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In a tap changing transformer, the tappings are provided on
Primary winding
Secondary winding
High voltage winding
Any of the above
High voltage winding
In a tap-changing transformer, the tappings are provided on the high voltage (HV) winding. This is done because the HV winding has a higher number of turns and carries less current compared to the low voltage (LV) winding, making the construction of the tapping mechanism easier and more economical.
In a tap-changing transformer, the tappings are provided on the high voltage (HV) winding. This is done because the HV winding has a higher number of turns and carries less current compared to the low voltage (LV) winding, making the construction of the tapping mechanism easier and more economical.
V=4.44fN╬жmтАЛ тАФ The induced EMF equation showing direct proportionality between voltage V and turns N
VsтАЛVpтАЛтАЛ=NsтАЛNpтАЛтАЛ тАФ The transformation ratio showing how tapping the winding affects output voltage
The transformer turn ratio is given by K=V2тАЛV1тАЛтАЛ=N2тАЛN1тАЛтАЛ. By changing the number of active turns N in the HV winding via a tap changer, the induced EMF per turn remains constant while the terminal voltage is adjusted. Since current I is inversely proportional to N for a constant MVA rating, the HV side handles lower current, reducing the arcing risk during switching operations and allowing for physically smaller tap-changing contacts.
HV windings are located on the outer side of the core, facilitating easier access to tap connections.
Lower current levels at the HV side reduce the mechanical stress and electrical arcing on tap changer contacts.
Taps are placed near the neutral end of the star-connected HV winding to minimize insulation requirements.
Lower current ratings for tap changer switches.
Reduced size and cost of the tapping gear.
Easier accessibility for maintenance on the outer winding.
Increased complexity in HV winding insulation if taps are not placed near the neutral.
Need for precise synchronization during on-load tap changing to prevent short-circuiting turns.
Grid voltage regulation in power transmission.
Maintaining constant secondary voltage despite load variations in distribution substations.
Placing taps on the LV side would require a much more robust mechanism to handle high current ratings, leading to rapid contact erosion.
If taps were placed on the LV winding, the bulky mechanical structure would significantly increase the size and footprint of the transformer tank.
C is correct тАФ Tappings are provided on the high voltage winding because it carries lower current and has more turns, making the tap changer design efficient and compact.
Always remember: HV winding = Higher Turns = Lower Current. This rule of thumb helps justify why protection devices and tap changers are usually placed on the HV side.