--- On Mon, 22 Jun 1998 00:44:00 -0700 "Liew, Shih Perng"
<shih.perng.l...@intel.com> wrote:
> Hi All,
>
> I have some different machines in one production line sharing a same
> power source, namely IX testers, ovens etc. I encountered a problem
> where some of the ovens tripped-off intermittently. The earth-leakage
> current was found to be excessive and causes the earth-leakage circuit
> breaker to trip. To find a short-term solution, the affected ovens
> were rewired from a new power source and the metal structures were
> insulated. The problem seems to be solved...however, I am not so
> convinced.
> rgds,
> sp
Shih:
Be careful! The ovens which caused the leakage path to exist have now "been
connected to a different power source" which I assume does not have ground
fault current sensing? And you have "insulated the metal structures"?
Seems like this creates a hazard, since the new arrangement will allow a
dangerous voltage potential to exist between the newly insulated metal
structures and earth ground.
Better find out where that fault path is in the ovens, and get the structure
grounded again. Look at the heater elements, look for corrosion and
contamination on the insulator supports. Check for corroded sensing and control
elements, and look at the fan motors for insulation degradation.
Ed
--------------------------
Ed Price
ed.pr...@cubic.com
Electromagnetic Compatibility Lab
Cubic Defense Systems
San Diego, CA. USA
619-505-2780
List-Post: emc-pstc@listserv.ieee.org
Date: 06/22/98
Time: 08:48:59
--------------------------
