profbuxton
- Joined Feb 21, 2014
- 421
Paulo, regarding your drawing. Please note that there is NO flow of electrons or anything else into or from the ground connection, end of story.
Consider the case of a very low frequency alternator(say 1 cycle per second). Now connect a center zero analogue meter across the output. This alternator is of course not connected to anything else.
The meter will swing from one side to the other at 1 cycle per second as the polarity changes with each cycle.
Note connect a load across the terminals. A current will flow at the same frequency as the voltage.
Now connect one terminal (either one) to a large metal object. The voltage on the meter will not change and current will continue to flow through the load.
Now connect your meter from the metal object to the other terminal. The meter will still show the same swing as before and load current will still flow. You have now a "Neutral" connection using the large metal object. Now you can measure between any point the large metal object and the other terminal and see the meter reading. Replace the large metal object with the "earth" and the above applies also.
One side of power distribution is connected as "neutral" for safety reasons. One side is connected to a solid earth at the supply transformer and each user has a "MEN" link in their switchboard. This connects the incoming "neutral"
conductor to a local earth stake. This ensures that if the"active" contacts any earthed metal it will trip the local protection.
Railway signalling supplies are "floating"(not connected to earth) but they use earth leakage detectors to alarm if one side becomes earthed. If a second earth occurs on the other wire the that could cause a short and rail problems.
Consider the case of a very low frequency alternator(say 1 cycle per second). Now connect a center zero analogue meter across the output. This alternator is of course not connected to anything else.
The meter will swing from one side to the other at 1 cycle per second as the polarity changes with each cycle.
Note connect a load across the terminals. A current will flow at the same frequency as the voltage.
Now connect one terminal (either one) to a large metal object. The voltage on the meter will not change and current will continue to flow through the load.
Now connect your meter from the metal object to the other terminal. The meter will still show the same swing as before and load current will still flow. You have now a "Neutral" connection using the large metal object. Now you can measure between any point the large metal object and the other terminal and see the meter reading. Replace the large metal object with the "earth" and the above applies also.
One side of power distribution is connected as "neutral" for safety reasons. One side is connected to a solid earth at the supply transformer and each user has a "MEN" link in their switchboard. This connects the incoming "neutral"
conductor to a local earth stake. This ensures that if the"active" contacts any earthed metal it will trip the local protection.
Railway signalling supplies are "floating"(not connected to earth) but they use earth leakage detectors to alarm if one side becomes earthed. If a second earth occurs on the other wire the that could cause a short and rail problems.