magdyfayad said:
thanks all
the problem is that the basics of this form are not clear to me , so my statements are not stable !!
if i study the basics well as keithkyll said , may be i have the answer
thanks keithkyll , thanks leitmotif , and thanks Jim Dungar
Maddy
Stop thinking neutral instead think "common".
PROJECT take any two batteries of equal voltage call em A and B
Wire negative of A to positive of B. Strip i cm insulation from this conductor. This is a common. Now measure
Positive of A to negative of B
Positive of A to common
Negative of B to common.
NOw take two litebulbs of equal voltage and wattage. Connect one side of a litebulb to A Pos. Connect one side of other lite to B Neg. Connect the two unconnected sides of the lites together and connect that to the common.
Turn both on
How much current
does lite A draw
does lite B draw
what is current in neutral OOPS now you have me doing it -- COMMON.
Turn one off
What is current in lite that is lit
What is current in common ---- WHY?
Does current in common differ with two lites than with only one
WHY?
ASSIGNMENT
Draw the current path for only one lite lit.
Draw teh current path for only the other lite lit.
Draw the current paths for lites A and B when both are on. Assume that the current for both goes thru the common. Use different colors.
Understanding this will go a long ways to understanding centertapped transformer windings. To rationalize AC it is easier to use intantaneous voltage and current. That is why I have you simulate using batteries.
Now then for further study
GIVEN 4 wire 3 phase Wye grounded neutral
What is worse getting shocked by one phase to ground
OR across 277.
GIVEN
Edison 3 wire 240 line to line and 120 either line to neut.
What is worse one leg of 240 to ground
OR acrosss 120?
Dan Bentler