Non-Cooperative Type Instruments and Train Detection

Non-Cooperative Type Instruments

• Requirements from paragraph 18.1.5 apply
• Automatic "Train On Line" sets the instrument to "Train On Line" when a train enters a block section, maintaining this status until the train passes the home signal and the instrument is set to "Line Closed"
• Audible indicator warns the receiving station when a train enters the block section
• Two shunting keys, one per line, are interlocked with the block instruments, granting authority for shunting within the block section

Train Detection for Proving Block Section to be Clear

• Track circuits or axle counters extend from the last stop signal to the first stop signal within a block section
• An indicator in each block station displays whether the block section is occupied
• A control ensures the last stop signal automatically switches to "ON" upon a train's passage and remains "ON" until the train clears
• A control ensures the first stop signal automatically switches to "ON" upon a train's passage

Block Working in RE Area

• Specific block instruments are required for 25KV electrified lines
  • Single Line Token Instrument (Neal's)
  • Single Line Token Instrument (Handle Type - Daido)
  • Block working with Axle Counter
  • Block Proving by Axle Counter
  • Block working directly from El
  • Neal's token instruments are being phased out
  • Push-button instruments may be used in non-electrified sections (max 1.5 km) connected to electrified sections

Media

• Block instruments may use special PVC-insulated quads in aluminum-sheathed cable or other communication methods like optical fiber and radio
• Quad cable usage requires transformers to work block telephone and block bell circuits through phantom pairs
• Optical Fiber/Radio usage requires a Universal Fail Safe Block Interface in a relay room, and a block panel in the ASM room

Protective Devices (Others)

• Two chokes in series with a four-terminal condenser and a surge arrester are required; their illustration is provided in Drawing 18-D4 to protect against surges in faulty conditions
• Each block instrument uses separate battery or DC-DC converter
• Separate earths are provided for Signal Protection Devices (SPDs) and Block and connected to the common ring earth of the indoor signalling system

Single Line Token Block Instrument in RE Area

• Earth return usage substitutes the instrument's rest contact with a slow-release relay
• Metallic return for block circuits is required if stray DC is present in the earth
• Modified filter circuit is used in place of a condenser

Double Line Block Instrument in RE Area

• IRS type block instruments with block filters are used for 25KV AC-electrified sections and circuit details are provided in drawing 18-D7
• Battery voltage must sufficiently provide 18–25mA current for the polarized relay

General Fixture for Block Instruments

• All block instruments must be of approved type
• Block instruments are securely fixed to the table/fixture
• Tables or fixtures must be substantial enough to support instruments
• Turn-table fixtures may be provided to assist with maintenance
• Block instruments should have distinct bell units/buzzers in the same room

Transmission Media and Wiring

• Line wires connecting adjacent block sections are either insulated or positioned at least 150 mm from other wires; insulated wires are preferred
• Line wires are terminated on pothead insulators
• Wires are led in an upward direction or drip loops are provided for wire routing to the building
• Indoor wires use troughs or trunking for separation from other circuits; a separate cable for each instrument circuit is recommended; braided or metal sheathed cables are suitable
• Alternative cable method used with suitable protection for better protection
• Radio/Optical fiber cable use requires approved type block interface (use in lieu of line wires)