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DC grounding for 2-wide power/controller carriers in a redundant controller node .

The M-Series Hardware pdf (Documentation Library) indicates that the 2-Wide power/controller carrier DC reference ground needs to be wired to the Isolated Common Ground Reference within cabinet.  However, I couldn't find any documentation whether both 2-wide carriers, in a node with redundant controllers, need to be grounded the same way.

 

fabuid

• 11 Aug 2016 9:06 PM
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2 Replies

• Andre Dicaire

  

  • 11 Aug 2016 10:19 PM

  I also could not find this in BOL. The Site Planning and Preparation guide (D800015X092 from December 2008) indicates in figure 5-4 (page 5-7)that when using the DC/DC system power supplies, you only need to connect one of the 2-wide carriers to DC Reference. The note on the diagram states:
  "Use the left-hand screw only. Only one ground wire is necessary because the return side of the DC power supplies is internally connected to the Ground terminal of either terminal strip."
  
  The Quick Reference guide for DeltaV Power, Grounding, and Surge Suppression (D800053X042 from July 2013) also shows that only one DC Reference ground wire is needed. It is shown connected to the left side carrier for S-series, while the Site Planning and Prep guide diagram shows it connected to the right side carrier for M-series.
  
  So both generations of documentation call for one DC Reference ground, and either carrier can be used. I personally would use the right hand carrier for this ground. This carrier is always present (i.e. the one connected to the first IO carrier.)
  
  Note that if you add an Injected power carrier, you have to run a DC Ground reference to the Injected Power Carrier to ground the bus to the right of this carrier.

  Andre Dicaire

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• Ray Emerson

  

  • 11 Aug 2016 11:16 PM

  In reply to Andre Dicaire:

  There are a couple of other considerations for DC/DC power supplies, since the VE5008 and VE5009 may be fed on either 24V DC or 12V DC, but the LocalBus is always 12V DC.
  
  If your feed SMPS is 12V DC, and you are referencing that bulk power supply AT the power supply, there should not be a ground wire on either 2-wide.
  
  If your feed SMPS is 24V DC, and you are referencing that bulk power supply AT the power supply, you need another DC reference ground at the DeltaV system power supply, since you're passing through an additional 24/12 stepdown transformer.
  
  For S-Series, since this can only be fed on 24V DC, you always need that reference ground on the carrier. For both M-Series and S-Series hardware, only the connection point that is marked as ground actually has a connection to ground. Look for the chassis / power ground symbol on the hardware.
  
  In a redundant configuration, since that ground is carried through the 12-pin redundancy connector, you only ground one 2-wide. Otherwise, you create a ground loop. This can be tested easily with a DVM.

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