[Sneap] sparking problem

[Chris Westerfeldt]

Hi Tom,
    We don¹t have any surge suppression in our motor circuits and have never
had any problems
such as you describe.  Our motor leads are run in that flexible conduit that
NEC provided with the kit.
The only preventative measure that we employ is to ³hide² the motor behind a
well grounded, 
perforated metal ³screen².  The screen in bolted to the motor mount right at
the ground plane.  
Our thinking was that any spark coming down the equipotential rings would
likely hit the motor or
it¹s mount as they were Œhanging out in the open².  I¹ve attached a photo to
illustrate.
Regards,
- Chris
-- 

Chris R. Westerfeldt
Research Scientist / T.U.N.L. Radiation Safety Manager
Duke University Physics Department &
Triangle Universities Nuclear Laboratory
Science Drive, Box 90308
Durham, NC  27708-0308
Tel: (919) 660-2600
Fax: (919) 660-2634
Email: Cwest at Tunl.Duke.Edu



From: "Miller, Thomas Edward" <millerte at purdue.edu>
Reply-To: Symposium of Northeastern Accelerator Personnel
<sneap at tunl.duke.edu>
Date: Sun, 1 Feb 2009 08:34:45 -0500
To: <sneap at tunl.duke.edu>
Conversation: sparking problem
Subject: [Sneap] sparking problem





SNEAPERs:
 
I need your advice. For our 2 drive motors inside the tank we have PI
filters inside a metal box in series with the 2 motors. Connections from the
tank feedthrus are made with copper conduit to the box and then to the
motor. It was found that spark damage inside the copper conduit between the
wires and the copper conduit had damaged the wires that are between the
motor and PI filter box. What was done was the PI filter box was mounted
outside the tank and the conduit connecting both the PI filter box to the
tank feedthrus and the tank feedthrus to the motors was replaced with
plastic conduit. What this did was bring the spark energy outside the tank
where it can now damage equipment outside the tank.
 
What is your recommended solution, i.e. how have you guys done it?
 
I would like to have a better robust filtering for the motors on the inside
to prevent the spark energy from getting out of the tank and a better
conduit system. Seems like spark energy is traveling thru the motor 208 VAC
wires and needs to be removed right at the motor. Any help would be great.
 
Thank you. Cheers!!!!
 
  Tom Miller
  Purdue University
  millerte at purdue.edu


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