Page 539 - IRSEM_Main Book

22.7.3 Rod Runs in RE Areas

The point rods in A.C electrified areas are subject to a certain amount of
induced voltage. In addition since the rods are in contact with the rails at some
point or other, the rail voltage, which can be quite high in case of faults, is
transmitted through them to the lever frame. Insulators shall, therefore, be
provided on the rodding as per instructions in para 22.7.4 for protecting the
Operating & Maintenance Staff from the effects of these voltages.

22.7.4 Insulated Rod Joints for RE

(a) The insulated rod joints shall be as per approved drawings.

(b) Each rod shall be provided with an insulator in the lead out as close to the
cabin as possible. While providing this insulator, it shall be ensured that
there is no possibility of a contact between the insulated portion of one rod
and the un-insulated portion of another rod or signal wires, the rail or
O.H.E mast.

(c) An additional insulator shall be provided between the last adjustable crank
and the point or the lock bar. The purpose of this insulator is to prevent
the rail voltage being passed on to the main run of rods.

(d) If the distance between the two insulators at either end is greater than 300
meters, additional insulators shall be provided on each rod, so that the
distance between two consecutive insulators on the same rod is not
greater than 300 meters.

(e) Each Point, Trap indicator and lock bar operated by rodding shall be
electrically isolated from the track.

(f) All insulators in a run shall be provided between the same two sets of
rollers and guides, so that there is no possibility of the insulated portion of
one rod coming into contact with the un-insulated portion of another rod.

(g) The clearance between the insulator and the adjacent rod roller shall be
adequate to permit normal movement of the rod.

(h) When a rod crosses the track, the top of the rod shall not be less than 40 mm
from the bottom of the rail. When steel or C.I sleepers are used, the distance
between the rod and the sleeper shall be also not less than 40 mm. Similarly,
the distance between any O.H.E mast and the point rods shall not be less than
40 mm.

(i) The operating rod of locally worked points on all electrified lines and of
similar points taking off from the non-electrified track adjacent to the last
electrified line shall also be provided with an insulator so that the point
lever or point box is insulated from the rail.

(j) When the Engineering department provides the point lever or point box,
Engineering department shall provide the insulator on the operating rod.

Chapter 22: Requirements Of Signalling in 25 KV AC Electrified Area Page 482 of 535