During Periodic Inspection and Testing, prospective fault current has been tested at the main distribution board (Main DB) using a single-phase test instrument.
The supply and installation form part of a 400 V three-phase TN-C-S system. The value of Zₛ (earth fault loop impedance) for this installation is 0.05 Ω.
Information about the protective devices installed at the remote distribution boards (DBs) is as follows:
Main DB: 3 phases, 10 kA
DB1: 3 phases, 7.5 kA
DB2: 3 phases, 7.5 kA
DB3: 1 phase, 7.5 kA
DB4: 1 phase, 6 kA
At which points in the installation must further testing be carried out?
a) DB1 and DB2
b) DB3 and DB4
c) DB1, DB2 and DB3
d) DB1, DB2 and DB4
Continue reading...
The supply and installation form part of a 400 V three-phase TN-C-S system. The value of Zₛ (earth fault loop impedance) for this installation is 0.05 Ω.
Information about the protective devices installed at the remote distribution boards (DBs) is as follows:
Main DB: 3 phases, 10 kA
DB1: 3 phases, 7.5 kA
DB2: 3 phases, 7.5 kA
DB3: 1 phase, 7.5 kA
DB4: 1 phase, 6 kA
At which points in the installation must further testing be carried out?
a) DB1 and DB2
b) DB3 and DB4
c) DB1, DB2 and DB3
d) DB1, DB2 and DB4
Continue reading...
