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ABB
Placement Papers
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1) 1)in
a ckt. We r giving voltage of 50 Hz as well as 60. then what will
be the resultant frequency.
(a)less than 50 (b)more than 60(c)in between 50 & 60
(d)none
2) In
a ckt a single resistor is connected across a d.c. source, what will
be the effect on current in first resistor if we connect one
more resistance in parallel with earlier one....
Answer.. no change since it is a parallel combination.
3) why
we don,t like flashover in transmission line
(t-line)- (a ) it may create earth fault(b )it reduces the
life of insulator.....
4) total
no of strands in a acsr conductor is 81, then what is the no.
of conductor in its outer layer....(a)36 (b)18
(c)24.......Also read some more on acsr.
5) Two
questions based on p.u. calculation like , p.u. calculation is
given with respect to some old base and u have to calculate
it with reference to new base. (new
resistance/old)=(mva new /mva old)*(old voltage/new voltage)2.
6) which
table is referred for sag calculation-
(a)stringing chart......answer
7) in
a R-L ckt a ac voltage is applied , such that instantaneous power
is negative for 2ms, then what will be thE power factor.
(a) 9 deg, (b) 18 deg, (c) 36 Deg......
8) In
an incandescent lamp
(a) luminous intensity is more than non-luminous intensity
9) In
which motor no-load to full-load diff. is lowest
(a) series motor, (b) shunt motor, (c) Compound motor
Ans: (b)
10) In a
60Hz induction motor full load speed is 850 rpm then what is
the Synchronous speed. (a) 900 rpm, (b) 950 rpm, (c)
1600
rpm....................Ans: (a)
11)A
sync. Motor is running at synch. Speed, if al of sudden D.C.
excitation is removed, then
(a) it will rotate at slip speed, (b) it will stop, (c) it will
continue to rotate at sync. Speed
Ans: (a), because actually it will acts as Induction motor.
12) A
transmission line is designed for 50Hz, 440KV. If we want to
transfer power at 60Hz, 440 KV, then the power transfer
capability will
(a) decrease, (b) Increase, (c)None
Ans: (a) ...as P=( |Vt| |Ef| sin (delta))
/ X, where (delta) is torque
angle.
13) ncreased
rotor resistance in rotor ckt of induction motor is related
with
(a) high starting torque, (b) more speed variation,.....................
Ans: (a)
14) In the
formulae E = 4.44 f N Ô, Ô is
(a) Avg value, (b) Rms value, (c) Maximum value
15) Voltage
& current in a ckt is given by V= V1+j V2 and I= I1 +j I2, then
rms power is
16) Input
impedence of MOSFET is
(a) more than BJT........(Ans)
17) Conversion
of Binary number into Equivalent decimal No.
18) Megger
is used for the measurement of (a)Insulation resistance,
(b)
Conductor resistance.............Ans: (a)
19) Form
factor for sinusoidal as well as DC
20) Formulae
of Regulation (Vs- Vr)* 100/ Vr, then transmission line is
(a) short transmission line, (b) long, (c)
medium...................Ans: (a)
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