24vDC power supply

Hello, I have a question about 24vDc powering instruments from a control panel. My question is why do we use a 2 core cable going to the device/instrument and do not provide a 3rd for for the earth connection like would be provided if the device was powered by AC single phase?

Thanks
 
Hello, I have a question about 24vDc powering instruments from a control panel. My question is why do we use a 2 core cable going to the device/instrument and do not provide a 3rd for for the earth connection like would be provided if the device was powered by AC single phase?

Thanks
Hello

Do you have any schematic ...single line diagram..showing such arrangements...

As we need to know what kind of instruments are you mentionning ..

James
 
Thanks for this power supply in this instance is Siemens Sitop 20A and instrument is E&H pro mass 300 and also a Siemens HMI
Humm..
Interesting device
.. I just had read OEM manuals...
Look at operating & instruction manual as they are différents way /type for connecting and configuring the instrument..
 
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