Understanding DC systems

[bhamoggy]

I'm trying to understand control circuits, perhaps someone can explain properly for me to understand .

Why do you not need to earth a DC system?

How are the sine waves formed? Is it positive, 0 volts negative?

In control circuits for example 24v circuit, what is the difference with cables called, N24, P24, + , - ?

 

[Sidewinder]

In d.c. you have no sine waves, that would be a.c.

The names of the individual wires would be down to the designer, and there is no specific definitive standard to specify the codes.

However, I would take N24 to be the negative side of the 24V d.c., i.e. -, & P24 to be the positive side of the 24V d.c., i.e. +.

This could be easily confirmed with a DMM.

The d.c. system will probably be derived from a SELV or FELV supply.

You don't earth the d.c. side so it is not referenced to the a.c. source, thus providing separation.

 

[wicksy]

Just to add to the above the best way of understanding control circuits is to study the components and their function as that will help you understand what the circuit is designed to do and what it's function is in the design.

A lot of the newer control circuits are plc controlled and that is a whole different subject