mirror of
https://github.com/idanoo/nzart-exam-generator.git
synced 2024-12-04 22:26:58 +00:00
150 lines
3.6 KiB
Plaintext
150 lines
3.6 KiB
Plaintext
% FILENAME = N22.TXT
|
|
% Regulated Power Supplies
|
|
% Release version 3, October 2001
|
|
% Q 4, 10 corrected 6 Mar 2012
|
|
|
|
%Question: 1
|
|
#22.1 The block marked 'Filter' in the diagram is to:
|
|
<img src = "regps.gif" align = center width = 511 height = 129>
|
|
<totallines = 13 >
|
|
|
|
filter RF radiation from the output of the power supply
|
|
|
|
smooth the rectified waveform from the rectifier
|
|
|
|
act as a 50 Hz tuned circuit
|
|
|
|
restore voltage variations
|
|
|
|
% ans 2
|
|
|
|
%Question: 2
|
|
#22.2 The block marked 'Regulator' in the diagram is to:
|
|
<img src = "regps.gif" align = center width = 511 height = 129>
|
|
<totallines = 13 >
|
|
|
|
regulate the incoming mains voltage to a constant value
|
|
|
|
ensure that the output voltage never exceeds a dangerous value
|
|
|
|
keep the incoming frequency constant at 50 Hz
|
|
|
|
keep the output voltage at a constant value
|
|
|
|
% ans 4
|
|
|
|
%Question: 3
|
|
#22.3 The block marked 'Transformer' in the diagram is to:
|
|
<img src = "regps.gif" align = center width = 511 height = 129>
|
|
<totallines = 13 >
|
|
|
|
transform the incoming mains AC voltage to a DC voltage
|
|
|
|
ensure that any RF radiation cannot get into the power supply
|
|
|
|
transform the mains AC voltage to a more convenient AC voltage
|
|
|
|
transform the mains AC waveform into a higher frequency waveform
|
|
|
|
% ans 3
|
|
|
|
%Question: 4
|
|
#22.4 The block marked 'Rectifier' in the diagram is to:
|
|
<img src = "regps.gif" align = center width = 511 height = 129>
|
|
<totallines = 13 >
|
|
|
|
turn the AC voltage from the transformer into a fluctuating DC voltage
|
|
|
|
rectify any waveform errors introduced by the transformer
|
|
|
|
turn the sinewave output of the rectifier into a square wave
|
|
|
|
smooth the DC waveform
|
|
|
|
% ans 1
|
|
|
|
%Question: 5
|
|
#22.5 The block marked 'Regulator' in the diagram could consist of:
|
|
<img src = "regps.gif" align = center width = 511 height = 129>
|
|
<totallines = 13 >
|
|
|
|
four silicon power diodes in a regulator configuration
|
|
|
|
two silicon power diodes and a centre-tapped transformer
|
|
|
|
a three-terminal regulator chip
|
|
|
|
a single silicon power diode connected as a half-wave rectifier
|
|
|
|
% ans 3
|
|
|
|
%Question: 6
|
|
#22.6 In the block marked regulator in the diagram below, a reversed diode may be present across the regulator. Its job is to
|
|
<img src = "regps.gif" align = center width = 511 height = 129>
|
|
<totallines = 15 >
|
|
|
|
Block negative voltages from appearing at the output
|
|
|
|
Blow a fuse if high voltages occur at the output
|
|
|
|
Blow a fuse if negative currents occur at the output
|
|
|
|
Bypass the regulator for higher voltage at its output compared to its input
|
|
|
|
% ans 4
|
|
|
|
%Question: 7
|
|
#22.7 A power supply is to power a solid-state transceiver. A suitable
|
|
over-voltage protection device is a:
|
|
|
|
crowbar across the regulator output
|
|
|
|
100 uF capacitor across the transformer output
|
|
|
|
fuse in parallel with the regulator output
|
|
|
|
zener diode in series with the regulator
|
|
|
|
% ans 1
|
|
|
|
%Question: 8
|
|
#22.8 In a regulated power supply, the 'crowbar' is a:
|
|
|
|
means to lever up the output voltage
|
|
|
|
circuit for testing mains fuses
|
|
|
|
last-ditch protection against failure of the regulator in the supply
|
|
|
|
convenient means to move such a heavy supply unit
|
|
|
|
% ans 3
|
|
|
|
%Question: 9
|
|
#22.9 In a regulated power supply, 'current limiting' is sometimes used to:
|
|
|
|
prevent transformer core saturation
|
|
|
|
protect the mains fuse
|
|
|
|
minimise short-circuit current passing through the regulator
|
|
|
|
eliminate earth-leakage effects
|
|
|
|
% ans 3
|
|
|
|
%Question: 10
|
|
#22.10 The purpose of a series pass transistor in a regulated power supply is
|
|
to:
|
|
|
|
suppress voltage spikes across the transformer secondary winding
|
|
|
|
work as a surge multiplier to speed up regulation
|
|
|
|
amplify output voltage errors to assist regulation
|
|
|
|
Allow for a higher current to be supplied than the regulator would otherwise allow
|
|
|
|
% ans 4
|
|
|