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The maximum permissible disconnection time is 0.4 s in TN system. Why and from where this value (0.4 s) is obtained?
Former Community Member
The maximum permissible disconnection time in in the event of a short circuit between a phase conductor and a body or protective conductor or a protective-neutral conductor is 0.4 s in TN system. Does anybody know this value (0.4 s) obtains from where? How this value is obtained?
Where R2 is the resistance of the CPC within the installation, if the installation is bonded - and is the whole resistance of the earth path if not bonded
That should illuminate admirably why bonding in a TT system is a jolly good idea
Regards
OMS
That's true of course but the OP wanted to know the origin of the 0.4s disconnection time. It probably also explains the 0.2s specified for the TT system. What remains for us to establish the is the origin of the 5s and 1s disconnection times.
Where R2 is the resistance of the CPC within the installation, if the installation is bonded - and is the whole resistance of the earth path if not bonded
That should illuminate admirably why bonding in a TT system is a jolly good idea
Regards
OMS
That's true of course but the OP wanted to know the origin of the 0.4s disconnection time. It probably also explains the 0.2s specified for the TT system. What remains for us to establish the is the origin of the 5s and 1s disconnection times.
