Barcelona 12-15 May 2003
Safety Limits for Touch Voltages
Transferred in LV Installations
HV safety limits applied in LV installations?
Yves Rajotte
(CA)
Session 2 – Block 1 – Question 3.1
1
Barcelona 12-15 May 2003
MV/LV Substation
LV Installation
Ground Potential
Profile
neutral
UtMV
UtLV
GPR
Distance
GPR and touch voltages transferred in LV
installations during a fault on the MV system
Yves Rajotte
(CA)
Session 2 – Block 1 – Question 3.1
2
Barcelona 12-15 May 2003
500
Ut (V/kA)
400
Typical fault currents:
1 - 5 kA
300
200
100
0
urban
rural
Touch voltages measured in LV installations during
a phase-to-neutral fault on overhead MV lines
Yves Rajotte
(CA)
Session 2 – Block 1 – Question 3.1
3
Barcelona 12-15 May 2003
Standards
LV installations (C22.1-1998)
• GPR and touch voltages neglected
• phase-to-ground voltages < 150 V
HV installations (IEC 61936, IEEE 80 Guide)
• Safety limits defined for touch voltages
• Same limits for transferred voltages in LV
installations
Yves Rajotte
(CA)
Session 2 – Block 1 – Question 3.1
4
Barcelona 12-15 May 2003
Conclusions
Today
• HV installations designed to comply with safety limits
• Transferred voltages in LV installations not investigated
Tomorrow
• More measurement data
• Standards offering a better guidance regarding
transferred voltages
Yves Rajotte
(CA)
Session 2 – Block 1 – Question 3.1
5