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Problems 1. A factory in the Philippines has the following generator sets: Elements X X'd X"d Xo Voltage MVA Remarks % % % % G1 18.00% 10.00% 3.50% 240.00 0.300 G2 18.00% 10.00% 3.50% 240.00 0.300 G3 25.00% 14.00% 5.80% 240.00 0.625 Design and/or specify the grounding reactor for each generator. Line to ground Gen Voltage voltage Computed Eq. 1-Eq. Ohmic Reactance 5 Current Rating Use Sequence Network 2. Power Station in Riyadh One-line Diagram Remark Elements X X'd X"d Xo Voltage MVA s % % % % 25.40 12.70 6.50 GT1 -GT4 % % % 13,800 29.600 26.00 13.00 7.00 GT5 % % % 13,800 10.000 Transformers - will become load bus 0.40 SYN BUS Reactors 13,800 ohms Diesel generating sets are to be retired. REQUIREMENTS: If grounding reactors for gas turbine generators GT1 to GT5 will be used, find the appropriate reactances. Diesel generating sets are to be retired. 3. Following are loads of main distribution board (MDB): Load MDB is 3-phase, 3-w +N +gnd, 220/127 v. Ckt. Description DP-1 is 3-ph; No. DP-2 is connected at phase AN. 1 DP-1: 250 KW, 0.8 DP-3 is connected at phase BN. p.f lag ., 3-ph., 220 v DP-4 is connected at phase CN 2 DP-2: 50 KW, unity p.f , 1-phase, 127 v Capacitor is 3-ph DP-3: 250 KW, DP-5 is connected at phase BN 3 0.85 DP-6 is 3-ph p.f lag , 1-phase, 127 v DP-4: 200 KW, 4 0.80 p.f lag , 1-phase, 127 v Capacitor: 3-ph, 220 5 v Max KVAR: 125.00 DP-5: 225 KW, 6 0.80 p.f lag , 3-phase, 220 v Draw the vector diagram showing ,phase voltage & phase currents. Compute line currents, phase current, ground current. Specify the circuit breakers. 4. Describe and evaluate the existing grounding system in your work site. 5. Discuss LVCB which have several function, including those with ground fault protection.
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