Construction
Siemens CVT's consist of two primary assemblies; the
high voltage capacitor sections and the base box,
housing the electro-magnetic components.
Series connected capacitor elements, housed in
porcelain shells, each hermetically sealed, are
referred to as capacitor sections. The dielectric of the
capacitor elements is made up of high quality
polypropylene film/paper and impregnated with
highly processed synthetic fluid. Each capacitor
section is equipped with a stainless steel bellow
which will allow the synthetic fluid to expand and
contract with changes in ambient operating
temperature while maintaining the hermetic sealing.
It is over these capacitor sections that most of the
high voltage will be dropped.
A tap voltage (approximately 5-12 kV depending on
type) is taken from the lowest capacitor section and
fed to an electromagnetic circuit in the cast
aluminum base box. The base box contains the
intermediate transformer which will provide the final
output voltages via multiple tapped secondary
windings, series compensating reactor and ferroresonance
control circuitry. The base box is filled with
dried mineral oil, protecting the components from
environmental deterioration.
Ferro-resonance is simply and effectively controlled
by utilization of low flux density designed magnetic
circuitry and a saturable reactor controlled damping
circuit connected across the secondary winding. The
ferro-resonance suppression circuit does not
adversely affect transient response.