Clause 3 – How to understand the definition of “rated frequency range”

rated frequency range: frequency range assigned to the appliance by the manufacturer, expressed by its lower and upper limits.

The rated frequency in the form of a range, generally 50-60 Hz, but all countries in the world have either 50 Hz or 60 Hz mains frequency, there is no intermediate frequency value, so the definition is not very meaningful. However, there are still buyers or manufacturers who give the frequency range in the form of 50-60Hz. In my opinion, even in order to consider the frequency fluctuation caused by the unstable utility voltage, 50-60Hz does not take into account the situation of less than 50Hz or more than 60Hz.
Therefore, I recommend marking the rated frequency as 50/60Hz directly.