Q2 (a) Define the meaning of the balanced supply in the three
phase system.
(b) Distinguish four (4) possible configuration of the
balanced three phase system.
(c) The line voltages applied across the life terminals of a
balanced four-wire system,
star connected load are 400 V. The load impedance consists of
a 4 Ω resistor that is
in series with an inductor while the power factor of the
system is equal to 0.75,
assume the phase sequence is RYB.
(i)...
A balanced three-phase delta-connected load is connected to a
balanced three-phase delta-connected source via a transmission
line. The line-line voltage for the source is 100∟0° V/phase and
the impedance of load is (27 + j18) Ω/phase. The transmission line
has an impedance of (1 + j4) Ω/line.
a) Draw the complete schematic of the power system showing the
location of wattmeters. (Two-Wattmeter system is considered for
this problem). Phase “a” could be considered as a reference
phase.
b) What must...
1. In a power system with negligible resistance, the three-phase
fault current at a point is 8 pu. The series reactance to be
inserted at the fault point to limit the short circuit current to 5
pu
2. A 3-phase, 15 MVA, 10 kV alternator has internal reactance of
6% and negligible resistance. Find the external reactance per phase
to be connected in series with the alternator so that steady
current on short circuit does not exceed 6 times the...
A 280-V, 3Ø AC power system, Y-connected three-phase generator
connected through a three-phase transmission line to a Y-connected
load. The transmission line has an impedance of (0.02+j0.4)
Ω/phase, and the load has an impedance of (4+j3) Ω per phase.
Determine the;(a)line current (IL) at the load [2Marks] (b)line and
phase voltage of the load[2 Marks](c)active power, reactive and
apparent power [2 Marks](d) power factor and specify whether it is
lagging or leading. [4 Marks]
A three-phase balanced star load No. 1 of (120 +j90) ohms in
parallel with another three-phase balanced star load No. 2 of (90
+j120) ohms, both are fed by three-phase balanced conductors of 3
ohms resistance and 4 ohms reactance. If the generator is 240
volts, with angle of -150° on phase c and reactance of 1 ohms,
determine: a) the current on load N°1 on phase C, b) the terminal
voltage of the generator on phase B, c) the...
1. a) Show the balanced half reactions and the total balanced
reaction for the following redox reaction in acidic solution.
RuO4 + H2SeO3 → Ru3+ + SeO42-
b) Comment on whether you expect this reaction to be
spontaneous. Show all of your work.b
2 (a) Use the Lattimer diagram for chlorine in basic conditions
to determine the potential for reduction of ClO4- to Cl2 .
(b) Write a balanced equation for this half reaction
Generally, a single-phase power is commonly found in domestic
households, whereas a three-phase power is preferable for larger
demands. For safety purpose, over-current protection components are
compulsory in the electrical distribution systems.
i. Explain two advantages of a three-phase system compared to a
single-phase system in the distribution system.
ii. Briefly describe the characteristic and the function of two
types over-current protection device installed in the distribution
board (DB) residential building.
iii. Miniature circuit breakers (MCB) with different current rating...
The total impedance of the circuit.
The voltage drop across the coil.
The total phase constant of the circuit.
Calculate the frequency band width.
Calculate the natural frequency.
An unbalanced three-phase wye-connected and grounded load is
connected to a balanced three-phase four-wire source. The load
impedances are Za = 14+j3 Ω , Zb = 5-j24Ω and Zc =1+j14
Ω and the phase a line voltage has an effective value of
18 Kv: use line-to-neutral voltage of phase A as a reference.
Find the line and neutral current, also find the reactive power
delivered to load and power factor.
Three balanced three-phase loads are connected in parallel. Load
1 is Y-connected with an impedance of 420+300i Ω/ϕ ; load 2 is
Δ-connected with an impedance of 2400-1780i Ω/ϕ ; and load 3 is
170.1+2201i kVA . The loads are fed from a distribution line with
an impedance of 2+17i Ω/ϕ . The magnitude of the line-to-neutral
voltage at the load end of the line is 23√3 kV.
Part A: Calculate the total complex power at the sending end of...