24VDC Power supply units - 0Volt earthing

[weso]

Is it recommended to connect all zero volt lines from separate 24VDC power supplies to earth, thus ensuring all zero volt lines are at the same potential?

And what if there is only one source of 24VDC power in the electrical panel, should the 0 volt line be connected to earth?

Thanks

 

[peebee]

Depends on your system. Grounded or ungrounded might be desireable. Corrosion might or might not be a consideration. Positive, negative, or mid-point grounding might all be options. Batteries might be treated differently than rectifiers.

Can you provide some more detail on your system?

 

[weso]

I am using a single phase and neutral to supply my 24VDC power supply unit in my panel, i am then using the +24VDC and 0VDC supply for my standard relay control circuit.

This is not a battery operation. Do you think I should connect my 0V line to earth? What if I also had a 5VDC power supply (would I connect both OV lines to earth?)


You mention positive and negative grounding, in which cases would you use each method?

Thanks for your initial reply

 

[buzzp]

If the supply is isolated from the rest of the system the neutral should not be tied to ground. However, the case (if conductive) should be tied to ground. WIthin the power supply itself, it may connect the 'neutral' to the case and the connection will already be made for you.

Your question can not be answered without knowing more details about your system and power supply.

I have not heard of negative grounding being used for quite some time although I am sure there may be cases where this might help for whatever reason. Negative grounding is like tying your positive of your 12VDC battery in an auto to the chassis and the negative to the equipment that needs power. Of course, this would not be a good idea for supplies that are not isolated (fuse blowing or breaker tripping along with some sparks).

 

[OldPfart]

It sounds like you are probably using a switchmode power supply. These things normally have internal isolation from the AC side to the DC side. If you ground the 0 volt you loose your isolation. Grounding the 0 will cause some switchmodes to fault and they will themn turn themselves off.

 

[peebee]

buzzp -- negative grounding is still the standard for telephone installations -- still pretty common even today!

The reason why was discussed in thread238-48040 .