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A system configuration and an estimated current flow are
shown in Figure 2.4-1. At a lightning stroke, a switching
equipment ISM (I-interface subscriber module) on the second
floor, was damaged and its operation was halted. An ISM
equipment located on the first floor was not damaged. No
other equipment, aside from the ISM was damaged, and there
were no error messages except those of the ISM equipment. The
ISM on the second floor was connected to two power
equipments, D-SSF and F‑SSF.
The main power equipment is MR-48 on the ground floor, and
the potential reference is a dc+ point in the MR-48. The
current flowing through the ISM on the second floor followed
a large loop, as shown in Figure 2.4-1. It is assumed that
the equipment is easily affected by lightning.
Figure 2.4-1 – System configuration |
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