60Hz or 230V 50Hz ?

For the same power, currents would be higher, wires would need to be significantly heavier. Buy shares in the copper industry on Earth. Their home planet would need to have plenty of conductive metals on the surface.

Power poles would not be needed for voltage isolation, the heavy cables used for distribution would be buried underground in a suburb.

Insulation could be thinner, but not by much. Switches would be heavier since they carry more current, but have less voltage to sustain an arc when turning that current off. More switches would have mercury wetted contacts.

Transformers would be inefficient and heavy, with more core and windings. Motors would run slower.

Yeah. So, could aluminum or steel wiring work? Of course, the high voltage lines would be in the dozens to hundreds of kV, so those can be in the sky, but then the home voltage can be 70-ish volts. So, how would a washing machine spin 1400 RPM? Would it need inverters?

 

[Borek]

Washing machines use transmission belts to get the required speed, so in this particular case the main difference would be just a different gear ratio.

Broadly speaking differences wouldn't be that large, I doubt they would be easy to spot for a layman.

 

[AlexB23]

Washing machines use transmission belts to get the required speed, so in this particular case the main difference would be just a different gear ratio.

Broadly speaking differences wouldn't be that large, I doubt they would be easy to spot for a layman.

Nice. Mine is direct drive, and inverter type.

 

[Baluncore]

Yeah. So, could aluminum or steel wiring work?

Because wiring heat losses are W = I²·R, aluminium wire would work, but never steel for the conductors, more likely copper or silver.

 

[Baluncore]

Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz.

If they were so silly as to standardise on such a low voltage and high current system, I doubt they would have advanced electrical technology very far. They would need to have a very different resource availability to justify that choice.
1 kW = 230V, 4.35A.
1 kW = 115V, 8.70A.
1 kW = 73V, 13.70A.

 

[AlexB23]

Because wiring heat losses are W = I²·R, aluminium wire would work, but never steel for the conductors, more likely copper or silver.

Nice. I am getting this now. Maybe for home usage, 73V works, while for business then maybe 146V.

 

[Averagesupernova]

Nice. Mine is direct drive, and inverter type.

I doubt a new one can be bought any different. Everyone thought when they came on the market that the reliability would be a problem but from what I've seen it's an improvement.

 

[AlexB23]

I doubt a new one can be bought any different. Everyone thought when they came on the market that the reliability would be a problem but from what I've seen it's an improvement.

Yeah, the inverter ones have good efficiency and no belt to deal with.

 

[Borek]

I doubt a new one can be bought any different.

Interesting. Could be something has changed lately or it is a difference between US/EU, but my previous one (bought ~10 years ago) was definitely with the transmission belt, not sure about the one we use now (and I won't risk opening it now to not void warranty, but next year - who knows).

 

[Averagesupernova]

Interesting. Could be something has changed lately or it is a difference between US/EU, but my previous one (bought ~10 years ago) was definitely with the transmission belt, not sure about the one we use now (and I won't risk opening it now to not void warranty, but next year - who knows).

There is definitely a different sound between the two. Once you realize it you'll always be able to tell the difference.

 

[Rob Trajon]

Hey guys. I have a question related to electricity and alternating current. Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz. How would appliances be designed, and what impact would the lower frequency and voltage have on transformers, wiring, TVs, computers, LEDs, motors, and heating, assuming the laws of physics and technology are the same as on Earth?

I'm not an engineer, but Australia uses (if I recall) 212V AC for everything. Makes things simpler? You mention a different "sound". Translating MW radar into sound we can hear (something as radar, we can't hear naturally), has allowed people to tell the type and mode of various radars almost immediately. Like two people saying the same words, you KNOW two different people are saying them. You might even think; "Hey, that's so-and-so, he sounds under the weather... Bonus: Electrical current can be used to "carry" communications. Often an overlooked hole, in communications hardening.

 

[AlexB23]

I'm not an engineer, but Australia uses (if I recall) 212V AC for everything. Makes things simpler? You mention a different "sound". Translating MW radar into sound we can hear (something as radar, we can't hear naturally), has allowed people to tell the type and mode of various radars almost immediately. Like two people saying the same words, you KNOW two different people are saying them. You might even think; "Hey, that's so-and-so, he sounds under the weather... Bonus: Electrical current can be used to "carry" communications. Often an overlooked hole, in communications hardening.

Well, electrical hum in the US is 60 Hz, so a 46 Hz would sound lower pitched. Australia uses 230V at 50 Hz.

 

[Baluncore]

Australia uses (if I recall) 212V AC for everything.

AlexB23 is correct, Australia now employs the international standard, 230V at 50Hz. There is a broad voltage tolerance, so in many places it still measures the same as the old 240V standard, while it fully complies with the preset 230V standard.

Translating MW radar into sound we can hear (something as radar, we can't hear naturally), has allowed people to tell the type and mode of various radars almost immediately.

If MW radar is microwave RADAR, then when detected, you can hear the PRF, (Pulse Repetition Frequency), of the microwave radiation with its harmonics, as it sweeps across you. The PRF will depend on the range being searched, as generally, the echo must get back before the next pulse. High PRF means the RADAR is looking nearby, while the lowest PRF means it is looking out as far as the horizon.

RADAR sets today are more statistical, so they add a dither time to each pulse transmitted, and so sound mushy. The display now shows a digital record of coincident reflections, which prevents synchronous interference from another RADAR, from appearing as artifacts on the screen.

But back to the transformer hum issue. For a 50Hz mains frequency, the magnetostriction of the metal in a transformer doubles that frequency, so a passer-by will hear a peculiar 100Hz pulse with harmonics. That sounds like a buzz, unlike the pure tone of a 50Hz sinewave.

 

[Rob Trajon]

AlexB23 is correct, Australia now employs the international standard, 230V at 50Hz. There is a broad voltage tolerance, so in many places it still measures the same as the old 240V standard, while it fully complies with the preset 230V standard.


If MW radar is microwave RADAR, then when detected, you can hear the PRF, (Pulse Repetition Frequency), of the microwave radiation with its harmonics, as it sweeps across you. The PRF will depend on the range being searched, as generally, the echo must get back before the next pulse. High PRF means the RADAR is looking nearby, while the lowest PRF means it is looking out as far as the horizon.

RADAR sets today are more statistical, so they add a dither time to each pulse transmitted, and so sound mushy. The display now shows a digital record of coincident reflections, which prevents synchronous interference from another RADAR, from appearing as artifacts on the screen.

But back to the transformer hum issue. For a 50Hz mains frequency, the magnetostriction of the metal in a transformer doubles that frequency, so a passer-by will hear a peculiar 100Hz pulse with harmonics. That sounds like a buzz, unlike the pure tone of a 50Hz sinewave.

Your correct. But even 30 years ago, military radar (not always civilian) could add a known "non-sensical artifact" to their emissions. To anyone trying to spoof it, it would look like non-sensical noise, which would be ignored by an enemy. It would be a signature, to "our guys" The original ID Friend or Foe, that pings back to the radar "interrogating" say any airplane only works if to any "nasty" airplane, thinks it's just noise. Historically, ground based radar could always pump more power to overwhelm early plans ECM. So we took a different track.

 

[Baluncore]

This thread is about low frequency, low voltage supply, not the game theory of ELINT and IFF etc.

 

[Dullard]

Military aircraft (back when I worked on them, anyway) use 400 Hz for precisely the reasons described in post #2. Size and weight are dominant considerations in that application.

 

[Rive]

Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz.

Th 46Hz part is within tolerable practical limits by my opinion, but I think that there would be some considerable pressure to raise the line voltage.

 

[Guineafowl]

I’d say 73V is an unlikely choice, assuming the aliens have a similar biological make-up and tolerance to electrical current.

Here on Earth, 50V is considered to be a safe threshold. For example, it’s the maximum touch voltage for earthed metalwork during a fault. However, we’ve decided to use much higher, lethal voltages and take other measures to make safe, so that the current and conductor size can be lower. I²R and all that.

So, 73V is a bit ‘middling’ - neither inherently safe nor high enough to bring those advantages.

 

[Baluncore]

.... but I think that there would be some considerable pressure to raise the line voltage.

But only on Earth. Back on their home planet, where 80% of their thin atmosphere was argon and neon, with many cosmic rays, there would be problems with voltage breakdown and corona discharge.

 

[Rive]

there would be problems with voltage breakdown and corona discharge

So they had to use insulation extensively even for an efficient distribution system. Then why keeping the user side uninsulated and inefficient?

Sorry, I just can't see the point. They had to tackle these issues just as we tackled the DC versus AC thing way back at the beginnings.

 

[Baluncore]

Sorry, I just can't see the point.

There is a reason why they originally settled on 73 volts.
Maybe insulation was expensive, while silver was free.

 

[tech99]

With present day standards, the International Electrotechnical Commission and the UK IET define 50V AC and 120V DC as the upper limit for electric shock. There is also another UK standard where 110V AC centre tapped to earth may be used, as on building sites. So 73V is not regarded as safe from shock.
When aircreft-borne RADAR was being developed in the UK in WW2, they initially operated it from the 48V aircraft supply, but the aircraft generator was then replaced with one for 400Hz AC, which revolutionised the electronics - small transformers for obtaining high voltage and small conductors etc.

 

[Baluncore]

48V, 400Hz was mainly used in aircraft for instrumentation, gyros, synchros, resolvers, and magnetic amplifiers, all of which were, in effect, small motors or transformers.
Those instruments have now been replaced by optical sensors and microcontrollers, with LED or LCD screens. Gone is the need for 400Hz.
Switching power supplies now use even smaller transformers, typically between 40kHz and 400 kHz.

Early Niagara Falls power generation was at 25 Hz.

In 1900, there were no accepted standards for frequency. Lower frequencies or dc worked well with electric motors because they produced better torque characteristics than ac at higher frequencies. Industrial processes and urban transportation were best served by direct current (dc) or low frequency ac at 16 or 25-cycle. Without any collaboration independent power producers developed systems that operated at 25 Hz, 60 Hz and 66⅔ Hz in Ontario and neighbouring jurisdictions.

https://www.lifebynumbers.ca/history/the-rise-and-fall-of-25-cycle-hz-electricity-in-ontario/

 

[tech99]

Any new invention is going to be really painful to launch, with competing interests trying to strangle the idea at birth. Ridiculous rules and regulations pop up from nowhere. Such was the case with Sebastian Ferranti, an Englishman who (according to Wiki) invented the alternator and had the idea of locating the power station outside the city it served, using 10kV coaxial cable for power transmission. But he was stopped after just one power station was built, at a place called Deptford, down river from the city of London. In the USA there was the battle of the giants between AC or DC. So setting standards for voltage and frequency is more than just a technical decision.

 

[Baluncore]

But he was stopped after just one power station was built, at a place called Deptford, down river from the city of London.

Ferranti was only hired to design the first.
Sebastian Ziani de Ferranti was hired by the London Electric Supply Corporation, to design the Deptford power station. It was a success, and set the standard as the first high voltage AC station, that used transformers to step down the AC voltage for the consumers.
Sebastian de Ferranti was President of the Institution of Electrical Engineers in 1910 and 1911 and was elected a Fellow of the Royal Society in 1927.
https://en.wikipedia.org/wiki/Sebastian_Ziani_de_Ferranti#Professional_career

https://en.wikipedia.org/wiki/Ferranti#Beginnings
It was the company bankers who placed the family business "Ferranti, Thompson and Ince" in the hands of receivers at the end of the boom of 1896–1903.
Restructured as Ferranti Ltd, it would outlive its founder and develop the Ferranti Mark 1, the world's first commercially available general-purpose computer, in 1951.

 

[Borek]

So setting standards for voltage and frequency is more than just a technical decision.

Not that it matters much - at some point you just live in a world where the standard exists, everyone is used to it and all applications are built around it.

It is like with some politicians - you look at them, you wonder "how they got there?", but there is not much you can do to change them.

 

[sophiecentaur]

Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz.

This reads very much like the sort of question that a teacher might set, in order to get the students thinking. Problem is that no one ever 'sets a standard' for electrical supply parameters. An unanswerable question is quite acceptable to make you (+us) think. I wonder how many of the above ideas occurred to the OP before they were put in this thread?

 

[AlexB23]

Th 46Hz part is within tolerable practical limits by my opinion, but I think that there would be some considerable pressure to raise the line voltage.

Yeah, I am sure the line voltage would be in the kV range, while home voltages could be in the 73V range. Also, maybe the alien civilization might realize doubling voltage to 146V might work better.

I’d say 73V is an unlikely choice, assuming the aliens have a similar biological make-up and tolerance to electrical current.

Here on Earth, 50V is considered to be a safe threshold. For example, it’s the maximum touch voltage for earthed metalwork during a fault. However, we’ve decided to use much higher, lethal voltages and take other measures to make safe, so that the current and conductor size can be lower. I²R and all that.

So, 73V is a bit ‘middling’ - neither inherently safe nor high enough to bring those advantages.

Yeah, 73V gives no advantages. Maybe the alien civilization stuck with that when they standardized electricity voltages in 1877. And yes, we can assume the aliens have skin 10-20% slightly thicker than ours, but same biology as us.