Siemens SIMATIC ET 200AL System Manual page 2059

What you should know about analog technology
2.9 Interference frequency suppression
Line frequencies used
The line frequency is the frequency used in an electricity network for AC supply. It is
measured in hertz and indicates the number of oscillations per second in a periodic signal. A
line frequency of 50 Hz, for example, means 50 oscillations per second.
Europe, Australia and most countries in Asia and Africa use a line frequency of 50 Hz. North
and Central America and most countries in South America have electricity networks with a
line frequency of 60 Hz.
Frequencies of 400 Hz are most commonly used in on-board networks for airplanes, in the
aerospace sector and for military applications. One reason for this is that engines with a line
frequency of 400 Hz can usually be made smaller and lighter. As, however, it is not
economic to transport such high frequencies over large distances, 400 Hz applications are
usually subject to significant spatial limits.
A frequency of 16 2/3 Hz is used for the traction power supply in Germany, Austria and
Switzerland. Some modules of the SIMATIC S7 product range also support the interference
frequency suppression of this line frequency. The configurable interference frequency
suppression in these cases is 16.6 Hz.
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Analog value processing
Function Manual, 06/2014, A5E03461439-AC