Grounding the 0V DC reg
Grounding the 0V DC reg
(OP)
There is a thyristor control panel for a Heater in one of the package and is mounted remote in a conditioned room. The panel vendor has derived 24V DC power for the package instrumentation ( Temperature transmitters). There has been a comment from Client that the 0V (-24V DC) has to be grounded.
Hence package vendor is proposing to connecting it to PE.
There has been objection from Instrumentation specialist that the PE being for AC , connecting the DC is not to be done as very high fault current if any in the AC power system may induce spikes in the DC system also. Vendor informs that it is not a common practice to separate 0V DC from AC ground. They are common and connected to the back panel.
My Queries
If the Individual Instruments in the package ( Transmitters) are already earthed separately, is there a necessity to ground the 0V (-24VDC) also?
Who is right in terms of connecting the AC and DC together to the common earth?
Thanks to clarify.
Hence package vendor is proposing to connecting it to PE.
There has been objection from Instrumentation specialist that the PE being for AC , connecting the DC is not to be done as very high fault current if any in the AC power system may induce spikes in the DC system also. Vendor informs that it is not a common practice to separate 0V DC from AC ground. They are common and connected to the back panel.
My Queries
If the Individual Instruments in the package ( Transmitters) are already earthed separately, is there a necessity to ground the 0V (-24VDC) also?
Who is right in terms of connecting the AC and DC together to the common earth?
Thanks to clarify.





RE: Grounding the 0V DC reg
RE: Grounding the 0V DC reg
Grounding and bonding is the rule today. There are some exercises trying to use separate PE, TE, GND and N systems and they are sometimes successful. But there is usually a common point where they are all connected together. Except for IT grids, where PE and N are always separate.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Grounding the 0V DC reg
Potentially lethal touch and step voltages are a known hazard. Isolated grounding electrodes may be subject to gradient induced voltages several times higher than the corresponding touch and step potentials and conduct those lethal voltages to exposed metal.
Bill
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"Why not the best?"
Jimmy Carter
RE: Grounding the 0V DC reg
Publication 1770-4.1 – February 1998
I think there are too many what if conditions on grounding dc common. Worth a read on if your applies to an example.