Page 491 - IRSEM_Main Book

(iv) Indication shall be provided on the control panel distinguishing
between locked and free condition of crank handle as below -
 When CH key is in & locked - Yellow Steady
 When CH key released from control panel but CH key is not
extracted/When CH key is inserted back but CH control is not
taken back from control panel - Red Flashing.
 When CH key released and CH key extracted - Red Steady
 When Emergency CH key release control given from control
panel with 120 Seconds timer in progress - Yellow Flashing

(v) The respective signal lock indication (white light) shall start flashing
when an emergency route cancellation is initiated, in an approach
locked condition of the route. This indication will extinguish after a
lapse of two minutes and cancellation of the route.

(vi) If push buttons are used on control panel, a buzzer to indicate that push
button/push buttons has/have been left pressed may be provided.

(vii) Suitable indications for slots shall be provided
(viii) Gate control shall be provided on the control panel as below-
 When gate is closed & locked - Yellow Steady

 When gate slot released from control panel to open but gate is
not open/When gate is closed but gate slot is not taken back
from control panel - Yellow Flashing
 When gate is open - Red Steady

(ix) The control panel indication lamps shall be operated by not more
than 24V miniature type bulbs or light emitting diodes.

(x) Return wires from indication lamps and relays shall be suitably
bifurcated so that excessive current does not damage them. Any
break in return wire shall not fail the indication/relay or give a wrong
indication or pick-up a wrong relay.

(xi) When an approved electronic flasher relay other than Mercury type
is provided, a flashing white indication shall be provided at
appropriate corner of the control panel to indicate to the operator the
satisfactory working of electronic flasher relay.

21.1.5 Interlocking and Circuit Requirements: General
(a) Before designing the detailed circuits, Control Table showing approach
locking, back locking, overlap release, isolation, interlocking, dependence of
signal aspect, grouping of crank handles and the condition for release of
crank handles, route release, gate release etc. shall be drawn up and
approved by the competent authority. Provisions of GR & SR shall be
observed.

(b) Signal circuits shall be so designed that the signal shall not change to a
lesser restrictive aspect than intended one and route shall not be
released because of fluctuations in power supply voltage or when the
supply resume following its failure.

Chapter 21: Relay & Electronic Interlocking Page 437 of 535