Applications :

The DACF 700 is the track side equipment for detect -ing track vacancy (Track Circuiting ) based on the principle of axle counting. It is mainly used for moni- toring single track sections in Railways such as :-

• BLOCK WORKING
• INTERMEDIATE BLOCK SIGNALLING
• AUTO SIGNALLING
• LOOP LINE
• MAIN LINE
• PLATFORM LINES

Single Section Digital Axle Counter (SSDAC)

Principle of Working :

The Single Section Digital Axle Counter DACF 700 comprises of Axle detectors and track side Electro- nic Counting Unit linked by connecting cables. It is installed at both limits of track section.

The Axle Detectors operate on high frequency (21K Hz & 23 K Hz) according to the proven method of electromagnetic wheel detection. When a train wheel enters in between the detectors, it influences the electromagnetic field and the wheel is detected.

The detected wheels of a train are converted into pulses and these pulses are counted at the entry and exit of the track section. The stored counts are exchanged by telegram packets between the units.

The track clear decision is arrived at if the counts are equal and Vital Relay is picked up for signall- ing the next train, otherwise the track is shown as occupied.

SSDAC in Block Section

Features :

• Trackside electronic counting equipment.
• Web type axle detectors.
• Compatible with 52 kg & 60 kg rail profiles.
• Detection of all wheels with diameter > 500 mm.
• Track clear / occupied at both stations.
• Normal operation during water logging on rails.
• Easy to install,commission and maintain.

Reliability :

• Reliable operation for short detection times.
• Immune to traction return currents, magnetic disturbances and other interference form signalling relays.
• Error free operation over large temperature range (Zero degree Celsius to +70 degree Celsius) even in conditions of extreme humidity.
• Protected against the effects of lightning.

Design :

• Designed as per CENELEC, SIL- 4 (European standards).
• 21 K Hz & 23 K Hz high frequency Axle detectors.
• Micro controller based design with 2 out of 2 decision.
• Counting through software.
• Cyclic Redundancy check (CRC).
• V.21 modem communication (2 wire).
• Compatible with OFC & Radio.
• Opto Isolated relay drive for Q type 24v, 1000 ohm.
• Fail safety tests conducted and found OK.
• MTBF is greater than 15 years.

Specification :

• Specification No. RDSO/SPN/177/2003.

Approved by :

• R D S O, LUCKNOW
  (software has been verified & validated by Rel Q, Bangalore)

Development & Field trials :

• The DACF 700 has been indigenously developed by CEL & RDSO under the aegis of DSIR (PATSER Programme).The system has undergone field trials at various locations of Indian Railways. The system has been thoroughly checked for all type of train movements & has been found working satisfactorily.The merit of the system is that vital relay output is available at both stations for block working.

Turnkey :

• CEL has been successfully manufacturing the Railway Signalling equipment for more than 20 years and providing turnkey solutions for track circuiting, Single line and Double line block working systems to Indian Railways. CEL is equipped for manufacturing , supply and installation of Digital Axle Counter on turnkey basis.

Note :- CEL reserves the right to alter the specification or other technical details / parameter with approval from RDSO for improvement of the system at any time.