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Re: [TCML] Variable RSG
What about using one of the heavy reactors that go out to the motor? I have
couple that are meant for three phase setups that I got off Ebay pretty
cheap. I think they are meant to protect the VFD and keep noise from getting
back into the wiring plant. I suppose RF would go right around it though.
They are definately Heavy Duty! Thoughts?
On Tue, Apr 8, 2008 at 8:58 PM, <FIFTYGUY@xxxxxxx> wrote:
>
>
> In a message dated 4/8/08 11:28:41 P.M. Eastern Daylight Time,
> resonance@xxxxxxxxxxxx writes:
>
> >Have you had any problems with the VFD setup being affected by the RF or
>
> >magnetic fields under the primary coil, eg, in the base when the RSG is
>
> >placed? Especially with DRSSTCs with their extremely high primary
> currents
>
> >and fast switching speeds producing large pulses in controller wires,
> etc.
>
>
>
> Who uses a RSG with a DRSSTC?
>
>
> >Does anything kick back into your controller causing full speed lockon,
> or
>
> >do you use some filters of some type between the RSG motor and the
>
> >controller which is usually at a remote location?
>
>
>
> A common practice is to use a shielded cable between the VFD and the
> motor. Of course, we're back to the issue of "what gets grounded to
> what". For
> safety, the motor should be tied to "green wire building ground". And the
> recommended practice is to run the motor's grounding wire directly to the
> drive's
> chassis, which is of course also tied to green wire/building ground. But
> it's in a close proximity to the spark gaps and primary wiring, not to
> mention
> usually under the primary itself. So it'll probably pick up a lot of RF
> and
> put it on the green-wire system.
> If any of the motor windings or the wires going back to the drive's
> output get too high a voltage on them, the drive will fail (usually a
> "non-passive end-of-life event"!). Another reason for using shielded
> cable between the
> drive and motor.
> With the pig coil, I'm paranoid about running any low-voltage winding
> out to the coil itself. I run fans off a battery and small inverter. For
> the
> VFD-to-motor, I use shielded drive cable, with the shield tied to
> green-wire
> ground/chassis. But then I run the cable inside flexible metallic conduit
> when
> it gets within striking distance of the coil. The flexible conduit lays
> on
> the ground, and is tied to RF ground. If a streamer hits the conduit, and
> manages to get back to green-wire ground, so be it. But it's a *lot*
> better than
> simply using a piece of SO cord.
>
> -Phil LaBudde
> Center for the Advanced Study of Ballistic Improbabilities
>
>
>
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