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a)In a 3-phase 4-wire circuit, a circuit breaker is selected to protect the circuit whose highest fault level is 6.6 MVA. Determine the required minimum breaking capacity in kA. (Note: Covert 3-phase power in terms of kA to find answer.) b)Using the below, determine the required minimum making capacity in kA as a “peak value”. Rate breaking capacity (Icn) ka: Icn<= 1.5 Factor = 1.41 1.5
17561. A 380 / 220 V r.m.s. 3-phase 4-wire circuit carries loads of 8 + j8.1 ohm; 4 + j4.1 ohm; and 2 +j2.1 ohmin the three phases respectively. The length of the circuit is 100 m, and the resistivity of the phase conductors is 0.0005 Ω/m. The neutral conductor is of the same size as the phase conductors. a) Select a reference angle 0for the first phase. Then write down the three phase voltages in both polar format and complex number format. b) Make appropriate assumptions, and take temperature effects on resistance is insignificant. Calculate the currents in the three phases. (Note: Determine conductor resistance, and apply Kirchhoff’s Voltage Law) Based on the result, suggest a main switch rating for the circuit. c) Show your preferred direction of neutral current in a diagram, and then determine its value. (Note: Apply superposition principle, and Kirchhoff’s Current Law) Use its magnitude to show that in this circuit, the unbalanced load may increase the voltage drop in some of the phases. (Note: Also observe the common volt drip in neutral) State your assumptions, if there are any. d) Suddenly the neutral wire of the circuit is broken. Estimate the new currents in the first phase, i.e. Phase L1. State your assumptions, if there are any.
2131what is the most permissible winding temp when we conducting a generator load test?(condition no load)
1784how i define power factor when some one ask me ,,,,,what is power factor ,,,,,pleas define it simple. (pleas dont use these worlds ,,the difrence bitween apparent power and actual power is power facter )
1 2469i have 500 amp inductive load of motors ,,,pleas tell me how can i calculate for capacitor bank for improving my power factor to 99 .....calcullations for capacitor bank,,,,
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