when the L2 coil is 180* out of phase it will cause the core to be constantly magnetized. The 5 -VIC transformer can be looked at as a CVT, Constant Voltage Transformer 
One other think I want to mention is that there will be a magnetic field running perpendicular to the coils magnetic field and this will cut out EMF
Interesting, do you mean: Ferroresonance ?
http://www.generaltransformer.com/transformer/ferroresonant-transformers.htm---
Ferroresonant Transformers
Ferroresonant transformers are a special type of laminated transformer which provides a regulated output.
These are sometimes known simply as "ferros", or "CVTs" (constant voltage transformers).
Using a special magnetic structure and a capacitor, ferroresonant transformers can supply a well regulated output voltage
which remains constant despite changes in input voltage and load. In some specialized applications, these devices can be
designed to supply a constant current output, rather than constant voltage. Current limiting is an inherent benefit of ferroresonant transformers.
If an overload, or even a short circuit is applied, secondary current is limited to a safe level and primary
current is actually lower than at normal full load. Another inherent benefit is that the ferro serves as a low-pass filter, supplying
to load with power, but effectively removing transient and surge voltages. Energy stored in the transformer structure even
allows the output to "ride through" brief input power interruptions.
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Br,
Webmug
