“150”, Aptitude Test Questions and Answers for Artisan II – Signal and Telecomm – TRC.
ABSTRACT
This aptitude test preparation material
contains 150 multiple-choice questions and answers for Artisan II – Signal and
Telecommunication (S&T), Tanzania Railways Corporation (TRC). It covers
railway signalling, telecommunications, electrical and electronic systems,
cable installation, fault diagnosis, maintenance procedures and occupational
safety. The questions use practical scenarios to assess technical knowledge,
problem-solving and safe working practices. Each question includes the correct
answer and an explanatory rationale to support effective revision and
examination preparation.
Prepared by Artisan II – Signal and
Telecomm – TRC.
Compiled by Artisan II – Signal and
Telecomm – TRC.
0628729934.
Date: September 30, 2026
Dear applicants,
This collection of questions and answers
has been prepared to help all of you to understand the key areas tested during
the interview. The goal is to provide a useful, and practical study guide so
you can all perform confidently and fairly in the selection process. I wish you
the best of luck, and may this resource support you in achieving success!
Warm regards,
Artisan II – Signal and Telecomm – TRC.
For Personal Use by Applicants Preparing
for Artisan II – Signal and Telecomm – TRC - at Public Service Recruitment
Service.
Artisan II –
Signal and Telecomm – TRC.
150 Aptitude
Test Questions and Answers
QUESTION 1
During routine
inspection of a railway signalling installation, an Artisan II observes that a
signal remains at STOP even after the route has apparently been requested. The
track circuit indicates that the section is clear, but the points indicator
does not confirm that the points have reached the required position. What
should the technician understand about this condition?
A. The signal
should clear because the track circuit confirms that the section is unoccupied. B.
The signal should remain at STOP because the required points position has not
been proved. C. The signal should clear after the points motor receives
another operating command. D. The signal should be treated as defective
because track occupancy is the only condition governing its operation.
Correct Answer: B
Rationale: Railway
signalling systems use interlocking principles to prevent unsafe train
movements. A signal authorising a train to proceed must not clear merely
because the track section is unoccupied; other essential conditions, including
the correct position and locking of relevant points, must also be proved. The
points indicator failing to confirm the required position means that the
interlocking cannot establish that the route is safely available. The signal
therefore remains at STOP until the fault is investigated and the required
conditions are safely established. Sending repeated commands or relying on
visual assumptions cannot replace the required electrical or mechanical proving
arrangements.
QUESTION 2
A technician is
inspecting an underground telecommunications cable connecting a railway station
to a control facility. A continuity test indicates that one conductor has no
electrical continuity between its two ends. The remaining conductors test
normally. Which fault is most directly indicated by this result?
A. An
open-circuit condition affecting the tested conductor. B. An insulation
breakdown between the tested conductor and earth. C. A short circuit between
the tested conductor and an adjacent conductor. D. An excessive resistance
caused by an incorrect supply frequency.
Correct Answer: A
Rationale: An
open-circuit fault occurs when the electrical path of a conductor is
interrupted, preventing current or a continuity-testing signal from passing
through the complete circuit. A damaged cable, disconnected terminal, broken
conductor or defective joint could produce this result. An insulation breakdown
would instead involve unwanted electrical leakage between conductors or between
a conductor and earth, while a short circuit would create an unintended
low-resistance connection. Since the other conductors test normally, the
evidence specifically identifies a discontinuity in the tested conductor rather
than establishing a general cable failure. Further sectional testing can help
locate the interruption.
QUESTION 3
At a railway
station, an S&T technician is testing a radio communication system. The
radio powers on normally, but the control operator reports that transmitted
messages are received intermittently, particularly when the train moves farther
from the station. What should the technician investigate first?
A. Whether the
radio battery has excessive charging current. B. Whether the microphone
circuit has reversed polarity. C. Whether the transmitter is operating at an
incorrect audio frequency. D. Whether the antenna, feeder connections and
radio coverage are functioning correctly.
Correct Answer: D
Rationale: Intermittent
communication that becomes more pronounced with increasing distance suggests a
possible radio-frequency transmission or reception problem. The antenna, feeder
cable, connectors, earthing arrangement and coverage conditions directly
influence the effective radio link. A damaged feeder or poorly connected
antenna can introduce signal losses, while unsuitable antenna positioning or
physical obstructions can reduce coverage. The fact that the radio powers on
normally establishes only that its power system is functioning sufficiently to
start the equipment; it does not prove that the radio-frequency path is
satisfactory. The technician should inspect and test the relevant components
using approved procedures before replacing the radio.
QUESTION 4
An Artisan II is
connecting a newly installed signalling component to a low-voltage supply.
Before making the connection, the technician identifies that the circuit is
still energised. Which action represents the correct electrical safety
practice?
A. Complete the
connection using insulated pliers while avoiding direct contact with terminals. B.
Switch off the equipment locally and immediately begin connecting the
conductors. C. Isolate the supply, secure against unintended re-energisation
and verify the absence of voltage using a suitable tester. D. Disconnect the
neutral conductor first and use the equipment casing to determine whether the
circuit is live.
Correct Answer: C
Rationale:
Electrical work involving connections should be performed under an appropriate
safe-isolation procedure. This involves identifying the correct supply,
isolating it, preventing unintended re-energisation through suitable locking or
control measures, and verifying that the relevant conductors are de-energised
using an appropriate voltage tester. The tester should itself be checked in
accordance with the applicable procedure to establish that it is functioning
correctly. Switching off equipment locally may not isolate every possible
source of electrical energy, particularly where alternative supplies or
backfeeds exist. Insulated tools provide an additional protective measure but
do not make live working an acceptable substitute for proper isolation.
QUESTION 5
A railway
station's signalling technician discovers that a track circuit intermittently
indicates OCCUPIED when no train is present. The indication changes after heavy
rainfall. Which explanation should receive particular attention during the
investigation?
A. The signalling
lamp has developed an incorrect colour temperature. B. Moisture may be
affecting cable insulation, connections or track circuit components. C. The
points motor is consuming less current than its normal operating value. D. The
station radio transmitter is producing excessive audio output.
Correct Answer: B
Rationale: A
track circuit depends on electrical conditions within a defined track section
to determine whether a train is present. Rainfall-related intermittent
occupancy can indicate moisture ingress affecting insulation, cable joints,
terminal boxes, connections or associated track circuit equipment. Moisture may
create leakage paths or alter electrical characteristics sufficiently to
interfere with reliable detection. However, the observation does not
conclusively identify the exact defective component; proper measurements and
systematic testing are necessary. The section must continue to be treated
according to the signalling system's safe operating rules until its condition
is established. A technician must never declare a track section clear solely
because no train is visible.
QUESTION 6
A technician
measures the voltage across the primary winding of a transformer and obtains
the expected supply voltage. However, the secondary output is significantly
below its specified value while the connected equipment is drawing an unusually
high current. Which condition should be investigated?
A. An open
primary winding that prevents magnetic flux from being produced. B. A reversed
polarity marking on the transformer casing. C. An excessive frequency in the
secondary circuit caused by the load. D. An overload or possible fault in the
secondary circuit.
Correct Answer: D
Rationale: A
transformer transfers electrical energy between windings through
electromagnetic induction. When its primary supply is normal but the secondary
voltage falls significantly under load while current is unusually high, an
overload or fault in the secondary circuit should be investigated. Excessive
load current can produce voltage drops associated with the transformer's
internal impedance and may activate protective devices. A short circuit or
defective connected equipment could also produce an abnormal current demand.
The technician should compare measured values with equipment ratings, examine
the secondary load and follow safe isolation procedures before conducting
resistance or insulation tests. The available readings alone do not justify
assuming that the transformer itself is defective.
QUESTION 7
A railway station
uses a battery-backed DC supply for its signalling equipment. During
inspection, the technician finds that the battery voltage is normal when the
charger is connected but falls significantly when the charger is isolated and
the equipment remains supplied by the battery. What should be investigated?
A. Whether the
battery has lost capacity or contains a defective cell. B. Whether the
signalling lamps are producing excessive light. C. Whether the track circuit
has changed its operating frequency. D. Whether the station telephone exchange
has incorrect numbering.
Correct Answer: A
Rationale: A
battery may show an apparently normal voltage while connected to a charger even
when its ability to supply the required load has deteriorated. A significant
voltage drop when the charger is isolated may indicate reduced battery
capacity, a defective cell, poor connections or another battery-system fault.
The technician should assess the battery condition using the manufacturer's
specified testing procedure and check the connections and charging system. The
battery should not be assumed serviceable solely because its voltage appears
normal while the charger is operating.
QUESTION 8
During
maintenance of a railway station's internal communication system, a technician
discovers that a telephone handset produces a clear dial tone, but the person
at the other end cannot hear the caller. The receiving party can, however,
communicate normally in the opposite direction. Which part of the system should
be investigated first?
A. The incoming
telephone line from the exchange to the handset. B. The telephone exchange's
main power supply frequency. C. The transmitting microphone circuit or its
associated connections. D. The loudspeaker circuit responsible for generating
the dial tone.
Correct Answer: C
Rationale: A
telephone communication circuit supports transmission in both directions, and
the reported condition indicates that the receiving function works while the
transmitting function may be defective. If the person at the other end can hear
normally but cannot hear the caller, the microphone, its wiring, associated
contacts or the relevant transmitting circuit should be investigated. A clear
dial tone indicates that at least part of the telephone's receiving and line
connection arrangements is functioning, but it does not establish that the
microphone circuit is operational. The technician should test the handset and
its connections systematically to distinguish between a local microphone fault
and a transmission-path problem elsewhere in the system.
QUESTION 9
A technician is
using a digital multimeter to measure the voltage across a signalling equipment
power supply. The equipment is operating, and the technician needs to determine
whether the supply voltage is within its specified operating range. Which connection
method is appropriate?
A. Connect the
meter in series with the supply while selecting the resistance function. B.
Connect the meter in parallel across the relevant supply terminals using the
appropriate voltage range. C. Connect the meter in series with the load while
selecting the continuity function. D. Connect the meter across the supply
using the current function and the highest available range.
Correct Answer: B
Rationale: Voltage
is measured by connecting a voltmeter in parallel across the two points between
which the potential difference is required. A digital multimeter configured for
voltage measurement normally has a high input impedance, allowing it to measure
the potential difference without significantly loading the circuit. The correct
AC or DC setting and an appropriate measurement range must be selected
according to the supply being tested. Connecting the meter in current mode
directly across a voltage supply can create a short-circuit path and may damage
the instrument or cause injury. Resistance and continuity functions must also
not be used on energised circuits.
QUESTION 10
A railway
signalling cabinet contains two protective devices. One is designed to
interrupt a circuit when excessive current flows, while the other is used to
provide a means of manually connecting or disconnecting an electrical circuit.
Which statement correctly distinguishes their principal functions?
A. A circuit
breaker provides overcurrent protection, while an isolating switch provides
electrical separation for safe work under applicable procedures. B. An
isolating switch automatically detects short circuits, while a circuit breaker
provides only manual disconnection. C. Both devices provide identical
protection, but the circuit breaker operates at a lower supply voltage. D. A
circuit breaker controls signal indications, while an isolating switch
regulates transformer output voltage.
Correct Answer: A
Rationale: A
circuit breaker is a switching and protective device designed to interrupt
current under specified abnormal conditions, including certain overload and
short-circuit conditions. An isolating switch primarily provides a means of
separating an electrical circuit from its source so that safe maintenance
arrangements can be established. An ordinary isolator is not necessarily
designed to interrupt load or fault current, and the applicable equipment
ratings and switching procedures must be observed. Although both devices may
physically open or close an electrical path, their intended functions are
different. Correctly identifying these functions is important when carrying out
maintenance on signalling installations and other electrical equipment.
QUESTION 11
A railway radio
repeater is installed to extend communication coverage between a station and a
remote section of the railway. Users report that they can hear transmissions
from the control station, but their replies are not retransmitted to the other
side. Which component or function should be investigated first?
A. The mechanical
locking arrangement of the nearest points machine. B. The colour coding of the
station's internal telephone wiring. C. The insulation resistance of the
railway track circuit. D. The repeater's ability to receive and retransmit
signals on its configured channels
Correct Answer: D
Rationale: A
radio repeater receives a radio signal and retransmits it to extend
communication coverage. If one direction of communication works but replies are
not retransmitted, the technician should investigate the repeater's receiving
and transmitting functions, channel configuration, antenna connections and
relevant control settings. The observed symptom does not by itself identify
which component has failed, so systematic testing is required. Telephone
wiring, track circuit insulation and points locking are separate systems and do
not directly explain the reported repeater behaviour.
QUESTION 12
During cable
installation, an S&T technician finds that the cable route passes through a
section where excavation work is planned. The cable is not shown clearly on the
available site drawing. What should the technician do before excavation begins?
A. Allow
excavation to proceed because the cable is not clearly marked on the drawing. B.
Identify and verify the cable route using approved records and suitable
locating procedures, then ensure the relevant personnel are informed. C.
Disconnect the nearest signalling equipment and assume that all underground
cables in the area are isolated. D. Mark the route based only on the direction
in which the cable enters the equipment cabinet.
Correct Answer: B
Rationale: Underground
cable routes must be identified and verified before excavation because drawings
may be incomplete, outdated or insufficiently detailed. The technician should
consult available records and use approved cable-location procedures to
establish the route as accurately as possible. Relevant personnel must be
informed so that excavation can be planned with appropriate precautions.
Disconnecting nearby equipment does not establish the location or isolation
status of every underground cable, and the direction of entry into a cabinet is
not sufficient evidence of the cable's route. The work should proceed only
under the applicable safety and permit arrangements.
QUESTION 13
A technician is
inspecting a railway signalling circuit and finds that a relay contact has
visible pitting and signs of overheating. The relay still operates, but the
contact resistance is higher than the specified value. What is the most
appropriate response?
A. Continue using
the relay because the contact still changes position. B. Apply lubricant to
the contact surfaces without checking the manufacturer's instructions. C.
Report the abnormal condition and replace or service the relay in accordance
with the approved maintenance procedure. D. Increase the coil voltage so that
the contacts close with greater force.
Correct Answer: C
Rationale: Pitting,
overheating and excessive contact resistance can indicate deterioration of a
relay contact and may affect the reliability of the controlled circuit. The
fact that the relay still changes position does not establish that its contacts
are suitable for continued service. The technician should follow the approved
maintenance procedure and equipment specifications to determine whether the
relay requires replacement or authorised servicing. Increasing the coil voltage
or applying an unapproved substance may damage the relay or alter its operating
characteristics.
QUESTION 14
A technician is
examining an electronic communication board after discovering that a component
becomes unusually hot during normal operation. The board continues functioning,
but the temperature is higher than the equipment's specified limit. Which action
is most appropriate?
A. Increase the
supply voltage to improve the component's operating stability. B. Continue
operating the equipment because its communication function remains available. C.
Remove the component while the board remains energised to prevent further
heating. D. Investigate the abnormal heating by checking operating conditions,
loading, ventilation and possible component or circuit faults.
Correct Answer: D
Rationale: Excessive
component temperature may indicate abnormal current, incorrect supply
conditions, inadequate ventilation, excessive loading, deteriorated components
or another circuit-level fault. Continued operation simply because the board
remains functional can accelerate component deterioration and potentially lead
to equipment failure. Increasing the supply voltage would be inappropriate
without a verified technical basis, while removing components from an energised
board introduces electrical and equipment-damage risks. The technician should
follow the relevant maintenance procedure, isolate the equipment where
necessary, and perform appropriate diagnostic checks against the manufacturer's
specifications. The objective is to identify the cause of overheating rather
than merely restore temporary functionality.
QUESTION 15
An Artisan II is
assigned to install a new cable gland on a signalling equipment enclosure. The
selected gland fits the cable diameter but does not provide a secure seal
against the enclosure entry. What is the principal concern?
A. The gland may
fail to provide the required environmental protection and cable retention. B.
The gland will automatically increase the cable's electrical resistance. C.
The gland will change the operating frequency of the signalling circuit. D.
The gland will prevent the cable conductors from carrying direct current.
Correct Answer: A
Rationale: A
cable gland must be suitable for the cable and enclosure, provide the required
mechanical retention and maintain the specified level of environmental
protection. A gland that fits the cable diameter but does not seal correctly
may allow moisture, dust or other contaminants to enter the enclosure. It may
also fail to provide adequate strain relief, exposing cable terminations to
mechanical stress. The technician should select and install a gland appropriate
to the cable construction, enclosure entry and environmental requirements,
following the manufacturer's instructions.
QUESTION 16
An Artisan II is
testing a circuit breaker installed in a signalling equipment cabinet. The
breaker trips immediately after being reset, even when the connected equipment
has been disconnected from the normal operating load. Which conclusion is
technically most appropriate?
A. The breaker is
necessarily defective because a healthy breaker should never trip twice. B.
The supply voltage must be too low to operate the signalling equipment. C. A
persistent fault may exist in the supply-side wiring, breaker connection or
associated circuit, and further investigation is required. D. The breaker
should be replaced with one having a higher current rating without additional
testing.
Correct Answer: C
Rationale: A
circuit breaker that trips immediately after resetting indicates that an
abnormal electrical condition may still be present. If the normal load has been
disconnected, the investigation should consider faults in the remaining
connected wiring, the breaker itself, its terminals or other parts of the
circuit that remain energised. The observation does not prove that the breaker
is defective, because it may be correctly responding to a persistent short
circuit or other fault. Replacing it with a higher-rated device without
checking the circuit could compromise protection and create a serious hazard.
Proper isolation, inspection and testing are required to establish the cause.
QUESTION 17
A
telecommunications technician is installing a new digital communication link
between two railway facilities. The equipment at both ends is powered, but the
link indicator remains inactive. The technician confirms that the correct cable
type is being used. Which additional check should be prioritised?
A. Verify the
cable termination, connector pin arrangement and compatibility of the
transmitting and receiving interfaces. B. Increase the operating voltage of
both communication devices until the link indicator illuminates. C. Reverse
the power supply polarity at one end to change the data transmission direction. D.
Replace the radio antenna because digital communication links always require
external antennas.
Correct Answer: A
Rationale: A
digital communication link requires compatible interfaces and a correctly
established physical transmission path. Even where the correct cable category
or type has been selected, incorrect termination, connector pin assignment,
damaged conductors or incompatible interfaces may prevent communication. The
technician should verify the wiring arrangement against the equipment
documentation, inspect the connectors and conduct appropriate cable testing.
Increasing supply voltage or reversing power polarity is not a legitimate
method of establishing a data link and may damage equipment. An external radio
antenna is relevant to wireless communication systems, not to every wired
digital communication connection.
QUESTION 18
A railway
communication system uses optical fibre between two facilities. After a cable
joint is completed, the communication link remains unavailable even though the
equipment at both ends is powered. Which test would most directly help assess
whether excessive optical loss has been introduced along the fibre link?
A. Measuring the
DC resistance between the fibre and the cable armour. B. Measuring the
operating current of the station's points machine. C. Checking the insulation
resistance of the telephone handset microphone. D. Measuring optical power or
link loss using suitable fibre-optic test equipment.
Correct Answer: D
Rationale: Optical
fibre carries information as light, so electrical continuity or resistance
measurements cannot establish whether the optical transmission path has
acceptable performance. Measuring optical power or link loss with suitable
equipment can help identify excessive attenuation caused by poor splices, dirty
connectors, sharp bends or damaged fibre. The technician should use test
equipment appropriate to the fibre type and system, and compare the results
with the installation specifications. The powered state of the equipment at
both ends does not prove that the optical path is intact.
QUESTION 19
A technician is
installing a replacement signalling lamp. The new lamp has the same physical
dimensions as the original, but its rated voltage differs from the equipment
specification. What should the technician do?
A. Install it
because matching physical dimensions establish electrical compatibility. B.
Use the lamp only if its rated voltage and other relevant characteristics meet
the equipment specification. C. Connect it in series with another lamp to
compensate for the voltage difference without further assessment. D. Increase
the supply voltage until the replacement lamp produces the same brightness as
the original.
Correct Answer: B
Rationale: Physical
compatibility does not establish electrical suitability. A replacement
signalling lamp must meet the specified voltage, power, type and other relevant
operating requirements for the equipment. Using a lamp with an incorrect rating
may cause abnormal operation, premature failure or damage to associated
components. Connecting it in series with another lamp or increasing the supply
voltage without an approved design basis may introduce additional hazards and
unreliable performance. The technician should verify the replacement against
the equipment documentation before installation.
QUESTION 20
A railway station
experiences intermittent failure of its internal communication system.
Inspection reveals that several communication cables run parallel to a
high-current electrical supply cable over a considerable distance. The
communication cables show no visible physical damage. Which corrective
consideration is most technically relevant?
A. Reduce the
length of the communication cables by changing the telephone numbering system. B.
Increase the communication cable conductor size without assessing the
installation arrangement. C. Assess electromagnetic interference and cable
segregation, routing, shielding and earthing requirements. D. Disconnect the
protective earth from the communication equipment to prevent unwanted signals.
Correct Answer: C
Rationale: Communication
cables installed close to high-current electrical conductors may be affected by
electromagnetic coupling, particularly where the cables run parallel over long
distances. This can introduce interference into sensitive communication
circuits and produce intermittent performance even when no visible physical
damage exists. Appropriate cable segregation, routing, shielding and bonding
arrangements can help reduce electromagnetic interference, depending on the
system design. Increasing conductor size alone does not necessarily resolve
electromagnetic coupling, while disconnecting protective earth connections can
introduce dangerous electrical conditions and must not be used as an
interference-control method. The installation should be assessed against its
technical requirements.
QUESTION 21
A technician is
checking a railway signalling relay that is expected to change contact position
when its coil is energised. The relay coil receives its specified voltage, but
the expected output contact does not change state. Which fault area should be considered
most directly?
A. The mechanical
contact mechanism or relay assembly may be defective despite the correct coil
supply. B. The supply frequency must have increased beyond the signalling
system's operating frequency. C. The external cable insulation must have
developed an open circuit because the coil is energised. D. The transformer
primary winding must be short-circuited because the relay receives voltage.
Correct Answer: A
Rationale: A
relay converts an electrical input at its coil into a mechanical movement that
changes the state of its contacts. If the specified voltage is present at the
coil but the expected contact transition does not occur, possible causes
include a defective coil under load, a mechanically obstructed armature,
damaged contacts or an internal relay fault. The actual voltage should be
verified under the relevant operating conditions, and the relay should be
tested according to the approved procedure. Correct voltage at the coil makes
an upstream supply failure less immediately indicated, but does not by itself
prove that the coil can generate the necessary magnetic force. The contact
assembly and relay operation therefore require further examination.
QUESTION 22
An S&T
maintenance team needs to work beside a railway track where trains may continue
to operate on an adjacent line. Which precaution should be established before
work begins?
A. Begin work
immediately because the team is not physically on the operating line. B. Rely
on each worker to listen for approaching trains while carrying out the task. C.
Follow the authorised railway protection arrangements for the work location and
ensure the team understands the applicable warnings and limits. D. Place tools
near the rail so that workers can move them quickly if a train approaches.
Correct Answer: C
Rationale: Work
beside an operating railway line can expose personnel to moving trains, even
when the work is not directly on the line. The required protection arrangements
must be established through authorised railway procedures before work begins.
The team must understand the limits of the work area, the applicable warnings
and the actions required if conditions change. Listening for trains or relying
on workers to move tools at the last moment is not a substitute for formal
protection arrangements. The precise measures depend on the railway's approved
rules and the nature and location of the work.
QUESTION 23
A technician is
inspecting a railway signalling installation and finds that a cable termination
has been made using a conductor that is not fully inserted into its terminal.
The terminal screw appears tight, but part of the conductor insulation is
trapped beneath the clamping surface. What is the most likely concern?
A. The terminal
will provide additional protection against short circuits. B. The connection
will automatically provide better insulation because the conductor is partly
covered. C. The cable will transmit signals at a higher frequency. D. The
connection may have unreliable electrical contact and increased resistance.
Correct Answer: D
Rationale: A
conductor that is not correctly inserted into its terminal may not make
reliable contact with the intended clamping surface. Trapped insulation can
prevent proper metal-to-metal contact, potentially causing increased
resistance, heating or intermittent operation. A tight terminal screw does not
prove that the conductor has been correctly terminated. The technician should
isolate the relevant circuit and remake the termination in accordance with the
terminal manufacturer's instructions and the approved wiring practice, then
carry out the required checks before returning the equipment to service.
QUESTION 24
A technician is
assigned to replace a damaged cable connecting a railway signal control cabinet
to a field installation. The replacement cable contains several conductors with
different identification colours. Before disconnecting the existing cable, which
practice is most appropriate?
A. Identify and
document the existing conductor terminations against the approved circuit
diagram before isolation and replacement. B. Disconnect all conductors
simultaneously and identify their functions after the new cable has been
installed. C. Connect conductors according to colour alone because railway
signalling cables follow one universal colour arrangement. D. Retain the
original connections without recording them because cable identification is
unnecessary after continuity testing.
Correct Answer: A
Rationale: Correct
cable replacement requires maintaining the intended electrical connections and
ensuring that the replacement installation corresponds to the approved circuit
design. Conductor colours can assist identification, but they should not be
treated as a universal substitute for circuit diagrams, terminal references and
verified identification procedures. Before disturbing the existing
installation, the technician should document the relevant terminations,
establish the correct circuit identification and apply the required isolation
arrangements. Recording the original connections also helps prevent wiring
errors during reinstatement and supports subsequent testing. Incorrect
conductor termination in signalling circuits can produce unintended equipment
behaviour and may compromise railway safety.
QUESTION 25
A railway
station's communication equipment is supplied by a DC power unit. During
inspection, the technician observes that the equipment restarts intermittently
when several connected devices operate at the same time. The supply voltage is
stable when only one device is connected. Which investigation is most relevant?
A. Whether the
station's track circuit is detecting a train. B. Whether the railway points are
mechanically locked. C. Whether the communication cable has the correct colour
identification. D. Whether the connected devices collectively exceed the power
unit's rated capacity.
Correct Answer: D
Rationale: A DC
power unit may operate normally under a light load but experience voltage
instability or protective shutdown when the combined demand of connected
devices exceeds its capacity. The technician should compare the total load with
the power unit's rated output and check relevant current and voltage
measurements under operating conditions. The investigation should also consider
wiring losses, defective devices and the condition of the power unit. The
observed restart pattern suggests a load-related issue but does not, by itself,
prove that the supply unit is undersized.
QUESTION 26
A railway
signalling technician is investigating a track circuit that intermittently
fails to detect a train approaching a station. During inspection, the
technician discovers that the track circuit receiver is receiving a signal
level close to its operating threshold. Which condition could most directly
contribute to this situation?
A. Excessive
illumination from the station's external lighting installation. B. Incorrect
mechanical alignment of the railway station entrance gate. C. Reduced ballast
resistance allowing unwanted leakage current between the rails. D. Increased
operating pressure within the points machine hydraulic mechanism.
Correct Answer: C
Rationale: Track
circuit operation depends on maintaining appropriate electrical conditions
within the rails and associated detection equipment. Reduced ballast
resistance, particularly where ballast is wet or contaminated, can allow
unwanted leakage current between the rails. This leakage can reduce the
effective signal reaching the receiver and potentially interfere with reliable
train detection. The actual effect depends on the track circuit design,
operating frequency and available signal margins. A receiver operating close to
its threshold indicates that the installation requires investigation rather
than adjustment based solely on the observed indication. Ballast condition,
rail connections, insulation and equipment performance should be assessed using
the prescribed maintenance procedures.
QUESTION 27
A railway station
uses an optical fibre communication system. During inspection, a technician
needs to determine the approximate location of a break or severe fault along a
fibre cable without excavating the entire route. Which instrument is most
suitable for this task?
A. A digital
multimeter operating in continuity mode. B. An earth resistance tester. C. An
optical time-domain reflectometer (OTDR). D. A clamp meter configured for DC
current.
Correct Answer: C
Rationale: An
optical time-domain reflectometer sends optical pulses into a fibre and
analyses the light reflected or scattered back from points along the cable. It
can help identify the approximate distance to a break, connector event or other
significant loss, making it useful for locating faults along an installed fibre
route. A conventional multimeter cannot directly establish the location of an
optical fibre fault because the fibre transmits light rather than electrical
current. The technician should use an OTDR suitable for the fibre type and
interpret the trace according to the equipment manufacturer's guidance.
QUESTION 28
An Artisan II is
assigned to inspect a transformer supplying railway signalling equipment. The
transformer produces the specified secondary voltage when disconnected from the
load, but the voltage drops significantly when the equipment is connected. Which
measurement would provide the most useful additional information?
A. The physical
length of the transformer enclosure. B. The resistance of the railway signal
lamp filament while operating normally. C. The frequency of the station's
internal telephone ringing circuit. D. The secondary current under load
compared with the transformer's rated capacity.
Correct Answer: D
Rationale: A
transformer that produces the expected voltage without a load but experiences a
significant voltage reduction when connected to equipment may be subjected to
excessive loading or an abnormal secondary circuit condition. Measuring the
secondary current under operating conditions allows the technician to compare
the actual demand with the transformer's rated capacity. An excessive current
may indicate an overloaded circuit, defective equipment or a developing
short-circuit condition. The transformer’s internal impedance also contributes
to voltage regulation, meaning that some voltage variation under load is
normal. The measured values must therefore be evaluated against the
manufacturer's specifications rather than interpreting every voltage reduction
as evidence of transformer failure.
QUESTION 29
A railway
technician is testing a normally closed relay contact used in an auxiliary
signalling circuit. With the relay coil de-energised, the multimeter indicates
an open circuit across the contact terminals. Which interpretation is most
appropriate?
A. The contact is
operating correctly because normally closed contacts remain open when
de-energised. B. The contact condition differs from its expected normal state
and requires investigation. C. The relay coil must be receiving excessive
voltage despite being disconnected from the supply. D. The circuit has
automatically changed to a normally open configuration because of the testing
instrument.
Correct Answer: B
Rationale: A
normally closed relay contact is designed to provide electrical continuity when
its operating coil is de-energised, assuming the relay is functioning normally
and the contact is not otherwise affected by the circuit arrangement. An
open-circuit reading under these conditions indicates that the contact path may
be defective, contaminated, mechanically obstructed or incorrectly identified.
However, the technician should first verify the relay terminal identification,
measurement setup and whether other circuit connections are influencing the
reading. Relay contact terminology describes the contact's normal state when
the coil is not energised, rather than the state during normal equipment
operation. The result must therefore be investigated before concluding that the
relay requires replacement.
QUESTION 30
A railway
station's radio system uses a duplex arrangement that allows transmission and
reception through a shared antenna system. Following maintenance, users report
that the radio can transmit but cannot receive reliably. Which component should
be examined as part of the initial investigation?
A. The duplexer
and its associated connections. B. The points machine operating mechanism. C.
The track circuit ballast resistance. D. The station telephone extension
numbering arrangement.
Correct Answer: A
Rationale: A
duplexer allows a radio system to use a shared antenna arrangement for
transmitting and receiving while providing the required separation between the
two paths. A fault, incorrect connection or unsuitable adjustment within the
duplexer can interfere with reception or transmission. The technician should
inspect the duplexer, feeder connections and configuration using the approved
radio maintenance procedure. The symptom does not prove that the duplexer is
defective, but it is a relevant component to investigate in a shared-antenna
duplex system.
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