2.4.
It necessary make note about Czech standards.2 the voltage which reasonably can occur the exposed
conductive parts shall not occur for longer time than the time given Table 4. The condition mentioned above is
introduced the ČSN 2000-4-41:1996.) Because impracticable determine the time duration such a
way, the maximum disconnecting time given for the used phase voltages supply system in
Table 5.2.4.2 (E.2.9
Fault loop and fault current TN-S system
.2 longer than 0,45 s.
Figure 5.3.4.2.FUNDAMENTAL RULES FOR PROTECTION AGAINST ELECTRIC SHOCK
44
b) The fault loop impedance ZS
(Figure 5.3.g.9) shall lower than the phase voltage divided the current ensuring
the automatic disconnection within the specified time:
c) The maximum disconnecting time
shall comply with Table 4. The value fault loop impedance shall low
that the short circuit current case failure would cause functioning protective device a
time shorter than that one prescribed table 5. the
voltage the exposed conductive part case fault system with phase voltage 230 V
may reasonably maximum duration this voltage shall not according Table
4
