Combined Indication & control panel, RRI-Free wired Route Setting,Station Layout,Point setting and locking sequence,Availability of selected route,Route Lock relays,RLR/NLR circuit,Route controls are mainly three types,Opposing Locking,Point Selection,Route initiation circuit, Relays in point control,Point status,Points called to the required position,Point control and detection circuits
RRI-Free wired Route Setting
Combined Indication & control panel
Point setting and locking sequence
Availability of selected route
Control table specifies the controls required for route setting Generally when route is initiated the following checks are made to confirm that the selected route is free to be called.
Points including overlap and flank points are either already set to the required position or free.
Directly opposing route not set.
Conflicting routes are not initiated.
Other routes of the same signal are not initiated.
Any other special conditions required.
Route Lock relays
Each route is provided with a pair of route lock relays NLR/RLR
NLR is a magnetically latched relay(BR935) –
It is having two windings.
When route is released PU winding gets feed and relay picks up.
It gets latched in even after the feed is disconnected.
This is the normal condition and indicates the route is free
When route is initiated the other winding gets feed and the relay gets de-latched.
This prevents any other conflicting or directly opposing routes are being set. RLR is a neutral relay
RLR is a neutral relay, normally de-energised
Energises when the route is set.
De-energises when the route is released either by normalisation of route e or by TORR.
Each circuit comprises two parts
Left side of the coil called positive path
Right side of the coil called negative path
Push button commands (S)R & (D)R etc. are proved on positive path
All route controls and special conditions are proved on the negative path
Route controls are mainly three types –
Opposing Locking – opposing routes with same setting points. Front contacts of opposing routes and front contacts of opposing USR of route section past the signal are proved.
Point Selection – all points in the route including flank points and points in overlap are either already set to the required position or free to move. other routes starting from the same signal are not locked out.
Route initiation circuit
Relays in point control
|Point NLR||Normal Point Lock Relay. Magnetically latched relay BR935. point RLR to be de-latched first for latching NLR. When latched calls the point for Normal operation.|
|Point RLR||Reverse Point Lock Relay. Magnetically latched relay BR935. point NLR to be de-latched first for latching RLR. When latched calls the point for Reverse operation.|
|WZR ↓||Points free relay. Slow to release relay BR934. Must be energised to unlatch point NLR and point RLR. De-energised whenever the points are called by route or individual point relay.|
|NKLPR||Points set, Locked and detected Normal|
|RKLPR||Points set, Locked and detected Reverse|
|NZLPR||Points set Normal or free to be set.|
|RZLPR||Points set Reverse or free to be set.|
|NWKR||Points set and detected Normal.|
|RWKR||Points set and detected Reverse.|
Points normal or free
Points reverse or free
Points normal and locked
Points reverse and locked
Points called to the required position
Point control and detection circuits