6 replies to this topic

[jraef]

10 hz is the difference.
The one that is better is the one that is supplied by your utility! Other than that, it makes no difference except that if you are in a country that promarily uses 50Hz, it will be dificult to get 60Hz motors, and vice versa. Stick with whatever is the local standard.

[marke]

As Jeff has said, you do not normally get the choice.

The two standards have been adopted in different regions and the choices have been based on a number of characteristics.

All lines have inductance. If we pass an AC current along a line, it will be affected by the reactance of the line. A high reactance will result in a higher line loss. Increasing the frequency on a given line will increase the voltage drop on that line. From a line reactance perspective, a lower frequency is desirable.

Underground Cables have capacitance. Higher frequencies result in higher capacitive currents. For cables, lower frequencies are preferable.

Supply systems require generators and transformers, both of which have iron cores. As the frequency of the supply is increased, the volume of the iron reduces reducing the size of the transformers, generators and motors. From an "iron" perspective, a higher frequency is desirable. - aircraft use 400Hz systems to keep the size and weight of motors and transformers down.

The frequency of the supply gets cross coupled into communications systems. The higher the frequency, the greater the interference problems.

These are some of the issues involved in frequency selection.

Best regards,

[jraef]

Actually, Tesla's first AC distribution system was 25Hz, because it was adapted from water turbines that turned at 250RPM, so he put in 12 poles and got 25Hz. That actually works fine for motors, but produced flicker in incandescent lights. So for power to supply every BUT motors he redesigned it to 60Hz after careful calculations on his part to determine that 60Hz was the MOST efficient compromse that was high enough to avoid flicker. He apparently initially went to 50Hz because it would have been a natural evolution from 25Hz, but he determined that 50Hz had higher losses over long distances, and he foresaw that in the US, long distance distribution was going to be an issue.

In Germany, AEG decided to get on the bandwagon for AC power, but selected 50Hz for the simple reason that it seemed to fit better in a metric system. Everyone else in Europe followed suit, and the fact that much of the rest of the world at that time were colonies of European countries, they ended up with the same as well.