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.
No Voltage
Partial Voltage
Fuse Blown
High Resistance Contacts
Broken Rail
IBJ Failure
DIS Between LOCs
Relay Not Energising
Main Decision
CAN SIGNALLER CLEAR SIGNAL OVER THE FAILED TRACK CIRCUIT?
YES → INDICATION ONLY FAULT → CHECK TKR CIRCUIT
NO → ACTUAL TRACK FAULT OR TPR FAULT → GO TO FEED OR RELAY END
Feed End Checks
CHECK VOLTAGE ON RAILS (METER ON DC)
NO VOLTAGE → PARTIAL SHORT © → SEE PAGE A
PARTIAL/LOW → TRACK CIRCUIT PROBABLY OK ©
HIGHER THAN NORMAL → TPR FAULT
FULL VOLTAGE → CHECK TR RELAY
Relay End Checks
CHECK TR RELAY IF AT LOC FIRST
CHECK VOLTAGE IF AT TRACK ENDS FIRST
FULL VOLTAGE → CHECK TR CONTACTS → HR CONTACTS = REPLACE RELAY
PARTIAL VOLTAGE → CHECK LOC & RAIL CONNECTIONS → IF OK → TPR FAULT
CHECK TPR FEED FUSE → BLOWN OR OK → INVESTIGATE
From Page One (A)
CHECK OUTPUT VOLTAGE ON TFU
NO VOLTAGE → WIRE OFF / TFU FUSE BLOWN → CHECK CURRENT → TEST TC
From Page One (B)
WALK TRACK, CHECK VOLTAGE EVERY 10m
CHECK PWAY INSULATIONS & IBJs
INSULATIONS/IBJs FAIL → TEST WITH K9 → R.O.A CHECKS → PWAY REPAIR
From Page One (C)
TPR B50 FUSE BLOWN OR WIRE OFF → CHECK & RECTIFY → TC NOT FAILED
From Page One (D)
FAULT IN TPR CIRCUIT IN FURTHER LOCS
CHECK 50v SUPPLY (45–55v)
IF HIGH → POSSIBLE DIS BETWEEN LOCS
RELAYS WON’T ENERGISE BELOW 37v
CHECK PREVIOUS RELAY CONTACTS FOR HR
TEST CABLE CONTINUITY IF NEEDED