[Physics] Hard disk rotational frequency


I noticed the other day that the rotational frequency of typical consumer grade HDD are either 5400rpm or 7200rpm. These correspond to 90Hz and 120Hz respectively.

Given that in parts of the world the grid frequency is 60Hz, and 120Hz is the first harmonic. What effects does this have on the platters.

It would seem to me that this choice in rotational speed (7200 rpm) would be problematic in these certain countries.

Best Answer

The power supply to a hard disk is DC not AC (5V and 12V) and the disks themselves are heavily shielded from external magnetic fields - for obvious reasons! So there is no interaction, adverse or otherwise, with the mains frequency.

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