DC TC FAULT (SOWC) FLOWCHART v1.3
THE FAILURE IS NOT A WSF. FOLLOW WSF TEST PLAN IF PROVEN TO BE A GENUINE WSF. DO NOT FOLLOW THIS GUIDE.
CAN SIGNALLER CLEAR SIGNAL OVER THE FAILED TRACK CIRCUIT?
YES → IT’S AN INDICATION ONLY FAULT
↓
GO TO THE SIGNALBOX AND CHECK THE TKR CIRCUIT (NOT AN ACTUAL TC FAULT)
NO → IT’S EITHER AN ACTUAL TRACK FAULT OR A TPR FAULT
↓
GO TO FEED END OR RELAY END (WHICHEVER IS CLOSEST)
Feed End Checks
METER SET ON DC AND CHECK VOLTAGE ON THE RAILS
NO VOLTAGE → PARTIAL SHORT © → SEE NEXT PAGE (A)
PARTIAL/LOW → TRACK CIRCUIT PROBABLY OK ©
HIGHER THAN NORMAL → TPR FAULT
FULL VOLTAGE → CHECK TR RELAY
Relay End Checks
IF YOU GET TO LOC FIRST → CHECK TR RELAY
IF YOU GET TO TRACK ENDS FIRST, CHECK VOLTAGE WITH METER ON DC
FULL VOLTAGE →
- CHECK CONTACTS WITHIN TR ON OHMS
- CONTACTS HIGH RESISTANCE → REPLACE RELAY ©
- CONTACTS OK → CHECK OUTGOING VOLTAGE FOR NEXT TPR (TIPR)
PARTIAL VOLTAGE →
- CHECK LOC & RAIL CONNECTIONS
- IF ALL OK © → TPR FAULT
CHECK TPR FEED FUSE
- BLOWN → CHECK FOR BROKEN RAIL, THEN CONNECTIONS. RECTIFY OR ARRANGE REPAIR ©
- OK → CHECK CURRENT DRAWN, REPLACE FUSE WITH CORRECT RATING AND INVESTIGATE CAUSE
Final Checks
THIS IS THE CIRCUIT
GO TO FEED END → FEED END OK → SEE NEXT PAGE (B)
FAULT RECTIFIED
WALK TO RELAY END, CHECK CONNECTIONS
FULLY TEST THE TC ©
- NO VOLTAGE → SEE NEXT PAGE (C)
- VOLTAGE OK → SEE NEXT PAGE (D)
From Page One (A)
CHECK OUTPUT VOLTAGE ON TFU
- OUTPUT OK
- NO VOLTAGE →
- WIRE OFF BETWEEN TFU AND LINKS OR RAILS. CARRY OUT REPAIRS
- TFU BX SUPPLY FUSE BLOWN
- CHECK CURRENT DRAWN, REPLACE FUSE WITH CORRECT RATING AND INVESTIGATE CAUSE
- FULLY TEST THE TC ©
From Page One (B)
WALK THE TRACK CHECKING VOLTAGE EVERY 10m
- VISUALLY CHECK PWAY INSULATIONS
- CHECK AND TEST IBJs AT BOTH ENDS
- NOTHING OBVIOUS FOUND
- PWAY INSULATIONS MISSING/DISPLACED OR IBJ(s) FAIL →
- USE RAIL INSULATION TESTER OR ‘K9’ TO TEST INSULATIONS ©
- FOLLOW R.O.A CHECKS. LIAISE WITH SUPY
- HAVE PWAY REPAIR INSULATIONS AND/OR IBJs
From Page One (C)
TPR B50 FUSE BLOWN OR WIRE OFF
- CHECK, RECTIFY AND INVESTIGATE CAUSE
- NO NEED TO TREAT ACTUAL TRACK CIRCUIT AS A FAILURE
From Page One (D)
FAULT LIES IN TPR CIRCUIT IN FURTHER LOCS
- CHECK ALL TPRs (TP2R, TP3R ETC)
- CHECK EACH 50v SUPPLY AT OUTGOING LINKS
- VOLTAGE SHOULD BE 45–55v
- IF HIGHER → PROBABLY A DIS BETWEEN LOCS
- RELAYS WON’T ENERGISE BELOW 37v
- CHECK PREVIOUS RELAY CONTACTS FOR HIGH RESISTANCE