Why is the current carrying capacity of cables higher in DC compared to AC__________?
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Answer: C. smaller dielectric loss
Explanation
Direct current systems maintain a steady voltage level, eliminating continuous capacitive charging currents that constantly flow through AC cables. Dielectric hysteresis losses caused by alternating electric field reversals are completely absent during continuous direct current cable power transmission operations. Reduced overall dielectric losses allow direct current cables to safely conduct significantly higher continuous operating currents without overheating. Dielectric hysteresis represents energy lost as heat within insulating materials due to the continuous realignment of molecular dipole moments. Capacitive charging current circulates continuously within AC power cables even when no external load is connected to the receiving end. Thermal limits of the surrounding insulation dictate the maximum permissible current carrying capacity for both alternating and direct current power cables.
Harmonics are primarily generated by non-linear loads connected to power systems rather than being an inherent property of direct current transmission. Power system stability limits depend heavily on generator synchronization and network configuration rather than the intrinsic current capacity of the cable. Ripple currents exist in rectified direct current systems, but they do not account for the fundamental reduction in baseline dielectric power losses.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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