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