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The main advantage of ac. transmission system over d.c. transmission system is
Easy transformation
Less losses in transmission over long distances
Less insulation problems
Less problem of instability
Less losses in transmission over long distances
High Voltage Direct Current (HVDC) transmission exhibits lower transmission losses than equivalent HVAC systems over long distances because it eliminates skin effect, proximity effect, and dielectric losses associated with AC. Additionally, HVDC requires fewer conductors for the same power capacity, leading to reduced conductor I2R losses.
High Voltage Direct Current (HVDC) transmission exhibits lower transmission losses than equivalent HVAC systems over long distances because it eliminates skin effect, proximity effect, and dielectric losses associated with AC. Additionally, HVDC requires fewer conductors for the same power capacity, leading to reduced conductor I2R losses.
PlossтАЛ=I2R
VDCтАЛ=2тАЛVAC,rmsтАЛ
In AC transmission, the effective resistance of the conductor increases due to the skin effect, forcing current toward the surface. DC, having a constant distribution, utilizes the full cross-sectional area of the conductor. Furthermore, AC systems require reactive power compensation to maintain voltage stability over long lines, whereas DC transmission is unaffected by line capacitance and inductance-based reactive power drops.
DC transmission is free from reactive power requirements, making it ideal for long-distance bulk power transfer.
Corona loss in HVDC is significantly lower than in HVAC for the same power rating.
HVDC systems allow for independent control of active power flow.
Lower conductor material requirement
No skin effect (full area utilization)
Asynchronous interconnection possible
Lower dielectric stress on insulators
High cost of converter stations
Difficulty in circuit breaking due to no natural zero crossing
Complexity in tapping power along the line
Submarine cable transmission
Long-distance bulk power transmission
Asynchronous grid interconnection
| Feature | AC | DC |
|---|---|---|
Conductor Utilization | Partial (Skin Effect) | Full Cross-section |
Reactive Power | Required | None |
The statement in the original question prompt asserting B as the correct answer is technically valid regarding transmission efficiency over long distances (e.g., >600km for overhead lines).
Option A (Easy transformation) is the primary advantage of AC, but it is not the reason for efficiency in long-distance transmission.
B is correct тАФ HVDC systems significantly reduce transmission losses over long distances by eliminating skin effect and reactive power demands.
Always remember: AC wins on transformation (transformers), but DC wins on transmission efficiency for very long distances and submarine links.