[Linked Image]

T4a = 1 Phase Split Coil Transformer [split primary and secondary coils].
Note jumper location - this is the infamous "Neutral" connection point
on the
Transformer.


This Transformer core is a common 1 phase Transformer with "Split Coils" on both the Primary side and the Secondary side.
It can be used with an input voltage of either 240 VAC [Parallel Primary connection], or 480 VAC [Series Additive Primary connection].

The output can be:

A: 120 VAC 1 phase 2 wire [Parallel Secondary connection],

B: 240 VAC 1 phase 2 wire [Series Additive Secondary connection],

or

C: 120 / 240 VAC 1 phase 3 wire [Series Additive Secondary connection with a tap at the X2 - X3 jumper point of connection for the "Neutral"].


If you look at the two busses in the middle [the ones with the jumper connected], either one of those busses would be where the Common Neutral wire would be derived from.

Viewing from Left to Right, the Terminals on these busses would be:

X1 [beginning of coil "A"'s winding. Line "A" comes from here],
X2 [end of coil "A"'s winding - jumper to next coil],
X3 [beginning of coil "B" winding - jumper from other coil],
X4 [end of coil "B"'s winding. Line "B" comes from here].

This should help explain how a Neutral works with 1 phase 3 wire multiwire circuits, plus point out the major differences between how a 1 phase 3 wire's Neutral works and is derived, as compared to how a 3 phase 4 wire Wye's common works and is derived.

Any comments??

Scott SET