Variac Tapping & Buck-Boost Transformer Design Calculations for Servo Controlled Voltage Stabilizers

The Variac (also called as ‘Variable Autotransformer’ as a technical name, and also called ‘Dimmer’ by using for dimming of the lights etc.) and BBT (Buck-Boost Transformer) are the main components in every servo controlled voltage stabilizer (SCVS). Variac's tapping and BBT's sizing calculations are one of the challenging task for designing of servo controlled voltage stabilizers. So, during this paper it is clearly explained with suitable example for 100 kVA (natural air cooled), 3-Phase SCVS.