KRV jumpers are not used with the adjustable resistor configuration
DCR's KRV ratio must be less than the parent branch's KRV. Confirm the MU has no jumper across R1-R2 (series resistor must not be bypassed) - TMUs have no built-in resistor for this configuration.
Impedance Bond Checks
Complete impedance bond resonance tuning before proceeding to KRV adjustment in the Receiver section
Transmitter
Ranges calculated in Section 1
On Track - Transmitter End (TMU)
Ranges calculated in Section 1
On Track - Receiver End (RMU)
Ranges calculated in Section 1
Receiver
Select the jumper fitted to confirm its expected delay
Ranges calculated in Section 1
Initial target from the KRV formula
Extraneous Voltage Test
Remove power from the TX, then measure R1-R2 at the RX. This checks for stray/induced voltage reaching the receiver from sources other than the intended transmitter.
Shunt Tests
For reference when interpreting these results: the track relay energises at 200–210 mV and de-energises at 170–180 mV (R1-R2). This is a design characteristic of the relay itself, not a value you measure directly.
One lookup covering both: whether track compensation capacitors are required for this frequency/configuration/length (NIST-012.7.35 6.3.1.6, Table 12), & the resulting KEM / KRV from the correct configuration table (Appendix A) - length is rounded UP to the nearest table entry, per the standard.
Per A1500 5.2.3, Universal Adjustment only applies to end-fed track circuits with an ESJ on one or both ends. Go straight to Specific Adjustment (Calculator 2, the 350 Rule) instead for: all centre-fed track circuits, all IDC (PPD/DCR) sub-track circuit RXs, end-fed IRJ–IRJ arrangements, track circuits over points, or the Melbourne Underground Loop.
Compensation
Compensation Required?
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Capacitor Value
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Quantity
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Half-Step Spacing
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KEM / KRV
Table Entry (rounded up)
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KEM
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KRV
-
KEM
Terminal 1
Terminal 2
Jumpers
KRV
R1 to
R2 to
Jumpers
Expected Ranges for This Setup (Appendix A)
TX Output
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TX Current
-
TMU TX Output V
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RMU Track V
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RX Input V1-V2
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Dynamic range based on results from Section 1 (length, frequency, configuration & compensation). Click "Apply to Test Record" to carry these ranges over.
Compensation & wiring notes
Full steps: 100 m between successive capacitors. Half-steps (first/last capacitor to adjacent TU): must be 35–85 m & equal at both ends. Capacitor spec: ±5% tolerance, non-electrolytic, non-polarised, 420 Vrms AC working voltage. Transmitter high-power jumpers (M2-M4 & M2-M5) must be installed when compensation is used.
For centre-fed circuits, apply this same lookup separately to each branch length (TX–RX-A & TX–RX-B), using the branch length in place of total track length. IRJ-IRJ configuration is not tabulated in Appendix A of the source manual - refer to the manual directly for that case.
2. Specific Adjustment - the "350 Rule" (KRV)
What does this calculate?
An empirical alternative to Calculator 1: instead of looking up KRV from track length, it derives KRV directly from a measured voltage across the receiver's V1–V2 using KRV = 350 mV × 58 ÷ V1V2 (measured), rounded up. Only use this where the universal adjustment method either doesn't directly apply, or has failed to provide a stable track circuit.
Confirm consent from the Infrastructure Manager to use specific adjustment.
Confirm the Weather condition (very wet / wet / dry) in the Test Record above - this drives which limit applies in step 6.
Measure the voltage across RX's V1–V2.
Calculate KRV using the formula below (result rounded UP).
Re-strap the receiver to the calculated KRV & re-measure R1–R2.
Confirm R1–R2 stays within the following limits: ≥ 240 mV if adjustment is made in wet weather, & ≤ 450 mV if adjustment is made in dry weather.
Formula: KRV = 350 mV × 58 ÷ V1V2 (measured), result rounded up. Uses the Weather condition from the Test Record above.
Raw Result
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KRV (rounded up)
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KRV
R1 to
R2 to
Jumpers
After re-strapping - R1–R2 limits
Where additional KRV adjustments are required for track circuit operation, the following limits are in place: voltage across RX's R1–R2 must be ≥ 240 mV if adjustment is made in wet weather; & ≤ 450 mV if adjustment is made in dry weather.
Note: Cross-check all calculated values against NIST-012.7.35 (UM71 CSEE Jointless Track Circuit Application Manual) & your controlling procedure before applying to a live track circuit.
New Test Record
Test Record
Track Configuration
Single rail: 50-500m. Double rail: up to 1800m (electrified) or 3500m (non-electrified)
Power Supply
Transmitter End
Receiver End
Extraneous Voltage Test
Also referred to as the Zero Voltage Test on the survey sheet - checks for stray voltage reaching the receiver from sources other than the intended transmitter.
Variable Shunt Test
Fixed Shunt Test (0.5Ω shunt)
Note: Cross-check all measured values against NIST-012.7.6 (High Voltage Impulse Track Circuits) & your controlling procedure before applying to a live track circuit.