[time-nuts] Re: What everyday uses are there for accurate clocks?

[Andrew Kohlsmith (mailing lists account)]

> On Nov 29, 2022, at 12:27 PM, Oz-in-DFW via time-nuts <time-nuts at lists.febo.com> wrote:
> If we use "better than NTP" as a reference there are a host of industrial applications that synchronize machinery.  High speed roll  fed multistage printing presses need to have the stages synchronized to prevent from piling paper up, or shredding it.  Any similar process flow of continuous material needs PTP level synch - so wire drawing, metal sheet mills, paper mills, and so on.  Older versions of these used timing shafts which limited ramp rates and had propagation problems related to shaft flexure that limited the size of systems. Application of mechanical buffers was used to some degree, but they have their own problems.

I used to work in this industry (industrial power electronics) and that was achieved through encoders on the spool shafts and computing the correct turning speed (as paper spooled or unspooled) rather than timing. The speed control of the motors driving those spools was done through VFDs (these were the types of product I designed) and their clock accuracy was no better than whatever off the shelf crystal or oscillator we put in them. We definitely didn’t need TCXO or clock sync between drives, but they were definitely networked and the higher level PLC kept the speeds within spec. There were also mechanical devices (web tensioners) which did the lion’s share of the work in keeping the paper correctly tensioned as it moved through the process.

-A.

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