Standard Resistance measuremen​t values for the fieldbus cables

[rangareddydv]

Can you please inform me the "Standard resistance measurement values at the H1 network / segment conductors coming in from the field" between the follwings
+ and - signal
+ and shield
- and shield
+ and ground bar
- and ground bar
shield to ground bar
WithRegards
RangaReddy

[rezabejd]

RangaReddy,

Download the AG-181 System Engineering Guidelines (http://www.fieldbus.org/index.php?option=com_content&task=view&id=150&Itemid=326) (free on fieldbus.org website). Page 126 or so (appendices) has a complete commissioning form / checklist for segment checking including expected values / tolerances.

[Mike ONeill]

One of the basic principles of FF is that there are no special cable requirements; what you use for standard 4/20mA instruments will work, albeit with different performances due to differences in cable specification.

For example, best performance comes with twisted-pair shielded cable ("Type A" in FF specs) and you can also use multi-pair cables with individual shielded pairs. Size of cable (AWG or sq mm) is your choice (bigger cables are lower resistance and therefore have less impact on segment capacity through series volt-drop, but more expensive and sometimes more difficult to handle & pull).

Your question is perhaps incorrectly phrased; only shield to ground bar is expected to be very low impedance (say, 0.1 Ohm or less), all others listed are very high impedance (say, 1 MegOhm or more).