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| {{Menu_Protection_against_electric_shocks}}
| | #redirect [[Protection against fire due to earth faults#Protection with "Ground fault protection"]] |
| <br>
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| __TOC__
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| == Different type of ground fault protections ==
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| (see '''Fig. F27''')<br>
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| Three types of GFP are possible dependind on the measuring device installed :
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| *“Residual Sensing” RS
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| The “insulation fault” current is calculated using the vectorial sum of currents of current transformers secondaries. The current transformer on the neutral conductor is often outside the circuit-breaker.
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| *“Source Ground Return” SGR
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| The « insulation fault current » is measured in the neutral – earth link of the LV transformer. The current transformer is outside the circuit-breaker.
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| *“Zero Sequence” ZS
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| The « insulation fault » is directly measured at the secondary of the current transformer using the sum of currents in live conductors. This type of GFP is only used with low fault current values.
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| ----
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| <br>[[Image:FigF27.jpg|500px|left]]<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>'''''Fig. F27:'''''<i> Different types of ground fault protections</i>
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| ----
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| == Positioning GFP devices in the installation ==
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| {| cellspacing="1" cellpadding="1" border="1" style="width: 65%; height: 63px;"
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| |-
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| | valign="top" bgcolor="#0099cc" | '''Type / installation level'''
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| | valign="top" bgcolor="#0099cc" | '''Main-distribution'''
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| | valign="top" bgcolor="#0099cc" | '''Sub-distribution'''
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| | valign="top" bgcolor="#0099cc" | '''Comments'''
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| |-
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| | valign="top" | Source Ground Return (SGR)
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| | valign="top" | <math>\color{RoyalBlue}\Box</math>
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| | valign="top" |
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| | valign="top" | Used
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| |-
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| | Residual Sensing (RS) (SGR)
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| | <math>\color{RoyalBlue}\Box</math>
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| | <math>\color{RoyalBlue}\blacksquare</math>
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| | Often used
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| |-
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| | Zero Sequence (SGR)
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| | <math>\color{RoyalBlue}\Box</math>
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| | <math>\color{RoyalBlue}\blacksquare</math>
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| | Rarely used
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| |}
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| <math>\color{RoyalBlue}\Box</math> Possible<br><math>\color{RoyalBlue}\blacksquare</math> Recommended or required
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