TLBI (Tokenless Block Instrument)

It is a single line Block Instrument (modified instrument) designed to work on Carrier frequency 1800 Hz or 2700 Hz and modulating frequency (65 Hz and 85 Hz). A pair of block Instruments are connected electrically through overhead or cable to control a single line Block section. It is installed at Station A & Station B and both the stations are linked through Tokenless Block Instrument and telephone. This being FAIL SAFE equipment, which is obtained by a mechanically operated rotary type handle, called Block Handle, located in the front on the lower part of the Block instrument. The handle has force drop locking arrangement which prevents the single handed operation of the device from one station without acknowledging the other Station. Token less block instruments (Handle Type) are used in Indian Railways for obtaining ‘line – clear’ in single or reversible line for electrified as well as non electrified sections.  No overhead wire connection is required for this equipment and it posses high immunity to noises (resulting from local electrical or overhead traction wires), it performs sending, receiving, push – back, shunting or canceling ‘line clear “operation for trains. It is vetted as a fail – safe equipment by the Research Design and standard Organization of Indian Railways (RDSO).  Since 1989 to the present day, it is performing at a 100% success-rate without occurrence of any accident. A set of  FM transmitter & receiver forms the heart of this equipment and  is  responsible  for the low  level  communication  from one station to other  and  in  combination with precisely  designed  durable and reliable  electrical,  electro – magnetic,  contacts / relays / switches with other mechanical  components,  the equipment  performs  authoritatively  fail –safe operations. All operations are instrumentally interlocked,  given clearance,  cannot be  withdrawn  without verbal confirmation  over telephone,  along with  instrumental  acknowledgement   from  the other end. However secondary arrangements are also kept in the instrument for verbal communication, if needed,   between stations through telephones. While transmitter or receiver is in use, the telephone circuit becomes isolated from signal line and vice-versa. Continuous R & D in the area of electrical, electronics, mechanical and metallurgy has made it a state of the art technology to meet the time – to – time demand for highest reliability along with the changes required for local and environmental suitability.

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Technical Specifications:

The instrument is designed to work on 24V DC voltage (normal) with variation between 19.2V to 28.8V. It works on Frequency modulated (FM) system utilizing FM TRANSMITTER & RECEIVER to immune from the effects of extraneous interference. Maximum Current drawn by the internal circuit is not more than 700mA and by the line circuit is not more than 110 mA during normal sequential operation. The instrument is suitable to work with a temperature variation from 0°C to 55°C with relative humidity of 95% at 40°C. Locking and sealing facilities are also provided in the instrument to prevent un-authorized tampering.