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FW: Magnifyer Coil Question (rotary)
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From: D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: Tuesday, June 16, 1998 6:33 PM
To: Tesla List
Subject: Re: Magnifyer Coil Question (rotary)
to: Mike
A synchronous rotary gap charges the cap (via xmfr) and then aligns the
electrodes to fire exactly as the 60 Hertz sine wave hits its peak value.
They charge and fire on every positive and negative peak so that maximum
cap energy is dumped into the primary. A typical synchro rotary gap for
use with small and medium size systems has 4 electrodes on the rotor and
runs in "sync" with the 60 Hertz line frequency at a speed of 1800 RPM.
Higher power systems usually use a 3600 RPM synchronous motor with two
electrodes on the rotor. Both gaps fire 120 times per second. The rotors
must be adjusted by be in exact phase with the motor amature so they fire
on the peak -- a storage o-scope is usually employed to achieve this
syncing. A nonsynchronous RSG fires many times per second and depends on
the total number of electrodes on the rotor and speed of the motor. A
typical non-synchro RSG fires 400 to 480 times to generate 400-480 pulses
per second. A common example of synchro motor is an electic clock where
the motor is in sync with the 60 Hz line frequency.
The non-synchro gaps are commonly used on pole xmfrs as they will quickly
destroy a NST due to their duty cycle which overheats the NST type xmfr.
The non-synchro units can produce longer sparks as they cause the corona
field to "grow" rapidly with each spark, however, the synchro type RSG
usually produces a much "hotter" spark channel and thick, bushy sparks as
noted on time photographs of this type coil in operation.
If you are running NST a 7 inch rotor running 1800 RPM with 4 electrodes
offers excellent performance on most systems with typical coeff. of
coupling in the "classic" range of 0.18 to 0.22.
Magnifier systems require as many as 900-1,000 pulses per second and very
tight coeff. of coupling, ie, 0.6 typically.
DR.RESONANCE-at-next-wave-dot-net
> From: Michael Nolley [SMTP:mhnolley-at-willamette.edu]
> Sent: Monday, June 15, 1998 4:33 PM
> To: Tesla List
> Cc: 'Tesla List'
> Subject: Re: Magnifyer Coil Question (rotary)
>
>
>
> On Sun, 14 Jun 1998, Tesla List wrote:
>
> >
> > ----------
> > From: Jeff Corr [SMTP:corr-at-enid-dot-com]
> > Sent: Sunday, June 14, 1998 2:34 AM
> > To: Tesla List
> > Subject: Re: Magnifyer Coil Question (rotary)
> >
> > Just be sure its syncronous, otherwise you know what will happen
> > to your trannies....
> >
> > >Thanks for the help Malcolm, I'll be using two 15kV, 60mA NST's wired
in
> > >parallel. This configuration may require a rotary gap as currents
levels
> >
>
> Sorry, another idiot q: what's the difference between synchronous and
> non-synchronous rotary gaps?
> Mike
>
>