??? 11/07/05 00:53 Read: times |
#103343 - ground vs neutral Responding to: ???'s previous message |
Suresh R said:
Hello Every one,
Can any one give me the difference that exists between GND and NEUTRAL. In designing circuits how these two things must be handled. Assuming you are asking about mains power distribution, and not low-level DC power supplies: Neutral and ground serve two different purposes. Neutral is the return for the mains hot wire; as such, it is a current-carrying conductor and must be sized appropriately. (It's worth noting that in a low-level circuit, such as what we deal with with microcontrollers and op-amps and the like, this circuit node would be called "ground.") Ground is better called "safety ground," because it is NOT normally a current-carrying conductor, but rather it only carries current in the event of a fault (the hot lead shorted to a chassis). The ground wire must return to the panel and be connected to some sort of grounding system (cold-water pipe, copper rods buried in soil, building steel, or something that is dictated by local electrical codes). This is to establish a drain for the fault current as well as a "zero volt" node. At the main panel, the neutral must be bonded to the ground (and only at the main panel -- not in any sub-panels; however, again check your local codes). Bonding neutral to ground in this fashion forces the neutral node to be at 0 V with respect to ground, so the connected equipment doesn't float relative to ground. I saw some circuits, in which the component's GND pin's are connected to the Centre Tap of the transformer. But no wires from the board lead to GND. What kind of system are you describing? Is that really necessary to have a GND path in addition to NEUTRAL when designing circuits. Power distro or otherwise? -a |