Bangladesh Oil, Gas and Mineral Corporation (Petrobangla) || উপ-সহকারী প্রকৌশলী (SAE) (Power Technology) (07-06-2024) || 2024

All Written Question

Given,H= 

Given,

Tmax=100+273=373°K

Tmin=15+273=288°K

We know,

η=373-288373=22.78% (Ans)

Given

D = 15cm, L = 30cm

We know,

Vs=π×D24×L=π×1524=5301.48cc

Engine Capacity, = Vs×4=21205.5cc(Ans)

Given,

Ta=50 , Na=200rpm 

Tb=25 , b=?

Rotational Direction?

Tax Na=Tb × Nb

Nb =50×20025= 400 rpm (Ans)

Rotational Direction of Driven gear is to be anti-clock wise. (Ans)

Given,

ρ=1.78×10-8 Ωm

L = 1000m

A=0.07mm2

RAC = 1.5 RDC

RAC = ?

 

R= ρLA.R= 1.78×10-8×10000.07×10-6

R = 254.25 Ω

RAC 1.5 x 254.25 = 381.42 Ω (Ans)

Given,

φ= 3

P = 12Kw P. f = 0.6 lead

VL=208V

IL =?, Zp =?

cos θ = 0.6

θ=-35.13° (Lead)

Soln :  

P=3 VLILcos θ

12=3 ×0.208 ×IL×0.6

At star connection IL=Ip=55.51Amp

VP=VL3=2083=120V

Zp=VpIp=12055.51 =2.16 Amp

Zp=2.16 -35.13° (Ans)

Given,

Vp=1500V  ,  Vs=230V

Ap=5cm2 ,  ρ=16 Acm-2 

Np = 200 Nos

KVA =?, Ns =?, As =?

 

Sol:

We know,

VpVs=NpNs, Ns = 200 ×2301500= 30.66  31 Nos (Ans)

Ip=Ap×ρ=5×16=80 Amp

Ip =KVAVp 

KVA = 80 x 1.5 = 120 (Ans)

VpVs=IsIp, Is = 1500 ×80230= 521.73  31 Amp

Is = As x ρ

As= 521.7316=32.60 cm2 (Ans)