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Ap Charles
05/28/12 23:53
  05/29/12 00:50

Read: 451 times

#187574 - pre-boxed solutions .. no
Responding to: Michael Karas's previous message
Michael Karas said:
Kai Klaas said:
Ap said:
Kai, as per your mail above a 1M resistor paralleled with 1.1....22nF capacitor is used, although it is for long running cables , but will it be beneficial to shunt the sensors floating terminal towards metallic PE, with this scheme.

This scheme can be useful when having RS485 signal lines like it's done in PROFIBUS applications. But for small analog signals this coupling between signal ground and PE can inject bad HF ground noise into the signal path as well. So, many analog sensors don't have this sort of coupling between signal ground and the metallic housing (PE) of sensor.
Kai Klaas

I totally agree with Kai here. The common problem we see so often, including in this thread, is that the original poster is looking for pre-boxed solutions without beginning to understand the rhyme or reason for what is going on inside the package!!!

Michael Karas

Hi Michael, If you see EX designs / application notes the floating voltages(+ve or-ve) in Hazardous Area at sensor poin are tied to PE through suitable resistor (not strictly prohibitive). When it comes to situations like these consultation with someone more experienced is necessary, if you say this pre-boxed solutions its your wish. If you see Kai's reply he says "So, many analog sensors don't have this ...." many but not every.


List of 15 messages in thread
Sensor installing      AP Charles      05/24/12 02:13      
   EX question ?      Kai Klaas      05/24/12 06:04      
      Manufacturer      AP Charles      05/24/12 07:53      
         Never tested? So not certified?      Per Westermark      05/24/12 09:08      
            Is it undesirable      AP Charles      05/24/12 10:05      
               As far as I know...      Kai Klaas      05/24/12 12:37      
                  No No..      AP Charles      05/24/12 13:32      
                     I agree...      Kai Klaas      05/25/12 10:39      
                        safety      AP Charles      05/28/12 02:01      
                           Yes and no...      Kai Klaas      05/28/12 16:48      
                              Looking for Pre-Boxed Solutions      Michael Karas      05/28/12 18:02      
                                 pre-boxed solutions .. no      AP Charles      05/28/12 23:53      
                                    But there's more to do...      Kai Klaas      05/29/12 05:40      
                                       not familiar with 'EX'      Erik Malund      05/29/12 06:41      
                                       Yes      AP Charles      05/29/12 07:25      

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