TMG G1492
FS2500 TRACK CIRCUIT TEST AND
INVESTIGATION GUIDELINE
Version 1.1
Issued December 2010
Owner:
Chief Engineer Signals and Control Systems
Approved
by:
Warwick Allison
Chief Engineer
Signals and Control Systems
Authorised
by:
Paul Szacsvay
Principal Engineer
Signalling Technology
Disclaimer
This document was prepared for use on the RailCorp Network only.
RailCorp makes no warranties, express or implied, that compliance with the contents of this document shall be
sufficient to ensure safe systems or work or operation. It is the document user’s sole responsibility to ensure that the
copy of the document it is viewing is the current version of the document as in use by RailCorp.
RailCorp accepts no liability whatsoever in relation to the use of this document by any party, and RailCorp excludes
any liability which arises in any manner by the use of this document.
Copyright
The information in this document is protected by Copyright and no part of this document may be reproduced, altered,
stored or transmitted by any person without the prior consent of RailCorp.
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Page 1 of 39
Engineering Procedure
Engineering Procedure
Signals
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Document control
Version
1.0
1.1
Date
January 2008
14 December 2010
Summary of change
Original Issue
Application of TMA 400 format
Summary of changes from previous version
Summary of change
© RailCorp
Issued December 2010
Section
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Page 2 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Contents
1
Introduction .............................................................................................................................4
2
Test & Failure Investigation Strategy....................................................................................4
3
3.1
3.2
3.3
Typical Problems ....................................................................................................................4
Faults with no significant change in recorded values ...............................................................4
Faults with a significant change in recorded values .................................................................5
Installation factors that can contribute to failures......................................................................5
3.3.1
General factors ..........................................................................................................5
3.3.2
FS2500 specific factors .............................................................................................6
4
Typical Symptoms ..................................................................................................................8
5
FS2500 Failure Investigation & Test Form 1 ........................................................................9
6
FS2500 Failure Investigation & Test Form 2 ......................................................................10
7
FS2500 Failure Investigation & Test Form 3 ......................................................................11
8
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12
8.13
8.14
8.15
8.16
Tests .......................................................................................................................................12
Test Equipment Requirements ...............................................................................................12
Power Supply Investigation and Test......................................................................................13
Transmitter Investigation and Test..........................................................................................15
Matching Transformer Investigation and Test.........................................................................17
Tuning Unit Investigation and Test .........................................................................................18
Tuning Unit Impedance Tests .................................................................................................20
End Tuning Unit Impedance Test ...........................................................................................21
Track Investigation and Test...................................................................................................22
DPU Investigation and Test ....................................................................................................25
Compensating Capacitors Investigation and Test ..................................................................27
Spark Gap Investigation and Test...........................................................................................28
Electrolysis bond Investigation and test..................................................................................29
Impedance Bond Investigation and Test.................................................................................30
Receiver Unit Investigation and Test ......................................................................................33
Receiver Lockup Investigation and Test .................................................................................36
8.15.1 Initial Receiver check...............................................................................................36
8.15.2 Receiver with contacts in the receiver power circuit................................................36
8.15.3 Receiver with contacts in the track relay circuit.......................................................36
8.15.4 Receiver fed from a TU............................................................................................36
8.15.5 Receiver fed from a DPU.........................................................................................37
8.15.6 Electrical noise.........................................................................................................37
Surge Protection Investigation and Tests ...............................................................................38
9
mV AC measurements in electrically noisy environments...............................................39
U
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Page 3 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
1
TMG G1492
Introduction
This document has been produced to improve performance in fault finding on the FS2500
Track Circuit.
This document details recommended practice for the testing and investigation of
No Cause Found (NCF) failures for FS2500 track circuits.
2
Test & Failure Investigation Strategy
Once a cause has not been able to be found for a failure then:
• All the investigations detailed on the I&T Form 1 must be completed. The tests
associated with the form are listed as Level 1 in the section detailing the tests.
• If the Rx Monitor voltage has changed by more than 80mV from last full test of the
track circuit, I&T Form 2 must be completed in addition to I&T Form 1. The tests
associated with the form are listed as Level 2 in the section detailing the tests.
Investigations of repeat No Cause Found failures (within 3 months of previous NCF
failure) and significant incidents must complete I&T Form 3. The tests associated with the
form are listed as Level 3 in the section detailing the tests.
Specific tests that are carried out during fault finding or when required by the Signal
Engineer or tester are listed as “As Requested”.
The information recorded on the forms is to be analysed by the Signal Electrician, and
Signal Engineer to determine further action required identifying and correcting the fault.
If no cause can be identified after 3 NCF failures with the same transmitter and receiver
in place then the transmitter and receiver are to be replaced as a pair and returned to the
repairer for a priority test to specifications. This is to determine that the modules are the
cause of the repeated no cause found failures or not.
3
Typical Problems
3.1
Faults with no significant change in recorded values
Cause
Test
Loose or poor connection
Covered in Level 1, 2, and 3 tests.
Tu - Loose back nuts for B/W
Covered in Level 1 test.
Rx - internal connections
Covered in Level 1 test.
Rx - Internal Drift
Covered by elimination of other causes.
Track stick
Covered in Level 1, and 3 test.
Track repeat relay, CBI, or
telemetry fault.
Tx - faulty output stage
Not covered. External to track circuit.
Tx - Frequency drift
Covered in Level 1 test. Excessive Tx DC current
draw.
Covered in Level 3 test
Tx - not recovering after passage
of train.
Tx - not recovering after power on.
Covered in Tx as requested tests.
Spark gap connection
Covered in Level 1 test.
© RailCorp
Issued December 2010
Covered in Tx as requested tests.
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RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
3.2
TMG G1492
Cause
Test
Traction imbalance
Covered in Level 1 test.
Impedance bond or electrolysis
bond
PSU - AC ripple
Covered in Level 1 test.
Covered in Level 3 test. PSU output ripple.
Track insulation defect
Covered in Level 1, 2, and 3 tests.
Rx - Lockup
Covered in Level 1 test.
Faults with a significant change in recorded values
Cause
Test
TU - connection
Covered in Level 1 tests.
TU - impedance change
Covered in Level 2 tests.
PSU - low output
Covered in Level 1 tests.
Tx - low output
Covered in Level 1 test.
Tx - faulty output stage
Covered in Level 1 test. Tx DC current draw.
Ballast condition
Covered in Level 1 tests.
Broken rail
Covered in Level 1 tests.
3.3
Installation factors that can contribute to failures
3.3.1
General factors
General installation factors that can contribute to no cause found failures are:
Factor
Modules recently put into
service.
Modules that have been inservice for more than 12 years.
Modules that are older than 20
years.
Long term heat stress.
Large day night temperature
swings.
Type of rail connections.
Stability of the track at or near
rail connections.
Track leads.
© RailCorp
Issued December 2010
Concern
Modules in service for less than 3 months may have
a defect that was not found in production or repair.
Modules continually in service for more than 12
years may start to have components that have
drifted or start to have internal connection problems.
Older modules are more likely to have components
that are subject to temperature and vibration effects.
Modules that have been operated for long periods
(>5 years) at high average temperatures will have
components that have deteriorated which can cause
intermittent faults or higher failure rate.
Modules that have been operated for long periods
(>5 years) with large (>20ºC) day night temperature
swings will have components that have internal
connection problems that can cause intermittent
faults.
Web welded connections are more stable and are
less likely to deteriorate or be the cause of
intermittent faults.
Vertical rail movement near track connections can
cause bolted connections to 'work loose'.
The leads from Tuning unit to rail should be held
together from Tuning unit to near rail by non-metallic
ties. A revised arrangement for securing track leads
to reduce damage due to track work was issued
during 2006.
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Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
Factor
Spark Gap connections
Power supply stability
Surge protection
Ballast condition and drainage
Impedance bond mounted
vertically
3.3.2
TMG G1492
Concern
Requirements for spark gap connections changed in
the late 1990's. Spark gap connections are only
required as per Electrical Specification EP 12 20 00
01 SP Bonding of Overhead wiring structures to
Rail.
Some areas have their normal power supply fed via
the railway 33kV network. The 33kV railway supply
is not regulated and this can affect PSU output
voltage.
Intermittent load changes (like train stop or points
operation) can cause output voltage of PSU to dip.
No surge protection, or poorly installed surge
protection will accelerate the deterioration of
modules and increase all types of module faults.
Installation of 120V bus MOV is particularly
important. Tuning units also require protection in
high lightning activity areas.
Poor ballast condition, ballast height above foot of
rail, and poor drainage can cause failures in wet
conditions, as the ballast resistance change
between wet and dry is too large for the normal track
adjustment to handle.
2000R type mounted vertically should have a rain
cover fitted. This is particularly important when two
vertically mounted bonds are connected with a solid
neutral bus bar.
FS2500 specific factors
Receiver version
Check Receiver version is V34.1 or later. The current version is 36.2. Version 34.1 was
introduced in June 2002.
Versions prior to V34.1 had a number of problems particularly in regard to power
disruption causing receiver lockups.
Prior to version V34.1 the brown out relay was sensitive to vibration. This was corrected
around year 2000. Earlier versions had an orange coloured brown out relay. A blue relay
is now used.
Since November 2003 (after V34.1) the brown out circuit has been adjusted and tested
for each receiver to achieve more consistent values.
Receivers originally used an electrolytic capacitor as C19, which was/is a significant
cause of receiver failure. Capacitor C19 has been changed to a polyester type since
November 2004. The polyester type capacitor has a longer life and better reliability.
Degradation of C19 in older receivers can cause intermittent lockups before a complete
failure.
Voltages of 1.2V or more on monitor point indicates the possibility of clipping the input
signal, which may produce frequency components that can lead to lock up of the receiver.
Therefore the monitor voltage must be less than 1.20V.
DPU Amp version
The DPU AMP Version should be QAJTC1 Issue 4.0 as a minimum. The earlier versions
did not have an isolated output.
© RailCorp
Issued December 2010
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Page 6 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
DPU
The DPU should have a later serial number than IC394 and Issue 3.0 or Issue 5.0 with an
R meaning it has been upgraded. This change was introduced in March 2004. Earlier
versions had a significantly higher failure rate.
TU version
Westinghouse changed the design of the Tu in September 2002 to improve the
effectiveness of the connections to eliminate Rx lockups or track failures due to Tu
connections. A retrofit kit is available from Westinghouse to improve the connection
method. Particular attention is required on the tightness of back nuts on Tx and Rx TUs
for the original connections.
Connection problems causing significant intermittent amplitude changes can cause the
Rx to lockup.
Tx
No significant known issues.
Relay Noise sensivity
Q relay noise can be a cause of FS2500 Receiver lockups. This is a likely cause if:
• The Receiver drives an un-snubbed track relay via a track stick circuit.
• Q relays are installed with-in 300mm of the Receiver.
• Input wiring from the track circuit cable terminals to the Receiver or DPU AMP is
longer than 5m and mixed in with Q relay circuit wiring.
Normal solutions are:
• Fit diode or RC snub to track relays with track stick circuits. The diode or RC snub
is to be mounted as close to the coil as practical and must be on the relay coil side
of any contacts.
and
• Have a design done to snub other relays as necessary. The design must snub all
relays (that need snubbing) mounted with-in 300mm of Receiver as a minimum.
or
• Fit a snap on ferrite choke around the input wires close to the Receiver terminals.
Snap on ferrite chokes like RS 260-6486 or Farnell 9640444 are appropriate.
© RailCorp
Issued December 2010
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Page 7 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
4
TMG G1492
Typical Symptoms
Symptom
Likely Causes
Slow to pick up after a train or
picked after 2nd train.
Tx - not recovering after passage of train, Tx - faulty
output stage, Rx, rail connection, track stick, train
stop, or PSU.
Tu, Traction imbalance, Spark gap, connection or
Rx.
Tu, Ballast condition, Tx, Rx, Power supply AC, or
DC, or un-intended rail connection (eg failed spark
gap).
People working in area, or Traction imbalance.
Dropped on the approach of a
train.
Drop and pick intermittently
without train present or nearby.
Drop again after picking up after
train had passed.
Drop and pick within 30 seconds
with no significant change in
Monitor voltage.
Drop and pick after 30 seconds.
Pick up of failed track on the
approach of a failed train.
DPU track not shunting for 1st
bogie
Failure after heavy rain
Rx lockup
© RailCorp
Issued December 2010
Tu, Traction imbalance, Spark gap, connection, Rx,
or People working in area. Tx frequency at limits.
Tu, connection (loose back nuts), Tx or Rx.
Defective Tu.
DPU Amp or Rx adjustment, and wheel rail contact
are potential causes.
Poor ballast
Water ingress to vertically mounted 2000R
impedance bond with internal fault. Impedance
bond will recover when it dries out.
Power supply disruption for Rx prior to V34.1.
Un-snubbed track relay with track stick circuit on
relay output.
Relay noise affecting the Rx.
Poor connections on Tu.
Interfering Traction harmonics picked up via a DPU.
The interfering traction harmonics are likely to have
been produced by a Millennium train.
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Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
5
TMG G1492
FS2500 Failure Investigation & Test Form 1
FS2500 Failure Investigation & Test Form 1
Track Name:
Inspection Date:
Location:
Failure Date(s):
Inspection By:
Time of Failure:
Track Frequency:
Hz
Track Length:
Metres
TRANSMITTER END
Failure Duration:
(Approx.)
Estimated temperature at time of failure:
RECEIVER END
PSU & Tx Connections Checked
PSU & Rx Connections Checked
PSU Input Voltage (Bx120/Nx120)
Vac
PSU Input Voltage (Bx120/Nx120)
Vac
PSU Output Voltage (B24/N24)
Tx Input Voltage (B24/N24)
Tx Input Current (B24 or N24)
Tx Power percentage
Tx Output Voltage (Loc. Track term.)
Tx Power Setting (Low is 1/2 on TU)
Vdc
PSU Output Voltage (B24/N24)
Has Track Stick
Relay voltage (Relay R1/R2)
Relay Output Voltage (R+/R-)
Drop Shunt
Rx Sensitivity Setting
Vdc
Last entry Monitor(Track History Card)
mVac
Receiver was locked up
Receiver lockup test OK
Rx Monitor(Track Unoccupied)
Rx Input Voltage (Loc. Track term.)
Rail to Rail Voltage (Rx end)
Vd Up Rail Conn. (Rx end)
Vd Dn Rail Conn. (Rx end)
Vd Up Rail Conn. (Rx end adj TU)
Vd Dn Rail Conn. (Rx end adj TU)
Yes/No
Vdc
mAdc
%
Vac
N or L
Vac
Rail to Rail Voltage (Tx end)
Vd Up Rail Conn. (Tx end)
Vd Dn Rail Conn. (Tx end)
Vd Up Rail Conn. (Tx end adj TU)
Vd Dn Rail Conn. (Tx end adj TU)
mVac
mVac
mVac
mVac
TU Connections checked OK
Record & Compare Track History Card
FAILED WITH TRAIN
Approaching
Departing
On Adjacent Line
In Vicinity
Not in Area
Unknown
Train Type was:
ADDITIONAL
CHECKS
Repeat Relays
Event Logs Reviewed
Telemetry/ CBI Reviewed
Work group(s) in area
Yes/No
Vdc
Vdc
ohm
Yes/No
mVac
Vac
Vac
mVac
mVac
mVac
mVac
TU Connections checked OK
DPU Checked OK
Record & Compare Track History Card
TRACK
P F G Ballast Condition
Track Inspected
Spark Gaps Checked OK
Impedance Bonds Checked
Impedance Bonds resonated
Traction Return Balanced on IB
Electrolysis bond checked and balanced
Equipment replaced in last 3 months:
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 9 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
6
TMG G1492
FS2500 Failure Investigation & Test Form 2
FS2500 Failure Inspection & Test Form 2 (Rx Monitor changed by more than 80mV from last full test.)
FS2500 Failure Investigation & Test Form 1 must also be filled out with this form.
Track Name:
Location:
Inspection By:
Inspection Date:
Failure Date(s):
FS2500 Failure I. & T. Form 1 Dated
TRANSMITTER END
RECEIVER END
TU Input Voltage (4/5 or 1/2)
TU Type
Vac
Tu or ETu
TU Output Voltage (1/2)
TU Type
Vac
Tu or ETu
TUNING UNIT (Track Under Test)
TX END SHUNT TEST AT TRACK FREQUENCY
Tx Rail volts
Vac
Tx Rail volts, 0R5 shunt
Amps
Shunt Vac
Rail Vac
Tx Voltage ratio
TUNING UNIT (Track Under Test)
TU IMPEDANCE TEST AT TRACK FREQUENCY
TU Voltage T1/T2
mVac
TU Current (T1 or T2)
Amps
mΩ
TU Impedance (Z Calculated)
TU IMPEDANCE AT ADJACENT TRACK FREQUENCY
TU Voltage T1/T2
mVac
TU Current (T1 or T2)
Amps
Z=TU(mV)
I(A)
mΩ
TU Impedance (Z Calculated)
TU IMPEDANCE TEST AT ADJACENT TRACK FREQ.
TU Voltage T1/T2
mVac
TU Current (T1 or T2)
Amps
Z=TU(mV)
I(A)
mΩ
TU Impedance (Z Calculated)
TUNING UNIT (Adjacent Track)
TU IMPEDANCE AT TEST TRACK FREQUENCY (Zero)
TU Voltage T1/T2
mVac
TU Current (T1 or T2)
Amps
Z=TU(mV)
I(A)
mΩ
TU Impedance (Z Calculated)
TUNING UNIT (Adjacent Track)
TU IMPEDANCE AT TEST TRACK FREQUENCY (Zero)
TU Voltage T1/T2
mVac
TU Current (T1 or T2)
Amps
Z=TU(mV)
I(A)
mΩ
TU Impedance (Z Calculated)
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Z=TU(mV)
Page 10 of 39
Version 1.1
I(A)
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
7
TMG G1492
FS2500 Failure Investigation & Test Form 3
Track Name:
Location:
Inspection By:
FS2500 Failure Inspection & Test Form 3 (Repeat Failure follow up)
Inspection Date:
Failure Date(s):
FS2500 Failure I. & T. Forms 1/ 2
TRANSMITTER END
Vd Bx120v fuse
RECEIVER END
mVac
Vd Bx120v fuse
mVac
Vd Nx120v Term.
mVac
Vd Nx120v Term.
mVac
Vd B24v fuse
mVdc
Vd B24v fuse
mVdc
Vd N24v Term.
mVdc
Vd N24v Term.
mVdc
PSU Output ripple
Vac
PSU Output ripple
Vac
Tx Frequency
Hertz
Vd Loc. Track Term
mVac
Zero feed test
mVac
mVac
Track Stick resistance
ohms
Vd Loc. Track Term
Shunt tested 0R15
Surge Protection Inspected
Surge Protection Inspected
3Y20 Arresters Tested
3Y20 Arresters Tested
Additional Tests
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 11 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
8
Tests
8.1
Test Equipment Requirements
Test Equipment
DMM (Digital Multi-Meter) General
DMM with fast min/max or peak min/max.
FSM (Frequency Selective Meter)
DC Tong Meter for Traction current
measurement
DC Tong Meter for general use
AC Tong Meter for general use
AC Current clamp
Rail current meter
General Requirements
Approved Test Equipment
Must have true RMS to > 3kHz
Frequency reading to 1 Hz.
Min/Max is 100mS response time.
As per the general Multimeter.
Fast Min/Max is faster than 5mS response time.
Centre frequencies of 1700hz, 2000Hz, 2300Hz,
2600Hz. Bandwidth < +/-0.5db at +/-30Hz, and >
60db rejection at +/-600Hz from centre frequency.
Fluke 8060, 179, 87, 187, 189
Continued use of Fluke 27 averaging meter with no freq, or fast
min/max facility is permitted. Comparison testing is to be carried out.
Fluke 187, 189. Fast min/max
Fluke 87V
Peak min/max
Selective Track Frequency Meter (STFM) or Track Circuit Filter
Adaptor (TFA) and DMM.
The TFA is not suitable for rejection ratio or TU impedance
measurements.
Accuracy of better than 1.5% of reading for
traction return. 0 to 2000A DC.
For conductor size 55mm diameter.
Resolution of better than 0.1A.
Resolution of better than 0.1A.
10Hz to 3kHz, 10mV/A, and 100mV/A.
Indication of rail current.
Resolution of 0.1A rail current at 1700Hz to
2600Hz.
Kyoritsu 2003, 2003A, 2009
Kyoritsu AC/DC Digital Clamp meters. 2003, 2003A, 2004, 2033
Kyoritsu 2033
Chauvin Arnoux 1000/1 A current clamp.
AMEC AC current probe SD661
Clancy meter: Calibrated at 50Hz. The Clancy meter tends to read
high at audio track circuit frequencies but does provide an indication
of comparative rail current.
RAS Coil: Output 1mV/A at 50Hz and about 1mV/A at 1700 2600Hz. Reads about 10-20% low at audio frequencies. The
readings are lower as the frequency increases. Used in conjunction
with a DMM. Must use a Fluke 189 or equivalent meter.
Using Hz button on multimeter can check the frequency of the
dominant rail current if the output of the RAS coil is high enough for
the meter.
Rail Current Meter: Output 1mV/A or 10mV/A. Used in conjunction
with a DMM.
CRO (Oscilloscope)
Arrestor Tester
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 12 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.2
TMG G1492
Power Supply Investigation and Test
Test
Test
Equipment
Test Point
Terminals
Readings
Checks
Action If Not
Compliant
Condemning
Visual and
Physical Checks
Hand tools
Visual
Inspect and check
all terminations
Terminations
effective and
secure
PSU Unit secure
Correct as
required
Loose or ineffective
connections.
PSU Input
Voltage
DMM on Vac
BX120 bus
AC voltage
110 – 132Vac
PSU Output
Voltage
DMM on Vdc
B24/N24
24Vdc – 27Vdc
PSU Output ripple
Voltage
DMM on Vac
B24/N24
< 0.1Vac
Fuse terminal
voltage drop.
DMM on Vac,
and Vdc
Bx120v fuse and
B24 fuse terminals.
<30mVac or
<30mVdc
Disconnect
terminal Voltage
Drop
DMM on Vac,
and Vdc
NX120 and N24
disconnect
terminals.
<5mVac or
<5mVdc
If voltage is <114V
Check the PSU
voltage tapping for
the voltage lower
than that read.
Supply voltage for
Tx and Rx.
See Note 1.
Power Supply
Ripple
Rxs are more
sensitive to
electrical noise
when PSU ripple is
high.
Test Required
Level 1, 2 and 3
Adjust input
voltage taps on
PSU.
Supply voltage
less than 108Vac.
Adjust or replace
power supply.
<22.5Vdc
>30.5Vdc
Level 1, 2 and 3
Track Circuit
History Card
Replace power
supply.
>0.2Vac
Level 3 –
Detailed
Investigation
Connections.
Clean and ReSecure or replace
fuse.
>60mVac or
>60mVdc
Connections.
Clean and ReSecure
>5mVac or
>5mVdc
Level 1, 2 and 3
Level 3 –
Detailed
Investigation
Level 3 –
Detailed
Investigation
Note 1: Most power supplies for this type of track circuit are not regulated. If the unregulated DC voltage is below 24 volts then check the 120 Vac voltage
on the PSU. The PSU DC voltage should be approximately 26 Vdc for the average 120Vac voltage for the location.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 13 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Power Supply Investigation and Test (Continued)
Test
VA loss
PSU output
voltage earth
balance
© RailCorp
Issued December 2010
Test
Equipment
Test Point
Terminals
Readings
Checks
Action If Not
Compliant
Condemning
DMM and AC,
DC current
tong.
Voltage at BX120,
and B24, AC
current input PSU,
DC current out of
PSU.
AC current
times voltage to
give VAinput
DC current
times by voltage
to give
VAoutput.
Va loss = VA input –
VA output.
Replace power
supply.
VA Loss more
than 50VA.
As Requested
Earth fault inside
modules or wiring
insulation.
Earth faults can
be caused by
internal faults in
Rx, or Tx.
Test surge
protectors.
Test insulation
resistance of
wiring.
Replace modules.
>2 Volts for either
B24 or N24 to
earth.
As Requested
DMM on Vdc
with 20k shunt.
B24, N24, and
earth bar.
< 0.5Volts from
B24, or N24 to
earth.
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Test Required
Page 14 of 39
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RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.3
TMG G1492
Transmitter Investigation and Test
Test
Test Equipment
Visual and
Physical Checks
Hand tools
Visual
Input Voltage
DMM on Vdc
Input Current
Output voltage
DC Tong meter
DMM on Vac
Test Point
Terminals
Readings
Checks
Action If Not
Compliant
Condemning
Test Required
Inspect and check
all terminations.
Terminations
effective and
secure
Check Mounting
and environment.
Roof leaking, and
vermin urine etc.
Correct as
required
Visible defects
Level 1, 2 and 3
B24/N24
24Vdc to 27Vdc
Test Power
Supply Unit
<22.5V or >30.5V
Level 1, 2 and 3
Wire to B24 or
N24
< 2.2 Amps.
Current
decreases with
power setting.
See Note 1
Increasing current
means an
increased load on
track or faulty
transmitter.
Replace
transmitter or find
cause of
excessive load.
Change
Transmitter
If above maximum
reading.
Level 1
Location Track
Terminals
2.6 to 13.0Vac
based on power
setting of 20 to
100%.
Dependant on
power setting.
Change
Transmitter or find
and correct any
fault loading the
track.
<2.3Vac,
>14.3Vac, or
more than +/-10%
based on power
setting.
TX Output cable
terminals
<5mVac
Clean and ReSecure
>5mVac
Location Track
Terminals
Base Frequency ±
2Hz.
Use Min/Max to
get Average if
unstable reading.
Level 1, 2 and 3
Track Circuit History
Card
DMM on vac
TX Output Terminal
Voltage Drop
See section 9 for
meter usage
details.
DMM on Vac, Hz
measuring output
of TFA, or STFM.
Transmitter
Frequency
Note 1:
© RailCorp
Issued December 2010
Drift in transmitter
components or loss
of modulation.
Nominally: 1699,
2002, 2299,
2602Hz.
Level 3 – Detailed
Investigation
Change Transmitter
Change
Transmitter
>Base
Frequency+6Hz
<Base
Frequency-6Hz
Level 3 – Detailed
Investigation
The DC current can fluctuate between upper and lower frequencies by up to 0.4A on normal power.
UNCONTROLLED WHEN PRINTED
Page 15 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Transmitter Investigation and Test (Continued)
Test Equipment
Test Point
Terminals
Readings
Checks
TX Output voltage
earth balance
DMM on Vac
Location Track
Terminals and
earth bar.
About 50% of
output voltage
from each leg to
earth.
Earth fault inside
modules or wiring
insulation.
Recovery after
shunt.
Shunt box on
short circuit.
Start-up at power
on.
-
Apply shunt at Tx
Tu for 10
seconds.
Pull N24 pin for
Tx, and restore
after 10 seconds.
Track relay drops
and picks due to
test.
Track relay drops
and picks due to
test.
Test
© RailCorp
Issued December 2010
Action If Not
Compliant
Test surge
protectors and
insulation
resistance of
wiring.
Replace modules.
Tx output voltage
recovers after
power limiting.
Replace Tx.
Tx starts working
at power on.
Replace Tx.
UNCONTROLLED WHEN PRINTED
Condemning
Test Required
One leg being
more than 75% of
output voltage to
earth.
As Requested
Track does not
pick within 3
seconds.
Track does not
pick within 3
seconds.
As Requested
As Requested
Page 16 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.4
TMG G1492
Matching Transformer Investigation and Test
Test
Test Equipment
Inspect for signs
of damage or
poor connections
Visual
Check voltage
ratio
DMM on Vac
VA Loss
FSM and AC
current clamp
Primary Current
DMM on Iac or
AC current Clamp
Note 1:
Test Point
Terminals
Checks
Action If Not
Compliant
Condemning
Connections
secure.
Repair/Replace
Visible defects
As Requested
Input terminals
and Output
terminals
Voltage ratio
matches the
transformer ratio
within +/- 20%
Operation of
transformer.
See Note 1.
Replace or find and
remove cause of
excessive load
current.
Voltage ratio
different from
Transformer
ratio by more
than
+/- 50%.
As Requested
Primary terminals
and secondary
terminals.
Primary current
times voltage to
give VA input
Secondary current
times by voltage
to give VA output.
VA loss =
VA input – VA
output
Replace
transformer.
VA Loss more
than 5VA.
As Requested
Typically <5A
Primary current
less than 50VA
transformer
rating.
Find and remove
cause of excessive
load current.
>5A
As Requested
Primary Terminal
Readings
Test Required
Matching transformers are used to compensate for longer distance cables from Tx to the Tu. They are not installed for the Rx end.
Matching transformers used in pairs are set to the same transformer ratio (normally 1:5 or 1:9), and have the primary connected to the
equipment.
Matching transformers used singly are normally set to 1:5 and have the primary connected to the Tx. The Tu connections are non-standard
when a single matching transformer is used. The Tu is connected to provide a similar transformer ratio as the matching transformer. This
means the Tx Tu connection is to 1/2 instead of 4/5.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 17 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.5
TMG G1492
Tuning Unit Investigation and Test
Readings
Checks
Action If Not
Compliant
Condemning
Test
Requirement
Terminations
effective and
secure
Current version or
modified Tu.
Correct as
required
Visible defect.
Level 1, 2 and 3
FSM and 0.5ohm
shunt
Apply a 0.5ohm
shunt at TX end
TU rail
connections.
Rail to Rail
voltage should be
halved.
If rail to rail
voltage is halved
then TX end
equipment and
connections are
okay.
Check TX end
equipment and
connections.
Rail to Rail
voltage less than
1/3 or greater than
2/3.
Level 2
Short Circuit Test
(Considered as a
track shunt rather
than Bridging or
Releasing)
A registered
jumper wire.
Apply jumper wire
across T1/T2 of
adjacent Tuning
unit at either TX
or RX end to
confirm TU.
Track voltages on
track circuit
should return to
track history card
values or better.
Track relay picks
up.
Replace adjacent
tuning unit
Rx end Rx short
circuit test
A registered
jumper wire.
Apply jumper wire
across 1/2 of Tu.
The Rx B/W.
T1/T2 voltage
should increase
by about 10%.
H/R connections
or open circuits in
Rx wiring or Rx.
Inspect receiver
circuit wiring and
connections.
Replace Rx.
Test
Test Equipment
Visual and
Physical Checks
Hand tools
Visual
TX end shunt test
© RailCorp
Issued December 2010
Test Point
Terminals
Inspect and check
all terminations,
including back
nuts.
UNCONTROLLED WHEN PRINTED
Track picks up
when adjacent
tuning unit is
short-circuited or
track voltage
increases by more
than 25%.
A low T1/T2
voltage returning
to 10% more than
the History card.
As Requested
As Requested
Page 18 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Tuning Unit Investigation and Test (Continued)
Test
Attenuation Ratio
Test
Test Equipment
FSM
Test Point
Terminals
VR1=Rail to Rail
Voltage of tuning
unit at track
frequency.
VR2=Rail to Rail
Voltage at
adjacent tuning
unit at track
frequency.
Readings
Checks
VR1/VR2>12 for
1Q, and 3Q.
VR1/BR2>18 for
2Q, and 4Q.
Both
measurements
are at frequency
of track under
test.
Action If Not
Compliant
Perform Short
circuit test and
change adjacent
TU is short circuit
test picks track
other wise change
track TU.
Condemning
VR1/VR2<10 for
1Q, and 3Q.
VR1/VR2<16 for
2Q, and 4Q.
Test
Requirement
As Requested
See also Section 8.6 Tuning Unit Impedance Test or Section 8.7 End Tuning Unit Impedance Test
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 19 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.6
TMG G1492
Tuning Unit Impedance Tests
Test
Test Equipment
Test Point
Terminals
Readings
Tuning Unit "Pole"
Impedance Test
AT TRACK
FREQUENCY
FSM
AC Current Clamp
1. TU Voltage T1/T2
2. Current to T1 or T2
Use readings to
calculate
impedance and
compare with Table
Tuning Unit "Zero"
Impedance Test
AT ADJACENT
FREQUENCY
FSM
AC Current Clamp
1. TU Voltage T1/T2
2. Current to T1 or T2
Use readings to
calculate
impedance and
compare with Table
TUNING UNIT IMPEDANCE RANGES
Z at 1700Hz
TU 1Q 1699
260<Z<320mΩ
TU 4Q 2602
Notes:
Condemning
Test
Requirement
Z = TU(mV)
I(A)
Change out
Tuning Unit
See Table for same
freq. as TU.
Level 2
Z = TU(mV)
I(A)
Change out
Tuning Unit
See Table for
different freq. to TU.
Level 2
Z at 2000Hz
Z at 2300Hz
Z at 2600Hz
Z<55mΩ
312<Z<382mΩ
TU 2Q 2002
TU 3Q 2299
Action If Not
Compliant
Checks
Z<55mΩ
Z<65mΩ
344<Z<422mΩ
Z<65mΩ
382<Z<470mΩ
The impedance ranges are different to the CSEE UM71 values.
The Tx end shunt test as per Section 8.5 Tuning Unit Investigation and Test is used to prove the "pole" impedance of the Tx tuning unit.
The "zero" impedance of the Tx tuning unit can be measured in service, but the "pole" impedance of the Tx tuning unit can not be measured
in service.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 20 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.7
TMG G1492
End Tuning Unit Impedance Test
Test
Test Equipment
Test Point
Terminals
Readings
Tuning Unit "Pole"
Impedance Test
AT TRACK
FREQUENCY
FSM
AC Current Clamp
1. TU Voltage T1/T2
2. Current to T1 or T2
Use readings to
calculate
impedance and
compare with Table
Tuning Unit "Zero"
Impedance Test
AT ADJACENT
FREQUENCY
FSM
AC Current Clamp
1. TU Voltage T1/T2
2. Current to T1 or T2
Use readings to
calculate
impedance and
compare with Table
END TUNING UNIT IMPEDANCE
RANGES
TU 1Q (1699Hz)
TU 2Q (2002Hz)
TU 3Q (2299Hz)
TU 4Q (2602Hz)
Notes:
Z at 1700Hz
Action If Not
Compliant
Condemning
Test
Requirement
Z = TU(mV)
I(A)
Change out Tuning
Unit
See Table for same
freq. as TU.
Level 2
Z = TU(mV)
I(A)
Change out Tuning
Unit
See Table for
different freq. to TU.
Level 2
Checks
Z at 2000Hz
Z at 2300Hz
675<Z<1620mΩ
Z at 2600Hz
Z<80mΩ
1000<Z<2400mΩ
Z<80mΩ
Z<80mΩ
1000<Z<2400mΩ
Z<80mΩ
1500<Z<3000mΩ
Normally only the "pole" impedance of the Rx End Tuning Unit can be measured in service. The "zero" impedance of an End Tuning Unit can
not normally be measured in service, as the adjacent frequency is not present.
The "pole" impedance of the Tx End Tuning Unit can not be measured in service. The Tx end shunt test as per Section 8.5 Tuning Unit
Investigation and Test is used to prove the "pole" impedance of the Tx End tuning unit.
The Rx B/W is connected to 1, and 2 in the ETu. Long Rx cable runs will decrease the ETU "pole" impedance.
The values for End Tuning Units and have not been verified by field testing.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 21 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.8
TMG G1492
Track Investigation and Test
Test
Test
Equipment
Test Point Terminals
Track Voltage
FSM
Rail to Rail
Readings
Checks
Action If Not
Compliant
Condemning
As per Track
Circuit History
Card
Voltage drops on
all Track
Connections.
This includes
both TU for TX
and RX tuned
loops.
DMM on Vac
See section 9
for meter
usage
details.
Test point depends on
the type of connection.
See Note 1
<10mV drop for
bolted
connections.
<40mV for
welded
connections.
Fixed Shunt Test
DMM
0.15Ω Fixed
Shunt
3 metres either side of
the TU at both Tx and Rx
end of the track as well
as mid point of the track
length.
Relay front
contacts should
be observed to
open.
Rail connections.
Target for rail
connections is
less than 1
mOhm.
Test Required
Level 1, 2 and 3
Repair/replace
connection and
make good
See Note 2.
Advise Civil of
any track
movement.
>20mV drop for
bolted
connections.
>60mV for welded
connections.
One rail
connection >
twice the other
connection and
>10mV
Level 1, 2 and 3
Report findings to
DSE and Signal
Engineering
Unable to shunt
track.
Level 3 –
Detailed
Investigation
Note 1:
Test points for track connection.
First meter lead is held on the palm of the crimp for tapered bolt and welded stud connections.
First meter lead is held on the exposed copper part of the bi-metallic inline crimp for direct welded connections.
The other meter lead should be held on the wheel/rail contact band on the head of the rail.
Note 2:
Direct welded connection tests include more than just the rail connection. Condemn at >3mOhms per complete connection.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 22 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Track Investigation and Test (Continued)
Test
General
Inspection
© RailCorp
Issued December 2010
Test
Equipment
Test Point Terminals
Visual
Track Connections
Trackside Equipment
(Incl. Impedance bonds
and spark gaps) Ballast
Condition, Ballast height,
Rails, Bonding, Bridge
Structures etc.
Insulation on spark gap
connections that pass
under the other rail.
No long pieces of rail
scale rail flow, or
conductive material
around IRJs.
Readings
Checks
Action If Not
Compliant
Condemning
Installed to
standards, free
of defects,
damage, and
contamination
Track Insulation
Plan
Standards
No cause of rail
to rail short
circuits or rail to
earth short
circuits.
Report, record
and if possible,
rectify.
Visible defects
UNCONTROLLED WHEN PRINTED
Test Required
Level 1, 2 and 3
Page 23 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Track Investigation and Test (Continued)
Test
Equipment
Test
Rail voltage drop
profile
Rail current
profile
FSM
Rail Current
meter.
Rail current
balance
Rail Current
meter.
Readings
Checks
Action If Not
Compliant
Condemning
Rail to rail voltages at
regular intervals.
(~100m)
From Tx to Rx.
Voltage drop
should range
from 1.5 to 0.3V
per 100m.
The voltage drop
per 100m should
reduce along the
track. The rate of
reduction should
decrease.
The reduction
can be constant
for good ballast.
Look for a rail to
rail connection
across the track.
See Note 3.
As Requested
Up rail, or Down Rail
currents at regular
intervals. (~100m) from
Tx to Rx.
This test does not
include measurements in
the tuned loop.
Initial rail
currents of 1.5
to 0.4A are
typical. Shorter
track circuits
tend to have
higher rail
currents.
See Note 4.
Look for a rail to
rail connection
across the track.
See Note 5.
As Requested
Unbalanced
leakage and
external currents.
Look for: external
connection to rail,
faulty spark gap,
or a common
mode external
current.
Clearly detectable
difference of at
least 0.2A.
As Requested
Test Point Terminals
Up rail, and Down Rail
currents at regular
intervals. (~100m)
Equal readings
for Up and
Down rails.
Test Required
Note 3:
A higher rate of voltage drop occurs on the shorter higher frequency tracks. A higher rate of voltage drop occurs between a transmitter and a mid-track
impedance bond. The voltage drop per 100m for each successive 100m should decrease when measured from transmitter to receiver end. The decrease
should reduce for each 100m segment. An increase in the rate of reduction indicates an extra load across the track in the previous 100m.
Note 4:
The rail current should gradually decrease from transmitter to receiver. The rail current at the receiver end should be at least 0.1A.
Note 5:
Tracks without impedance bonds or electrolysis bonds should have a decreasing reduction in rail current for every 100m when the rail current is measured
once every 100m from transmitter to receiver end. An increase in the current reduction indicates an extra load across the track in the previous 100m.
Tracks with impedance bonds or electrolysis bonds should have a decreasing reduction in rail current for every 100m when the rail current is measured once
every 100m from transmitter to receiver end except for the 100m segment with the impedance bond or electrolysis bond. An increase in the current
reduction indicates an extra load across the track in the previous 100m.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 24 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.9
TMG G1492
DPU Investigation and Test
Test
Test Equipment
Test Point
Terminals
Visual and
Physical Checks
Readings
Checks
Action If Not
Compliant
Condemning
Version numbers.
See Note 1.
DPU is secure,
parallel to the rail
and correct
spacing from the
rail.
Correct mounting
Visible defects
Level 1
Output Voltage
less than 20mV.
As Requested
Unable to achieve
DPU Amp output
current.
As Requested
<28mA or >60mA
As Requested
<22.5V or >28.8V
As Requested
High gain output
voltage < 1.8
times low gain
voltage.
As Requested
DPU Output
voltage
FSM
Output voltage of
DPU.
AC output voltage
in the range of 20
to 60mV.
Sufficient output
voltage
DPU Amp Input
voltage
FSM
Voltage at
A1/A2
AC voltage
Sufficient input
voltage
Sufficient output
current to drive
Rx.
DPU Amp output
current
DMM on Iac
Rx input current
DPU Amp DC
voltage
DMM on Vdc
DPU Amp R1/R3
24 to 27Vdc
Power supply to
DPU Amp.
DMM on Vac
DPU Amp Output
A5/A6
With D1/D2 bridge
(High gain) and
without.
Output Voltage on
high gain should
be twice voltage
on low gain.
High gain strap
effectiveness.
DPU Amp High
gain setting
effectiveness.
Note 1:
Check
connections or
replace DPU.
Insufficient rail
current due to
connection or RX
Tuned loop.
Check
connections and
adjustment or
replace DPU.
Readjust DPU
Amp gain, Tx
power or find and
correct fault.
Test Power supply
unit, fuses and
connections.
Replace DPU
Amp.
Test Required
DPU Version: Serial number IC394+ with Issue 3.0+ or Issue 5.0 with an R for revised.
DPU Amp Issue 4.0 as minimum.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 25 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
DPU Investigation and Test (Continued)
Test Point
Terminals
Test
Test Equipment
Over-energisation
FSM and short
circuit shunt 1m
on Rx side of
DPU.
Rx input current
DMM on Vac
Each DPU cable
wire to earth
connection.
Voltage balance
to earth
© RailCorp
Issued December 2010
Readings
Checks
Rx input current
should increase
but not exceed
the condemning
limit given.
About 50% of
output voltage
from each leg to
earth.
Over-energisation
of receiver. Overenergisation can
drop the Rx
output.
Earth fault on
wiring insulation
or in DPU Amp.
UNCONTROLLED WHEN PRINTED
Action If Not
Compliant
Re-adjust track
circuit. The track
may need to be
set on Normal
power.
Test insulation
resistance of
wiring, and check
DPU Amp.
Condemning
Test Required
>120mA
As Requested
One leg being
more than 75% of
output voltage to
earth.
As Requested
Page 26 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.10
TMG G1492
Compensating Capacitors Investigation and Test
Test
Impedance
© RailCorp
Issued December 2010
Test Equipment
AC Current Clamp
and FSM
Test Point
Terminals
Voltage across
the capacitor, and
current through
the capacitor at
the track
frequency.
Readings
Checks
Impedance is
Voltage divided by
the current.
(Z=V/I)
The 33uF cap. for
1700Hz, and
2000Hz tracks
impedance should
be in the range of
1.9 to 3.4 ohms.
The 22uF cap. for
2300Hz, and
2600Hz tracks
impedance should
be in the range of
2.2 to 3.8 ohms.
UNCONTROLLED WHEN PRINTED
Action If Not
Compliant
Condemning
Check
connections or
replace capacitor.
Impedance
outside the range.
Test Required
As Requested
Page 27 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.11
TMG G1492
Spark Gap Investigation and Test
Test
Test Equipment
DC Volts
Readings
Checks
Stanchion or
Structure to Rail
Connection
Range:
>3Vdc &
<115Vdc
Voltage should
vary with electric
train movements.
Voltages < 3Vdc
may occur if no
electric trains are
in the area.
DC Tong Meter
Connection from
rail to structure or
stanchion
Not greater than
minimum
sensitivity of tong
meter
Should be zero
current
AC Current clamp
Connection from
rail to structure or
stanchion
Not greater than
minimum
sensitivity of tong
meter
Should be zero
current
DMM on Vdc
DC Current
AC Current
Test Point
Terminals
Action If Not
Compliant
Report to
Electrical
Discipline any
spark gap outside
the condemning
limits
Report to
Electrical
Discipline any
spark gap outside
the condemning
limits
Report to
Electrical
Discipline any
spark gap outside
the condemning
limits
Condemning
Test Required
<3Vdc or
>115Vdc
Level 1, 2 and 3
See note.
Measurable
current
Level 1, 2 and 3
See note.
Measurable
current
Level 1, 2 and 3
See note.
CAUTION
Electrical safety issues exist relating to Over Head Wiring structures. Refer to Signalling Maintenance Procedure TMG J042
Safety Issues for Signalling Personnel for more details.
Note:
© RailCorp
Issued December 2010
Only one of these three tests is required to test a spark gap.
UNCONTROLLED WHEN PRINTED
Page 28 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.12
TMG G1492
Electrolysis bond Investigation and test
Test
Test Equipment
Test Point
Terminals
Readings
Action If Not
Compliant
Inspect
connections and
Store 54.
Visual and
Physical Checks
Store 54 Balance
DMM on Vac
Store 54
Impedance
AC current clamp
and FSM
Leakage current
AC current clamp
and FSM
Note:
Checks
Measure voltage
from centre to
each rail
connection.
Voltage across
Store 54 and
current.
Measure track
circuit current in
electrolysis
connection
Voltages
approximately
same
Each half of
choke should be
the same.
Impedance of
Store 54 not
loading the track.
No track circuit
current should be
leaving or
entering the track
via the
electrolysis bond.
Condemning
Test Required
Visible defects
Level 1
Check
connections and
Store 54.
> 10% difference.
Level 1
Replace Store 54
<500 ohms at
track frequency.
See Note.
As requested.
Find and correct
leakage path.
> 0.1A
As requested
Impedance across Store 54 should be 30 ohms at 50Hz, 1020 ohms at 1700Hz, and 1560 ohms at 2600Hz.
DC resistance of each leg of Store 54 to centre tap is 20 milliohms.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 29 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.13
TMG G1492
Impedance Bond Investigation and Test
Test
Test Equipment
Test Point
Terminals
Readings
Inspect bond for
signs of damage
Visual
Rain cover when
mounted
vertically.
2000R/AF
Inspect
resonating
capacitor box
(when fitted).
Visual
See Note 1, and
Note 2.
Check for
Traction Return
balance
2 off DC Tong for
traction
Impedance bond
side leads.
DC Rail currents
are similar with
variance <10%
FSM
(V1) Rail to Rail
Voltage
(V2) Resonating
winding Voltage
The Resonating
winding Voltage
(V2) should be
>60 times the rail
to rail voltage (V1)
FSM
(V1).Up Rail to
Imp. bond 4 way.
(V2).Dn Rail to
Imp. bond 4 way.
V1 ≈ V2
2000R/AF
Resonating
winding Test
Voltage
Comparison
Up and Down
Rails to Neutral
Lead
Checks
Connections
secure. Side
leads are equal
lengths. Bond
okay.
Capacitor links
securely open, or
closed. Transzorb
not fitted across
capacitors. MOV
(B32K385) fitted.
Turns ratio of
resonating
winding.
Action If Not
Compliant
Condemning
Test Required
Repair/Replace
Visible defects
Repair/Replace
Visible defects
Level 1, 2 and 3
Check connections,
bond, side leads
Variance >33%
Level 1, 2 and 3
< 40 times
As Requested
> +/-20%
difference.
As Requested
Level 1, 2 and 3
Try to re-resonate
bond and if unable
to achieve
acceptable value
then do impedance
test.
Check connections
and possible rail
faults to earth.
Replace impedance
bond if no other
cause found.
Note 1:
If the 2000R/AF Impedance bond is resonated then typically the resonating capacitors should be about 9nF for 1700Hz, 5.7nF for 2000Hz,
4.7nF for 2300Hz, or 3.2nF for 2600Hz. Lower capacitor values should be used for tracks with a DPU. During the 1990's higher capacitor
values were used, which are no longer recommended.
Note 2:
The 2000R/AF Impedance bond resonation is affected by capacitance of the MOV (~1.5nF) protecting the capacitors.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 30 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Impedance Bond Investigation and Test (Continued)
Test
Test Equipment
Side Lead Current
AC Current Clamp
FSM
Test Point
Terminals
Each individual
side lead
Readings
Checks
All individual
measurements
should be equal
Can have errors
due to large
changes in DC
currents.
(V)=Rail to Rail
(I)=Sum of a set
of side lead
currents
Z=V/I
17 to 26 Ω
AC Current Clamp
FSM
(V)=Rail to Rail
(I)= Sum of a set
of side lead
currents
Z=V/I
Not Resonated:
2 to 3 Ω.
Resonated.
10 to 30Ω.
Impedance bond
loading the track.
See Note 3.
CIT1400
Impedance bond
impedance
AC Current Clamp
FSM
(V)=Rail to Rail
(I)=S Sum of a set
of side lead
currents
Z=V/I
Not Resonated:
9 to 15 Ω.
Resonated.
1 to 4 Ω
Impedance bond
loading the track.
See Note 3 and 4.
2000R/AF
Secondary coil
resistance.
DMM ohms scale
Across winding
1.5 to 2 ohms.
MJS, MJX,
Macolo
Impedance Bond
Impedance
2000R/AF
Impedance bond
impedance
AC Current Clamp
FSM
Impedance bond
loading the track.
See Note 3.
Action If Not
Compliant
Check connections
and possible rail
faults to earth.
Replace impedance
bond if no other
cause found.
Replace bond.
Not Resonated:
Replace bond.
Resonated:
Re-resonate bond.
If unable to reresonate, check coil.
Not Resonated:
Replace bond.
Resonated:
Check capacitor,
and coil.
Replace bond.
Condemning
> +/-10%
difference.
<8 Ω
Test Required
As Requested
As Requested
Not Resonated:
< 1.5 Ω
Resonated:
<8 or >40 Ω
As Requested
Not Resonated:
<4Ω
Resonated:
>9Ω
As Requested
<1 ohm or
>3 ohms
As Requested.
Note 3:
This test is normally only used for mid-track impedance bonds as impedance measurements at Tx end have the track in parallel with the
bond, and at Rx end have the ETU in parallel with the bond. This typically results in significantly lower impedances measured for
impedance bonds at the Tx end, or Rx end of a track.
Note 4:
CIT1400 bonds should only be resonated for tracks longer than 600m or when two bonds are installed on the track.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 31 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Impedance Bond Investigation and Test (Continued)
Test
Test Equipment
Vac Case to
Resonating Coil
Leads
DMM on Vac
20K Shunt
Vdc across
impedance bond
Note 5:
© RailCorp
Issued December 2010
Precision DMM on
Vdc. Eg Fluke 187
or 189.
Test Point
Terminals
(V1) Coil Lead (1)
to Case.
(V2) Coil Lead (2)
to Case
Rail connection
bus bar to Rail
connection bus
bar.
Can be from palm
to palm of side
lead connections.
Readings
Checks
V1 <0.5Vac
V2 < 0.5Vac
< 10mV DC
Value will vary
with train
movement.
Ignore readings
with train on track
circuit.
See Note 5.
Traction current
balance.
Action If Not
Compliant
Condemning
Verify by megger
test and replace
impedance bond.
V1 >0.5Vac or
V2 > 0.5Vac
Further investigation
as to reason for
traction imbalance.
> 200mV for
2000R
> 300 mV for
Macolo
> 350mV for
other bonds.
Test Required
As Requested
As Requested
If using Min/Max then a suitable scale (eg 500mV) must be manually set before Min/Max is selected.
UNCONTROLLED WHEN PRINTED
Page 32 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.14
TMG G1492
Receiver Unit Investigation and Test
Test
Equipment
Test
Visual and Physical
Checks
Hand tools
Visual
Test Point
Terminals
Inspect and
check all
terminations
and Rx
version.
Readings
Checks
Action If Not
Compliant
Condemning
Terminations
effective and secure
Check
Mounting
and
environment
Correct as required
Visible defect or
Rx version is less
than V34.1.
DMM
R+/R-
Acceptable Range
50Vdc to 65Vdc
Track Receiver Input
Voltage
FSM
Location Track
Terminals
Comparison to
History card value.
Receiver Monitor
Voltage
Track Unoccupied
FSM
Monitor
voltage
See Note 1.
Drop Shunt Test
Variable
Shunt Box /
DMM
Relay Output Voltage
Zero Feed
Receiver Voltage
Track Stick contacts
resistance
Note 1:
© RailCorp
Issued December 2010
DMM on Vac
DMM on
ohms
Rail to Rail
Between 0.8 and 1.2 Ω
Monitor
voltage
Take readings with
Tx feed disconnected
Should be < 250mV.
Track Relay
A1/A2 (stick
finger).
Typically less than 2
ohms per contact.
Change Receiver
Investigate
connections from Rx
TU to Rx.
Identify and correct
cause or readjust track
circuit.
Readjust or Refer to
DSE.
DPU may be higher.
<40Vdc or
>65Vdc
More than 25%
change from
History Card.
<0.9 or >1.2Vac
Test Required
Level 1, 2 and 3
Level 1, 2 and 3
Level 1, 2 and 3
Track Circuit
History Card
Level 1, 2 and 3
Track Circuit
History Card
Normal power:
<0.7 Ω or >1.3 Ω
Low power:
<1.0 Ω or >2.0 Ω
Level 1, 2, and 3
Track Circuit
History Card
Interference
from same
freq. tracks.
Investigate source of
supply.
>400mV
Level 3 –
Detailed
Investigation
Track Circuit
History Card
Measure
resistance
with receiver
deenergised.
Replace relays with
HR contact/s.
>10 ohms
Level 3 Detailed
investigation
Drop away voltage is 0.8V, and the monitor voltage saturates at 1.2Vac.
UNCONTROLLED WHEN PRINTED
Page 33 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Receiver Unit Investigation and Test (Continued)
Test
Test
Equipment
Receiver Monitor
Voltage, Track
Shunted
DMM on Vac
Fixed Shunt
Track Stick Voltage
Drop during pickup.
DMM Vdc set
for Fast or
peak
min/max
Track Relay
A1/A2 (stick
finger)
(Meter set up
with relay
de-energised.)
Adjacent Frequency
FSM
Monitor
Voltage
Adjacent frequency
should be less than
100mV.
FSM
Monitor
Voltage
The measured value
should not change by
more than 50mV.
Beating
Note 2:
© RailCorp
Issued December 2010
Test Point
Terminals
Readings
Checks
Action If Not
Compliant
Condemning
Use 0R15 shunt at
Rx TU.
Operation of
Track.
Zero feed test.
Readjust track.
>400mV
Track Circuit
History Card
Maximum between
0V and 2Vdc
(Once relay
energised)
Voltage drop
on track stick
contacts
during
pickup.
Test pick-up and
holding path for HR
contact/s.
>3V drop across
contacts.
As Requested
Investigate RX tuned
loop.
Beating with
other track
circuits.
Isolate and find source
of interfering signal.
See Note 2.
> 1/3 of voltage
from own
frequency.
Changes of more
than 50mV when
observed for 10
seconds.
Test Required
As Requested
As Requested
Fluctuating Rx voltage can occur due to differing series impedances of Tuning units at upper and lower frequencies. The Adjacent
Frequency and Zero feed tests are the preferred method to find interfering signals for this type of track circuit.
UNCONTROLLED WHEN PRINTED
Page 34 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
Receiver Unit Investigation and Test (Continued)
Test
Test
Equipment
Receiver Input current
from track.
DMM on Iac
Receiver current from
power supply
DC Tong
Meter
N24
Receiver Track Input
impedance
DMM
Location term.
Vac and Iac.
RX Input voltage earth
balance
© RailCorp
Issued December 2010
DMM on Vac
Test Point
Terminals
In series with
location
terminals
Location Track
Terminals and
earth bar.
Readings
Checks
15mA to 100mA
0.2Amps to 0.5Amps
with relay up.
Approx 0.05 Amps
with relay down.
Rx Input Z approx.
24Ω and varies with
sensitivity setting.
About 50% of input
voltage from each leg
to earth.
Earth fault
inside
modules or
wiring
insulation.
UNCONTROLLED WHEN PRINTED
Action If Not
Compliant
Condemning
Test Required
Find and correct cause
or readjust track.
<15mA
As Requested
Change Receiver
>0.7 Amps
As Requested
Analysis by Engineer.
Determination by
Engineer.
As Requested
Test surge protectors.
Test insulation
resistance of wiring.
Replace modules.
One leg being
more than 90% of
track voltage to
earth and the
other leg being
less than 10% of
track voltage to
earth.
As Requested
Page 35 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
8.15
Receiver Lockup Investigation and Test
8.15.1
Initial Receiver check
Measure B24/N24 on receiver. If below 20V then correct power supply voltage first. The 24V led turns off below 16 volts, and turns on above 19.5V.
Power off and power on the receiver and check that it restarts.
If the receiver re-starts then perform the following checks otherwise replace the receiver.
Tap the receiver about 50mm back from the monitor terminals or the right hand side. Confirm that the receiver does not restart or lockup. This checks
the stability of the brown out relay due to vibration.
Check the manufacture and/or repair date of the receiver. Receivers manufactured or repaired prior to November 2004 use an electrolytic capacitor as
C19. This capacitor has been changed to a polyester type since November 2004. Degradation of C19 in receivers dated prior to November 2004 can
cause intermittent lockups before a complete failure. Receivers with a manufacture and/or repair date prior to November 2004 should be replaced after a
lockup.
8.15.2
Receiver with contacts in the receiver power circuit.
Power off receiver, and remove track relay. Then power on receiver and measure receiver B24/N24 voltage, which must be greater than 22 volts.
Otherwise check the back proving track stick contacts.
Power off receiver, and restore track relay. Then power on receiver and measure receiver B24/N24 voltage, which must be greater than 22 volts.
Otherwise check track relay stick contact.
8.15.3
Receiver with contacts in the track relay circuit
Check RC snubber or diode is fitted across track relay coil. If no RC snubber or diode fitted then arrange for Signal design to fit a snubber or diode to the
track relay.
8.15.4
Receiver fed from a TU
Check the tightness of back nuts on Tx and Rx TUs. Westinghouse changed the design of the Tu in September 2002 to improve the effectiveness of the
connections to eliminate this type of problem.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 36 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
TMG G1492
The TUs made after September 2002 and the modified TUs were produced to design out the main causes of intermittent connections that cause
significant amplitude changes, which can cause the Rx to lockup.
Check millivolt drop on all associated TU connections from/to rail. This includes both TU in the TX tuned loop, and both TU in the RX tuned loop. <5mV
per connection. TU connections on up and down rail should be the similar.
Check rail connections in tuned loop. This includes for both TU in the TX tuned loop, and for both TU in the RX tuned loop. <20mV per connection. Rail
connections on up and down rail should be the similar.
Note:
8.15.5
Rail connection checks are not required for direct web welded connections. TU connections still need to be checked.
Receiver fed from a DPU
The drop shunt should be > 1 ohm so that the receiver is not over energised when a train shunt is approaching the DPU.
Voltage drops across location disconnect terminals are less than 5mV.
Traction return current harmonics from a millennium train could have been the cause.
8.15.6
Electrical noise
Check for noise sources like un-snubbed QN or QB style relays installed with-in 300mm of the Receiver or input wiring from the track circuit cable
terminals to the Receiver or DPU AMP longer than 5m and mixed in with Q relay circuit wiring.
Suppress electrical noise by fitting a snap on ferrite choke around the input wires close to the Receiver terminals. Snap on ferrite chokes like RS 2606486 or Farnell 9640444 are appropriate. Alternatively organise for a signal design to snub relays as necessary. The design must snub all relays (that
need snubbing) mounted with-in 300mm of Receiver as a minimum.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 37 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
8.16
TMG G1492
Surge Protection Investigation and Tests
Test
Test Equipment
3Y20 Gas
Arrestor Visual
Inspection
Visual
3Y20 Gas
Arrestor Test
Arrestor Tester
MOV on 24V bus
Visual Inspection
Visual
Test Point
Terminals
Unplug unit and
plug into arrestor
tester.
Readings
Approximately
290Vdc for Line to
earth.
MOV on 24V bus
DMM on
Ohmmeter, and
diode test.
Disconnect one
leg and measure
across the MOV
Ohmmeter should
read >10 meg
ohm.
Diode test should
read OL in both
directions.
MOV on 24V bus
Arrestor Test
Arrestor Tester
Disconnect one
leg and measure
across the MOV
Approximately
40Vdc.
MOV on 120V
bus Visual
Inspection
Visual
MOV on 120V
bus Arrestor Test
Arrestor Tester
© RailCorp
Issued December 2010
Disconnect one
leg and measure
across the MOV
Approximately
210Vdc.
Checks
Action If Not
Compliant
Condemning
No visible
cracking, splitting,
burn marks or
blackening of the
case.
Replace arrestor
Visible defects
Level 3 –
Detailed
Investigation
Break down
voltage
Replace arrestor
<220Vdc
>360Vdc
Level 3 –
Detailed
Investigation
No visible
cracking, splitting,
or burn marks.
Replace MOV
Visible defects
As Requested
Replace MOV
Ohmmeter
reading of <10
meg ohm or
Diode test of less
than OL.
As Requested
Maximum
operating voltage
Replace MOV
<36Vdc
>45Vdc
As Requested
No visible
cracking, splitting,
or burn marks.
Replace MOV
Visible defects
As Requested
Maximum
operating voltage
Replace MOV
<190Vdc
>230Vdc
As Requested
UNCONTROLLED WHEN PRINTED
Test Required
Page 38 of 39
Version 1.1
RailCorp Engineering Procedure — Signals
FS2500 Track Circuit Test and Investigation Guideline
9
TMG G1492
mV AC measurements in electrically noisy environments
mV AC measurements made in electrically noisy environments can have significant
errors due to induced currents, and meter input impedance.
Measurements made for mV drop on rail connections for audio frequency track circuits
can have errors due to the high currents (up to 20A) and higher frequencies (up to
2600Hz) from the track circuit as well as harmonics in the electric traction currents for
trains.
A test measurement can be made with both meter probes touching same connection
point. Any reading on the DMM will be the residual reading that the meter is capable of in
that environment. Move the meter leads and check if the readings vary significantly. If the
readings vary significantly then twist the meter leads (about 10 times) and repeat the test.
If the residual meter reading is not significantly less (< ½ ) than the value to be measured
then the meter is not suitable for the measurement.
A comparison of commonly used meters is:
• Fluke 87 typically has a minimum valid reading of 2mV. It is the least sensitive to
the electrical environment.
• Fluke 87 III, or V typically has a minimum valid reading of 1mV. It is slow to show
the reading, as it will gradually decrease to a stable reading when measuring low
voltages.
• Fluke 189 typically has a minimum valid reading of 0.1mV with leads twisted. It has
the best resolution but is most sensitive to the electrical environment.
© RailCorp
Issued December 2010
UNCONTROLLED WHEN PRINTED
Page 39 of 39
Version 1.1