Hz

Hi,

Why do we use 60Hz instead of 50Hz?
If we run any appliance of 60Hz at 50Hz, what will happen to that appliance?

Regards,
Asif

Most 60 Hz appliances will run OK on 50 Hz. A bigger issue is voltage. Most of the 50 Hz countries I'm aware of are 230-240, but you can find transformers. I recently took a household from Canada to New Zealand, including a TV which I was able to adapt with a NSTC to PAL converter. I found transformers c/w NA outlets in NZ.

I would hesitate to take large power consumers like a range, microwave or washer dryer, but all your bench-tops, stereo system and radio are OK. I wouldn't recommend the TV though unless the system is the same.

Roy

Hi,

As this is an international list, words like 'we' have little meaning, where are you located?

Plenty has been written about the effects of appliance operation.

http://www.google.com/search?q=50Hz+vs+60Hz

Marc Sinclair

To Asif,

60 Hz is a standard followed in some countries whereas 50 Hz is accepted in some other countries. Why? I am also eager to know the reason behind.
Thermal or lighting loads (more specifically resistive load) will have little effect if used in a different frequency supply. But rotating loads (MOTORS) designed for 60Hz will rotate at a slower RPM if operated from 50 Hz source.

Regards,
MAGK

I don't know how or when the U.S. adopted the 60 Hz standard, but if I hadn't run across some rather large flood control pumps in the City of New Orleans, I would have assumed that 60 Hz was always the American standard. It turns out this is not so.

In the late 70's, curiosity got ahold of me (I was a tech rep for a big pump company after all) when I drove by an old brick building in a residential neighborhood that had seven huge pipes sticking out of one side. I stopped in and got a grand tour form a city engineer. He said that New Orleans had several of these 14 foot diameter "A.B. Wood screw pumps" that were driven by 25 cycle motors. He explained that in 1910 when these pumps went on line, there was no national standard. At the time of our encounter, New Orleans was still operating a 25 cycle power plant just to power these flood control stations.

It may seem a bit odd that they hadn't upgraded the motors to 60 cycles by then, but that would have been a very expensive project given the scope of the flood control system. And besides, up until the late 70's, and probably not again until again Katrina struck, they had only experienced one failure of an A.B. Wood screw pump since 1910.

Torrential rains had ripped a huge magnolia tree away from from a canal bank and one of the monsters sucked it through the protective bar screens, breaking the pump base and one of the screw blades. He said they repaired the base with concrete and were able to repair the screw.

By the way, A.B. Wood is considered to be the father of New Orleans' flood control system, and there's a hall at Tulane University named after him. He designed the pumps himself in 1890, and oversaw their construction at a foundry that did not manufacture pumps. The old pump drawings he showed me were works of art. I was in nerd heaven.

Back on the 50/60 Hz question, I understand from an old boss of mine who came from the medical field, that 60 Hz was not the best standard to settle on. That's because it's the frequency at which the impulses to human heart operate. He says that you're more likely to suffer cardiac arrest when shocked at 60 Hz then 50 Hz because of this. I'll take his word for it.

ETA: I should have googled A.B. Wood screw pumps rather then rely on memory. Mr. Wood was born in 1879, according to the ASME web page on the subject, so it's unlikely he designed the pumps in 1890. It also appears that they went online in 1915 in New Orleans, and they were later used in Chicago and world wide.

MAGK is right, an induction motor will rotate slower but for an appliance like refrigerator, washing machine you won't notice the difference (wash may take longer if the timer runs slower).
Bench-top appliance like cake mixer are universal motors so the speed is not effected. If you have an old turntable or reel to reel it might improve your music, ha, ha.

Regards,
Roy

You would also find 25 Hz. electric systems in early Niagara Falls hydroelectric installations. I understand that when used for lighting, the filaments would have a noticeable flicker which was annoying to most users. The higher frequency eliminated that problem and also allowed the transformers and other power equipment to be made smaller/lighter.

I've been told that is a reason why aircraft electrical systems are typically 400 Hz., they require smaller and lighter hardware.

Russ

In the part of Canada that I live in, we used 25Hz until the late 1940s. 25Hz originated by historical accident. A company was building a compressed air plant driven by a water fall. Compressed air was once distributed to industries just like electric power is today (although obviously over shorter distances).

They had already placed the order for the turbines. Before they placed the order for the compressors though, they decided to complete the project as an electric generating plant instead. Since the shaft speed was already determined (the compressors were ordered), that left selecting the number of generator poles to determine the frequency. Of the frequencies available to them, they selected 25 Hz as the fastest they thought they could manually synchronise.

The plant was a financial success. When new plants were built (including by other companies), they had to operate at the same frequency if they wanted to use the same transmission lines and sell to the same customers. This spread in a ripple across the province. We later changed to 60Hz in order to allow interconnection to adjacent utilities.

You will probably find similar stories everywhere. It is unfortunate that we didn't all standardise on 50Hz, but although that would have been practical in 1950, I don't think it is feasible today.

Airplanes use 400 Hz. This allows lighter transformers. However, it also means that eddy current losses are greater for a given thickness of lamination.

Also, Televisions in Europe sync at 50 Hz vertical, verses 60 Hz in USA. The older (40's) TVs synced 'off the wall' i.e. they synchronized to the AC phase rather than to the brodcast signal which they could have.

Eric
www.icpdas-usa.com

As an apprentice I worked on 400 Hz power tools, they were similar in size to air powered tools, light and simple.

I have also used a submersible well pump operated at that frequency 0.5 HP in a housing 1.8" diameter.
It's quite easy to find a VFD that will put out 400 Hz.

Roy