Chapter 6, Problem 6.72P

a) Determine the setting of the overload protection of the circuit breaker intended to protect a 50hp, 380V, IV-pole motor, powered by a unipolar copper-PVC conductor circuit, with a cross-section of 25mm², installed in a buried conduit: The short-circuit current at the motor terminal is 5KA. It is assumed that the overload current of the conductor throughout its useful life is controlled and will not exceed 100 hours for 12 consecutive months or 500 hours throughout the useful life of the conductor. Data: fp = 0.86; efficiency = 0.92 a) Determine the minimum operating time of the circuit breaker in the event of a short-circuit at the motor terminals.

Q1:A: Derive four elements only of diagonals Jacobian matrix of NR method in polar coordinate for a system consist of 4 buses, bus 1 is slack and the other three buses are PQ buses.

Pls show neat and whole solution