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Protective Earth Bar for AC and DC voltages

Protective Earth Bar for AC and DC voltages

Protective Earth Bar for AC and DC voltages

(OP)
For the one of the packages to be installed in a NORSOK project. The Package vendor is supplying the control panel. CONTRACTOR provided one 690V AC connection to the control panel, vendor will derive all the auxiliary connections required for the package from this.

24 V DC required by the package instrumentation and the same is derived. This 24 V DC is used to power the instruments inside the package.

Now the query is, Vendor connecting OV line of the 24V DC connection and an electrical ground connection (AC) in the same PE bar.

Third Party Agency is saying that good engineering practice is to make the PE bar separate for the AC and DC connection. As far as we seen, NORSOK doesn't say anything for this requirement.

Why having separate PE bar for AC and DC connection? Pls advise.

RE: Protective Earth Bar for AC and DC voltages

It makes sense to provide a dedicated instrument earth (clean earth or reference earth) which has one connection to the main earth terminal of the machine. That minimises the chance of power currents getting into the instrument earthing system through direct conductive paths, although there are also a multitude of inductive and capacitive routes by which it can get in if the system isn't carefully designed to prevent that happening.

RE: Protective Earth Bar for AC and DC voltages

DC power supplies have grounds on them so this ground goes to same ground bar in that panel as the ac power grounds. All these grounds do they not just carry back thru the power distribution ground system in whatever plant you have? Seems like a simple answer. This is all bonding and earthing questions. I have never seen a ground rod driven next to a panel just for DC. So what is this person trying to say with a seperate earth bar?


everyone has an opinion
National Electrical Code (ANSI/NFPA 70) — Article 250 of
this code provides information about the types and sizes of
conductors and methods for safely grounding electrical
equipment and components. Articles 725-5, 725-15, 725-52, and
800-52 restrict the placement of different types of conductors in a
composite cable, a raceway, or a cable tray.
• IEEE Recommended Practice for Grounding of Industrial and
Commercial Power Systems (IEEE Std 142-1991)
• Grounding for the Control of EMI (by Hugh W. Denny —
publisher, Don White Consultants Inc., 1973)
• Electromagnetic Interference and Compatibility, Volume 3 (by
R.J. White — publisher, Don White Consultants, Inc., 1981)
• Military Handbook 419, “Grounding, Bonding, and Shielding for
Electronic Equipment and Facilities”
• IEEE Guide for the Installation of Electrical Equipment to
Minimize Electrical Noise Inputs to Controllers from External
Sources (IEEE Std 518-1982)
• IEEE Recommended Practice for Powering and Grounding
Sensitive Electronic Equipment (IEEE Std 1100-1992)

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