Page 373 - IRSEM_Main Book

Section 5: Maintenance of Cables

15.5.1 Testing of Cables

(a) All conductors in signalling cables must be tested for their insulation in dry
weather once in three years provided cables are monitored through ELD
else annually preferably before monsoon as per instructions specified in
section 4. Reading shall be recorded as per the format mentioned in
Annexure: 15-MS1. Tail cables should be tested for insulation once a year.
A comparison of the test results between successive tests carried on a
cable under similar conditions will give an indication of the trend towards
deterioration of the insulating material over a period of time. If a sudden fall
in insulation is observed, the cause should be investigated and immediate
steps taken up to repair or replace the cable.

(b) In addition to the regular testing of cables in dry weather, random tests in
wet weather may also be carried out, where considered necessary, to
localise any sudden deterioration in insulation of cables.

(c) All cables termination devices, pillar boxes, cable heads and glands shall
be kept clean and dry. These parts shall be frequently inspected and any
tendency for moisture or water leak shall be immediately attended to.

(d) No excavation in the vicinity of underground signal cables shall be
undertaken without a representative of the signal & telecommunication
department present and without taking suitable precautions for the safety of
the existing cables. Suitable instructions in this regard shall be issued by
the Railway in the form of a joint circular.

(e) The protective works provided for the cables at places like track crossings,
culverts, bridges etc shall be regularly inspected by the maintenance staff,
special attention being paid to these protective works soon after the
monsoon.

(f) Earth Leakage Detector (ELD): Shall be provided in all signalling installations
and shall be interfaced with Datalogger (where ever feasible) for remote
monitoring.

Note: For Maintenance Schedules of ELD, please refer to Annexure: 15-MS2.

15.5.2 Periodical Testing of Signalling cables shall be as under;

(a) First measurement of insulation of the cable should be carried out after
laying of the cable and after first monsoon for all the conductors.

(b) After major work in a yard, all cables should be meggered afresh.

(c) In all other cases, Insulation Resistance shall be tested periodically as
given below.

Type of Cable Periodicity
i) Main Cable Every 2 years
ii) Tail Cables – Signal/Track/Points etc Once in 1 year
iii) Spare conductors Once in 1 year

Chapter 15: Cables Page 321 of 535