A positive integer m is created so that its digit sum is 900 and when m is doubled, its digit sum does not change. The digits of m include at least one of each of 3, 4, 5, and 6, and no other digits. Let m+ be the maximum such value of m, let m− be the minimum such value of m, and let P be the result of m+ × m−. Determine the number of digits of P .

explain how a capacitor stores energy as an electrostatic charge. also draw a couple pictures

A 20MVA, 11kV/132 kV, star-delta transformer is being protected by a biased differential protection
system. The transformer is supplied from 132 kV grids and on full load operation. Determine the
suitable CTs ratio at both side of the transformer if current at restraints coil is rated at 5 A. (CT ratios
available: 100/5A, 300/5A, 600/5A, 800/5A, 900/5A, 1000/5A, 1500/5A, 2000/5A, 3000/5A) If
lightning strikes at the secondary of the transformer which injecting IL=10kA to the system;

(i) Determine the primary current, Ip and secondary current, Is for the 20MVA transformer at the CTs’
output. Ignore the impedance of the cables.
(ii) Determine the average restraint current and operating current in the relay.
(iii) The bias characteristic of the relay is y = mx + c where y is the operating current, x is the
average restraint current and m is slope. Draw a neat sketch of the characteristic curve of this
relay if relay setting IS = 0.2A and percentage bias setting is set to 25%. Clearly mark the scales
used for both the x-axis and y-axis neatly on the sketch.
(iv) Mark the operating point of the relay due to this fault on the sketch. Will the relay operate? If
yes, give your explanation.

1. Design and implement a 4 bit binary to excess 3 code converter using CMOS transistors. (Note: Students are expected to design the circuit with truth table, solve the output expression by use of K Map or suitable circuit Reduction technique and implement using CMOS transistors.)

Several reports show the drawbacks and ineffectiveness operation of fuses and circuit breakers in the power lines. From your opinion, justify their potentials to protect equipment against voltage surges. Any disagreement shall be presented in relevant facts

Give the energy band description of conductor, semiconductor and insulator. Why are the valence electrons so important in the materials?

Plate values of a three-phase transformer are given below:
1600 kVA, 15 kV / 0,4 kV, 50 Hz, i0 = 1.2%; ukN= 6%, idle losses 2450 W, rated power copper losses 14500 W; Dy5 connected..

Calculate the secondary VOLTAGE separately at 75% load in the power factor with 0.85 inductance and 0.85 capacity. Compare and interpret the results. At what times of the day can capacity loading be seen? What solution should be applied to prevent voltage change?

Question 5
b) Determine the value of the current I1,I2,I3 and I4 indicated on the diagram below;
CR[10marks]
c) A capacitor C is connected in series with a 40 Ω resistor across a supply of frequency 60 Hz. A current of 3A flows and the circuit impedance is 50 Ω, Calculate: (i) the value of capacitance, C, (ii) the supply voltage, (iii) the phase angle between the supply voltage and current, (iv) the p.d. across the resistor, (v) the p.d. across the capacitor.

In Microcomputers, address 0X345E, what does the "X" mean? Similarly, address "0FFFFh", what does the "h" mean?

For a Double SideBand – Large Carrier (DSB-LC) Modulated Amplitude Modulator (AM) with a carrier frequency Fc = 1100kHz z and a maximum modulating signal frequency Fm (max) = 22kHz, determine:

a. Frequency limits for the lower side bands (LSB) and upper (USB).

b. Bandwidth

c. The equation for the AM signal if the carrier has a Vrma voltage of 6V and the modulating signal has a Vrma voltage of 1V. Consider the fm(max) transmission.

d. Lower (LSB) and upper (USB) side frequencies when the modulating signal is a 10kHz tone.

e. Draw the frequency spectrum when the modulating signal has a frequency of 20kHz and when it has a frequency of 10kHz.

1. What is the difference between resistive, reactive, and apparent power and why utilities companies care about power factor? Provide an example