IS barriers with motor RTD's
IS barriers with motor RTD's
(OP)
We have a customer requiring IS barriers for machine instrumentation in a haz area. Most instruments are fine but we are discussing embedded RTD's in a large (1000HP), haz rated, induction motor.
Is it not true IS barriers require physical distances from non-IS devices when wired? This certainly true in a terminal box. If RTD's are embedded in the stator of a 10KV motor, are IS barriers the proper solution.
I'm thinking sealed conduit and the like, would be better.
Any comments?
Thanks!
Is it not true IS barriers require physical distances from non-IS devices when wired? This certainly true in a terminal box. If RTD's are embedded in the stator of a 10KV motor, are IS barriers the proper solution.
I'm thinking sealed conduit and the like, would be better.
Any comments?
Thanks!





RE: IS barriers with motor RTD's
You need barriers so if the machine reading the RTDs spazzes out and injects power to the RTD it can't shove more energy than allowed into the hazardous area.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: IS barriers with motor RTD's
yours
RE: IS barriers with motor RTD's
My concern is more with the RTD's being nestled in with the high voltage windings of the motor. Worst case, a failure could put high voltage on the RTD leads.
These lead back to the IS wiring in the control enclosure for other instruments.
IS installation required 2" air space between IS wiring and non-protected wiring (ie motor windings).
In my mind, IS protection should not be applied to motor wind RTDs. Does this logic seem correct?
RE: IS barriers with motor RTD's
12fish
As Iron sharpens Iron so does a man sharpen the countenance of his friends.
RE: IS barriers with motor RTD's
IS barrier cannot protect you from the fault on high voltage which then skips onto the RTD wiring. Its only purpose is to protect RTD and its wiring from excessive energy surge from the main control panel and as a result rising the temperature of RTD or its wires above the explosion temperature.
You can avoid IS barrier if you are able to put RTD wiring in sealed conduit (and by sealed I mean sealed on both ends in certified way). Sealing should be according to the class and division, but you should check for local regulations. If you do not use the sealed conduit, I would certainly use IS barrier or otherwise prove by calculations that there is no way that those wires from control panel to the RTD can be overheated above the temperature on which surrounding gas might explode.
RE: IS barriers with motor RTD's
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RE: IS barriers with motor RTD's
BK
RE: IS barriers with motor RTD's
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