On Friday, August 19, 2011 10:29:11 AM Jan de Kruyf did opine:
> The whole thing looks high current related so:
> can you set the spindle acceleration down in the parameters of the
> control?
>
> what % of max. current does the spindle draw at 6000rpm?
>
> Way-out idea:
> I once had a rotten circuit breaker in the main board arcing on high
> current.
> The Lathe caused it, but it buggered the brains of the mill!
>
> Enjoy,
>
> jan.
That reminds me of the time when I was working for NETV as a tx supervisor
at KXNE-TV. A 3 phase Heinman breaker lost a contact and single phased the
15hp klystron cooling pump motor. The visual klystron, using about 120KW &
making heat out of 90KW of it, instantly burned a hole through the anode
bucket and filled a $125,000 klystron full of steam from a 30% ethylene
glycol & de-ionized water coolant. All in the space of my recognizing the
sound of a big motor being single phased with my hand 3 feet from the off
button. My arm was in motion when the building went dark because the 1200
amp entrance breaker dropped when the 20 kilovolt beam supply, good for 20
amps or so, was crow barred by the resultant arc. Not more than 1.5
seconds elapsed time.
That led to a design change in how the protection circuits worked, with a
pair of Jennings 50 kilovolt, 50 amp vacuum relays in series with the high
voltage, with the activation coils watching the 3 phase delta primary
supply to that motor. It had minimum flow meter interlocks, but their
response times were 100's of times slower. Now the beam voltage was
removed in under 50 milliseconds if the power sneezed. That stressed the
20kv rated filter caps by surging them up to about 30kv, but that was a lot
easier fixed in terms of cost than losing the klystron was. $5K would have
replaced all of them if they arced over. They had to call a quorum of the
Nebraska legislature to appropriate the money for a new klystron as it was
not in the ETV budget for that year.
An expensive lesson in protective circuitry that didn't.
Cheers, gene
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Fuch's Warning:
If you actually look like your passport photo, you aren't well
enough to travel.
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