The mechanical effects of short-circuit currents in - Montefiore

5.2.2. A global Approach
For analyzing existing structures, RTE proposes a
two-step approach:
Step 1: Check using the local deterministic values of
the short-circuit current, the time constant and the
clearance time, taking the safety factors into account.
Step 2: Check using the probabilistic values of the
short-circuit current intensity, the voltage phases
having caused the fault, and possibly the wind
velocity concomitant with the occurrence of the fault
and the direction of the wind (in this case, the
prevailing wind may be taken as perpendicular to the
busbars).
Negative
verification
Verification by
probabilistic
approach
Calculation of
the risk of
collapse
Checking
against the local
deterministic
values, taking
the safety
factors into
account
Step 2
Positive
verification
End of the
verification
This type of approach has been developed below for
rigid busbar only.
5.2.3. A Calculation Method
Step 1
Given the choice of possible approaches, it is best to
take into account either the design situation which, if
well chosen, corresponds to a penalizing situation, or
a more detailed method, described in 5.2.3.1.4. This
section is not intended to define that situation
specifically for each company and according to local
particularities, but rather to outline the main steps in
an approach that may be broken down as follows:
80
Definition of the P.D.F. for the primary variables
Definition of the parameters characterizing the mechanical loads
Calculation of the mechanical loads distribution
Definition of the C.D.F. for the mechanical strength variables
Calculation of the risk of collapse as a function of Gamma 7.4
Definition of occurences of stress-generating faults
Definition of the number of loaded elements
Calculation of the failure recurrence time