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Comment by jacquesm | Hacker News Reader

One reason for the rock-solid requirement was that over time instead of just power the grid became a distributed time-base. After discouraging that kind of practice the grid operators found they had more freedom. Examples of such use: record players and various clocks running on grid power would use the frequency stability to drive synchronous motors.

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Yes, that was exactly the kind of thing I had in mind. Old-fashioned TVs depended on this, too, IIRC, and probably a lot of other stuff. (Newer TVs might still depend on it, for all I know. I haven't really looked into the matter.)

As I recall, the original goal was to try and maintain a solid 60Hz at all times. Then that was relaxed to trying to maintain an average of 60Hz over a 24-hour period. And I think that requirement has now mostly gone away, too, which is a good thing because with so many renewables in the mix these days you probably can't really do it anyway. But you can't let it slip too far because then you still might run into any number of operational problems.

The largest reason why you want grid frequency stability today is because phase shifts on short notice can cause large parasitic currents within the grid itself. Get it wrong by too much and you end up with circuit breakers tripping and that can cascade into much larger failures.

Interesting. Naive question: does that mean audiophiles with vintage gear have to rely on custom power setups to get their old stuff to play correctly?

This stuff was usually easily adjustable, so you could compensate for various irregularities. But some turntables had built-in strobe lights for aiding in adjustments, so if the line frequency was off then the strobe would be off and then your adjustments would be off, too. And even if generally well-adjusted, should the line frequency vary too much while playing a record then you would probably notice that. During musical passages it would probably definitely be noticeable, while during singing and speech maybe not at all.

Most audiophile gear from back in the day used DC motors or AC motors with multiple phases driven from on-board oscillators and advertised that fact. Consumer stuff tended to use synchronous motors. But even relatively high end stuff (Thorens TD 160 for instance) would use net-synchronous motors.

Vintage gear has interesting challenges, such as finding good drive belts, they tend to turn to sticky mush after a couple of decades.

Depend on how vintage the gear is. After '70's when quartz crystals became the norm for everything involving hertz? No need to worry. Before that? Yeah, pretty much

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