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A Δ ΔT/F having rating 132KV/66KV, 50 MVA, the base impedance on primary side
The impedance of a Δ Y 11000/400V 3ΔT/F of capacity 100 KVA as on its name plate as z = (0.02 + j0.07) pu. The ohmic impedance in Ωreferred to primary (11000 V) side
The sequence voltage of a 3φ system is given as
0.87 pu = V_{a1}
0.33 pu = V_{a0}
0.54 pu = V_{a2}
What is the phase voltages on 11KV
V_{a} = V_{a0} + V_{a1} + V_{a2} = 0
V_{b} = V_{a0} + α^{2}V_{a1} + αV_{a2}
= 0.33 + 1 ∠240 (0.87) + (1∠120) (0.54)
= 1.232 ∠97.69 KV
V_{c} = V_{a0} + αV_{al} + α^{2}V_{a2}
= 1.317 ∠112.6^{0} pu
V_{a}(KV)= 0KV
V_{b} (KV) = V_{b} (pu) x KV_{basd/pm}
= 8.36 KV
V_{c} (KV) = 8.36 KV
An unsymmetrical fault on a transmission line gives the sequence voltage and sequence current
V_{a1} = 0.837 pu
V_{a2} = 0.45 pu
V_{a0} = 0.2 pu
and sequence current I_{1} = I_{2} = I_{0} = j1.2 pu. What is the type of the fault.
As all the sequence current is
same, fault is LG.
V_{1} = V_{2} =1pu , what is the maximum power flow in this Network.
= 55 pu
Notice that without capactior pr.
In which of the following condition the system is stable (ω is speed)
For stability, speed must never
be continuously increase or
decrease so
An alternator having E = 1.2 pu connected to ∞ bus through a power network. The transfer reactance between alternator and ∞ bus before fault, during fault, and after clearing fault are X_{1} = 0.5, X_{2 }= 2.0, X_{3} = 1.5 pu. If initially P_{m0} = P_{eo} = 1 pu then what is δ_{cr} made by rotor such that system is stable?
as p_{m} is 1 pu, which is greater than
p_{max3}, even if fault is cleared,
mech. input will always be
higher. System will remain
unstable.
A 50 bus system with 200 transmission line. How many zeroes are in Y bus matrix.
For a 3 bus network
a shunt capacitor of j0.5 is added at 2^{nd} bus, Y_{22} new = ?
z_{22} new = j15 + j2 = j13
A Network having postive, negative and zero sequence bus impedance matrix as
what is the LG fault current at bus 2 with z_{f} = j0.1 pu. Prefault voltage at bus 2 is 1.05 pu
A 3φ load of 50 MW, 0.6 pf, is operating at 33KV, what is capacitance per phase required by the capacitor bank connected in Δ to improve pf to 0.8 lag.
As at load, no imaginary term is
given. This is active power only
= 0.267
as only active load is present a
capacitor must be installed to
get reactive power zero
so, θ_{required} = 0.267
A Network containing 20 voltage controlled bus, 10 reactive power support bus, a generator bus, 5 fixed shunt capacitance bus, total voltage controlled bus is
Shunt capacity is not voltage
controlled bus,
Total no. of voltage controlled
bus
= 20 + 10 + (9  1)
= 38
A transmission line of length 300 km operating at 50Hz, the receiving end voltage under no load V_{S} = 1pu is
A transmission line of length 600km, has a phase shift in degree of
A generator having H = 6 MJ/MVA is connected to generator having H = 4 MJ/MVA. A fault reduce the pr. out put to 0.6 pu which was initially 1 pu. Find angular acceleration in elect degree/S^{2}
A transmission line has impedance (3 + j4) Ω/phase. The power factor of the load for maximum V.R.
For maximum V.R
= 0.6
A 3φ transmission line has ABCD parameters as A= 0.75 ∠0° = D, B = 100∠90°Ω, C = 0.5 x 10^{6} ∠90° ℧ operating at V_{s} = 200 KV, V_{R} at no load, and shunt reactor for compensating Ferrantieffect
In previous question, the charging current at no load is_____
A TL has z_{S} = 400Ω is terminated with a cable with z_{L} = 50Ω. A rectangular pulse of 100KV is travelling towards the cable. The transmitted volt will be
A 3φ transmission line having a surge impedance of 400Ω is operating at 400 KV line is compensated with 30% of shunt capacitor at the load end. The other end is connected to a generator which is delivering power at 200 MW. SIL of the above system is
= 400 MW
A TL supported by 3 insulation disc, the maximum voltage of each disc is 25 KV. Find the operating voltage per phase of the line given efficiency η = 78%
as (V_{1} + V_{2} + V_{3}) is per phase voltage
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