BCIC-SAE- BUET 14.02.2025 Question Solution

BCIC-SAE- BUET 14.02.2025

Bangladesh Chemical Industries Corporation (BCIC)

Post: Sub-Assistant Engineer (ET) , Exam Date: 14.02.2025, Time: 60 minutes, Full Marks: 100 

Questions-01: A Generating Station has a connected load of 50MW and a maximum demand of 30MW; the units generated being 60x10^6 per anum. Calculate (i) The demand factor (ii) load factor [Similar to 3.2 Mehta]

Questions-02: An Unbalanced Y connected load has balanced voltage of 100V & the acb sequence. Calculate the neutral current. Taking Z_A =15 Ω, Z_B = 10+j5 Ω, Z_C =6-j8 Ω.

[Similar to 12.9 sadiku]

Solution: 

Here, Voltage Source is balance and acb sequence,

V_an =100 < 0°

V_cn = 100 ˂ -120°

V_bn = 100 ˂ -240° =100 ˂ +120°

Neutral line Current: I_n = -(Ia+I_b +I_C)

= – (6.67˂0° + 8.94 ˂ 93.44°+ 10˂- 66.87°)

= 10.06˂178.4° (Answer)

Questions-03: A 108 MHz carrier is frequency modulated by a 10 KHz sine wave with a frequency deviation of 50 KHz. Determine the modulation index,the highest and lowest instantaneous frequencies of the FM wave.  

Questions-04: a. Find the voltages V_ab and b. Calculate the source current I_s.

Solution: 

Questions-05: Draw a negative clamping Circuit, If the input is a rectangular wave, draw both the input & output waves.

Solution: 

Questions-06: The Voltage across a load is v(t) =50 cos (ωt-20°) V and the current through the element in the direction of the voltage drop is i(t) =

2 cos (ωt+70°) A.

Find the (a) real, reactive & apparent powers (b) power factor (c) load impedance (d) type of load.  [Similar to 11.11 sadiku]

Questions-07: A 400 V DC motor takes an armature current of 100 A when its speed is 1000 rpm.If the armature resistance is 0.25 ohm, calculate the torque  produced in Nm.