7 S5E Power Signalling

7/21/2019 7 S5E Power Signalling

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SYLLABUS NO S 5E

POWER SIGNALLING

INDIAN RAILWAYS INSTITUTE OF SIGNALENGINEERING AND TELECOMMUNICATIONS

TARNAKA ROADSECUNDERABAD - 500 017


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SYLLABUS NO S 5E

POWER SIGNALLING

CONTENTS

S.No Chapter Page No

1. Electrical Signal Reverser 1

2. Inter Cabin Slotting 12

3. Electric Lifting Barrier 20

4. Electric Key Transmitter 33

5. Signal Arm and Light Repeater 40

No.of pages : 45 Revised by

or B.Prabhakara Rao; Lecturer Sigg.

No.of sheets : 24 D.Raju, Instructor-Sigg.

March, 2002

IRISET

No part of this publication may be stored in a retrieval system, transmitted orreproduced in any way, including but not limited to photo copy, photograph, magnetic,optical or other record without the prior agreement and written permission of IRISET


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CHAPTER 1 S5E

ELECTRIC SIGNAL REVERSER

1.1 Introduction: Electric Signal Reversers are used in the Mechanical Transmission ofSemaphore Signals to establish an electrical control over the operation of the Signal by one ormore of the following agencies.

a) Cabin in which lever operating that Signal is situated.b) Other controlling cabins.c) Station Masters Control andd) Signal Control Track Circuit.

The reverser consists of an Electro-magnet for which feed is established through slot. slottingagencies proving contacts such as a contact of station master's control slide, the circuitcontroller contact of the slot lever of the other controlling cabins and normal condition of track

circuit, besides of course the normal position of the operating lever for the conflicting signals.The reverser mechanism is so designed that only when the reverser Electro-magnet isenergised and its armature is picked up, it establishes a rigid connection between the down rodof the signal at one end and the transmission from the cabin at the other, transmitting the signalto go to the off position when the operating lever concerned is pulled. Any one of the agencieswithdraws the slot, or there is any interruption of current to reverser when track circuit isprovided, the signal is immediately returns to ON.

The reversers are suitable for post mounting, being mounted between the signal arm andcounter weight reverser as shown in the sketches 1.6 & 1.7. The following are the standarddrawings for such reversers:

1.2 CABIN TYPE (STYLE-A) REVERSER: This type of reverser is fitted in the cabin. It isconnected to the lever tail and signal wire transmission. It consists of an electromagnet, anarmature and a slide when the electromagnet is energised on receipt of slot its armature isattracted and held firmly; Fig 4.1

Fig 1.1 CABIN TYPE (STYLE A) REVERSER


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in turn the armature holds the movement of reverser slide by pushing a cylindrical roller in thebevel notch provided in the slide as shown. In this condition, if the signal lever is pulled, theslide is prevented from moving upwards as it is held in position by the roller. Therefore, the pullof the lever acts on transmission wire, which lowers the signal arm. If the supply to theelectromagnet is now cut-off, the armature and the roller shall release the slide, which will waveupward and throw back the signal to danger. Conversely if the lever is pulled without obtainingthe corresponding slot, the reverser slide will be free to move upwards and no stroke will be

transmitted for actuating the signal arm.

Disadvantages of cabin type reverser: In the absence of slot, the signal arm can be taken off bypulling the signal wire from outside. To avoid this type of unsafe working by outsideinterference post type reversers have been developed.

1.3 Style A reverser is designed for installation in the down rod connection at thesemaphore signal. The general arrangement for fixing the same is shown in figure 1.1 Thedown rod fixed with the spectacle is rigidly connected to the body of reverser and the bottomend of the reverser slide is connected to the counter weight arm. On the slot being receivedelectromagnet is energised and it holds its armature in the attracted position, which inturn,pushes a cylindrical roller into the bevel notch in the reverser slide, counter weight will impart anupward stroke to the reverser slide. Since the slide is prevented from moving up, the reverseras a whole moves up and the signal is taken off. When the slot is withdrawn, the armaturereleases the roller. Now although the slide will remain stationary as it is fastened to the counterweight lever the body of reverser will slide down wards.

When the signal lever is operated without obtaining the slot, the electromagnet remains de-energised and the slide alone moves up without importing any stroke to the signal arm.

1.4 DISADVANTAGES OF THE STYLE A:

1. The signal arm can be taken off at site by forcing the arm down while the operating leverand the slot lever are normal.

2. The working parts such as the slide are not enclosed to make the arrangement dust proofand may get jammed with the body and thus it is possible to take off the signal withoutsupply.

3. The entire load of the signal has to be borne by the armature and hence, becomes sensitiveto voltage fluctuations.

4. There is no provision for locking.

The above disadvantages have been overcome in the following STYLE B (Post type) reverserstandardised by R.D.S.O.

1.5 POST TYPE REVERSERS (STYLE - B): The electromagnet has a resistance of 600ohms. Normal working is 10V and minimum working 7.5V DC. Spectacle crank and spectaclelevers are connected rigidly with each other. Similarly operating crank spectacle lever andoperating lever are connected with each other. Operating lever, coupling lever support leverwith roller bearing assembled in the bridge stripe. Spectacle lever and operating lever-havingarrows, which are aligned with bridge stripe marks at the time of installation.

The case is of cast iron; The cover is fabricated from mild steel. Both are of robust construction

to withstand heavy jerks and shocks under working conditions. The cover is hinged to the caseand when open hangs downward. When closed, the interior is protected against dust and rain.


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The cover is provided with drawer type lock to prevent unauthorised interference with themechanism. The following are the main parts of STYLE B reverser

1. Electromagnet laminated core, winding and Armature.

2. Spectacle (Semaphore) lever.

3. Operating lever.

4. Coupling lever.

5. Spectacle (Semaphore) crank.

6. Operating crank.

7. Supporting lever.

8. Dash Pot.

9. Lock pawl and gear teeth on Spectacle lever.

10. Contact arrangement:

11. Terminal Block and Lightning Arrester.

1. Electro Magnet: This consists of Electro-magnetic coil core, armature lever with springs.The core and armature of 600 Ohms are laminated to overcome the effect of eddy currents.Unauthorised resetting of the signal arm to "OFF" position by physically pulling, the armdownwards is prevented by the tooth of the pawl engaging in the toothed portion of thespectacle lever.

2. Spectacle (Semaphore) lever: Spectacle arm lever is rigidly connected to other end ofSpectacle crank and teeth also provided which engages with lock pawl, which preventsoutside interference.

3. Operating lever: Operating lever is rigidly connected to other end of operating crank.

4. Coupling lever: Coupling lever is accommodated between Spectacle lever and Operatinglever, which couples both i.e. Spectacle lever and Operating lever when armature isattracted condition.

5. Spectacle (Semaphore) crank: Spectacle (Semaphore) crank is connected in rear with thesemaphore arm lever.

6. Operating crank: Operating crank is connected in rear with the operating lever.

7. Supporting lever : Supporting lever supports Spectacle lever, Coupling lever and Operatinglever when the armature is attracted condition.

8. Dash Pot: This consists of a sliding cylinder, plunger nozzle, guide block and a helical springassembled together. It is mounted at the top of the reverser and guided in the guide block.Oil level in the dash not must be atleast 35mm. Above the bottom of the sliding cylinder.Dash pot acts as shock absorber when arm fly back to ON position.

9. Lock pawl and gear teeth: Lock pawl and gear teeth on Spectacle lever with sliding plungerarrangement is provided to prevent outside interference of signal arm moving to OFFposition. During reverser operation lock pawl is kept away from spectacle teeth by sliding

bar, which is operated by armature lever. Sliding bar moving upwards when armature isattracted.


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10. Contact arrangement: To provide ON and OFF positions of semaphore arms circuitcontrollers are used. Contact arrangement can be provided inside the reverser itself (or)outside. Outside contact arrangement are in two way or four way. Arrangement is mountedat the upper left quadrant of the reverser. The contact assemblies are connected by meansof links and cranks to the Spectacle lever.

11. Terminal Block and Lightning Arrester: Terminal Block for wiring purpose through lighting

Arrester.

Fig : 1.2 (A) POST TYPE (STYLE B) REVERSER L.Q.


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Fig : 1.2 (B) POST TYPE (STYLE B) REVERSER U.Q.

1.6 Performance of STYLE B Reverser:

Normal Position: (Fig 1.3 ): Operating Lever connected with Operating Crank keeps ArmatureLever in the lifted position i.e., closer to the Electromagnetic Core. Spectacle lever connectedwith the Spectacle Crank is released from the pawl. Signal is in "ON" position corresponding tothe normal position of the lever.


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Fig : 1.3 LEVER NORMAL ON (STYLE B) REVERSER L.Q.

Operation: (Fig.1.4 A & B) : When the Coil is energised and the Signal Lever is pulled, theOperating Crank is pushed and the Operating Lever moves downwards. Roller "B" of theOperating Lever comes in contact with the cam surface of the Coupling Lever. Since theArmature Lever which is electrically held, holds the ball bearing of the support lever connected

to the coupling lever, the pressing of the Roller "B" on the cam surface of the Coupling leverpulls the spectacle lever. The spectacle crank is thus pushed up and the signal is lowered. Itmay be noted that in this position the holding of the armature lever by the operating lever is nolonger existing. However, the signal remains in the off position. This is due to the fact that thetip of the armature that comes in contact with the roller is shaped in such a manner thatreleasing force of the armature is independent of the load on the spectacle.

Fig : 1.4(A) LEVER REVERSED SIGNAL OFF TO 45 (STYLE B) REVERSER L.Q.


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Fig : 1.4(B) LEVER REVERSED SIGNAL OFF TO 90 (STYLE B) REVERSER U.Q.

Disengagement of Reverser: (Fig.1.5): Any interruption in holding current releases thearmature. Ball bearing loses its support and coupling lever gets disengaged so that the weightof the semaphore signal pulls the operating lever. This strikes against the Dash Pot to dampenthe return movement of the Semaphore Signal.

Fig : 1.5 LEVER DIS-ENGAUGED SIGNAL RETURN TO ON (STYLE B) REVERSER U.Q.


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Once the armature lever is disengaged, the Armature cannot pick up again electrically but thesame must be mechanically reset. The lever operating the sign must be put back to normal,which imparts a stroke of the Operating Crank and in turn the Operating Lever which movesupwards, presses down the Spring of the Armature Lever bringing the other end closer to theElectromagnet Core. This pushes the sliding bar on electromagnet, which in turn pushes thepawl thus making the spectacle lever free for the next operation.

Fig : 1.6 (STYLE B) REVERSER - SINGLE WIRE WORKING

Fig : 1.7 (STYLE B) REVERSER - DOUBLE WIRE WORKING


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1.7 COMPARISON OF STYLE A & B REVERSER:

A TYPE B TYPE

1. Reverser moves along with the spectacle Reverser does not move - Fixed type signalFloating type.

2. The slide of the reverser has to be Minor changes in position changed ofchanged when converting from LQ to HQ. cranks can be made of to UQ site easily

for converting to UQ working.

3. Inferior in design. The entire load of the Superior in design due to leversignal is borne by the armature and hence arrangement which does not make thebecomes sensitive to voltage fluctuations. armature to take the load of the

signal directly and hence the workingis satisfactory and will be lesssensitive to voltage fluctuations.

4. The reverser slide is exposed atmosphere Reverser is enclosed in a dust proofand collection of dust etc., results in unsafe case.Working.

5. Locking arrangement is not provided. Locking arrangement is provided.

6. Physical operation of signal arm when Not possible.the electromagnet is de-energised is possible.

7. No shock absorber is provided. Shock absorber is provided.

8. Separate circuit controller arrangement Circuit controller is provided inside

has the to be provided for proving the reverser.position of arm.

9. No lighting discharge and terminal board Lighting discharge and terminal boardsis provided. are provided.

1.8 The following checks should be made before installation.

Oil level in the dash pot should be at least 35mm above the bottom of the sliding cylinder.

Check whether all the parts are there in the reverser and check the tightness of bolts and

nuts. See that all split pipes are in proper position and their ends are opened. Check the correctness of internal wiring upto the terminal board.

Lubricate the parts wherever necessary and operate and ensure smooth working.

Fix the reverser as per standard drawings and connect the signal down rod to thesemaphore crank and the down rod to the operating cranks.

Adjust the down rod such that in the normal position the operating and semaphore leversare in proper position. This can be done by aligning them to the arrow mark made on thebridge and the levers.

Ensure that the armature houses properly on the core face of the electromagnet in thenormal position.


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Ensure that the clearance between the link lever and the spectacle lever is not more than1mm.

Holding the armature by hand or by suitably clamping the operating lever and by pulling thesignal lever observe the following :

a) Signal is cleared

b) The operating lever roller is in contact with coupling lever

c) Circuit controller contacts for OFF position are made

d) All the cranks and levers are at their respective reverse stops.

Put back the signal lever and ensure that the cranks and levers are at their respectivenormal positions.

Check the circuit controller for correct adjustment of its contact bands.

The counter weight lever is connected to the operating crank and the spectacle to thesemaphore crank.

When the lever is normalised the operating lever (which is connected to the operating crank)presses the spring connected to the armature to maintain only the minimum air gap between thearmature and the electromagnet.

With the electromagnet energised the armature lever holds the ball bearing of the support leverand prevents the movement of support lever. Consequently the coupling lever cannot movetowards the armature but is free to move down wards. When the lever is operated the roller ofthe operating lever rests over the cam surface of the coupling l lever which connected to the

semaphore arm lever causes the movement of this lever also downwards imparting a stroke tooperate the signal. By suitably positioning the cranks the reverser can be used for L.Q. andU.Q signals.

When the supply to the electromagnet is disconnected the armature is released the supportlever is forced to move below the armature lever by the coupling lever thereby releasing thesemaphore arm lever. The signal returns to ON due to gravity. In contact with the working ofstyle A reverser. Its armature does not share the entire load of the signal arm due to the leverarrangement. Thus, the armature retains stable even when the battery is slightly rundown.

Additional facilities such as on dash pot to absorb the shock. Circuit controller and locking ofthe reverser are provided.

1.9 PERFORMANCE TEST :

1. When the electromagnet is energised at 10V and the signal lever is pulled, see whether thesignal is reversed to the fully operated position.

2. Strain the transmission and ensure that the armature does not disengage and the signaldoes not fly back to on position.

3. With signal OFF disconnect the supply, it should return to ON smoothly.

4. Now force the signal arm manually and ensure that the link lever locks the semaphore armlever and the signal arm remains in ON position.


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5. Put back the lever check whether the armature houses close to the core face. Check theposition of different levers. They should be in their normal position.

6. Put back the lever check whether the armature houses close to the core face. Check theposition of different levers. They should be in their normal position.

7. Without energising the electromagnet operate the lever the signal should remain ON.

8. Check whether link lever has engaged with the semaphore arm lever. Check whether thearmature is disengaged from the core or not. It should be dis-engaged.

9. Put back the lever and strain the transmission the signal should not be towered and thearmature should disengage from the core face.Note: Refer sketches showing positions of reverser cranks and levers during operation.

1.10 MAINTENANCE :

1. An intervals all the moving parts must be well cleared and oiled. Oiling must be done atleast once in a fortnight. Excessive oiling should be avoided. Ball bearings should not beoiled but greased.

2. Screws split pins and nuts must be checked and if loose tightened immediately.

3. Check the oil content and level of the dash pot once in three months. If the height of the oilis reduced fill up to the required level with the insulating oil for the transformer. If the oil isfound sludgy.

4. The contacts of the circuit controller should be kept cleaned and free from dust.

5. Check the alignment of levers, adjust suitably if necessary.

6. The surface of the core and the armature should be cleared free from dust. Theelectromagnet sliding bar should be lubricated and see that it slides freely.

7. If it is observed that at any time the armature sticks due to residual magnetism. The polarityof supply to the Electromagnet must be changed to nullify this effect. If it still exists, replacethe core. To prevent acquisition of residual magnetism the manufacture has providedlaminated core and laminated armature.

8. Sometimes the armature sticks mechanically due to bending of the fulcrum pin of thearmature. Under such circumstances the reverser should be sent to workshop for repairs.

9. If the reverser does not function at the rated voltage the voltage should not be increased,but the reverser sent to workshop.

10. It should be periodically overhauled after every 7 years.


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CHAPTER 2 S5E

INTER CABIN SLOTTING

2.1 Introduction: In a Station Yard having two or more cabins, a stop signal operated byone cabin may read over or have its overlap in the portion of track controlled by another cabin.

The cabin operating such a signal should not be able to take off the signal along without the co-operation of the other agencies, which have to ensure the safe conditions on the portion oftracks controlled by them. Under such conditions, it is necessary that the agency giving suchpermission should after setting and locking the route and ensuring that the concerned track isfree of any obstruction, release his control by means of operating a slot lever. The slot lever inturn holds the route set for lowering of signal till the arrival of the train after which the slot leveris put back. While the cabin operating the signal is referred to as operating agency, the cabinASM giving the slot is referred to as the controlling agency.

2.2 A few relevant paras of the Signal Engineering Manual are produced below:-

Para No.158 : Except where qualified cabin men are employed, the Station Master must be

provided with interlocked mechanical or electrical control of the Warner. Home and last stopsignal.

Para No.159 : Control of Starters/Advance .Starters on single line. At single line stations wheretoken instruments are in use, the Advanced Starter or where there is no Advanced Starter, thestarters must be controlled by the token instrument of corresponding section.

Para No.160 : Control of starters/Advance Starters on double line. At double line stationswhere block instruments are in use, and where the signals are not operated from the samelocation as the block instruments, the Advance Starter or where there is no And. Starter thestarter must be controlled by the line clear indication of the block instrument of thecorresponding section.

2.3. Essential Principles of Slotting:

1. It should not be possible to take off a signal, which is slotted by one or more agencies,unless the corresponding slots have been received from these agencies.

2. Visual indication should be provided in the cabin to indicate the receipt of slot.

3. In case of any emergency it should be possible or any operating or slotting agency to putback the signal arm to ON position independently.

4. Where track circuits are provided, the concerned slot circuits should prove clearance oftrack circuit.

5. Where track circuits are provided, the occupation of any of these track circuits shouldreplace the signal to ON automatically.

6. Suitable cross protections should be provided against any contact fault or cross feedvoltage.

7. When a slotted signal is replaced to ON either by withdrawal of slot or actuation of TC bya train, other signals, which are released by the slotted signal should also be replaced toON automatically. (Example: An outer signal should be replaced to ON when the slot

for Homes Signal is withdrawal.


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2.4 METHODS OF SLOTTING : These are four methods:

1. Mechanically by 3 lever slot method2. By electrical transmission of E type key released from a lock fixed on the slot ever. This key

is used to release the slotted signal.3. By providing an electrical lever lock and circuit controller on the operating lever of the slotted

signal.4. By using an electrical signal reverser on the slotted signal.

2.5 SMS SLIDE CONTROL :

SMs control box manufactured to standard patterns are 10 way, 16 way and 20 way. Inaddition, another slide called a station Master slide is provided to lock the SMs control slidesboth in normal and reverse positions to prevent unauthorised operation. Arrangement to lockthis SMs slide in reverse position is also provided by means of a drawer type lock, the key ofwhich will be in the personal custody of SM. Mechanical locking is provided between the slides.

Each control slide consists two sets of normal and reverse contacts. These are used forelectrical slot and cross protection circuits.

Locking and sealing arrangements are provided to guard against unauthorised opening of thecontrol box.

2.6 SLOT INDICATORS :

There are two types of indicators.

a) Disc type

b) Banner type indicators with ON & OFF indications.

These indicators have a resistance of 1000 ohms and work on a few milli-amperes and are notsensitive to the polarity. In Electro- mechanical signalling areas these indicators are replaced byluminous white lint indicators, which are provided with 12V/4W lamps.

These indicators are necessary to guide the cabin-man to set the desired route for the receptionand dispatch of trains and to take off the relevant signal. Also this confirms that he has obtainedthe permission from the slotting agencies.


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Fig : 2.1 TYPICAL ICC CIRCUIT FOR ONE SLOT AND ONE STATER (S/L) L.Q.


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Fig : 2.2 TYPICAL ICC CIRCUIT FOR ONE SLOT AND ONE STATER (S/L) C.L.S


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2.7 CIRCUIT EXPLANATION:

2.8 In this chapter the principles of slot circuits for

i) Single line LQ Signalling with end cabin.ii) Single line UQ Signalling (Double wire) with end cabins andiii) Slot circuits using metal contacts are dealt with.

2.8.1 Single line L.Q Signalling:The arrangements are as shown in layout (Fig. 2.4) Eachsignal is provided with a slot relay to eliminate line drop. The slot relay shall not pick up unlessthe following conditions are fulfilled.

1. The overlap is set and locked by the far end cabin and slot lever is reversed.

2. The signal can be taken off only on obtaining permission from the stationmaster (SM's)control slide is reversed.

3. Conflicting Signal slot relays cannot operate simultaneously conflicting signal slot relaysare energised.

4. Track is not occupied - OPTR.

5. Adequate Cross protection to prevent taking off signal due to false feed. This should beprovided separately (a) for portion between far end cabin and SM's office by shortcircuiting slot control lines by normal band of far end cabin by short circuiting controllines by normal contact of SM's slide.

When the slot relay is energised a visual indication appears and the operator can nowtake off the signal provided the following conditions are fulfilled.


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1. YSR relay is up. This relay ensures that for each slot only one movement can takeplace.

2. Slots are received from all controlling agencies.

3. Economiser contact of the Signal lever to conserve power.

4. Cross protection to prevent energisation of signal reverser when the controlling lever isnot operated.

5. Outer Signals cannot be taken off unless one of the Home signals is taken off by proving'OFF' position contact of Home Signal arm.

6. The Warner Signal shall not be not taken off unless all main signals are taken off i.e.,Advance Starter (Proving permission to approach from station in advance has beentaken on block instrument) Main line starter, Main Home Signal and outer signals aretake 'OFF'. This signal should also be controlled by the Station Master.

2.8.2 SINGLE LINE U.Q. SIGNAL (D.W.) WITH END CABINS: Layout (Fig.2.5) shows athree line single line station provided with D.W. MAUQ signals. The principles involved inslotting are the same but certain additional facilities have to be provided in this type of signallingsuch as route holding etc., Unlike in LQ Signalling, first stop signal at station provided with threeaspect U.Q. Signalling is located at 300 m from the first facing points. In such cases, the routeholding can be achieved by providing an extra miniature lever in the cabin to hold the route. Theoperation of this route lever in the cabin should also be controlled by Station Master. This isachieved with the help of the same slot controls as used for controlling the signals. Similarly theroute lever normalisation is also controlled by the Station Master.

The slot levers used in D.W. frames are miniature lever 2 position or 3 position type, 3 positionminiature levers are used for two conflicting slots say Dn. 1 loop Home and Dn. II loop Home.

They may also be used as a route lever cum slot lever. For example, the push position (F)centre to- top may be used for Dn. main slot and pull position (T) centre to bottom may be usedfor up route lever.

In the case of main Home signal which has 3 aspects, the taking off of this signal from 45 to

90should fulfil all the conditions as that of a LQ Warner. Since the reverser is already fed for

taking off through the AR band of 45aspect controlling lever, without fulfilling the condition

stipulated for clearing the signal to 900aspect, the signal can be taken off by just pulling the 90aspect controlling lever (successive operation). In order to ensure that the signal can be taken

off from 45 to 90by pulling the second lever only on fulfilling the requisite condition a 90aspect controlling relay is made use of. The supply to the signal reverse is taken through

Normal band of 90aspect control lever cut by 90aspect controlling relay front contact. With

this arrangement when the 90 controlling relay is in de-energized condition (i.e., advanced

starter and main line starting signals are at 'ON' the 90aspect controlling lever is operated, thesupply to the signal reverse is opened and the signal will fly back to danger.

2.8.3 Slot circuits using metal to metal contact relay.

2.8.3.1 Of late metal to metal contact miniature relays (K-50 type) assembled in-groupsare being employed for signalling circuits. The use of metal to metal contact relays may lead tofailure due to welding of contacts and therefore various precaution will have to be taken tosafeguard signalling circuits provided. Some of the precautions generally followed are listed as

under:a) The front contacts of these relays should be proved in two or more circuits so that no

unsafe condition may arise.


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b) De-energisation of the relay must be proved before commencing the next sequence. Ibisis achieved by proving the back contact of the relay in signalling circuits.

c) In important circuits double cutting must be provided.

In addition to saving of space the design of the contacts of these relays are having many

advantages. The contacts are double make double break type which give the following facilities:

a) The air gap is doubled reducing the possibility of arising ( intensity of arcing is reduced).

b) If a contact gets welded at one end, the circuit can still be opened at the other end.

c) The contacts are reversible. Front and back contacts can be easily interchanged.

d) At time. of make and break , there is a wiping action and thus they become self cleaning.

The circuit elements (Seimen's make) used in Inter-cabin control system are generally availablein group units designated as group Bl, group B2 and group R3. These group relays aresufficient for controlling all signals at a three road single line station. The group B1 consists offifteen relays of which five relays have 6F/2B contacts, eight have 5F/3B and the remaininghave 4F/74B contacts. Five relays used for slotting purposes namely YSR, YSPR, YSP2R,YSPR1R, YSPR2R1 & ZR relays.

Relay group B2 consists of ten relays with 5F/3B contacts. These relays are used as track stickrelays for LVT and FVTS and for f irst track repeater relays.

The principles of signalling circuiting using these relay groups are shown in figure 2.6.

YSR :All slots (different controlling agencies slot lever normal proving relay).

YSPR: Repeater of YSR. This also proves that all reception and despatch (advanced starteronly) signals controlling levers on the local cabin are normal.

YSP1R: First repeater of YSR.

YSP2R: Second repeater of YSR.

YR : Slot relay. Picks up when slots are released by all the slotting agencies. Individual slotrelays are provided for each signal (Home and Advanced starters).

LVMR :Last vehicle track repeating relay.

LVMR & LVMR: Repeaters for LVTP1R.

TCS: Track stick relays. This checks correct functioning of the already set. Also helps innormalising the route in case of failures.

2.8.3.2 Circuit explanation:All the track circuits used in this system are closed trackcircuits. See Fig. 2.6 A & B.

Normally relay YSR, YSPR, LVTR, FVTR, TCS and their repeater relays are in the energisedcondition. When any one of the slotting agencies releases it slot relays YSR drops but YSPRremains stick. Subsequent release of slots from other agencies for the same route, the

concerned slot relay YR operates provided the track circuits in route are clear. A visual indicatorappears.


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CHAPTER 3 S5E

ELECTRIC LIFTING BARRIER

3.1 Introduction: Level crossing gates are classified as Special, A, B, C & D depending on

importance of road & volume of rail - road traffic All Special, A & B class level crossings areprotected/gradually being protected by signals. These level crossings are operated at least 30times on average per shift of gate-man and as rail-road goes up, the number of operations willincrease. IRS Spec: S41

The level crossings are provided with lifting barriers, which are operated by a central winchthrough wire transmission. The lifting barriers are locked through rod-operated mechanism.

Necessity of introducing electric operated lifting barriers on Special, A & 8 class level crossinggates.

Fig : 3.1 A TYPICAL DIGARAM OFELECTRICALLY OPERATED LIFTING BARRIER GATE


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3.2 Drawback of mechanical lifting barrier is:

a. Present design is heavy maintenance oriented. Wire transmission is prone to failures andoutside interference. Hence, there is need for minimum maintenance system.

b. Mechanical operations, demands physical exertion and with frequent opening / closing ofgate.

c. Mechanical gate pedestals erection on same side of road i.e. both barriers are operated inparallel. This impedes flow of road traffic in one direction.

3.3 Advantage of electrical operation: Electrically operated lifting barriers are very simplein design. Frictional horsepower electric motor, motor speed reduction gear and camoperated switches can be of highest quality. The main bearings of barrier can also bedesigned for more than 5 years of failure free service. Thus the system will be almostmaintenance free. The other advantages are:

a. Absence of physical strain on gate man. Even in isolated case of failure of electrictransmission system, barriers can be hand cranked, the mechanical advantage can bekept high for effortless operation. (However both barriers will have to be crankedseparately as they are not mechanically linked).

b. Barrier pedestals can be erected on opposite sides of roads for equal flow of road trafficwhen barriers are raised. If barrier pedestals are erected on LHS of road at entry ends,road vehicles get more time to clear while closing the barriers.

c. The time of operation is only 10 sec. against 60 sec. for manual operation.

d. Barrier width is enlarged to increase its visibility to road users.

e. Barrier consists of segments bolted together. In case of damage to barrier by roadvehicles, the damaged segment can be replaced easily and down time can be reduced

The power requirement for electrical lifting barriers only will be around 200 Watt for 10 seconds.In CLS territory (both RE & non-RE) and in semaphore signal territory with electrical circuitry,this much power can be derived from existing power source for signals. For semaphore signalterritory, where gate signals are purely mechanical, solar power with battery back up will beadequate.

3.5 Application of electric lifting barrier: For special, A & B class level crossings, it is

suggested that electrically operated lifting barrier are gradually introduced. Typical layout isshown in sketches 'A'&'B. The system should comprise of following and should be integrated formaximum benefits:

The benefits

Increased interval between maintenance visits

Elimination of failures and reduction of down time when barrier is damaged.

No risk of blank signal either for rail or for road.

Logging events possible.


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Increased safety due to boom lock and lock detection

Feasibility of remote operation in conjunction with close circuit TV

Effortless operation and hence improved service condition of gate man.

TERMENOLOGY:

Electric lifting barrier: An electrically operated device for closing the level crossing gateagainst road traffic and comprises an electric motor, operating mechanisms. Circuit controller,road, signals, and audible device. Boom etc.

Level crossing: The section of a road where the railway track crosses it at the same level.

Operating mechanisms: Consisting of clutch, reduction gear, boom shaft and suitable blockingdevice.

Boom: That part of the barrier, which in horizontal position prevents passage across the levelcrossing.

Snubbing device:A device employed apart from the clutch, to minimise the physical shock-due to stopping the mechanisms at the end of its stroke.

Time of operation: The time required to operate the barrier form horizontal to the verticalposition and Vice versa, but does not include the warning time.

Short time rating: A rating which specifies the load at which the motor, starting at the ambienttemperature may be operated for the period and under the conditions specified on the ratingplate, while complying with the requirements of this specifications.

Crank handle: An appliance by which electrically operated lifting barrier. may be manuallyoperated at the mechanisms.

3.4 General requirements:

i. Lifting barrier shall be robust in construction and the operating mechanism shall beprotected from unauthorized interference.

ii. The boom of the barrier shall be light in construction and shall extend across the full widthof the road.

iii. The height of the boom from the rail level shall be 1m.

iv. A support mounted on a base shall be provided for the tip of the boom in the horizontalposition.

v. The lifting barrier shall be provided with a pedestal suitable for mounting on a base.

vi. Fringes, if provided, shall be clear of road surface by not more than 15cms. When theboom is in the horizontal position.

vii. The raised or open position of the lifting barrier shall be within 858 to 908 from the

horizontal and lowered or closed position shall be within 58from the horizontal.


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viii. At the centre of the boom, the lifting barrier shall be provided with a 600mm diameter. Reddisc having red reflector buttons facing the road traffic.

ix. The boom shall be painted / pasted with radium sticker alternately with 300mm Bands ofblack and yellow. The fringes, if provided, shall also be painted similarly.

x. Lifting barrier shall be so designed that it can be stopped, reversed or its movement

obstructed at any point during operation without damage.

xi. The mechanism shall be designed to prevent movement of the lifting barrier due tovibration or any external force applied to the mechanical connections or boom.

xii. The design of mechanism shall be such and the boom so balanced that in case of failureof power supply, the barrier shall remain in the position last assumed.

xiii. The mechanism shall be so designed that if the boom is obstructed during operation itshall stop and on removal of the obstruction shall assume the position corresponding tothe control apparatus, unless protective devices have operated.

xiv. The movement of the lifting barrier shall be arranged to prevent any undue shock on themechanism. Suitable snubbing device capable of operating efficiently under all weatherconditions shall be provided.

xv. Means shall be provided to adjust the counter-balance of the lifting barrier.

xvi. The operating mechanism shall include a suitable device to lock the lifting barrier in thevertical and horizontal positions.

xvii. Electrical contacts shall be easily accessible and independently adjustable.

xviii. Electrical contacts shall be of low resistance, quick acting, self-aligning and wiping typeand shall conform to IRS Specification No.S-23 [Electrical Signalling and InterlockingEquipment (Tentative)].

xix. In addition to regular contacts for controlling the lifting barrier, a minimum of 4-additionalcontacts shall be provided for controlling the external circuits, unless otherwise specifiedby the Purchaser.

xx. Bearings shall be of ample dimensions to ensure durability and conform to IRSSpecification No.23 [Electrical Signalling and Interlocking Equipment (Tentative)] and shallbe so constructed as to prevent entry of water.

xxi. Provision shall be made for proper lubrication at convenient locations of the bearingsurfaces and moving parts of the machine wherever necessary.

xxii. Exposed oil holes, cups or grease nipples shall be provided with weatherproof springloaded covers.

xxiii. Lifting barrier shall have two booms, one across the road on either side of the levelcrossing, operated by independent mechanism.

xxiv. Means shall be provided for manual operation of the lifting barrier by a hand-crank in caseof power failure. The insertion of hand-crank shall disconnect the power supply to themotor and it shall not be possible to reconnect the power supply until the hand-crank is

withdrawn, and a switch is operated.


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xxv. A separate fracture segment shall connect the boom with the mechanism near the pivot.Fracture segment mounting shall be of such a design that in can be replaced easily andquickly, and in case of a mighty hit, shall allow for the break of the segment withoutendangering mechanism itself.

3.6 Road signals:

Fig : 3.2 TYPICAL DIAGRAM FOR ROAD SIGNAL WITH ELECTRIC LIFTING BARRIER


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Road signals:

a) Where required , audible and/or visual warning arrangements for the road traffic shall beprovided along with the lifting barrier.

b) Audible and visual warning arrangements for the road traffic shall start operating 6 to 8

seconds before operation of the barrier from its vertical or open position and shall continuetill both the booms reach within 108of the horizontal position.

c) The audible warning arrangement for road traffic shall consist of an electric bell operating onthe same voltage as of the boom. One bell shall be provided at each side of the levelcrossing.

d) The bell warning shall operate with a clear ringing sound and shall be audible for a distanceof not less than 300 metres in a direction that the sound waves are not obstructed on a clearday, with the wind velocity and the extraneous noises negligible.

e) The visual warning arrangement shall consist of a road signal of the colour light signal typeand the range of visibility shall not be less than 180m, burning at 90% of the rated voltage.

f) The colour light signal may display either a steady red light or a pair of horizontally mountedflashing red lights as specified by the Purchaser.

g) Where a steady red light is specified to be provided , it shall continue to be displayed whenthe boom is horizontal and when the boom is being raised till the boom assumes the verticalposition. Thereafter a steady white light shall be exhibited to the road traffic.

h) Flashing red lights, where provided, shall flash alternately @ 45 to 55 flashes per minute, sophased that one of the pair of red lights is always exhibited to the road traffic during the

flashing period. They shall become steady once the boom reaches within 10 of thehorizontal or closed position and shall continue to display a steady red indication, when theboom is being raised till it assumes the vertical position. Thereafter, a steady white lightshall be exhibited to the road traffic.

i) The roundels used for the road signals shall have 30 horizontal spread light with 158downward deflections.

3.7 SEQUETNICE OF OPERATION: The operation of the lifting barrier shall takes place inthe following sequence:

i. Open the detection contacts

ii. Unlock the boom,

iii Move the boom

iv. Lock the boom in the full horizontal or vertical position

v. Close the detection contacts


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OPERATING CHARACTERISTICSLow voltage 24VDC 6-8 Amps for boom lengths upto 8 metres

Low voltage 24VDC 8-12 Amps for boom lengths above 8 metresHigh voltage 110VAC 50 Hz single

phase2 Amps.

Time of operation of the lifting barrier shall not exceed 10 seconds at rated voltage and 20seconds at 75% of rated voltage at the motor terminals.

3.8 Control panel:The control panel incorporates facilities to operate the two boom individually as well as

simultaneously. The control panel may be either of the miniature lever type or provided withpush buttons. In either case suitable arrangements are incorporated to stop the barrier in anyposition.

In case of power failure during the operation of the barrier it is not possible to resist tonormal working. On resumption of power supply. Unless an additional switch or lever providedfor this purpose is operated. Contractors of the approved type are provided for the operation ofthe barrier. Suitable protection devices we provided to disconnect the circuit in the case of

overloading of the motor. The control panel incorporates flashes and a time limit of approveddesign. Then control the initial delay for warning and the correct flashing rate as specified underroad signals.

Fig : 3.3 CONTROL PANAL OF ELECTRIC LIFTING BARRIER


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3.9 INSTALLATION OF HIGH VOLTAGE (110V) ELECTRIC LIFTING BARRIER:

1. Prepare the foundation. In case two Barriers are installed in the sameline to cover thelonger road span, the two foundation must be in the same line with accuracy of + off centrein both holes. This can be easily achieved by stretching a twine line along the complete span ofthe road.

2. After properly settings up the foundation bring the pedestal and put on the foundationtighten up all the four foundation nuts firmly.

3. Put declutching bolt from the side and de-clutch the friction clutch.

4. Make the boom actuator horizontal by hand and give the support from front and rear tokeep firm in that position. Take out the declutching bolt.

5. Assemble the complete length of boom separately (without fringes).

6. Join the boom with boom actuator in position. Naturally the boom will be supported at farend also.

7. Fix the fringes to the boom in proper position.

8. After putting the counter weight bolts on the rear side of the boom actuator, the counterweight plates should loaded one by one. Please note that heavier plates should come first,while loading. After putting all the plates and tightening the nuts, the balancing can bedone.

9. BALANCING: The Barrier must be balanced perfectly before operation. The counter weightcan be shifted backward of forward to achieve perfect balancing. The friction clutch shouldbe Declutch by the declutching bolt and the boom will be free to move. By putting the onehand pressure on the counter weight the Barrier should be able to move. Once this is

achieved take off the supports and move the barrier to 45position by hand. After relieving

the hand pressure the barrier should have the tendency to come down (rather than goingup) very slowly. Once this is achieved it means that the barrier is perfectly balanced.

Before switching on the supply and operating the barrieron. Electric motor, proper care must betaken to ensure the correct direction of electric supply. There is always the chance that thesupply may be in reverse direction. This can be tested as follows,

Declutch the friction clutch by clutching bolt and make tile boom free gearing system. Switch onthe supply in one direction, which will get in motion, the system before friction clutch. Watch thefriction in which it is rotating. Suppose it is moving to bring the barrier horizontal move thebarrier by hand to horizontal and see that the proper limitswitch operates to stop the motor. Ifthis is not the case only the supply lines should be interchanged to change the direction of

motion. This will not happen in single-phase D.C. supply if the limit switches are connectedproperly.

Please note:

1. That if the barrier is not properly balanced it will give excess of load (unbalanced) on thegearing system and motor, which may damage the bearings, gears or electric motor. Thebarrier is designed to take unbalanced load (such aswind pressures for a short time, butcontinuos unbalanced operation may damage the barrier.

2. Ensure all the Parts to be free for rotation and properly lubricated before giving the electricsupply.

3. Foundation bolts and counter weight bolts must be firmly tightened. Otherwise any shifts ofthe pedestal or counter weight will. Damage the barrier in operation.


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S.No. Name of Part S.No. Name of Part

1 Boom First Piece B Lock 10 Hex. HD. /Nut

2 Reduction Gear Box

Double Extended Type

11 Needle Bearing

3 Friction Clutch 12 Lever Pin

4 Clutch Facing 13 Shaft no. 1 with Gear levering

5 Friction Plate with Pin 14 Gear 18 teeth with round Nut6 Cross Bolt 15 Circuit Controller with Limit switch

6ways

7 Compression spring 16 Drive belt No. A-28

8 Gear pin 17 Declutching Bolt

9 Gear Pin Hex. HD. Nut 18 Mechanical Lock

Fig : 3.5 GATE MACHINE - DRIVE MECHANISM


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Fig : 3.6 TYPICAL CCT FOR POWER OPERATED LIFTING BARRIER


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Fig : 3.7 WIRING DIAGRAM FOR POWER OPERATED LIFTING BARRIER MACHINE


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Fig : 3.8 (B) WIRING DIAGRAM FOR ELECTRICALLY OPERATED LIFTING BARRIERPERMANENT MAGNET TYPE


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CHAPTER 4 S5E

ELECTRIC KEY TRANSMITTER

4.1 Introduction: The simplest way of controlling a signal or point or level crossing gate forthe SM is to retain the key of the controlled apparatus (which is normally locked) and issue the

key for releasing the apparatus when required.

As the physical transmission of the key to the controlled spot entails delay, Electrical KeyTransmitters are provided in which key is normally kept locked in a Transmitter at site and asimilar key Transmitter is fixed in stationmasters room. They are electrically interconnected.The instruments have galvanascopes to indicate visually that a key is transmitted for callingattention either a bell or phone connection is provided between the end.

The Electric key Transmitters are of robust construction and are normally fixed close to theappliances, which is to be released by the key. The keys are so designed that one does notenter any other instrument of its kind. They are provided with locking or sealing arrangementsfor security reasons.

4.2 General requirements:

The Key Transmitter shall be such as to receive an interlocking Key of an approved type. It shall not be possible to insert and operate in the lock any other key except the one for

which the Key Transmitter is intended.

The tumblers proving the wards of the key shall be provided with an arrangement to forcethem back to their normal position before the key can be extracted.

The transmitting key shall get locked in the Key Transmitter before the control can betransmitted to the Key Instrument at the other end.

It shall not be possible to extract a key once inserted and locked in the Key Transmitterunless it is released by the electrical control received from the other end.

It shall not be possible to transmit control to the instrument at the other end andsimultaneously release the key from the Key Transmitter transmitting the control.

It shall not be possible to release the key by jerks or any other irregular means. The Key Transmitter shall be suitable for operation on two wires. There must not be any opening giving access to the interior of the Key Transmitter through

which it is possible to operate the mechanism by any irregular means.

Facility shall be provided for locking and/or sealing the Key Transmitter. The Key Transmitter is shall be of robust construction fit to withstand rough handling.

4.3 Description of E.K.T: The Electrical Key transmitter consists of a cast iron case in twoparts.

a) The front portion or cover having a hole for the insertion of key and a galvana-indicator with aweighted needle to rest in vertical position to indicate the incoming and outgoing currents Fig4.1 (A).b) The back portion interior mechanism of base consists of three parts, viz.,As shown in Fig 4.1(B).

1. Electro-magnetic unit assembly.2. Contact arrangement unit and

3. Locking unit.


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Fig. 4.1(A) ELECTIC KEY TRASMITTER ASSEMBLY DIAGRAM FRONT COVER(Heppers Key Transmitter)


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4.3.1 Electro-magnetic unit: The Electro-magnet occupies the upper portion of the case

having a coil resistance of 12.5 . The minimum voltage required to operate the magnet is3.75V DC and working voltage is 5V DC and current 350mA as per Specification No.S.21 of1.3.71 (correction slip). The Magnet has Four pole faces. The main pole faces attracts thearmature which in turn releases locking plungerfor extraction through its extension formed witha detent at its extremity. The auxiliary pole face has a staggered position and is placed behindthe Visual Indication in the cover. The needle of the dial works as a Galvo and deflects towardsRight Sideas soon as the Coil becomes energized.

4.3.2 Contact unit: The contact unit consists of 5 contacts insulated from each other.Contact numbers 1& 2and 3 & 4normally remain connected at the Receiverend with key In thetransmitter, whereas at the sending end contact nos.1&2 and 3&5are connected when the keyis depressed and turned, to establish the line circuit with Electro-magnet coils connected inseries.

4.3.3 Locking unit: The locking unit consists of twoplungers, namely locking plunger andreleasing plunger.

a)Locking plunger: The locking plunger placed on the left side of the unit carries an insulatedpin, which makes contact between contacts 1 & 2 when, the key is IN. When the key isextracted, the plunger moves downwards and disconnects the line connection by breakingcontacts 1 and 2. The movement of the locking plunger is restricted by means of the armature-extension when the Electro-magnet is not energized, thus, preventing the key from extraction.

The provision of a spring plate at the LHS bottom of the Locking Plunger is to keep the lockingplunger in correct position either in key ln or key out otherwise the locking plunger can notmove down and breaking the contact 1&2 and disconnecting the circuit.

b) Switch plunger: The switch plunger placed right side of the unit is normally retained in its

upper position by the action of a spring. It carries on insulated pin, which makes contactbetween 3 & 4 when the key is not turned towards right hand side. When the key is turned theplunger moves downwards and contacts 3 & 5 are made connecting the battery positiveterminalto the line circuit. The provision of a helical spring at the RHS bottom of the ReleasingPlunger is to ensure continuous and conscious key transmission from sending end of theinstrument

A small roller (tappet lock) is fixed between the locking plunger and releasing plunger so thatone of the plunger can be depressed at a time. The movement of the key is controlled by threenumbers of brass tumblers. The proper combination of wards, lug and feather accepts onlycorrect key in the transmitter.

4.4 Force drop arrangement: Force drop arrangement provided on the armature of theElectro-magnet to avoid the effects of residual magnetism and ensure that the lock plunger isproperly locked before transmitting to release other end instrument key, otherwise, both keysmay be simultaneously release. The electrical lock shall be of gravity type and provided with anefficient forced-drop arrangement


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Fig. 4.1(B) ELECTIC KEY TRASMITTER ASSEMBLY DIAGRAM(Heppers Key Transmitter)


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LEGEND:

1. Metallic Base2. Contact spring Assembly3. Pin (L.H.)4. Electro-Magnetic coil5. Base

6. Strap7. Drum Assembly8. Stud9. Spring10. Contact Spring Assembly11. Quick Return Gear

Fig. 4.2 ELECTIC KEY TRASMITTER ASSEMBLY DIAGRAM(Rotary Key Transmitter)


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Fig. 4.3 E.K.T.WIRING DIAGRAM IN NON RE-AREA

4.5 Electrical Key Transmitter Instrument in RE AREA : The working of the instrument inAC Traction Area from the given circuit diagram and bring out the important difference in the

circuit arrangement.

RE AREA NON-RE AREA

1. Separate AC immunized line relays areused.

1. Separate AC immunized line relays arenot used.

2. Telephone must be required because nobell is there for indication (audible).

2. No telephone is required due to thepresence of bell.

3. Two sets of supply is required (4V and12V).

3. One set of supply is required.

4. KTR (250 Ohms) relay is used. 4. KTR relay is not used.5. Circuit is not completed through earthbecause no earthing is permitted.

5. Circuit is completed through earth; butno earth fault is permitted.

2. Key Transmitter relay in RE circuit is 250 Ohm Instead of 1000 Ohms becauseIn internal circuit (N1B1) only 4V is applied, actuates both the (1) Galvona indication (2) KTRrelay. If the resistance of KTR increases the voltage will not function.


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4.6 Electrical Key Transmitter Instrument working in RE area: The working of theinstrument in AC as follows:

Fig. 4.4 E.K.T.WIRING DIAGRAM IN RE-AREA

Key transmission from X end to Y end: As the key is not inserted in location X contact1&2 not made. In location Y as key is inserted, contact No.1&2 is made. Contact e&4 is madein both the instruments. Now, key is inserted into the instrument of location X and contact 1&2is made now and when it is turned to right 3&5 is also made. Now the Key Transmitter Relayenergized and through front contact of KTR of location X current is transmitted to location Y.

And as KTR not energized in location Y through back contact of KTR (Y), LR relay of locationY is energized and through front contact of LR, armature coil is energized in location. So keycan be extracted at Y end.


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CHAPTER 5 S5E

SIGNAL ARM AND LIGHT REPEATER

5.1 Introduction:Where signals have to be placed in a Position entirely out of sight of thepersons operating them, arrangements should be made to repeat the arm as well as light.

According to General Rules (26) "The arm & light of any fixed signal which can be seen fromthe place from which the signal is worked shall be repeated to such a place by means of anefficient electric repeater.

Two forms of electric repeaters are necessary one to indicate the position of arm and the otherto indicate whether the light is burning or not, at night. Separate indicators will be provided inthe use of arms. But at signals where more than one light arm in use, such as at combinedWarner and outer signal, signals on a gantry or bracket posts (Signals manual 549), only onelight indicator may be used.

5.2 Working of instrument: The arm repeater consists of a dial with a miniature arm, whichcan assume three positions. Viz., ON, OFF and WRONG. When the indicator points to

ON it means that the arm of the signal is in its most restrictive aspect. When the indicatorpoints to OFF it means that the arm has been taken off and the signals is in the PROCEEDaspect. When the indicator points to WRONG it shows that there is something wrong and thateither the signal arm; is not fully ON or OFF or that the repeater circuits is out of order. Thearm repeaters are so adjusted that the repeater should show

(a) For two aspect lower quadrant signal:

(i) "ON when the arm Is + 5 deg. From the horizontal.

(ii) 0FF when the arm is 40 deg. To 60 deg. From the horizontal.

(Ill) *WRONG" in any other Position.

(b) For a multiple aspect upper quadrant signals:

(i) "ON when the arm Is + 5 deg from the horizontal.

(ii) 0FF when the arm is 40 deg. To 90 deg. from the horizontal.

(Ill) WRONG" in any other Position.

The light repeater consists of a dial with an Indicator having two positions viz. IN and OUT.

When the indicator points to 'IN' It Indicates that the light is burning and when points to OUT,the light in extinguished. Light repeater is provided with an alarm bell, so that if by night theSignal light goes out, the alarm bell rings.

Each signal light to be repeated need not be provided with an individual light repeater. Lights onthe same bracket signal or gantry. May be series repeated through on indicator. Audiblewarning devices may be common to all light repeaters.

A switch is provided marked "DAY" & "NIGHT" to out the ball circuit during day time when thelamp as removed. During night, the switch will be changed over to 'NIGHT" position to bring thecircuit in.

The arm and light repeaters may be combined in one instrument, the arm indicator taking theform, of a miniature semaphore and the light indicator being a disc or pointer showing "IN" orOUT.


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5.3 Description of the equipment: The apparatus consists of the following components:

(a) Arm Repeaters:

(i) Indicator with dial(ii) Contact box

(b) Light Repeaters:

(i) Indicator with dial(ii) Signal lamp with expansion contacts (or thermostat or pyrometer)(iii) Relay(iv) Alarm bell with 'cut out switch.

Fig. 5.1 SIGNAL ARM AND LIGHT REPEATER

5.4 Indicators:The indicator for the arm in wound to a total resistance of 300 Ohms, pointer(or miniature semaphore for arm repeater) is attached to the armature to indicate the actualpositions of arm and light.


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In the arm indicator when the current flows in one direction (say, when the signal arm ishorizontal) the magnetic fields set up round the needle deflects it in a direction, which causesthe miniature semaphore to take up a horizontal position. (a small stop pin prevents it frommoving beyond the horizontal position) When no current flows through the coil, the needlereturns to the neutral position by gravity and the arm in this position indicates OUT OFORDER or WRONG. When the current flows in the reverse direction, the miniature aredeflects to "OFF", indicating clear.

In, the light indicator when a current flows in the coil the indicator moves to the position 'IN'.' andwhen there is no current the needle is so balanced that it returns by gravity to the position whichindicates 'out'. When the indicator is in, this position, it makes a contact for an independent bellcircuit.

5.5 The contact box:This is used for the arm repeater only and is fitted on the signal postwith a slotted lever fixed to the ' arm concerned contact segments are fitted in the box on acontact shaft which in turn is connected to the slotted lever. The slotted lever moves accordingto the positions of the arm and makes the required contact or causes a disconnection in thecontact box. The contact segments are so arranged that with the deflection of the arm from 0deg to 5deg, one polarity of the battery (say positive) is connected to line and the negativeearthed. From 6 deg to 40 deg both positive and negative are disconnected from line and earthrespectively and from 41 deg onwards negative connected to line positive earthed. In effect itsets as a commutator with a complete disconnection from 6 deg. to 40 deg. Shown in fig 5.2

Fig 5.2. CIRCUIT DIAGRAM OF ARM & LIGHT REPEATER WITH EARTH RETURN.

5.6 Signal lamp with expansion contacts:The signal lamp is the same as any other lampwith the addition of a thermostat or expansion contact. This works on the principle that a lampwhen gives off heat and heats two different metals (such as iron and copper) having differentcoefficients of expansion. The two dissimilar metals are coupled together in such a manner thatany variation of temperature causes one piece to project beyond the other. This expansionlargely increased by leverage raises a contact arm, which connects battery to line and works,when the light is put out the thermostat cools and breaks the contact which in turn opens theindicator circuit. In other types the heat operated thermostat contact operates on the principlesthat if two. Strips of metal having differing co-efficient of expansion are secured together, theywill exhibit a tendency to bend when heat is applied, and thereby make an 'electrical contact.When heat is withdrawn the thermostat regains its original position and the contact is broken.


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5.7 Relay: This is an electromagnet (Horse shoe type wound to a resistance of 300 Ohms)This is used in the light repeater circuit only, the alarm bell circuit is either made or openedthrough its armature to warn the operating staff when light at the signal is out.

5.8 Alarm bell with cut out switch:This is also a horseshoe electromagnet wound to aresistance of 25 Ohms and used for light repeater circuit only. It has interrupter springs and anarmature with a hammer to ring the gong when the switch is in 'ON' or Night position and the

light at the signal is out. The switch is to be put in 'OFF' or Day position during day or when thelight is not in use and should be placed in 'ON' or Night position when the light is in use.

5.9 Circuits: There are three types of circuits.

Fig. 5.3(b) CIRCUIT DIAGRAM OF SIGNAL ARM & LIGHT REPEATER(IN RE - AREA)


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(1) Separate lines for arm and light repeaters, but with no arrangement for providing the alarmin case the switch is not turned from Day to Night position.

(2) Common wire for both arm and light repeater but with no arrangements for providing thealarm in case the switch is not turned from Day to Night Position.

(3) Common wire for both arm and light repeater and with arrangement to draw the attention of

the Station Master to change over the switch to appropriate position i.e., to Night when thelamp is lit and to 'DAY when the lamp is put out and also for proving the first stop signal inthe ON position before permission to approach is give.

There are indicated in figure 5.3(a), the arm repeating battery is connected to the contact box inthe signal arm in such a way that position goes to line and negative to earth 'when the arm is'ON' and negative to line and positive to earth when it is 'OFF.

The indicator end of the line is connected to one terminal of the arm repeater coil of which theother terminal is connected to earth. When the signal arm is at 'ON' indication whereas

When the signal arm is at OFF, current though the coil gets reversed and the indication gives'OFF' indication. (The line at the other end) i.e. indicator end is connected to one of the armrepeater coil of which the other side is connected to earth and the repeater gives 'ON' indicationwhen the signal arm is 'ON'. When the arm is OFF current through the coil flows in reversedirection and the repeater gives OFF indication. If the arm is neither fully 'ON' nor fully 'OFF',i.e., between 5 deg and 40 deg or if the battery is run down or there is a breakage in the wirethere can be no current through the indicator coil and the indicator, actuated by gravity assumesWRONG position.

The positive side of the lamp repeating battery at the signal is connected to one side of thethermostat or expander contact the other side of the which is connected to line. The negativeside of the battery is earthed at the signal.

The end of this line wire is connected to the lamp indicator one end of which is earthed. Theindicator will give lamp 'IN' indication when the expander or thermostat contact in the lampcloses and a current flows through the indicator. When no current is flowing -through theindicator coil due to the signal lamp being extinguished, line wire broken or the battery havingrun out, the indicator shows 'OUT'.

A warning bell is connected so that it rings in case the relay armature drops down. and theswitch is put in the 'Night' position.

In Fig 5.3 A , the batteries are connected at the arm contact maker just as in the previous circuitand the outgoing line is connected in series with a 750 ohms resistance across, the thermostat

contact. At the indicator and the. line is connected to the arm and lamp repeaters in series. Thearm repeater will show 'ON' when the semaphore signal arm is horizontal. When the lamp is notlit the 750 Ohms resistance comes in series in the circuit and prevents the lamp indicator beingoperated. When the thermostat contact closes the resistance is cut out and both the lamp andarm repeaters operate. The alarm bell functions in, the same way as explained under fig.5.2A.

In figure 5.3 B the batteries and or thermostat are connected in the same manner as in theprevious case with the values of resistance and relays as shown in the circuit.

When the lamp is not light the tapped resistance comes in the circuit only the polar relay andthe arm repeater operate in one direction when the signal is 'ON' and in another direction whenthe signal is 'OFF'.


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The, polar relay controls the outgoing battery of the block with the result, permission toapproach can only be given if the indicator repeats the 'ON' position of the first stop signal andthereby the signal is proved in the block circuit.

When the thermostat constant is made the tapped resistance is cut out and the lamp relay alsoworks which controls a visual indicator and the warning bell.

7 S5E Power Signalling

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