STUPIDSID
1(a)
Find equivalent resistance across the terminal AB.
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3 M
1(b)
Find load resistance which dissipate maximum power.
3 M
1(c)
Find the rms value of a sinusoidal waveform.
3 M
1(d)
Draw resonance graph and write any four conditions of series reasonance.
3 M
1(e)
Write equations for three phase active power ans reactive power along with its units.
2 M
1(f)
Derive the conditions for maximum efficiency of a single phase transformer.
4 M
1(g)
Draw the input and output voltage waveform of a half wave rectifier.
2 M
2(a)
Using Mesh analysis find current through 2Ω resistor.
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6 M
2(b)
The impedances (12) Ω and (10-j20) Ω are connected in parallel and current through 12Ωis 10<0. Determine current through other branch, total current and kVA, kVAR, kW and power factor of the whole circuit.
8 M
2(c)
Draw phasor diagram of a single phase transformer connected to a inductive load.
6 M
3(a)
In a delta connected load each phase consists of a resistance of 100Ω in series with a capacitor of capacitance 31.8μF. When it is connected to a 400 V, three phase 50Hz supply calculate < br> i) the line current ii) Power factor iii) The power absorbed and iv) total kVA.
8 M
3(b)
A 50 kVA, 2200/220V, 50 Hz single phase transformer gave the following test results. Open circuit test(H.V side): 2200 V, 0.5A, 1000W
Short circuit test (H.V side): 100V, 20 A, 500 W
Determine i) Half load efficiency at 0.8 pf lagging and
ii) KV A at which maximum efficiency occurs and maximum efficieny at unity power factor
Short circuit test (H.V side): 100V, 20 A, 500 W
Determine i) Half load efficiency at 0.8 pf lagging and
ii) KV A at which maximum efficiency occurs and maximum efficieny at unity power factor
6 M
3(c)
With neat circuit diagram and characteristics explain the input and output characteristics of a CE transistor configuration.
4 M
3(d)
Draw the circuit diagram and output voltage waveform of a full wave bridge rectifier with capacitor filter.
2 M
4(a)
Find current through 10Ω using source transformation.
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7 M
4(b)
A balanced three phase star connected load has an impedance of 50<60Ω each phase connected across a three phase 1100 V, 50Hz supply. Two watt meters are used to measure power. Find the reading of each wattmeter.
4 M
4(c)
An alternating current of frequency 50 Hz has a maximum value of 12 A. Write down instantaneous current eauation. Find the value of current after 2.77 ms. Also find time taken to reach 9.6 A for the first time.
5 M
4(d)
Derive rectification efficiency and ripple factor of a full wave centre tapped rectifier.
4 M
5(a)
Calculate the current through 5Ω resistor using Thevenin's theorem.
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8 M
5(b)
For an RL circuit prove that average power over one complete cycle is Vrms Irms cosθ.
4 M
5(c)
A 12 kVA, 400/200 V single phase 50Hz transformer has maximum efficiency of 95% at 85% of full load at unity power factor. Determine the efficiency at full load at 0.8 power factor lagging.
8 M
6(a)
Find current through 9Ω resistor using superposition theorem.
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7 M
6(b)
A series RLC circuit has the following parameter values R=10Ω, L=0.01H, C=100μH. Compute the resonant frequency , Q factor of the circuit , band width, lower and upper cut off frequency.
7 M
6(c)
Prove that the power and power factor in a balanced three phase circuit can be calculated form the reading of two watt meters. Draw relevant connection and phasor diagram.
6 M
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