S 10 Colour Light and Automatic Signalling PDF

 S 10 COLOUR LIGHT AND AUTOMATIC SIGNALLING VISION : TO MAKE IRISET AN INSTITUTE OF INTERNATIONAL REPUTE, SETTING ITS OWN STANDARDS AND BENCHMARKS MISSION : TO ENHANCE QUALITY AND INCREASE PRODUCT...

 S 10 COLOUR LIGHT AND AUTOMATIC SIGNALLING VISION : TO MAKE IRISET AN INSTITUTE OF INTERNATIONAL REPUTE, SETTING ITS OWN STANDARDS AND BENCHMARKS MISSION : TO ENHANCE QUALITY AND INCREASE PRODUCTIVITY OF SIGNALLING & TELECOMMUNICATION PERSONNEL THROUGH TRAINING The Material Presented in this IRISET Notes is for guidance only. It does not over rule or alter any of the Provisions contained in Manuals or Railway Board’s directives. INSTITUTE INDIAN RAILWAYS OF SIGNAL ENGINEERING & TELECOMMUNICATIONS SECUNDERABAD - 500 017 Issued in June 2013  S-10 COLOUR LIGHT AND AUTOMATIC SIGNALLING CONTENTS S.NO CHAPTER PAGE NO 1 Multiple Unit Colour Light Signal 1 2 Signal Aspect Control Circuit 15 3 Signal Indication Circuits 20 4 Triple Pole Lamps 24 5 Inner Distant Signal 30 6 LED Signal Units 35 7 Automatic Colour Light Signalling 44 8 Annexure – 1 56 9 Review Questions 58 Checked By IOS-3, JE (D), LS2, PS-1 No of Pages 59 Date of Issue June , 2013 Revision No A3 Incase of any suggestions please write to LS2/PS1 or mail to LS2/PS1, at email address [email protected], [email protected] © IRISET “ This is the Intellectual property for exclusive use of Indian Railways. No part of this publication may be stored in a retrieval system, transmitted or reproduced 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, Secunderabad, India” http://www.iriset.indianrailways.gov.in  MULTI-UNIT SIGNALS CHAPTER 1: MULTIPLE UNIT COLOUR LIGHT SIGNAL 1.1 Multi-unit Signals The light units are specifically designed to avoid “phantom” effects in sunlight, which otherwise might occur due to internal reflection and tend to give the impression of a cleared signal. Each light unit comprises a low voltage concentrated filament lamp at the focal centre of a double lens system in order to provide an efficient optical arrangement without the use of a reflector. Colour Light Signals as the name implies give the different aspects both by day and night by colours corresponding to the night aspects of semaphore signals. The multi-unit type signals are of 2-unit, 3-unit or 4-unit type depending upon the number of aspects to be displayed. They are made of cast iron, sheet metal or fiber reinforced plastic. The 4-unit type is also derived by combining (2+2) units, (3+1) units or single unit also. The grouping of the light units is usually vertical with the Red aspect the lowest so as to be as close to the driver’s eye level as possible. In the case of a 3-aspect signal the green is placed uppermost for the best sighting, whereas with a 4-aspect signal the two yellow aspects must be as widely separated as possible to give a clear “double yellow” indication at a distance. 1.2 Advantages over Semaphore Signals The following are the main advantages of multiunit colour light signals over semaphore signals. (a) The same aspect is displayed both by day and night. (b) High intensity beams produced by these signals have great penetrating power. This is important when atmospheric conditions are unfavourable. This increases the range of visibility. (c) No moving parts are used. Hence, maintenance required is less, No of failures is also less. (d) As the structure is light and small, mounting is easier. (e) Backgrounds such as trees and buildings etc., which are bad backgrounds for semaphore signals, are good backgrounds for colour light signals. (f) Aspects can be displayed at driver's eye level. (g) Long range of operation & very quick operation also. The disadvantages of colour light signals are: - (a) Close up view is difficult. (b) Glare at night. (c) Limited visibility on curves. (d) Lamp failures are frequent. (e) However with latest technology like LED Lamps, the above Disadvantages can be minimised. Page 1 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING MULTIPLE UNIT COLOUR LIGHT SIGNAL 1.3 Description In multi-unit type a separate light unit is provided for each aspect to be displayed. The main parts of a 3-unit type are shown in Fig.1.1 (a). Multiple Unit Colour Light signal units are separated from each other and fitted one cast aluminium/ a sheet metal/ fiber reinforced plastic. The light units are generally arranged vertically about 300mm apart green on top, yellow in the middle and red at the bottom, for 3-aspect signal. Each signal unit is provided with a shield for providing good background and each light unit with a hood to prevent sunlight falling directly on the lens. Below the units a compartment with two terminal blocks for the termination of cable and for internal connections is provided. Separate waterproof-hinged covers are provided for the light units and terminal box. Multiple Unit Colour Light signal units are locked by universal locks. HOOD CABLE TERMINATION BOX MOUNTING SOCKET Fig.1.1 (a) 3-ASPECT - MACLS UNIT IRISET Page 2  SIGNAL COLOUR LIGHT MULTI- UNIT TYPE TOP PLATE COVER 1. Clear Outer Lens 2. Coloured Inner Lens 3. Frame 4. Lamp Holder Unit 5. Bracket 6. Lamp 3 LIGHT UNIT 2 6 CLEAR LENCE 4 1 COLOUREDLENCE 5 TERMINAL BOX MOUNTING SOCKET Fig.1.1 (b) SIGNAL COLOUR LIGHT-MULTI UNIT TYPE 1.4 Normally the Red aspect is kept at the lower compartment at driver's eye level. Breathing holes are also provided on the cover, one for each compartment to ensure ventilation. Suitable expanded metal netting may also be provided over the external lenses to prevent damage of the lenses. To increase the visibility, steel backgrounds are provided. Each aspect is normally provided with a hood to shield the lens unit from external light. Reflectors are not used in multiunit signals as it is necessary to ensure that outside light source such as that from an engine headlight or sunbeam are not reflected back, through the lens to give phantom indications to the drivers. Page 3 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING MULTIPLE UNIT COLOUR LIGHT SIGNALS 1.5 Focusing Arrangements To ensure good visibility it is essential that the light unit is focussed to align the beam of light towards the driver. As the red aspect is more important, it is kept at driver's eye level. For the purpose of focussing all signals are fitted with lugs drilled with small apertures at the bottom of the unit to form an aperture sighting arrangement. These two holes are aligned in the direction of the approaching train. The mounting socket (turn table) is fixed on the post with three bolts and by proper adjustment of these bolts; the entire unit can be titled either vertically or horizontally for correct alignment of the beam of light. The complete CLS unit is fixed over the turntable. It is useful to turn the unit both horizontally and vertically for correct adjustment of the beam light. For sighting a signal from a particular spot on the track, Sighting Apertures are provided on the right side of the signal units on terminal box (two numbers). These two holes are provided externally and aligned in the direction of the approaching train. Signal Lamp Holder & Bracket- It will have slotted notches both in horizontal and vertical position. Bracket is fixed over the conical casting of the signal unit. Vertically it can be aligned, for vertical adjustment of focusing of the signal. In horizontal slotted notch the lamp holder will be fixed for keeping the main filament exactly at the focal point of the lens combination. Focus the aspect lamps as per the procedure explained below: See that the signal post is in proper plumb and that all the fixing bolts of foundation base and unit base are tight. See if the unit is properly aligned with aspects turned towards the track at the farthest Point, where the signal should be sighted first. If the unit seems to be away from or closer to the track, loosen nuts on the turntable bolts and adjust its position. The curve or gradient within the signalling distance shall be taken into account while doing it. Unit may be tilted forward or backward, as necessary before fixing it. Fix a sighting object at the point of maximum required visibility on track (minimum 200 m) or place a man there with a walky-talky. Now, for focussing of the lamp, loosen the fixing studs of lamp bracket moving it gradually up and down, arrive at a position so that a complete round bright spot is formed at the middle of outer lens. Fix the bracket in that position by tightening its screw studs. Loosen the nuts on holder bolts below bracket. Moving holder to and fro, bring it to a position at which the aspect is able to be sighted its brightest form from the maximum required visibility distance. Tighten the nuts. Finally moving along the entire sighting distance, make sure that the signal can be sighted well and continuously for 200 m towards the signal from the farthest point of visibility. Each CLS unit consists of (a) Lens arrangement, (b) Signal lamp (c) Sig Transformer (110/12V,40VA ) IRISET Page 4  LENS ARRANGEMENT 1.5.1 Lens arrangement Each aspect of a colour light signal is a complete light unit in it. Each unit comprises a concentrated filament electric lamp accurately focussed behind an efficient lens system, using a doublet combination of 2 lenses Fig.1.2 (a). These lenses are concave, convex, combination the inner lens being coloured, red, yellow or green and the outer clear lens being a plane lens (clear). The 5½" (140 mm) dia x ½" focus inner lens is stepped outside whereas the outer lens is stepped inside and is of 8 ⅜" (213 mm) dia x ½” focus mounted on a conical casting of the unit. Polycarbonate lenses are used as outer lens to increase signal visibility and these are unbreakable lenses. The advantages of a step lens over a plane convex lens are: (a) Reduced variation in thickness, which reduces the light absorption. (b) The improved accuracy of refracting surface. (c) Saving in weight (about 1/7th of plane convex lens). (d) Increased thermal endurance (max. safe tem. is about 1000C as against 450C in case of plane convex). (e) Flexibility in optical design, which enables better use of the light, emitted. It would be impracticable to make a (213 mm x 100 mm) plane convex lens. The strongest lens of that dia is of 11 ½ “focus, which only collects 6% of the light from the source. A single step lens usually collects 20 to 25% of the light and the combination of 2 lenses are used in multi-unit signal, known as toric combination which may collect upto 50% of the light emitted due to reduction of focal distance by the combination of lenses. Doublet lens is used on the unit because more beam candlepower is obtained by this arrangement than with a single optical lens. The lens combination collects light from the lamp through a solid angle of 1550 and refracts this into almost parallel beam of light. The amount of useful luminous flux cannot be increased by using reflectors due to the possibility of phantom indications from the reflected headlight of trains approaching on sunrays. If accurately aligned and focussed, the clear visibility of these signals is more than 1000 m in bright sunlight. The visibility of the signal at close range is however poor on curves as the driver passes out off the beam as he approaches the signals. This can be however remedied by the use of spread light lens giving 80 or 160 or 320 angular deflection instead of the usual clear lens. The greater the deflection the less efficient is the main beam and care has to be taken to accurately align the signal for maximum sighting distance combined with good close range visibility. A driver standing very near a signal cannot read the signal properly as he is out of the direct line of focus of the beam. To obviate such a situation, close up indications are provided on the signal. This may be sidelight or deflecting prism in the outer lens. Where sidelights are provided a separate side light lamp and optical system is used for each aspect so that there cannot be any phantom indication in the main lens. The side light lamp is connected in parallel with the main signal lamp. It consists of a lamp and a colour lens. The lamp rating is 12 V / 4 W (SL 5) or 12 V / 6 W (SL 8) 2-Pin single filament. The code SL 5 indicates Signal Lamp serial number five. A deflecting prism (Fig.1.2 (a) & 1.2 (b)) is fitted to the outer lens which diverts a part of the light as subsidiary beam at an angle of 350 from the main beam. This should be carefully adjusted and kept either to the right or left of the track depending on the location of the signal to give the best possible effect to a driver on the foot plate of an engine or cab standing at the signal. Page 5 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING MULTIPLE UNIT COLOUR LIGHT SIGNALS OUTER STEPED LENS COLOURED LENS DEFLECTING PRISM Fig: 1.2 (a) SIDE VIEW OF STEPPED LENS Fig: 1.2 (b) FRONT VIEW OF LENS The double lens unit used for long range signals has an outer lens of 8 ⅜" (213 mm) diameter with 4 inch (100 mm) focal length and an inner lens of 5 ½ " (140 mm) diameter where as that for short range signal the outer lens is 5" dia., and the inner coloured lens is 3.5/8" dia. The focal point of this lens combination is (½ ") at the back of the inner lens. Due to short focus of the 13 mm combination the lens collects 1550 of effective light from the front of the lamp. The vazil rings and frame, which is hold the two lenses, are accurately machined so that when the signal unit is assembled the lenses will be held in their correct positions. The inner lens is coloured lens and stepped outside. Where as the outer lens is plane / clear lens and stepped inside. The stepped surfaces of the outer and inner lenses face each other. As both the lenses are concave convex, they help to throw a parallel beam of lights of high intensity. 1.5.2 Types of Multi-Unit Signals: - Multi Unit colour light signals may be of short range or long-range type. The range of visibility of long-range signals is not less than 1000 m and for a short-range signal 350m. Doublet combination lens is used in both the cases but in short range type the outer clear lens is 160 mm (6 ⅜") dia against 213 mm (8 ⅜”) clear lens used in long range signals. The coloured inner lens with outside step in either case is of 140 mm dia (5½ "). The short-range type is not generally used on Railways and the description given in this chapter pertains to long-range signals. Sl. DIAMETER NOMINAL APPLICATION AND TYPE FOCAL No COLOUR LENGTH 1 Colour light signals multi unit 140 mm Outside step 13 mm# type. Red / green/ Yellow 2 Colour light signals multi unit 213 mm Inside step with 102 mm type (for stop signals only). Clear spread light. 3 Colour light signals, multi 213 mm Inside step with 102 mm unit type (for stop signals Clear moulded prism for only). close up indication 4 Colour light signals multi unit 213 mm Inside step without 102 mm type (for permissive signals Clear moulded prism for only). close up indication 5 Route indicator inner lens 92 mm Outside step 16 mm* (Direction type indicator) Lunar white IRISET Page 6  LAMPS USED FOR COLOUR LIGHT SIGNALS Sl. DIAMETER NOMINAL APPLICATION AND TYPE FOCAL No COLOUR LENGTH 6 Route indicator outer lens 125 mm Inside step with 70 mm (Direction type indicator) Clear. moulded prism for close up indication 7 Point & trap indicators, target 101 mm Inside step 89 mm type (clear only) Red / Green / lunar white /Clear 8 Semaphore signal lamps 136 mm Inside step 89 mm Clear 9 Calling “ON” colour light 136 mm Inside step 89 mm signal Yellow 10 Position Light Shunt signal 101 mm Inside step 89 mm Lunar white * The focal length refers to doublet combination of the lens with 127 mm dia x 70 mm focal length inside step clear lens. * The focal length refers to doublet combination of the lens with 213 mm dia x 102 mm focal length inside step clear lens. ** The inside step clear lens, moulded out of polycarbonate material, shall confirm to Drg. No: S - 24845 1.6 Lamps Used for Colour Light Signals A signal lamp consists of a helix of tungsten wire mounted within a sealed glass envelope. The tungsten wire or filament as it is called is so designed that it is raised to incandescence by the flow of electric current through it when voltage is impressed, across its terminals. The envelope is either evacuated or filled up with gas, which will not combine chemically with tungsten filament even at high temperature. Although rapid chemical decomposition of the filament is eliminated, the wire wears away gradually as the lamp "burns". This process is called "evaporation", atoms of incandescence, which condenses and forms a black deposit on the bulb. A B Fig: 1.2 (c) TUNGSTEN FILAMENT During the life cycle the lumen output or candlepower of the lamp diminishes, partly on account of attenuation of the metal conductor, which reduces the wattage, consumed and partly as a result of black deposit of tungsten, which has evaporated. In common type of signalling lamps, the lumens output will have reduced to approximate, 15% just before the lamp fails. Page 7 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING MULTIPLE UNIT COLOUR LIGHT SIGNALS The light output of a tungsten filament depends entirely upon the temperature at which it operates, which in turn depends on the voltage impressed. This relationship is illustrated in curve, of Fig. 1.3(a). The efficiency of the lamp as a light generating device also varies with the filament temperature and voltage. This is shown in Fig. 1.3(b) by curve 'P'. 140 130 PERCENT LUMENS 350 120 300 110 PERCENT LUMENS OR PERCENT LIFE 250 PERCENT PER WATT 100 PERCENT LIFE PERCENT LUMENS PER WATT 200 90 150 80 100 70 50 60 90 100 110 90 100 110 PERCENT VOLTS PERCENT VOLTS Fig: 1.3 (a) LIGHT INTENSITY Fig: 1.3 (b) LIFE OF LAMP Light output and efficiency increase or decrease in proportion to the voltage impressed on the lamp, but the life of a lamp decreases as the light output and efficiency increases. The life, therefore, varies inversely with the voltage. It results from the fact that the rate of evaporation is determined by the operating temperature of the tungsten wire. With higher operating temperature, the rate of evaporation is greatly increased. As the light output varies quite rapidly with variation in voltage, at 90% of the rated voltage, the candle power of the lamp is reduced to about 70% of the value of full rated voltage. Consequently, care must be exercised in reducing the lamp voltage that the intensity of the beam is not reduced to a point where atmospheric conditions can affect the integrity of the signal aspect. Lamps burned at less than 80% of the rated voltage may have their filament temperature reduced to a point where chromatic of the signal light colour will be affected. For colour light signals a low voltage lamp (12 V) is preferred. Low voltage lamps take higher currents and therefore, current density is higher. Higher current density gives higher temperature thereby increasing light output and efficiency. A high voltage lamp (110 V /33 W) has resistance of 110 X 110 = 367 Ohm and 300 ma. 33 A thick filament would technically strong. Especially for the colour light signals kept closer of the track and subjected to vibrations. A long filament will have most of its light outside the focal point and hence the brilliance of the lamp will be effected. IRISET Page 8  ILLUSTRATIONS OF LAMPS 50 2 mm AUXILIARY FILAMENT MAIN FILAMENT 14 mm 78 ± 5 mm min. 42mm 0.5mm SIDE VIEW Fig: 1.3 (c) FILAMENT CONNECTED IN PARALLEL 135 135 3mm 0.5mm 90 PLAN FROM TOP OF BULBS, CAP DOWN Fig: 1.3 (d) ILLUSTRATIONS OF LAMPS NOS. SL -17, 21 and 22 The following three types of signal lamps are generally available for use on multiple aspect colour light Signals: - Sl. Type of Light output Rating of filaments No. Signal in lumens 1. SL 17 Main filament 12 V / 16 W, Auxiliary filament 16 V / 12 W 150 lumens 2. SL 18 12 V / 24 W 275 lumens 3. SL 21 Main filament 12 V / 24 W, Auxiliary filament 16 V / 12 W 230 lumens In the earlier installations of multiple aspect colour light signals, cascading arrangement was not provided. Therefore, in those days and in such installations it was necessary to provide double filament signal lamps so that even in case of main filament failure, the auxiliary filament will be there to display the aspect though it may be very dim. This reduced the chances of drivers coming across blank signals. But some Railways continue to use double filament lamp even after (cascading) “Cutting-in” arrangement has been entered with the result that daily complaints are being received from the drivers and motor-men of signals displaying conflicting aspects such as Red and Yellow or Green and double Yellow etc. Because, the lamp proving relays are not adjusted properly. If the signal is to function efficiently, the lamp proving relay, connected to the OFF aspect signal lamp should drop only when both the filaments have fused and the proving relay connected to the ‘ON’ aspect signal lamp should be capable of de- energising when any one of the filaments has fused for timely detection. Page 9 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING MULTIPLE UNIT COLOUR LIGHT SIGNALS To overcome the problem, Railway has switched over to the use of single filament lamp (SL 18, 12 V / 24 Watt) for the “OFF” aspects of colour light signal where ‘cutting-in’ is provided. If SL 18, 12 V / 24 W lamp is used where earlier SL 21, 12 V / 33 W lamp was in use for the “OFF” aspect, there may be complaints from the drivers and motor-men regarding impaired visibility of OFF aspect after the change-over. This argument is ill founded because it is evident from the specification of the lamp and which has been verified from actual use that the light output from the SL 18 lamp is much more than obtained from the SL 21 lamp. Even though the wattage is less by as much as 9 W, still the light output is more by 45 lumens because in the SL 18 lamp there is only one filament and the same is correctly focussed at the focal point of the lens whereas in the case of SL 21 there are two filaments and one of them have to be necessarily out of focus. It is therefore SL 18, 12 V / 24 W lamps for the OFF aspects of multiple aspect colour light signals where “Cutting-in” arrangement is already catered in the design of circuitry. Lamp failures with single filament lamps caused considerable traffic delays. This led in the first place to devising an arrangement with 2 similar single filament lamps; the second being normally comes in circuit by the failure of the first. As the second lamp will always be out of focus, the visibility was greatly reduced and hence, the later development has the 2 filaments known as "main" and "auxiliary" placed in the same envelope in the shape of double filament lamps. These are classified as two pole known as double pole (parallel burning) or triple pole (independent burning) as shown in Fig. 1.4(a). 135   135 PIN 90 DOUBLE TRIPLE POLE Fig : 1.4POLE (a) DOUBLE POLE Fig : 1.4 (b) HOLDER PINS MAIN BX110 110/12V BX 12 AUX MECR NX110 NX 12 Fig: 1.4 (c) SCHEMATIC WIRING DIAGRAM Double Pole Double Filament lamps may have centre contacts of 2-pin bayonet cap or triple pin type. As both the filaments are burning always, it is essential to maintain the auxiliary filament at a lower voltage to prevent its failure before the main filament fails. As an example, in the type SL 17 (12 V / 25 W) double filament double pole 3 pin lamps, main filament is rated at 12 V / 16 W and the auxiliary filament at 16 V / 12W. The other type of lamp used for multiunit type is SL 21 (12 V / 33 W) double filament, double pole, 3 pin in which the main filaments is rated at 12 V 24W and the auxiliary 16 V / 12 W. The main horizontal filament is placed at the focal point of the lens combination whereas the vertical auxiliary filament is slightly away. IRISET Page 10  DIMENSIONS OF SIGNALLING LAMPS In order to ensure that the main filament is at the correct focal point 3-pin caps are used. As shown in Fig.1.4 (b), the three pins are not at 120 deg apart and hence, insertion of the lamps in any position other than the desired position is not possible. The lamp has 2 bases, the inner one is for sealing the envelope and the top one with the pins is used for rebasing to get the filaments in the correct position. In SL 21, one filament is horizontal in position and other filament is vertically placed. As the two filaments are burning simultaneously, at the place of crossing of the filaments, more heat is generated and the filament is fusing earlier. So the life of the lamp getting reduced. This is the hot spot problem. To overcome this problem, triple pole lamps came in existence. In these lamps, the common connection of the filaments is connected to the shell and the other end of each of the filament connected to the contact plate Fig.1.4 (a). With triple pole lamps, a lamp-proving relay (MECR) is used in series with the main filament. When the main filament fails, the auxiliary filament is brought in circuit through the de-energised contact of the MECR Fig.1.4 c. As both the filaments are not burning together the auxiliary filament can also be rated at the same voltage (12 V) as that of the main filament. In SL 21 double Pole, double filament and the main filament is horizontally located with the ratings of 12 V/ 24 W and the auxiliary filament rating of 16 V/12 W vertically placed. In these lamps, when main filament fused the auxiliary filament came into circuit with a dim light because of less wattage. In SL 35A Triple Pole, double filament and both filaments are kept horizontally located with the ratings of 12V / 24 W main filament and auxiliary filament.(12 / 24 W ) In SL 35B Triple Pole, double filament and both filaments are kept horizontally located with the ratings of 12 V / 33 W &12 /33 W for both main and auxiliary filaments. Table-1 Dimensions of Signalling Lamps (B.S. Specification No.469) PURPOSE * Types Rating Ref. Recommended Watts Remarks Volts By RDSO Signal and point Indication behind levers. Signal box *SL5 diagrams, multi lamp route 12 4 V or Bow filament indicator with parallel connection 12 Main 16 *SL17 Multi Aspect CLS. Double Pole 16 Aux 12 12 24 *SL21 Multi Aspect colour light Signal Double Pole 16 12 Illuminated diagrams and *SL30 12 1.2 V or Bow filament control panels. Page 11 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING MULTIPLE UNIT COLOUR LIGHT SIGNALS Table-1 Dimensions of Signalling Lamps (B.S. Specification No.469) PURPOSE Rating Ref. * Types Recommended Watts Remarks Volts By RDSO Illuminated diagrams and Red end piece, Yellow SL 30 24 24 control panels. end piece. *SL 33 Position light junction 110 25 - Multi lamp type Route indicator *SL 13 6 1.2 V or Bow filament with series connections *SL 18 Multi Aspect colour light Signal 12 24 - Sl. RATING Specified No. Reference Volts Watts Life in hours 1 SL 5 12 4 100 2 SL 21 12 33 1000 3 SL 30 12 16 1000 4 SL 31 24 1.2 - 5 SL 33 110 25 500 6 SL 18 12 24 1000 7 SL 35A 12 24 1000 8 SL 35AL 12 24 5000 9 SL 35B 12 33 1000 10 SL 35BL 12 33 5000 The following are the important instructions for the maintenance of signal lamps: - (a) Lamps must be replaced with similar lamps. (b) Lamps must be inspected at intervals specified by the officials to see that they are burning properly. (c) Receptacle and base of lamp must be clear to ensure proper contact. (d) Care must be exercised when replacing lamps to see that the pins in the base are turned to the end of the slots in the receptacle and forced into place by the contact spring. (e) Applied voltage must not be more than the rated voltage of the lamps and should not be more than 90 % of the rated voltage (10.8 V). Not less than 80% percentage of the rated voltage (9.6 V). (f) Lamps should be stored in clear dry place. (g) Where practicable, signal lenses roundels and reflectors should be cleaned without removing the lamp. IRISET Page 12  SIGNAL TRANSFORMER (h) Voltage reading at lamp must be taken each time when the lamp is replaced. (i) Double filament lamps must be replaced when one filament fails. (j) New lamps should be handled carefully and as little as possible before placing in service. Jerking should be avoided so that filament will not be distorted. (k) Maintainers should not carry lamps in their toolboxes. A spare lamp should be stored in one apparatus case near every station. Records of Signal lamp failure Signal lamp failure should be maintained as under given table: S.No Type of Signal Lot no. Lamp testing Voltage on Lamp lamp and date lamp holder replacement make terminal date 1 2 3 4 5 6 2 3 1.7 Signal Transformer (IRS: S 59) The rated voltage of colour light signal of multiunit type is 110 V 50 C/S AC (high voltage) or 12 VAC (low voltage). Usually the high voltage is used for CLS. The low voltage type is preferred where the signal lamp is fed from a standby battery. In the high voltage type a transformer 110 / 12 V / 40 VA 50 C/S is provided for each aspect in the respective unit. Without a transformer, if the lamp is directly connected to the cabin as the lamp current is about 3 A (for SL 21 12V / 33W), the voltage drop in cable will be very high. As an example, let us assume a cable resistance of say 10 ohms, the voltage drop being roughly 30 V. Hence, the voltage to be maintained at the cabin is about 42 V, and in this case, most of the power supplied is lost in the cable. Further, the voltages to be maintained at the cabin will have to be different for different signals, as all signals are not located at the same distance. Use of a transformer at the signal reduces the current in the cable to about 33 W / 110 V = 0.3 A. Hence, the drop in voltage under the same condition will be only (0.3 A X 10 OHMS) about 3 V out of 110 V supplied. Hence, the voltage drop is negligible and the same 110 V supply can be used for all signals. Tapings are provided either on primary side or on secondary side of the transformer to get the specified voltage across the lamp irrespective of line drop and drop due to series repeating apparatus, in the figure 1.6. Page 13 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING MULTIPLE UNIT COLOUR LIGHT SIGNALS PRIMARY SIDE SECONDARY SIDE Signal Transformer (110/12, 40 VA) CABIN BX110 SIGNAL 110 OTHER CONTROLLING CONTROLS CONTACTS 0.5V 1.0V 13V 14.5V 16.0V NX110 0 Fig: 1.6 TYPICAL CIRCUIT DIAGRAM Transformer rating is 110 V / 12 VAC, 40 VA, 50Hz. Minimum capacity of the transformer is 40 VA continuous. No load current shall not be more than 15 mA No load voltage – Full load voltage % Regulation = x 100 No load voltage % Regulation measured on secondary side shall not be more than 15%. Signal Transformers are available in two types. (a) IRS type (IRS: S-59). It is having tapping on secondary winding. (b) Siemens type: It is having tapping on primary winding. Voltages mentioned above on Transformer tapping are nominal voltages at “No Load”. Insulation Resistance shall not be less than 100 MΩ with 500 VDC Megger. It shall be measured between the core and each winding and also between the primary and secondary windings. NOTE: As per Railway Board’s Letter No.96/Sig/M/4 dated 01.10.1997, 110 VAC feed system should be provided on all colour light signal installations. IRISET Page 14  INTRODUCTION CHAPTER 2: SIGNAL ASPECT CONTROL CIRCUITS 2.1 Introduction In CLS, a Signal Control Relay must always control the signal. Without a control relay, the signal may have no aspect, when the signal lever is left in a mid-position. To make the circuit simple, signal aspect control relays are introduced. For 2-aspect signal, one control relay is required. Similarly for 3-aspect signal, two control relays; and for 4-aspect signal three control relays are required. 2.2 Two-Aspect Colour Light Signal Control Circuit The relay HR is controlled through the selection circuit proving all the conditions including signal/lever/button-operated contacts. The energisation of this relay connects "OFF" Aspect YELLOW. If any one or more conditions required to take OFF the signal is not fulfilled HR is de-energized and the signal is maintained at "ON" Aspect. 2-Aspect Signal Lamp Control Circuit is given in Fig.2.1. TWO-ASPECT CONTROL TABLE S.No RELAY CONDITION ASPECT 1 HR  HG 2 HR  RG RELAY ROOM LOCATION BX110 HR 110/12 V HG NX110 HR HR 110/12 V RG HR Fig 2.1 TWO-ASPECT CLS CONTROL CIRCUIT (LOOP LINE STATER) 2.3 Three-Aspect Colour Light Signal Control Circuit (STOP SIGNAL) In this circuit HR and DR (two) control relays are used. Where HR is a Yellow Aspect control relay and DR is a Green Aspect control relay. HR relay is energized proving the conditions required up to next signal and overlap in advance of it. DR relay is controlled by the off aspect (Y or G) of the 3-Aspect Signal in advance. When HR itself is not energized the signal is maintained at Red Aspect irrespective of the Signal Aspect ahead. When HR is energized Yellow Aspect is selected through HR relay front contact.. When DR is energized Green Aspect is selected through HR &DR relay front contacts. A front contact of DR relay is used for green aspect lamp circuit. A back contact of DR relay in yellow lamp circuit is used to prevent both yellow and green lamps lighting up when DR picks up. The control circuit for 3-aspect stop signal is shown in Fig.2.2. Page 15 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING SIGNAL ASPECT CONTROL CIRCUITS THREE-ASPECT CONTROL TABLE S.No RELAY CONDITION ASPECT 1 HR  + DR  DG 2 HR  + DR  HG 3 HR  RG RELAY ROOM LOCATION BX110 HR DR 110/12 V DG NX110 HR DR DR 110/12 V HG DR HR 110/12 V RG HR Fig. 2.2 THREE-ASPECT CLS CONTROL CIRUIT (STOP SIGNAL) THREE ASPECT SIGNAL IRISET Page 16  THREE ASPECT C L S CONTROL CIRCUIT 2.4 Three-Aspect Distant Signal Control Circuit (PERMISSIVE SIGNAL) In this case, the green aspect-controlling relay of the distant (DR) is controlled through home signal DR Relay. The attention aspect controlling relay HHR is energized whenever the Home Signal is OFF irrespective of whether the route is set for the straight or turnout (loop line). Distant signal clear aspect (Green) will lit only when run through permitted on main line. Normally, the distant signal displays yellow through DR back contact. When HHR energizes the signal displays double yellow i.e. the top yellow lamp is lit through HHR front, and bottom yellow is lit through DR back contact. The green aspect is displayed through HHR back and DR front contacts. The control circuit for a 3-Aspect distant signal is given in Fig.2.3. THREE-ASPECT CONTROL TABLE S.No RELAY CONDITION ASPECT 1 HHR  + DR  HHG 2 HHR  + DR  DG 3 DR  HG 110/12 V 110/12 V 110/12 V Fig. 2.3 THREE-ASPECT CLS CONTROL CIRUIT (PERMISSIVE SIGNAL) 2.5 Four-Aspect Colour light Signal Control Circuit: They are two methods 2.5.1 First Method In this case, both HHR & DR are not allowed to energize at a time. HHR picks up only when the signal in advance displays Yellow aspect. DR picks up only when the signal in advance displays Double Yellow or Green aspect. When HR is up, the bottom Yellow is brought in circuit, which is maintained to given double Yellow aspect when HHR picks up. When DR is up, this Yellow lamp is disconnected and Green lamp is connected through HR-Front and DR-Front Contacts. This is shown in Fig 2.4.This method is used in Absolute Block working. Page 17 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING SIGNAL ASPECT CONTROL CIRCUITS FOUR-ASPECT CONTROL TABLE S.No RELAY CONDITION ASPECT 1 HR  + HHR + DR  HHG 2 HR  + HHR  + DR  DG 3 HR  + DR  HG 4 HR  RG RELAY ROOM LOCATION BX110 HR HHR DR 110/12 V HHG NX110 HR HHR DR DR HHR 110/12 V DG DR HHR DR 110/12 V HG DR HR 110/12 V RG HR Fig. 2.4 FOUR-ASPECT CLS CONTROL CIRUIT 2.5.2 Second Method When HR is de-energized, the signal will display Red aspect. When HR alone is energized and the next signal is at "ON" the signal displays YELLOW aspect through DR back contact. When HHR is energized in addition to HR and the next signal is showing Yellow, the signal displays attention (Double Yellow) aspect. When DR is energized in addition to HR & HHR and the next signals is showing attention (Double Yellow) or proceed (Green), the signal displays GREEN aspect shown in Fig 2.5.This method is generally used in Automatic Block signalling. FOUR-ASPECT CONTROL TABLE S.No RELAY CONDITION ASPECT 1 HR  + HHR  + DR  HHG 2 HR  + HHR  + DR  DG 3 HR  + DR  HG 4 HR  RG IRISET Page 18  FOUR ASPECT CLS CONTROL CIRCUIT FOUR-ASPECT SIGNAL RELAY ROOM LOCATION BX110 HR HHR DR 110/12 V HHG NX110 HR HHR DR DR 110/12 V DG DR DR 110/12 V HG DR HR 110/12 V RG HR Fig. 2.5 FOUR-ASPECT CLS CONTROL CIRUIT Page 19 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING SIGNAL INDICATION CIRCUITS CHAPTER 3: SIGNAL INDICATION CIRCUITS 3.1 INTRODUCTION As no backlight is provided on colour light signals, the aspects of the signals are repeated in the cabin when the signals are either manual or semi-automatic/Automatic. Even though in lever controlled signals all the aspects are repeated individually, it is often considered sufficient to give only two indications, one for 'ON' and the other 'OFF' indication common for all 'OFF' aspects. As cabin indicator used for lever-controlled signals is designed as a single unit so arranged that additional units can be bolted to the top of it. Any number of units (2 or 3 or 4) can thus be used to form a multi-aspect indicator. The case is of black moulded insulation and the pull off door of the same material at the back of the case provides easy access to the lamp holder. For signal repeating, it is usual to have a coloured dome glass of about 1 1/4" dia, the colour corresponding to the aspect repeated. (The same indicator can be used for repeating point indications and in such case the coloured dome will be replaced by a ground glass with stencils N or R behind it). The lamp used is SL 5, 12 V / 4 W single filament bayonet cap 2-pin type. 3.2 The methods adopted for repeating signal aspects are (a) Using current transformer method. (b) Using signal proving relays method. 3.2.1 INDICATION TRANSFORMER METHOD The first method uses a current transformer shown in (Fig.3.1). Transformers working with the same principle are used for indication purposes and hence, they are called indication transformers. When the signal lamp is burning the current drawn by the signal transformer primary is large to compensate for the secondary load ampere-turns. Hence, the ampere turns produced in the primary and therefore, in the secondary of the current transformer are more which gives nearly 10 V for the indication lamps to light up. When the signal lamp is fused, the signal transformer draws less current and therefore, the current in the primary of current transformer is reduced. This reduces the secondary induced emf and therefore the lamp is dim. This current transformer having the indication lamp (12 V / 4 W SL 5) directly connected is known as I type. The primary current is in the range of 0.3 A, the voltage ratio primary to secondary is 10/7 volts + 5%. The secondary load is 2.5 VA at 7 V. If the cascading arrangement is to be provided, ECR methods are used. Drawbacks: (a) Dim glow indication may appear in case of signal lamp failures. (b) Not suitable for cascading arrangement. (c) Failure of the indication lamp affects the signal lamp voltage. IRISET Page 20  ECR METHOD BX110 HR 110/12 V, 40VA 300 ma HG NX110 HR I-Type Transformer 2.5VA HGKE SL 5 (12V/4W) HR 110/12 V, 40VA RG HR I-Type Transformer RGKE SL 5 (12V/4W) Fig: 3.1 INDICATION TRANSFORMER METHOD 3.2.2 ECR METHOD (a) ECR Method using ‘ L’-type Transformer This method is suitable where the signal lamps are directly fed from the cabin, for AC RE area & Non-RE area. Fig 3.2 (a,b) In this, L-type current transformer is connected in series with lamp circuit (i.e., with primary of signal lamp transformer). L-type Transformer is suitable for low current in the range of 300 mA On the primary; the secondary develops 9 V across it. The capacity of the L-type transformer is 0.09 VA. The voltage ratio is 0.5 V / 9V, +5%. BX110 HR 110/12 V, 40VA 300 ma HG L-Type Transformer NX110 HR 0.5V 0.09VA 9V HECR HR 110/12 V, 40VA RG L-Type Transformer HR 0.5V 9V RECR Fig: 3.2 (a) ECR METHOD BY L - TYPE TRANSFORMER Page 21 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING TRIPLE POLE LAMPS RELAY ROOM B24 HECR HGK N24 SL 31 (24V,1.2W) RECR RGK SL 31 (24V,1.2W) Fig: 3.2 (b) INDICATION CIRCUIT The Bridge rectifier is connected across the secondary of the L-type current transformer. If the signal lamp burning, then the ECR picks up; and if the signal lamp is fused or not glowing, then the ECR drops. Concerned indications will appear on the panel through ECR contacts. (b) ECR Method using ‘H’-type Transformer In this, H-type current transformer is connected in series with the secondary side of the signal transformer. H-type current transformer is suitable for high current in the range of 2.5 A on primary the secondary develops 9 V across it. The capacity of the H- type transformer is 0.09 VA. The voltage ratio is 0.3 V / 9 V; +5%. The Bridge rectifier is connected across the secondary of H-type current transformer. Lamp checking relay called as ECR is connected to the output of the rectifier. When the signal lamp is glowing the concerned ECR picks up. Then its repeater relay picks up in the cabin. When the signal lamp is fused or not glowing, the concerned ECR drops. There by its repeater relay also drops. Signal lamp indications in the cabin are given through the contacts of ECPRs. Fig 3.3 (a, b and c). RELAY ROOM LOCATION 110V/12V , 0.3V BX110 HR 40 VA H-Type 2.5A 0.09V HECR HG NX110 HR 0.3V HR 110V/12V 40 VA H-Type 2.5A 0.09V RECR RG HR Fig: 3.3 (a) ECR METHOD BY H - TYPE TRANSFORMER IRISET Page 22  INDICATION CIRCUIT RELAY ROOM LOCATION RECR B24 RECPR RECR HECR N24 HECPR HECR Fig: 3.3 (b) ECR REPEATERS CIRCUIT RELAY ROOM CABIN B24 HECPR HGK N24 SL 31 (24V,1.2W) RECPR RGK SL 31 (24V,1.2W) Fig: 3.3 (c) INDICATION CIRCUIT Advantages of ECR Methods: (i) Less line voltage drop. (ii) Failure of indication lamp does not affect the signal lamp voltage. (iii) Contacts of ECR can be used for the circuits requiring the proving. When the signal lamp fails the supply for the indication lamp is completely cut off thus avoiding the dim glow. Drawback: It is costly since lamp proving unit and separate 24 VAC or 12 VAC indication supply is required. Page 23 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING TRIPLE POLE LAMPS CHAPTER 4: TRIPLE POLE LAMPS 4.1 Introduction Measures are being taken to improve the safety & punctuality of railway traffics. Signalling system plays a vital role in running the trains at higher speed with utmost safety to passengers & carrying materials in goods. One step in the direction of improving the punctuality of the train is the signalling arrangements. In signalling arrangements glowing of signalling lamps are the main tools for giving proper communication to driver through the indication in non- verbal fashion. 15 to 20 percent of the signalling failures causes due to no light of signalling lamps on account of lamp fusing or any other causes. This is hampering the punctuality of the train running. In colour light Signalling, where there is no cutting-in arrangement, lamps SL 21, 12 V / 33 W double filament 3-pin are used. In case of cutting in arrangement, single filament 2-pole 3-pin lamps SL 18, 12 V / 24 W used for OFF aspect. But in this system there is a chance of signal going blank if ON aspect also fuses. The fusing of signal lamps failures contributes failure on account of signal. To arrest the failure due to the signal lamp fusing the schedule of replacement of signal lamp is fixed according to the aspects. (Forty-five days or thousand hours for ON aspects and 90 days for OFF aspects. It is varied railway-to-railway, division-to-division with local orders. 4.2 Problems with 2-filament and 2-pole lamps (Fig 4.1 (a)) (a) The main problem is that both the filaments lit at a time & on fusing of main filament, ECR drops & even when the signal is glowing at the site. Therefore the incidences of signal failures & detention of the train on approach are more in the existing system. (b) Lamps are schedule to be placed periodically hence it doesn't only involve the up keeping of records but also large number of signalling lamps required annually. (c) To have better reliability these lamps are required to be pre-stressed for a given period before using them on site. This also bears additional burden over the signal staff. 4.3 Introduction of triple pole lamps It was decided that above mentioned anomalies of conventional lamps must be removed & a more reliable signal lighting arrangement with lesser inputs is required. This decision gave a birth to the concept of "TRIPLE POLE LAMP” Fig 4.1 (b). Fig 4.1(a) DOUBLE POLE LAMP Fig 4.1(b) TRIPLE POLE LAMP IRISET Page 24  TRIPLE POLE LAMP HOLDER As the name suggests in this lamp, in place of 2-poles of conventional type there is an additional third pole, which is used to prevent the disconnection of lamp circuits, when the main filament fused. There are 2-filaments in this lamp. These filaments are connected to third pole with one common pole for the both the filaments. As such when the signal is lighted, auxiliary filament, which is connected to the 3rd, remains idle. The auxiliary filament lighted as soon as the main filament is fused. Simultaneously an indication regarding the fusing of the main filament is given in the cabin so that lamp can be replaced before the failure of auxiliary filament; this prevents the signal becoming no light. With these arrangements, the chances of signal becoming no light due to lamp fusing are drastically reduced. TRIPLE POLE LAMP WITH HOLDER 4.4 Triple Pole Lamps In Triple pole lamps, there are two filaments of equal wattage. The main filament lits normally and the auxiliary filament serves as a standby, to be switch ON when main filament fuses. Since both the filaments have the same ratings and lumen output, the visibility of CLS is not so affected when the main filament is fused and the auxiliary filament is switched ON. The new design of the lamp has been developed with RDSO in which the two filaments are provided in parallel configuration to avoid possibilities of hot-spot formation. The circuit arrangement for triple pole lamp is shown as per RDSO Drg.No.SDO/RRI- 263. In this H-type transformer is used as per IRS: S62 with certain modifications in the secondary side of the signal transformer MECR unit can be connected to the signal lamp circuit. MECR unit shall be fixed inside the signal unit or in the signal location box. This MECR unit basically consists of one H-type current transformer and the transformer secondary output voltage is rectified and the rectified out voltage is connected to one miniature relay (MECR). This relay gives the condition of main filament of the triple pole lamp. This relay picks up when the main filament is burning. It drops when the main filament is fused. Then through the back contact of this relay auxiliary filament lits. In the auxiliary filament circuit path 1 Ohm, 15 W resistor is provided in series with the MECR back contact to bring the main filament first in circuit when the aspect is switched ON. In the new installations and in the old installations wherever possible, the railways may cater for the additional conductors required for providing the individual "Signal MECR" indication shall be provided. Page 25 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING TRIPLE POLE LAMPS S1 BX 110V DG 110V/12V 1 2 NX 110V MECR DMECR 115W 3 S1 S1 DMECR B24 MECR S1 50 m.sec HMECR S1 RMECR N24 Fig. 4.2 RDSO TRIPLE POLE LAMP CIRCUIT WITH MECR S1 MECR is normally up and made slow to release to avoid wrong indication at the time of aspect changing. S1 MECR down indicates that main filament is fused for its aspect burning at that time. In the existing installations due to shortage of available conductors, railways may decide, to give a common indication to the maintenance staff by suitable grouping of signals. Signal lamp main filament checking (MECR) relay circuit using triple pole signal lamp is shown in Fig.4.2 The following are the triple pole lamps used in our Indian Railways: Bulb No. Rating Life Applications Normally used for OFF Aspect in CLS, SL 35A 12 V / 24 W, 24 W 1000 hours with or without cascading arrangement. SL 35AL Normally used for ON Aspect in CLS, 12 V / 24 W, 24 W 5000 hours (Longer life) with or without cascading arrangement. SL 35B 12 V / 33 W, 33 W 1000 hours Normally used for OFF Aspect. SL 35BL 12 V / 33 W, 33 W 5000 hours Normally used for ON Aspect. (Longer life) 4.5 Inputs required 4.5.1 Materials (a) Triple pole double filament lamps. (b) Triple pole lamp holder with base. (c) Switching unit (MECR). (d) Push button switch. (e) Buzzer, indication lamps. (f) PVC wire. (g) ARA terminals & other accessories. IRISET Page 26  SIGNAL LAMP CHECKING & ALARM CIRCUIT (TRIPLE POLE) 4.5.2. Additional requirements (a) 2- Spare cores from signal location to relay room for MECPR (Q-Style) is required. (b) 1-extra core for each aspect in tail cable form location to signal post. (c) If there is no space in the location for providing RMECR, HMECR, DMECR relay & indication transformers then extra location is also required. 4.6 Advantages (a) Reduction in number of signal failures due to lamp fusing. (b) No detention of trains even when the main filament is fused. (c) Reduction in maintenance staff. (d) Reduction in the duration of failures as indication of main filament fusing appears in the cabin immediately. (e) Periodical replacement of lamp avoided. (f) Generally pre-stressing of lamp is not required. MECR Page 27 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING TRIPLE POLE LAMPS RELAY ROOM LOCATION HHG BX110 HR HHR DR 110/12 V HHMECR 115W HHMECR NX110 HR HHR DR HHECR DR HHR 110/12 V DG DMECR 115W DMECR DR HHR DECR 110/12 V DR HG HMECR 115W HMECR DR HECR 110/12 V RG HR RMECR 115W RMECR HR RECR Fig 4.3 4-ASPECT LAMP CONTROL CIRCUIT (TRIPLE POLE) A Typical four aspect signal lamp control circuit with triple pole lamps showed Fig no 4.3 which is being used in RE area with double cutting arrangement. IRISET Page 28  ADVANTAGES B24 UPMECR ACK.PB N24 P GXPR GXPR UPMECR ACK.PB P ACKNR ACKNR GXPR ACKNR BELL INDICATION OTHER SIGNAL OTHER SIGNAL DMECR DMECR HMECR DMECR HMECR 50 m.Sec RMECR RMECR RMECR 7 5 7 5 7 5 UP MECR RMECR RMECR RMECR 8 6 8 6 8 6 HMECR DMECR HMECR DMECR DMECR B24 N24 Fig 4.4 SIGNAL LAMP CHECKING & ALARM CIRCUIT WITH TRIPPLE POLE LAMP MECR Alarm circuit (Fig No.4.4): Signal Lamp filament Proving Relay (GXPR) is normally up. If the main filament is fused, then the concerned aspect MECR drops. There by the concerned signal/signals group MECR in the cabin drops. In this circuit UPMECR drops. Dropping of UPMECR drops GXPR. Through GXPR back contact and ACKNR (Failure Acknowledgement Relay) back contact BELL rings and failure indication lit. BELL stops only after pressing the ACK.PB (Acknowledgement Push Button), since ACKNR picks up through UPMECR-B and ACK.PB pressed contact path. After replacing the signal lamp UPMECR picks up, results ACKNR drops. Through GXPR-B and ACKNR-B contact BELL rings again for acknowledgement of failure rectification. After pressing ACKPB through ACKPB-pressed contact, GXPR picks up. Picking up of GXPR disconnects the supply to BELL and indication. Page 29 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING INNER DISTANT SIGNAL CHAPTER 5: INNER DISTANT SIGNAL 5.1 Introduction In a multiple aspect colour light signalling system (MACLS), the driver of a train is warned of the approaching stop signal by a permissive signal. This signal, called the distant signal, is located at an adequate distance in rear of the stop signal, the aspect of which it pre- warns. An adequate distance of one Km has been normally adopted by Indian Railways. This distance together with the distance at which the warning board is located in rear of the distant signal is adequate for a driver to stop his train at the stop signal in case it is at ON. The braking distance (adequate distance) is reckoned from the warning board and not from the distant signal in the existing system of multiple aspect colour light signalling. This arrangement is considered satisfactory upto certain speeds and haulage capacity of trains. Fig. 5.1 DISTANT SIGNAL 5.2 With increase in speed and haulage capacity of passenger and goods trains, the above mentioned distance is not sufficient, which brings out the braking distances required for some of the loads and speeds. A general rule (GR) 3.07(6) stipulates that "Wherever necessary more than one distant signal may be provided. In such a case the outer most signal, to be located at an adequate distance from the first stop signal shall be called the distant and the other called the inner distant signal”. From the above, it can be seen that even though in the present system of MACLS the distant signal can be placed at adequate distance in the rear of home signal, placing it more than 1 Km where higher adequate distances are required is not recommended by GR. In such cases, the GR recommends placing of second distant signal. This may be to enable the driver not to forget the aspect of the signal he has picked up in case of too much distance between subsequent signals. 5.3 Provision of a second distant signal Comprehensive instructions regarding placing of second distant signals have been issued by Railway Board/RDSO. According to this, the existing distant signal shall continue and an additional distant signal shall be placed at 1 Km from the existing distant signal in rear. The warning board in such cases shall be dispensed with. This provides a distance of 2 km, which may not be sufficient in certain cases. Fig 5.2 INNER DISTANT SIGNAL The IB signals are also provided with second distant signals, interlocked level crossing gates which are also provided with second distant signals. With the new signalling arrangement drivers encounter a signal in the block section at every 1.5 to 2 Km approximately. At some locations, the signals such as Advance starter and IB home signal had to be combined with the second distant signal. IRISET Page 30  ASPECT CONTROL CHARTS 5.4 Aspect Control Chart (Single Distant Territory) Distant Main Sl. Adv. Indication to Driver Signal Home Signal line No Starter starter 1 May stop at home Yellow RED RED RED 2 May stop at main line Double Yellow RED RED starter yellow 3 To stop at loop starter Double Yellow with - - (or) pass via loop line Yellow Route Indicator 4 To run through Green Green Green Green Note : As per railway board letter No-2009/Safety (A&R)/19/24 dated 27-07-2010, Distant signal will display GREEN ASPECT only for run through on Main Line 5.5 Aspect Control Chart (Double Distant Territory) Inner Sl. Distant Main line Adv. Indication to Driver Distant Home Signal No Signal starter Starter Signal 1 May stop at home Double Yellow RED RED RED yellow 2 May stop at main line Green Double Yellow RED RED starter yellow 3 To stop at loop starter Double Double Yellow with - - (or) pass via loop line yellow Yellow Route Indicator 4 To run through Green Green Green Green Green 5.5 Advantages (a) Driver can know the information of the signals ahead well in advance (2 Km in advance). (b) Confidence in the driver is increased since he is having sufficient breaking distance for high speeds. (c) Sectional average speed is improved. (d) Goods warning board is not required. Page 31 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING INNER DISTANT SIGNAL 5.6 Inner Distant and Distant Signal Control Circuit (Fig 5.4) INR DIST DR & INR DIST HHR are controlled directly by the Home Signal aspects. INR DIST HHR picks up when Home Signal is displaying yellow, through Home HR,HECR front and INR DIST DR back contacts, INR DIST HHR Pickup.. Inner distant DR picks up only when Home Signal is displaying green aspect (controlled by Home Signal HR, DR & Home DECR front contacts And INR DIST HHR back contact). The indication circuit is similar to the aspect control circuit. As there are 2 yellow lamps in this signal for the display of double yellow aspect, When INR DIST HHR is picked up, both the yellow lamps will glow. Inner distant signal is normally displaying yellow aspect through INR DIST DR back contact. When inner distant DR is picks up Green aspect will be displayed by the signal. If DG lamp fuses, the signal is made to display double yellow, through inner Distant DR front contact and DECR back contact path provided. S-6 2A, C2A 1C, C1C INNER DISTANT DISTANT C-2 S-2 A/B/C Adv. S-10 Starter S-7 2B, C2B 1B, C1B S-8 S-9 2C, C2C 1A, C1A S-11 INNER S-1 A/B/C C-1 DISTANT DISTANT S-5 Fig: 5.3 TYPICAL 3 ROAD STATION WITH MACLS 2 2 2 DID B24 HR DR DECPR HHR N24 DID DR 2 DID HECPR DR DID HHR 2 2 DID DID 2B UECPR HECPR HHECR HECR NRR DD DR 2 DID DECPR DECPR 2 2 2A 2C 10 10 2B HR UECPR UR UR DR DECPR NRR 2 DR Fig 5.4 INNER DISTANT AND DISTANT SIGNAL CONTROL CIRCUIT IRISET Page 32  INTRODUCTION 110/12 V 110/12 V 110/12 V Fig 5.5 INNER DISTANT SIGNAL LAMP CONTROL CIRCUIT WITH LED LAMPS Distant Signal: The normal aspect of this signal is double yellow. The both yellow lamps are lit through DIST DR back contact and top yellow lamp glow when INR DIST HECR is picking up. Distant signal shall have at least one yellow lamp burning. The DIST DR picks up only when the train is either received on main line or run through on main line. HOME UECR back & HECR front contacts and INR DIST HHECR, HECR front contacts along with 2B NRR front contact proved to pick up Distant DR. There by Distant signal will display GREEN aspect. Page 33 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING INNER DISTANT SIGNAL 110/12 V 110/12 V 110/12 V Fig 5.6 DISTANT SIGNAL LAMP CONTROL CIRCUIT WITH LED LAMPS The provision of Second Distant Signal has given more confidence to driver to run his train at maximum permissible speed thereby improving punctuality along with enhanced level of safety in train operation. IRISET Page 34  INTRODUCTION CHAPTER 6: LED SIGNAL UNITS 6.1 INTRODUCTION Signals are provided to guide the rail engine driver for safe journey. Therefore, it is necessary that signals display correct aspect. In colour light signalling territory, signal may go "blank". A blank signal is a grave safety risk as it can cause confusion to the drivers and can result in accidents if driver does not take action to control his train in time. Various CRS inquiry reports have recommended that adequate protection against blank signal must be taken. Railway Board have accepted the recommendations. Signal may go blank either due to failure of signal lamp or due to interruption in power supply. At present, filament lamps light signals. Rate life of lamp is only 1000 hours. Replacement of a signal lamp is not a simple work, as focusing is to be checked and adjusted after replacement of each lamp. With increase in signalling gears at most of the stations, signal technicians in general are not able to cope up with the huge work of adjustment of focusing. To overcome these problems RDSO developed LED Signal units, which has the life of not less than one lakh hours. LED SIGNAL FIG : 6.1 LED SIGNAL 6.2 LED SIGNAL (Light Emitting Diode) LED light sources are solid state p-n semiconductor devices. By doping substrate material with different materials, a p-n junction is formed within the semiconductor crystal. The dopant in the n region provides mobile negative charge carriers (electrons), while the dopant in the p-region provides mobile positive charge carriers (holes). Within a semiconductor crystal, when a forward voltage is applied to the p-n junction from the p-region to the n-region, the charge carriers inject across the junction into a zone where they recombine and convert their excess energy into light. The materials used at the junction determine the wavelength of the emitted light. A clear or diffuse epoxy lens covers the semiconductor chip and seals the LED. It also provides some optical control to the emitted light. LEDs have been developed that have a luminous efficacy (lumens per watt) exceeding that of incandescent lamps. However, the relatively small lumen package that is produced by a single LED still means that dozens, if not hundreds, of LEDs must be used together to produce even a modest amount of light. Page 35 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING LED SIGNAL UNITS 6.3 Salient features of LED Signal Unit There is no Phantom effect (a) LED lamp is Pre-focussed and do not need external lenses or periodic focussing. (b) LED lamps are compatible with existing signal housings, hence can be retrofitted. (c) Traffic hazards while bulbs are being changed by maintenance staff are eliminated. (d) LED signals use less energy. (e) DC power feeding to signals possible, thereby eliminating transformers. (f) Wide voltage variation in power feed is tolerated. (g) One design of ECR for all LED signal lamp application including shunt signal and route indicator (universal ECR). (h) Maintenance costs reduced, as they don't need frequent replacement. Only occasional cleaning of transparent cover needed in dusty areas. (i) Power factor of LED signal lamp shall be 0.8 or better. 6.4 CONSTRUCTION OF LED LAMP 6.4.1 LED Signal aspect unit It comprises of a cluster of LEDs in series and parallel combinations. LEDs in a signal aspect are arranged in more than one array so that in the event of failure of even a single LED, whole unit does not become blank. LEDs in the arrays are interleaved so that effect of failure of any array is spread out equally to maintain uniform visibility. All aspects (except route and shunt) use two arrays for higher noise immunity and also provide the redundancy. LED’s in each array are provided electrically independent path so that failure of any LED does not affect operation of other LED and the same shown in fig No-6.3. The optical sensors are provided for each aspect and output from optical sensors is given to the current regulator unit for corrective / alarm action. A few LEDs in the signal unit are so arranged as to ensure near visibility of 5 meters so that the signal is clearly visible to a driver stopping at the foot of the signal. FIG: 6.2 LED LAMP UNIT AND UNIVERSAL CURRENT REGULATOR IRISET Page 36  LED SIGNAL ASPECT UNIT Fig : 6.3 LED’S CONNECTED IN SERIES IN LED SIGNAL ASPECT UNIT Optical Sensor Fig : 6.4 LED SIGNAL ASPECT UNIT In LED signal aspect unit number of LED’s used should not be less than 60 for RED and YELLOW, 30 for GREEN main LED signal lighting unit,16 for Route and 13 for Shunt signal lighting units. Variation from stipulated number shall be considered based on merits of the design. Signal lighting unit shall not light up to 60 V. LED signals for use of road traffic shall be used without ECR. Page 37 (S-10) COLOUR LIGHT & AUTOMATIC SIGNALLING LED SIGNAL UNITS 6.4.2 Current regulator unit (CR) LED is a current driven device therefore; LEDs clusters in a LED signal lamp are fed with constant current irrespective of input voltage fluctuations by current regulator. It consists of solid-state variable resistance controlled by feedback from sensors (current and voltage for each array & optical sensor) and current regulator for each LED array. If optical sensor detects signal blank / dim, it reduces the current less than ECR pick up current to generate alarm and cut-off the aspect. (a). Limits the current to cause low current alarm or (b). Boosts the current to cause high current alarm. LED signal unit housing is made either of mild steel sheet or of industrial grade plastic like ABS or fibreglass. The front cover is made of CV stabilised polycarbonate dome. LED signal unit is hermetically sealed in order to ensure that it is able to withstand the environmental severity. A gasket made of EPDM (Ethylene propylene Diene Monomer)-20 rubber shall be provided and pasted on the rim with the help of Anaerobic adhesive to the LED unit The dimension of LED signal unit is such that it can fit securely in the existing CLS units without any modification to them. An MOV or Gas discharge tube of rating 200V shall be provided at the input terminals of CR to take care of power surges. 6.4.3 FUNCTIONAL REQUIREMENTS: The LED lamps should satisfy the following functional requirements: 1 The colour coordinates of LED Red, Green and Lunar Class ‘C’ of BS:1376-1974 signal unit white aspect. Yellow aspect. Class ‘B’ of BS:1376-1974 2 The visibility of each main 600 m in clear day light aspect of LED signal unit 3 Visibility of Route indicator 400 m. 4 The minimum illumination of Red aspect. 50 Lux LED signal units measured at a distance of 1.5 metres in axial Yellow and Green 100 Lux direction. aspect 5 LED signal lighting units display Main and Calling-On 125 mm diameter. area. signals Route and Shunt 85 mm diameter. signals IRISET Page 38  OPERATING PARAMETERS 6.5 OPERATING PARAMETERS Calling-on Route Position Light Parameter Main Signal Signal Indicator Shunt Signal Rated Voltage at Input terminals of 110 VAC 110 VAC 110 VAC 110 VAC C.R. Wattage 15 W 15 W - - Current at rated 140mA 25 mA 55 mA