[time-nuts] Maser 0.7 nsec jumps solved

[Orin Eman]

On Wed, May 25, 2016 at 9:59 AM, Mike Monett <timenuts at binsamp.e4ward.com>
wrote:

> >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.
> >
> >< https://de.wikipedia.org/wiki/Einschalten_des_Transformators > (German)
> >
> ><
> >
> http://electrical-engineering-portal.com/practical-considerations-of-transformer-inrush-current
> > >
> >
> >regards, Gerhard
>
> LTspice shows  switching  at 0V is the best point in  time.  With no
> flux in the magnetics, the inrush current is limited by  the circuit
> resistance. The magnitude is given by Ohm's law: I = E / R.
>
> Switching at 0V,
>
> I = E / R
> = 0 / R
> = 0A
>
> However, switching  at  the peak of the voltage can  give  very high
> inrush currents. You can verify this with LTspice. The  schematic is
> at
>
> http://www.pst.netii.net/misc/48b961a6.gif
>
> There are two circuits. They are identical except the second has the
> applied voltage  shifted  by 90 degrees. The  inductors  have  1 Ohm
> series resistance (not shown.)
>
> The waveforms are at
>
> http://www.pst.netii.net/misc/48b96217.gif
>
> The currents are IL1 and IL2.
>
> Switching at  0V, IL1 starts at zero. It rises to a  peak  of 900mA,
> then falls  back  to  zero. The DC offset takes 3  or  4  seconds to
> decay, then the current is stable at zero +/- 450mA.
>
> Switching at the peak, IL2 is
>
> I = E / R
> = 169.7 / 1
> = 169.7A
>


Er, no.  It's an RL circuit for which:

V(R) = E(1-e^(-(R/L)t)

so I(R) = I(L) = (E/R)(1-e^(-(R/L)t)

for t close to zero where E is essentially constant, I is going to rise
with the time constant of R/L which for a 1H inductor and 1 ohm resistance
is 1 second.

I suggest running the simulation with a pulse voltage source, Tdelay 1ms,
period 1s, Ton 0.5s (Period and Ton are fairly arbitrary, the Tdelay is
important).

You only need to run the simulation for a few ms.  You will get a very
different result.

Now as Poul-Henning Kamp suggested, an induction motor is anything but an
ideal inductor...