# current on the neutral wire?

Discussion in 'General Electronics Chat' started by lukus08, Mar 16, 2009.

1. ### lukus08 Thread Starter Active Member

Mar 14, 2009
34
0
why am i getting around 980.000fA current on the neutral wire

Last edited: Mar 16, 2009
2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Is that actually 980 picoamps? Imagine the minute magnitude of voltage needed to push that current in copper wire.

3. ### lukus08 Thread Starter Active Member

Mar 14, 2009
34
0
its 10pa. why is the current through the neutral wire this value?

Last edited: Mar 16, 2009
4. ### wr8y Active Member

Sep 16, 2008
232
1
What is 10pa? Is that PICOamps?

5. ### lukus08 Thread Starter Active Member

Mar 14, 2009
34
0
yes 10pa (picoamps)

6. ### kubeek AAC Fanatic!

Sep 20, 2005
4,689
806
I bet this some output from simulation software. This result is just an error caused by imprecise calculations. I think you could never measure that small current in reality, especially on high-voltage three phase line.

Hypotethicaly:
If you imagine a piece of wire connected on one side to Earth (like in your case), anything insulated connected to the other side (chassis, etc.) will create a small capacitor in respect to Earth. My guess is that current induced in this LC tank by all the radio waves and static will be orders of magnitude higher than 10pA. So some current through the "disconnected" wire is possible, but highly irrelevant.
Anyway, because the wire you are talking about is neutral, this also can be casued by some very very very small imbalance in the load, which in reality will be also at least 1'000'000'000x higher.

Last edited: Mar 16, 2009
7. ### lmartinez Active Member

Mar 8, 2009
224
6

In a perfectly balanced three phase system, there would be no current flowing through the neutral conductor. The impedances in such three phase system are balanced when they are identical in magnitude and angle. Based on the 10 pico Amps readings (or calculated values) you mentioned, it can be said that such system is very close to be a balanced three phase system. On the other hand, if the impedances of a given three phase system are not balance, it is then when the sytem will be experiencing a current flow in the neutral conductor. Mathematically, this can be verified by using one of many methods such as vectors analysis.

8. ### wr8y Active Member

Sep 16, 2008
232
1
Is this something that you are MEASURING or SIMULATING?

In any real 3 phase power handling circuit, I would not care if there is 10 picoamps of current flowing - I'd expect more than that, in fact.

Welcome to the real world!

If you are SIMULATING it, well... find your simulated imbalance!