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Breaktru Forum  |  AutoSim Software  |  General Discussion: AutoSim Software  |  Topic: Facts about Automatic Signals
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Online Breaktru

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Facts about Automatic Signals
« on: November 24, 2008, 05:09:42 PM »
THE FOLLOWING TEXT WAS TAKEN FROM THE New York City Transit TYPICAL CIRCUITS:


AUTOMATIC SIGNALS ARE LOCATED BETWEEN INTERLOCKING TO KEEP TRAINS SPACED FOR SAFE BRAKING DISTANCE. IN ITS SIMPLEST FORM, THE TRACK IS SIGNALED FOR RUNNING IN ONE DIRECTION ONLY, AND EACH SIGNAL HAS A MINIMUM OF TWO TRACK CIRCUITS IN ITS CONTROL LINE. THE CIRCUITS DEPICTED IN THESE DRAWINGS ARE FOR SIGNAL 121, WHICH CAN DISPLAY EITHER YELLOW (APPROACH) OR RED (STOP), AND SIGNAL 119 WHICH CAN DISPLAY GREEN (CLEAR), YELLOW OR RED. IN ORDER FOR SIGNAL 121 TO DISPLAY YELLOW, TRACK CIRCUITS 119T AND 121T MUST BE VACANT AND 121 TRIP ARM MUST BE DRIVEN TO THE CLEAR (NON-TRIPPING) POSITION. FOR SIGNAL 119 TO DISPLAY GREEN, THE CONDITIONS TO DISPLAY YELLOW MUST EXIST. AND IN ADDITION, SIGNAL 117 MUST DISPLAY YELLOW OR GREEN.

THE FEATURES OF THESE CIRCUITS ARE AS FOLLOWS:

*NOTE: THE NUMBERING CORRESPONDS TO THE NUMBERS ON THE DRAWING.


1.   THE H (HOME CONTROL) RELAY CHECKS THAT THE TRACK CIRCUITS IN
ITS CONTROL LINE ARE VACANT. AS WELL AS THE STOP CYCLE CHECK.

2.   TO PROVIDE SOME MEASURE OF PROTECTION AGAINST UNSAFE CONDITIONS CAUSED BY HOOKED STOP ARMS, THE TRAIN STOP MUST BE IN THE TRIPPING POSITION BEFORE THE H RELAY MAY BE ENERGIZED. THIS REQUIREMENT, COUPLED WITH THE REQUIREMENT THAT THE TRAIN STOP BE IN THE CLEAR POSITION BEFORE A CLEAR SIGNAL MAY BE DISPLAYED. ENFORCES A FULL CYCLE OF STOP OPERATION FOR EACH TRAIN PASSING THROUGH THE SIGNAL'S CONTROL LINE. NVP CONTACT IS USED WHERE SIGNAL HAS NO DISTANT (GREEN) CONTROL. AND DV CONTACT IS USED WHEN DISTANT CONTROL IS PRESENT.

3.   WHEN THE H RELAY BECOMES ENERGIZED, THE CYCLE CHECK CONTACT HAS SERVED ITS PURPOSE AND IS NO LONGER RELEVANT. STICK CONTACT OF H RELAY BYPASSES CYCLE CHECK CONTACT UNDER THIS CONDITION.

4.   H RELAY CONTACT ENERGIZES STOP, DRIVING IT CLEAR AND PERMITTING A MOVE PAST THE SIGNAL.

5.   WHEN THE TRAIN ACCEPTS THE SIGNAL, A BACK CONTACT (5) OF THE TP RELAY HOLDS THE TRAIN STOP IN THE CLEAR POSITION UNTIL THE TRAIN VACATES THE TRACK CIRCUIT IN ADVANCE OF THE SIGNAL. FOR AUTOMATIC SIGNAL LAYOUTS, THE TRAIN STOP IS TYPICALLY 10-15 FEET IN ADVANCE OF THE INSULATED JOINT MARKING THE BEGINNING OF THE TRACK CIRCUIT. SHOULD IT BE NECESSARY TO PASS A RED AUTOMATIC SIGNAL (H RELAY DE-ENERGIZED), THE TRAIN OPERATOR (AFTER RECEIVING PERMISSION WHERE APPROPRIATE) MOVES SLOWLY ONTO THE TRACK CIRCUIT, CLOSING THE BACK CONTACT (5) OF THE TP RELAY AND DRIVING THE STOP CLEAR. AFTER OBSERVING THAT THE STOP IS IN THE CLEAR POSITION, THE OPERATOR MAY PROCEED AT RESTRICTED SPEED AND EXTREME CAUTION. ACCORDING TO THE OPERATING RULES.

6.   WHEN THE TRIP STOP (V) IS ENERGIZED TO DRIVE TO THE CLEAR POSITION. IT IS ENERGIZED OVER ITS OWN TRIPPING POSITION CONTACT. WHEN THE STOP DRIVES TO THE CLEAR POSITION, THE CONTACT OPENS AND INTRODUCES THE RC CIRCUIT IN SERIES WHICH HOLDS THE STOP ARM IN THE CLEAR POSITION WITH REDUCED CURRENT AND A HIGHER POWER FACTOR.

7.   THE HV RELAY IS ENERGIZED ONCE THE H RELAY ENERGIZES AND THE STOP IS DRIVEN TO THE CLEAR POSITION, CONDITIONING THE SIGNAL TO CLEAR.

8.   HV RELAY DIRECTS LIGHTING ENERGY TO DISPLAY RED OR CLEAR (YELLOW/GREEN) SIGNAL ASPECT AS APPROPRIATE.

9.   WHERE THERE IS NO DISTANT CONTROL ( I.E. NO GREEN ASPECT). NVP RELAY IS ENERGIZED WHEN TRAIN STOP IS IN TRIPPING POSITION, FOR CYCLE CHECK.

10.   DISTANT CONTROL IS COMBINED WITH STOP CYCLE CHECK BECAUSE DISTANT CONTROL IS UNNECESSARY WHEN SIGNAL IS RED AND CYCLE CHECK IS UNNECESSARY WHEN SIGNAL IS CLEAR. DV RELAY REPEATS STOP FOR CYCLE CHECK WHEN SIGNAL IS RED (HV DOWN), AND REPEATS NEXT HV IN ADVANCE FOR DISTANT (GREEN) CONTROL WHEN ITS OWN SIGNAL IS CLEAR (HV UP).

11.   SELECTS FUNCTION FOR DV RELAY AND ISOLATES DC POWER SUPPLIES FOR STOP REPEATER (VB/VC) AND LINE CONTROL (LB/BC) FUNCTIONS.

12.   WHEN SIGNAL IS CLEAR. THE POSITION OF THE DV RELAY SELECTS YELLOW OR GREEN ASPECT AS APPROPRIATE.

13.   SIGNALS OPERATED FROM RELAY ROOMS OR CIR'S ARE POWERED USING ABX-ACX 110/120AC FOR SIGNAL LIGHTING TRANSFORMERS IN THE SIGNAL HEADS AND TO DRIVE STOP MOTORS. IN UNIT CASE AREAS, THE TRAIN STOP IS DRIVEN FROM THE BX-CX MAIN. AND THE SIGNAL LIGHTING CIRCUIT OPERATES AT LAMP VOLTAGE (APPROXIMATELY 10 VOLTS)--THERE ARE NO TRANSFORMERS IN THE SIGNAL HEADS. TYPICALLY, THIS LIGHTING ENERGY I S FED FROM AN ADDITIONAL SECONDARY WINDING OF THE TRACK FEED TRANSFORMER. IN EITHER SITUATION. THE LIGHTING COMMON (ACX OR CXI0> IS LOOPED THROUGH THE NEGATIVE SIDE OF THE SIGNAL.
{bmlt Typical Circuits.bmp}

Offline tomrichard211

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Re: Facts about Automatic Signals
« Reply #1 on: April 11, 2011, 07:19:37 AM »
Thanks for sharing. I hope it will be helpful to many people that are searching for this topic. Keep posting guys and keep this forum a great place to learn things.

Breaktru Forum  |  AutoSim Software  |  General Discussion: AutoSim Software  |  Topic: Facts about Automatic Signals
 

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