Floating Systems: Earth Faults & Detection

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Discussion Overview

The discussion revolves around the behavior of floating electrical systems with respect to Earth, particularly focusing on the implications of grounding, fault detection, and the effects of capacitance in such systems. Participants explore theoretical and practical aspects of electrical fundamentals, including the conditions under which a person might receive a shock when touching a conductor in a floating system.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that if a system is floating with infinite impedance, a grounded person touching a conductor would not experience a shock due to the absence of a return path through Earth.
  • Others argue that capacitive effects would allow some current to flow depending on the system's voltage and size, challenging the initial assumption of no current flow.
  • A participant requests clarification on the concept of capacity in electrical systems, leading to further elaboration on line-to-earth capacitance and its implications.
  • There is a discussion about the stability of unearthed systems, with some participants noting that they are too unstable for public distribution due to potential overvoltages and fault conditions.
  • Another participant introduces a formula for calculating fault current, emphasizing the relationship between phase-to-earth capacitance and voltage levels in a three-phase system.
  • Questions arise regarding the behavior of an ideal voltage source when measured against Earth, with varying interpretations of expected voltage readings under different conditions.

Areas of Agreement / Disagreement

Participants express differing views on the implications of floating systems and the role of capacitance, indicating that multiple competing perspectives remain. The discussion does not reach a consensus on the initial question regarding shock potential or the necessity of grounding.

Contextual Notes

Participants highlight limitations in understanding related to the definitions of grounding and floating systems, as well as the assumptions made about ideal conditions versus real-world applications. The discussion also reflects varying levels of familiarity with electrical theory and practical implications.

Who May Find This Useful

This discussion may be of interest to electrical engineers, students studying electrical systems, and professionals involved in power distribution and safety protocols.

  • #31
Averagesupernova said:
I always like your boring anecdotes Jim.
Ditto
 
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  • #32
You can make the same with 3 Ph AC -- resistors and light bulbs. Still used today in older factories with 3 Ph ungrounded or high impedance grounded systems.
 

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