Frequency 50hz System by 60 hz System

Slightly smaller conductors?

OK, I give up. What are they?

Higher better... smaller

None, it just is what it is.

During the development of commercial electric powersystems in the late 19th and early 20th centuries, many different frequencies (and voltages) had been used. Large investment in equipment at one frequency made standardization a slow process. However, as of the turn of the 21st century, places that now use the 50 Hz frequency tend to use 220-240 V, and those that now use 60 Hz tend to use 100-120 V. Both frequencies coexist today (Japan uses both) with no technical reason to prefer one over the other and no apparent desire for complete worldwide standardization. Unless specified by the manufacturer to operate onboth50and 60 Hz, appliances may not operate efficiently or even safely if used on anything other than the intended frequency. http://en.m.wikipedia.org/wiki/Utility_frequency

The higher the frequency, the "cleaner" the power. We had some extreme precision equipment in the US Navy that needed 400hz power.

The Navy reason for high frequencies were smaller inductors, therefore lighter equipment.

Also DC supplies could interfere with radio and radar signals due to the commutator switching being of a quite high frequency on DC ships.....so all RN masthead lighting, even on older DC ships was AC.

I personally see no advantage in 50 Hz, to my mind 60 Hz would be slightly more efficient (100Hz would be even better!), but I prefer the 240 volts as 120VAC needs such huge amounts of copper to transfer the same power.....

It has been proved time and time again that the safety aspect of 120VAC is a pipe dream....so that is no reason to use it.

So my vote would be for 240VAC at 60Hz, but we are so far down the paths set over a 100 years ago in many areas with either 50 or 60 Hz, its too far to back up and start again.....sadly!

So to answer the question exactly, but only with reference to the frequency is that 60Hz is better....

I would guess that these low frequencies are more to do with the technical problems of the prime movers for over 100 years than anything else....today higher frequencies would be no problem.....

There are not much relation between frequency and clean power.

The main reason for different frequencies is that higher frequencies use smaller magnetic components that save on weight. Weight is a big problem in the aeronautical industry. Since the Navy share high technology communication equipment with the Air Force, they use the same power distribution. I suspect the Army and related industries also use 400Hz for communication equipment.

Higher frequencies increase the losses in the cables through skin effect and magnetic cores from eddy currents. We would not use 400Hz for power distribution across a country.

DC power is more likely the next standard. It will start at the main lines, then large industries, and eventually reach the residential distribution.

The frequency used is a trade off between power losses and size of the magnetic components (Transformers, motors...)

One of these two frequencies will be the frequency of your power distribution. Even in the very few countries that utilize both power grid frequencies, one cannot choose which one resides at your location. So there is no advantage because one cannot choose which one to use.

The chief advantage of 400Hz power in aircraft is the compactness and light weight of the motors.

More is better....

Slightly tangential, but then, does equipment designed for 50 Hz work at 60 Hz too, and at voltage being the same?

Not all 50hz equipment can run on 60hz

For example?

Example fluorescent lamp with ballast designed for 50hz will not ignite on 60hz supply

Motors run slower on 50 Hz than 60 Hz, ask anyone with a vinyl record player if that matters.....!

A motor's speed may be important for the application.

Some 60Hz motors can possibly overheat on 50Hz.....not all but some. The mechanical load often plays a role as well...

Many motors can be used on either frequency, provided the change is speed does not matter for the application. Look at the name plate on the motor for advice in this area....

Electric motor still can run on 50hz with same speed and torque, all you need is 380v 50hz

??????????

The volt/second ratio should be about the same to keep the magnetic circuits polarized with the same flux. For a given design lowering the frequency requires lowering the voltage proportionally.

This applies to most motors and transformers.

Some magnetic devices have enough margins to operate at both. But even if it seems to work, the reliability can suffer in the long run.

Nicolai Tesla did do a brilliant job inventing the induction synchronous motor. For many good reasons the induction synchronous motor is the most common electric motor used today but it is not the only motor used directly connected to the AC grid frequency. If the motor is a universal motor where the stator and rotor windings are wired in series then with the same voltage and no mechanical load a 50 Hz driven motor will run very slightly faster than when it is run on 60 Hz.

Getting back to the OP question. There are some task specific advantages for one power frequency over another. However, with 60 being only 20% greater than 50 this difference is not a significant difference. The major difference between the grid standards is the nominal voltage each provides.

When doing calculations it is easier to visualize time periods in milliseconds as parts of a wave cycle at 50Hz. eg One cycle = 20 msecs

Motors, generators, and transformers need less iron and are slightly smaller.

It depends on the country, for me 50Hz is superior to 60Hz because more equipment will run on our 50Hz power grid down here.

@marcot, with respect I doubt wether "DC power is more likely the next standard" , as:

• for the same ampacity, savings on conductors size is minimal
• for people safety, it is clear that we cannot accept to do less than what exists.
• people protection at high DC levels (ie 200V and above) would need protection and switching devices much more costy than what can be produced today.

So I think that DC will stay in some specific uses (ie railway, Data centers) but would be extremely slow to come (if ever) in buildings / residential.

Although in general I agree with you that I also cannot see us leaving AC for DC, especially since over the last 30 years or so we have such wonderful electronic components to help with motor speed control etc..

The reasons you cite though are mostly invalid. As has been shown time and time again and here on CR4 as well, DC IS SAFER THAN AC for the same effective voltage.

DC tends to throw people off, whereas AC puts muscles in a spasm and they cannot move.....

Please research your comments yourself here on CR4 as this subject continually arises with a new person or two with NO DC experience or practical knowledge, even some good engineers actually believe it!

Last but not least there are even textbooks around with the same wrong information.

Talk to someone that has worked on DC year in year out and has "tested" the voltage inadvertently HIMSELF, not secondhand from reading or listening to a professor in the Uni (they know nothing!!)....

I have to admit that there is plenty of wrong information around that misleads many, you are certainly NOT alone here.

By the way, I have worked on DC and AC ships in the RN, I have actually done fault finding on ground faults on DC 220V using two fingers on the same hand across the fuse positions (I can give you full details if the method is new to you, it is VERY simple). I would NEVER do that even on 120VAC let alone 240VAC....NEVER EVER!!! Too dangerous.

I have also had a few accidental AC shocks over the years of 120, 240, 380 and 440 volts (all three phases on one arm!), all were painful and pretty damn dangerous at the same time...... Your brain simply stops......sometimes maybe forever.... I was always lucky.....I think!! DUUUUHHHHH.......

DC won't become the next standard but DC is cropping up in transmission systems. Long distance high voltage DC transmission has become desirable with the development of efficient solid state inverters. No capacitive and inductive losses with DC.

There are applications for both. I like the idea of all 400Hz but that would make series wound motors a tad lethargic. Think of the range on your VFDs and how compact transformers and synch/inductive motors would be. Aircraft and military went for better tech rather than shore compatibility. Its nice to see positive attributes exploited in favor of legacy thinking.

Didn't Tesla do his really long range conductorless electricity transmission at 8Hz utilizing the Earths resonant electrical frequency or something like that?

Maybe we should all switch to 8Hz....

This entire thread subject is second only to the "Why multiples of 11..." subject as the most often asked and most annoying questions posed in this forum. If the posters of these questions would just use the Search function over to the right before launching this kind of thread, I would be less judgemental. But it never seems to happen.

Soooooo boring...