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4. Signals
  
Up ] 4.1 Automatic Signals ] 4.2 Controlled Signals ] 4.3 Call-on Signal ] 4.4 Typical Signal Layout ]
 
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Railway
Sri Lanka

Signal posts carries signal light units consisting one or more aspects. This is the final stage of communication that gives the driver necessary orders and warnings about the track segments ahead.  The signal aspects are powered individually by 110 V a .c. and each aspect has its own step down transformer.  In the secondary circuit a  relay is connected in series with the lamp to get the indication back to the interlocking plant.  The figure below illustrates the circuit of a signal aspect.

Signal can be classified according to their mode of operation as follows:

 Automatic Blocking Signal
 Automatic 
 Automatic Approach Signal
Signals 
 High Controlled Signal
 Controlled 
 Dwarf Controlled Signal
 

 
Up ] 4.1 Automatic Signals ] 4.2 Controlled Signals ] 4.3 Call-on Signal ] 4.4 Typical Signal Layout ]
1. Introduction ] 2. Track Circuit ] 3. Relays ] [ 4. Signals ] 5. Moter Points ] 6. Gate barriers ] 7. Automatic Blocking System ]

R. Jayanthan
Last updated on 01 January, 2002