[time-nuts] Maser 0.7 nsec jumps solved

Poul-Henning Kamp phk at phk.freebsd.dk
Tue May 24 06:55:35 EDT 2016


--------
In message <57441ACA.8070609 at arcor.de>, Gerhard Hoffmann writes:
>Am 23.05.2016 um 05:15 schrieb Jim Palfreyman:
>> As far as a remedy goes we are going to try a solid state relay that only
>> switches on at 0V in the AC waveform. This should slow the inrush current,
>> and hopefully the magnetic impulse.
>>
>>
>In the context of transformers and motors, switching on at 0V is 
>actually the worst point in time.

Well...

The motor is almost certainly an "Squirrel-cage" induction motor and
that means it is three phase, although one of the phases is probably
created with a "starting capacitor".

So which of the three phases is going to be the lucky one that
switches at maximum voltage, or are you going to switch the phases
on sequentially ?

A 4kW Variable Frequency Drive costs less than $1k and allows you
to control *both* the voltage/time and the frequency/time *both*
during startup and during rundown.

I wouldn't bother fuzzing around with hacks - I'd just go for the
known-to-work solution.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


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