City&e
Guilds
9209-502
Advanced Technician Diploma in Electrical and Electronic Engineering
ectrical and electronic engineering
Sample questions
You should have the
following for this assessment
A non-programmable scientific calculator
A pen with blue or black ink
Drawing instruments (full set)
A pencil
.Smith Chart paper
.Graph paper
The purpose of these sample
questions is to provide examples of the type of question that will be set,
giving an indication of the breadth and depth of knowledge that is expected. It should be noted that
these
are
sample questions and not a
The City and Guilds of London Institute 2015.
full
sample question paper.
1
Aseries RL circuit has a constant voltage V appled at t=0.
a) Express the time in terms of the circult components when v
=V
1002and L=2H, calculate the time in seconds when va =V1
c If V=12 v, find the time in seconds when v = 3v.
d) Both the values of the inductor and resistor are
changed to
whether these component changes make a difference to R=502and L 1H, evaluate
the prevlous values calculated.
b)If
R
=
2
For the series-parallel RLC circuit shown in Figure 1, determine the
a) equivalent circuit impedance model
b) supply voltage
c) circuit phase angle.
42
/3 2
2520 A
10 2
5
i20 2
Figure 1
2
3
a)
A 230
v,
50 Hz
single-phase supply feeds the following loads:
air
tnree
Compressors
with a total load current of 50 A at a
0.8
combined
power factor (P.F) o
fluorescent lamps drawing 64 A at a P.F. of
0.75
four 2.5 kVA motors all
at full load with a combined P.F. of 0.8
operating
a static capacitor.
Determine the
i) total current drawn by the
and motor feeds
i) overall P.F. for these feeds lamps
ii total power
dissipated by these feeds
iv) capacitor value to improve the overall P.F. to 0.95
lagging.
b) An RLC series circuit is energised then
and short circuited. Figure 2 shows three
de-energised
alternative current decays, explain in terms of one component value, the reason for each
response (1, 2 and 3).
Initial
offset
Figure 2
4 a) Two point charges of 1 Ceach and ofthe same sign are placed 1 mm apart in air.
i) Calculate the magnitude of the repulsive force.
i) Analyse the effect of this force in terms of the mass (weight) required to counteract this
repulsion.
b) Figure 3 shows two series-connected rectangular blocks of iron. The permeabilty of Block 1 is
A 500, and the permeability of Block 2is 4, = 2000,4,. Assuming that B is uniform
throughout each block, calculate, between the ends of the combined blocks, the total
i) reluctance
i) permeance.
50 mm
30 mm
Block 2
A
B
"H
200 mm
Block1
Vsomm
100 mm
Figure 3
i s the permeability offree space.
3
30 mm
5a) Maxwell'sequations in differential form are given in Table 1together with the application (case)
for both the H and E fields. Complete thetable by inserting the case or equation in the blank spaces.
Case
General
VxHJ+
Vx H =
VxH=
D
OD
(o
Steady
+joe)E
Static
General
VxE =
Vx E =
OB
OB
ot
VxE =-jwuH
Steady
Static
Table 1
b) With reference to Smith Charts,
identify
i) their general purpose
I) why normalised values are used
ii) the values plotted on a Z Smith chart
iv) the values plotted on a Y Smith chart.
A
c)Atransmission line of characteristic
resistance of
Z, (50+ j40)2 as per
Figure 4.
a
R =1002 is terminated in a load
Using Smith Chart,
determine the
=
i) VSWR
i) impedance
Z, at x =0.2A
ii) two shortest distances
where Z, is
Zx
6
non-reactive.
R
Figure 4
Figure 5 shows a symmetrical r-network with an input port
impedance Z, and the same load
impedanceZ,. Determine this characteristic impedance Z, when
Z = (10-120)
Z -8+ j6)
Z
V
Z2
V2
Zo
Input
Output
port
port
Figure 5
5
Zo
7 In the two-port network shown in Figure 6 the impedances are purely resistive, where
Z = R =6%2 and Z, = R, = 12k2.Determine the voltage gain in dB
a) with no load
b) when the load is Z, = R, = 40k2.
2
V2
Figure 6
6