A Δ -ΔT/F having rating 132KV/66KV, 50 MVA, the base impedance on primary side
The impedance of a Δ- Y 11000/400V 3-ΔT/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
take 6.6 KV, 20 MVA on G side, the pu impedance of line is
The sequence voltage of a 3φ system is given as
0.87 pu = Va1
-0.33 pu = Va0
-0.54 pu = Va2
What is the phase voltages on 11KV
Va = Va0 + Va1 + Va2 = 0
Vb = Va0 + α2Va1 + αVa2
= -0.33 + 1 ∠240 (0.87) + (1∠120) (-0.54)
= 1.232 ∠-97.69 KV
Vc = Va0 + αVal + α2Va2
= 1.317 ∠112.60 pu
Vb (KV) = Vb (pu) x KVbasd/pm
= 8.36 KV
Vc (KV) = 8.36 KV
An unsymmetrical fault on a transmission line gives the sequence voltage and sequence current
Va1 = 0.837 pu
Va2 = -0.45 pu
Va0 = -0.2 pu
and sequence current I1 = I2 = I0 = -j1.2 pu. What is the type of the fault.
As all the sequence current is
same, fault is LG.
What is fault impedance value on the base of 11KV, 20 MVA
|V1| = |V2| =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
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 X1 = 0.5, X2 = 2.0, X3 = 1.5 pu. If initially Pm0 = Peo = 1 pu then what is δcr made by rotor such that system is stable?
as pm is 1 pu, which is greater than
pmax3, even if fault is cleared,
mech. input will always be
higher. System will remain
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 2nd bus, Y22 new = ?
z22 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 zf = j0.1 pu. Pre-fault 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.
what is reactive power support required at bus 2.
As at load, no imaginary term is
given. This is active power only
as only active load is present a
capacitor must be installed to
get reactive power zero
so, θrequired = 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
Total no. of voltage controlled
= 20 + 10 + (9 - 1)
A transmission line of length 300 km operating at 50Hz, the receiving end voltage under no load VS = 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/S2
A transmission line has impedance (3 + j4) Ω/phase. The power factor of the load for maximum V.R.
For maximum V.R
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 Vs = 200 KV, VR at no load, and shunt reactor for compensating Ferranti-effect
In previous question, the charging current at no load is_____
A TL has zS = 400Ω is terminated with a cable with zL = 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
In above question, SIL after compensation is
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 (V1 + V2 + V3) is per phase voltage