Problem: Consider a 20 kV network that supplies a HV/LV substation via a 2 km overhead line, and a 1 MVA generator that

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Problem: Consider a 20 kV network that supplies a HV/LV substation via a 2 km overhead line, and a 1 MVA generator that

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Problem Consider A 20 Kv Network That Supplies A Hv Lv Substation Via A 2 Km Overhead Line And A 1 Mva Generator That 1
Problem Consider A 20 Kv Network That Supplies A Hv Lv Substation Via A 2 Km Overhead Line And A 1 Mva Generator That 1 (61.05 KiB) Viewed 16 times
Problem Consider A 20 Kv Network That Supplies A Hv Lv Substation Via A 2 Km Overhead Line And A 1 Mva Generator That 2
Problem Consider A 20 Kv Network That Supplies A Hv Lv Substation Via A 2 Km Overhead Line And A 1 Mva Generator That 2 (49.12 KiB) Viewed 16 times
Problem: Consider a 20 kV network that supplies a HV/LV substation via a 2 km overhead line, and a 1 MVA generator that supplies in parallel the busbars of the same substation. Two 1,000 kVA parallel-connected transformers supply the LV busbars which in turn supply 20 outgoers to 20 motors, including the one supplying motor M. All motors are rated 50 kW, all connection cables are identical and all motors are running when the fault occurs. The Isc3 and ip values must be calculated at the various fault locations indicated in the network diagram (see Fig. 1), that is: . Point A on the HV busbars, with a negligible impedance . Point B on the LV busbars, at a distance of 10 meters from the transformers Point C on the busbars of an LV subdistribution board Point D at the terminals of motor M Then the reverse current of the motors must be calculated at C and B, then at D and A.

Upstream network U1 = 20 kV Ssc = 500 MVA Xpu =0.98 Zpu Overhead line 3 cables, 50 mm², copper length = 2 km x=0.3hom/Km Generator 1 MVA Xub= 15% 2 transformers 1,000 KVA secondary winding 237/410 V 5% Main LV switchboard 3 bars, 400 mm²/ph, copper length = 10 m Cable 1 3 single-core cables, 400 mm², aluminium, spaced, laid flat. length = 80 m LV sub-distribution board neglecting the length of the busbars Cable 2 3 single-core cables 35 mm², 3L copper 3-phase. length = 30 m Motor 50 kW (efficiency 0.9; cos - 0.8) x = 25% Note: Xcb1=0.15hom/Km:: Xcb2-0.09hom/Km 1. Determine the parameters of the impedance diagram of the network 2. Calculate the threes phase faults in all point in the network 3. Choose breakers A, C and B 4. Choose CTRA, CTRC, CTRB 5. In the power system in figure 1. three phase short circuit in point D 31 10 m 3L
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