問題一覧
1
For a sinosoidal wave of maximum value 30 amperes, what is the average valur over half cycle
19.09 A
2
The greatest value attained during one half of the cycle is called
peak value
3
Root mean square is also called
effective
4
Whar is the rms value of an AC current?
The steady current that produces the same rate of heating a resistor as the actual current
5
When the sole purpose of AC is to produce hear, the selection of conductor is based on the valye of the current
RMS
6
The value of the form factor for a pure sine wave is
1.11
7
The time domain equations representing the three generators are et=46 sin (377t + 56 deg) V, e2= 51 sin (377t + 76) and e3=96cos (377t-144)v, what is the resultant voltage
67 V
8
In a PURELY INDICTIVE circuit the current lags the voltage by ____
1/4 of the cycle
9
The impedance triange is similar to the ___ triangle with the resistance phasor in place of the ___
voltage, resistor voltage
10
A coil draws 0.5 from s 120V, 60Hz source at 70% lagging power factor, what are the coil resistance in ohms and inductance in H?
R= 168 and L=0.455
11
The currebt in a series cicuit of R= 10 ohm and L= 60mH lags the applied voltage vy 80 def. What is the source frequency in Hz?
150.4
12
An inductive load consisting of R and C in series feeding from 2.4KVsupply absorbs 288KW at a lagging power factor at 80%. Determine R and X.
R = 12.8 ohms & X= 9.6 ohms
13
A coil connected in series with resistanc draws 1A when supplied from a 240V, 60Hz source. The voltage across the coil and across the series resistance are both equal to 160V. Find the coil resistanc in ohms.
20 ohms
14
If the resistance in a series RC circuit is increased, the magnitude of the phase angle
decreases
15
A series RC circuit is connected to a capacitor and resistor having a voltage of 60V and 80V. What is the total voltage of the circuit?
100V
16
In a RLC Circuit, the source voltage is leafing the current at a given frequency f. If f is lowered slightlt, the circyut
decreases
17
What is the combined opposition to current by resistance and reactance
Z
18
The net reactance in a series RLC circuit is
XL -Xc
19
A coil of wire having a valuebof 10+j16 is connected in series with a cpacitance reactance Xc and this series combination is then connected in parallell with resistor R. If the equivalent impedance of the circuit is 8+j0 ohms. what us the value of Xc in ohms
16
20
What is the power id V and I are 90 degress out of phase
zero
21
The power factor or an induxtige circuit can be best improved by connecting a capacitors to it in
parallel
22
A singlenphase inductive load draws 10MW at 60% lagging power factor. Determine the reactive power of a capacitor in MVAR to be connected in parallel with the load to raise to the power factor to 85%? Troubleshoot 10MW to 60MW
43
23
The powe factor incandescent bulbbis
unity
24
Find the power factor of the impedance 5 angle -25 deg ohms
0.9063 leading
25
For an circuit, the power factor cannot be less than __ or greater than __\
0,1
26
Which of the ff AC device is used to measure the ANGLE BETWEEN THE VOLTAGE AND ITS CURRENT
phase angle meter
27
If the washing machine takes 311 watts and 4.5 W from 155V source when operating normally. Find the power factir (Troubleshoot 155V to 115V)
60%
28
A 20 microF capacitor and a parallel 200 ohms resistor draws 4A at 60Hz, fine the power consumption
0.98 - j 1.47kVA
29
in RLC Circuits, the impedance at resonance is
minimum
30
The current flowing in L and C at parallel resonant are ___
equal
31
An LC series circuit with an inductance L and a capacitor C has an oscillation frequency of f. Two inductors. each with inductanc L and two capacitors each with capacitance C. are all wired in series and the circuit is completed. The oscillation frequency is
f
32
A series circuit consist of a 20 ohm resistor, a 0.2 H inductor and a 50 micro farad capacitor. If a variable frequency 120V source us connected across its terminal, what is the resonan frequency in hertz?
50
33
In RLC resonance circuit, it has resistance if 100 ohms, lower half power frequency of 800 rad/sec and bandwidth of 80 rad/sec. What us the inductance L and capacitance C of the circuit.
1.25 H & 1.13 microF
34
To a series RLC circuit, a voltage or 10V is applied. If Q of the coul at resonance frequency is 20, the voltage across the inductor at resonan frequency will be
200V
35
A series connected circuit has R=4 and L=25mH. Calculate the value of C that will produce a qualitt power factor of 50z
0.625 microF
36
A capacitor is connected parallel to a coil of impedance 10+j80 ohms across 100 bolts 60hz source. What is the capacitanc eig the capacitor so that the resulting power factor is unity
28 microF
37
What is the rms value id complex current having fundamental, 3rd harmonic and 5tg harmonic rms components of 2.5A, 0.8A and 0.5A
2.67A
38
Find rhe averabf powe un a resistance R=10 ohms if the current in series form is I=10sin wt+5 sin 3wt + 2 sin 5Wt amperes
645W
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