Chapter 18: Block Instruments, BPAC & IBS Working PDF

Chapter 18: Block Instruments, BPAC & IBS Working Section 1: Block Instruments General Requirements 18.1.1 General (a) All block instruments shall be of robust construction and approved type only. (b) On sections where AC voltages are induced due to power line par...

Chapter 18: Block Instruments, BPAC & IBS Working Section 1: Block Instruments General Requirements 18.1.1 General (a) All block instruments shall be of robust construction and approved type only. (b) On sections where AC voltages are induced due to power line parallelism, suitable block instruments with appropriate protective measures shall be provided as per Section. (c) Block instruments shall normally be worked on physical conductors. Where required, block instruments may also be worked on Radio/Optical Fibre Cable with appropriate security features. (d) Lightning Discharger: All Block instruments shall be provided with lightning discharger to approved specification. Where a return line wire is used, lightning discharger must be installed on both wires. (e) Prevention of Irregular Operations: There shall not be any opening giving access to the interior of the instrument through which it is possible to operate the mechanism by any irregular means. (f) Locking and Sealing Facilities: Facilities shall be provided for locking and sealing the Block instruments. The doors of the Block instruments giving access to the internal mechanism shall be provided with a double lock, the key of one of which shall be in the custody of the Station Master on Duty and the key of the other will be with the technician signal in charge of the maintenance of Block Instruments. It shall not be possible to open the door of the Block Instruments without the co-operation of both the agencies. (g) Prevention of Unauthorized Operation: A lock or other device shall be provided to enable the Station Master on duty to prevent unauthorized manipulation of the instrument during his absence. (h) Isolation of Telephone Circuit: Telephone instrument shall be provided in conjunction with block instruments. It is desirable that the condenser or other means provided for isolating the telephone circuit from the instrument circuit is located within the instrument or in such a way as to be inaccessible for outside interference. (i) Bell Push: A Bell push button or a bell plunger shall be provided on the instrument for exchange of bell codes. (j) An isolated power supply (battery in standalone mode or DC-DC Converter with isolated output) shall be used for line circuit for each block instrument. This power supply shall only feed the block instrument and not any other circuits. The power supply housing shall be locked and sealed if provided in the SM’s Room. Note: Where Integrated Power supplies (IPS) are used for Block working, isolated DC-DC convertor Modules shall be used for each Block separately. (k) Tokenless Block Instruments worked on physical conductors shall be worked on metallic return circuits. Chapter 18: Block Instruments, BPAC & IBS Working Page 356 of 530  (l) If section is installed with Embedded type Block working i.e. Block working built into Electronic Interlocking, VDU kept in ASM room shall have Block Indication display in both the VDU with hot standby feature. Display Descriptions shall be followed as per Drawing No. RDSO/S/32019. 18.1.2 Special Requirements of Single Line Token Block Instruments (a) Fixed Indications: The instruments shall be provided with visual indication clearly giving the following indications: (i) When the instruments are normal and there is no train in the block section, "Line Closed" at both the stations. (ii) When Line Clear for a train to leave the Block station in rear has been given, "Train Coming From" at the receiving station. (iii) When Line Clear for a train to leave a Block station has been received from the Block station ahead, "Train Going To" at the sending station. (b) Current Indicator: An indicator, indicating the polarity of current, shall be provided to indicate incoming and outgoing line currents. (c) Operation: "Train going to" and "Train Coming From" - The instruments shall be such that the cooperation of the Station Master at the other end of the section shall be necessary. Even with the co-operation of the Station Master at the other end, the Station Master has to go through one or more definite moving operations on the instrument in addition to working of bell plunger. (i) Before he can grant Line Clear to the Station Master at the other end of the section to release a token, or (ii) Before he can obtain Line Clear and extract a token. (d) "Line Closed": Both the instruments shall be restored to normal before a further operation of setting the instrument to "Train Going To"/"Train Coming From" can be carried out. It shall not be possible for the instruments at either end of the section to be restored to normal without the cooperative features indicated in para 18.1.2(c). (e) Operation of "Line Clear" Receiving and Granting Mechanism: It shall not be possible for the mechanism which permits a "Line Clear" to be received and that which permits a "Line Clear" to be granted to be in operation at the same time. (f) The instrument that is set to "Train Going To" for initiating a train movement shall be the first one to be restored to "Line Closed" on complete arrival of the train at the receiving station. (g) Extraction of Token: It shall be possible to extract one token only when the instrument has been set to "Train Going To". It shall not be possible to change the "Train Going To" condition until the token has been inserted in one of the instruments of the Block section. Chapter 18: Block Instruments, BPAC & IBS Working Page 357 of 530  (h) Token instruments shall be so installed that a token of one block section cannot be placed in the instrument of an adjacent section and preferably such that if the token is over carried, it cannot be placed in an instrument at the next station. (i) The Tokens of each section shall be engraved with the code name of the stations at both ends of the block section and with a serial number. 18.1.3 Special Requirements of Single Line Tokenless Block Instruments (a) Fixed Indications: In addition to the fixed indications specified in para 18.1.2(a) the instrument shall be provided with means to indicate "Train on Line" at both the sending and receiving stations when a train has entered the block section. (b) Immunity from Extraneous Currents: Single Line Token less block instruments shall work on coded impulse/frequency modulated current system so as to be immune from the effects of extraneous currents. (c) "Train going to" and "Train Coming From": The instrument shall be such that even with the cooperation of the Station Master at the other end of the section, the Station Master has to go through one or more definite moving operations on the instrument in addition to the working of bell plunger. (i) Before he sets his instrument to "Train Coming From". (ii) Before he sets his instrument to "Train Going To". (d) "Train on Line": Means shall be provided to ensure that the instruments are set to "Train on Line" automatically by the entry of the train into the block section and maintained in that position until the train has cleared the block section. This indication shall be in addition to the "Train Going To" or "Train Coming From" indications of the handle. (e) "Line Closed": Both the instruments shall be restored to normal before a further operation of setting the instrument to "Train Going To"/"Train Coming From" can be carried out. It shall not be possible for the instruments at either end of the section to be restored to normal without the cooperative features enumerated in para 18.1.3(c). 18.1.4 Operations: Push Button Tokenless Block Instruments (a) "Train going to" and "Train Coming From": The co-operation of the Station Master at the other end of the section may be dispensed with. The instrument shall be such that a button in addition to the bell button shall be operated for "Train Going To" position. (b) "Train on Line": Means shall be provided to ensure that the instruments are set to "Train on Line" automatically by the entry of the train into the block section and maintained in that position until the train has cleared the block section. This indication shall be in addition to the "Train Going To" or "Train Coming From" indications. Chapter 18: Block Instruments, BPAC & IBS Working Page 358 of 530  (c) Line Closed: Both the instruments shall be restored to normal before a further operation of setting the instrument to "Train Going To"/"Train Coming From" can be carried out. The instrument shall be such that a button in addition to the bell button shall be operated by the receiving station for setting both the instruments to the "Line Closed" condition. This feature can be dispensed with where an automatic device of closing the Block section is provided. (d) Operation of "Line Clear" receiving and granting mechanism - It shall not be possible for the mechanism which permits a "Line Clear" to be received and that which permits a "Line Clear" to be granted to be in operation at the same time. (e) Token less block instruments shall be provided with (i) Audible indicators to warn the receiving station.  When the train enters the block section at the sending station.  When the train has passed the Home Signal at the receiving station. (ii) Shunting key suitably interlocked with the Block instrument for use as an authority for shunting behind the Last Stop Signal and up to the opposing First Stop Signal. 18.1.5 Special Requirements of Double Line Block Instruments (a) Indicators for Up and Down Lines: The Instruments shall be provided with Visual indicators separately for Up and Down Lines to show the following three conditions: (i) Line Closed (ii) Line Clear (iii) Train On Line (b) Current Indicator: The indicators provided as per para 18.1.5(a) may also serve as the current indicators. (c) Operation before Granting or Receiving Line Clear: The instrument shall be such that the Station Master has to go through one or more definite moving operations on the instrument besides working the bell or plunger before he can grant Line Clear. (d) Audible Indicator: Where required, the instruments may be provided with audible indicators (i) to warn the receiving station when the train has passed the Home Signal, and (ii) to warn the sending station when the train has passed the Last Stop Signal. Chapter 18: Block Instruments, BPAC & IBS Working Page 359 of 530