Page 449 - IRSEM_Main Book

Section 7: Fuses

19.7.1 (a) Fuses shall be of approved type and appropriate rating. When fuse is not
provided with fuse blown off indication, additional indication circuit may be
provided.

(b) At the time of commissioning of any signalling installation, the normal load
current of every circuit shall be measured and recorded. These recorded
values shall be checked with the theoretically obtained values. Fuse of
correct capacity which should be not less than 2.5 times the rated current,
shall be provided.

(c) When there is a case of fuse blowing off, the concerned circuit current
shall be measured and compared with the original recorded value. If there
is a variation, action shall be taken to locate and remove the defect before
a new fuse is inserted.

(d) For LED signal aspects, fuse of prescribed rating (0.6 Ampere if not
prescribed otherwise) shall be used.

19.7.2 Fuse change over system:
Fuse Auto Changeover System with monitoring panel and alarm facility along
with audio & visual indications suitable for signaling installations of Railways
may be used for minimising failures due to fuse blown off. The changing over
of circuit operation from main fuse to spare fuse shall be automatic, without
affecting the functioning of signaling circuits, when main fuse is blown off. At
every change-over, audio/visual indication shall appear and Equipment shall
work either on 24 V DC, 60 V DC or 110 V AC, Reverse polarity protection and
overload protection voltage may also be provided in the power supply circuit.
The system shall be of approved type. These shall be maintained as per
Annexure: 19-MS5.

Note: Electrical signalling equipment shall be painted in accordance with the

approved Colour Scheme
Section 8: Testing of Signalling Circuits

19.8.1 General The checking and testing of signalling installations may be divided
into five different groups as detailed below:

(a) Physical inspection of the installation.

(b) Checking of the wiring and cables.

(c) Testing of the individual circuits.

(d) Testing of the individual apparatus.

(e) System testing of the installation.

Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 397 of 535