Discussion Overview
The discussion centers around the flow of current from high voltage power lines to Earth ground, exploring concepts such as voltage differences, resistance, capacitance, and the conditions under which current can flow. Participants examine theoretical and practical implications, including scenarios involving grounded and isolated power plants, as well as the behavior of birds near power lines.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
- Conceptual clarification
Main Points Raised
- One participant questions why current flows to ground when a conductor is placed between a high voltage wire and Earth, noting that Earth acts as a resistor.
- Another participant argues that while Earth has resistance, the high voltage (e.g., 100 kV) allows significant current to flow, even with a resistance of 10 kOhm.
- Some participants discuss the capacitance of Earth, suggesting that it can influence current flow even if the generator is isolated from ground.
- A participant presents a scenario comparing a discharging capacitor to a bird landing on a power line, questioning why current flows in one case but not the other.
- There is a discussion about the implications of AC versus DC current in relation to the capacitance of the bird and its interaction with the power line.
- Some participants mention that birds are rarely seen on high voltage lines, speculating on the reasons related to voltage gradients and current flow.
- One participant clarifies that when a bird lands on a wire, it does not get shocked because both feet are at the same voltage, thus no current flows through the bird.
- Another participant emphasizes that the resistance of the wire is negligible compared to the bird's resistance, affecting current flow dynamics.
Areas of Agreement / Disagreement
Participants express a range of views regarding the flow of current to ground, the role of capacitance, and the behavior of birds near power lines. There is no consensus on the exact mechanisms at play, particularly concerning the differences in current flow scenarios involving the bird and the capacitor.
Contextual Notes
Participants note that the resistance of Earth can vary based on factors like soil type and moisture content, which may influence current flow. Additionally, the discussion includes unresolved questions about the implications of capacitance and AC current in relation to the scenarios presented.