Central Electronics Ltd.Central Electronics Ltd.Single Section Digital Axle CounterSingle Section Digital Axle Counter

DACF-710P

Phase reversal type axle detectors with trackside electronic axle counting equipment

Designed as per RDSO Specification No. RDSO/SPN/177/2012 Ver 3.0 or latest

Meets CENELEC SIL-4 standards

Fail safe, reliable and easy to install and maintain.

(Approved by RDSO in Part-I)

What is SSDAC...?

Principle of Operation:Ÿ

Ÿ

Ÿ

The basic principle of system is based on counting the number of axles passing at each detection point.

These stored counts are transmitted to the second unit of the system and vice versa by means of modem communication.

If counts registered at both detection points are equal then section is cleared. Otherwise the section is shown as occupied.

SSDAC System Design:Ÿ

Ÿ

Ÿ

Ÿ

Ÿ

Ÿ

21KHz & 23KHz High frequency axle detectors.

Pulse detection and counting through Microcontroller.

2 out of 2 decision making.

V.21 FSK Modem communication between two distant units (2 independent channels).

Opto isolated Dual Vital Relay drive.

Fail safe operation.

DACF-710P

Single Section Digital Axle Counter(SSDAC) is a microporcessor based embedded system which counts the axles of trains when they pass over the detection point. This axle counting system is used for proving of a section of railway track, i.e. SSDAC provides the status of railway track section wheather it is clear or occupied.

Features of SSDAC:Ÿ No trolley protection circuit required.

Ÿ Web mounted type Axle Detectors.

Ÿ In built event logger.

Ÿ Compatible with 90R, 52 Kg & 60Kg rail profiles.

Ÿ Unaffected by 4 or 8 spokes push trolley wheel with flange height <22mm, width <10mm and wheel base <100mm..

Ÿ Monitors section length up to 20 Kms.

Ÿ Low power consumption ( <2.0A at 24VDC for complete system ).

Ÿ Requires only ½ Quad Cable for system communication.

Ÿ Q type 24V, 1000 Ohm Vital Relays.

Ÿ Immune to traction return currents, magnetic disturbances and other interference from signaling relays.

Ÿ Reliable operation for short detection times.

Ÿ Protected against the effects of lightning.

Function Block Diagram of SSDAC Unit:

AXLE DETECTORS (21KHz)

SCC1CARD MLB1

MLB2

MODEMV.21

RELAYDRIVER

24V

DC-DCCONVERTER

To 2nd Unit of SSDACAt other end

VITAL RELAY BOXQ Type, 24V, 1000 Ohm

Tx1

Rx1

AXLE DETECTORS (23KHz)

SCC2CARD

Tx2

Rx2VR PR

BATTERY24V

Pulse 1

Pulse 2

Relay Read Back

SCC1&2: Signal Conditioner CardMLB1&2: Microcontroller Logic BoardTx1&2: Transmitter CoilsRx1&2: Receiver Coils

Vital Relay Box:The Vital Relay Box (VR Box) encases one Vital Relay and one Preparatory Relay. The Preparatory Relay is used to remove the danger associated with system becoming clear on direct traditional reset. So one pilot train has to be moved in the section for system to become clear. The final output of the system is taken from the contacts of Vital Relay to make the section Clear or Occupied this output is also extended for railway interlocking.

The system comprises of trackside SSDAC units, which are installed near the detection points of railway track. The SSDAC unit performs functions like: generation of carrier signal, demodulation of received signal, pulse shaping and validation, pulse counting, transmission and reception of counts between two units of SSDAC, generating output for Vital Relay, read back of Vital Relay etc. On the basis of comparision of wheel counts of both side Clear or Occupied status of section is given.

SSDAC unit keeps track of its health and logs the status of each event in event logger to record event statistics.

Reset Box of SSDAC sends reset command to trackside unit to normalize the system on system failure. It provides the status of system and error information to station master. The Reset Box also logs the last ten errors of system which makes the tracking of the system easy form the SM’s room

Filter and Surge Voltage Protection Device:To protect the system from noise all the modem signals and 24V input power line are passed through a specially designed noise filter and to overcome the effect of surge voltage the 24V input power line and 48V resetting signal are passed through surge voltage portection device (SVPD).

DACF-710P

System Description:The SSDAC System consist of several components. The description of these components is as follows:

Axle Detector:An Axle Detector consist of 2 transmitter(Tx) and 2 receiver(Rx) coils. One pair of Tx & Rx coil works on 21KHz frequency and other on 23 KHz. SSDAC unit feeds the Tx coils and receives signals from Rx coils. The phase type axle detectors remains unaffected by passing of push trolley i.e. there is no need of trolley protection circuit for working of SSDAC.

Reset Box:

SSDAC Unit:

Central Electronics Ltd.4 - Industrial Area, Saur Urja Marg, Sahibabad – 201010, Uttar Pradesh

Email: spdmktg@celsolar.com, Website: www.celindia.co.in

Uses of SSDAC:SSDAC can be used in :

DACF-710P

Specification of SSDAC:

VR Box VR Box

To BlockInterlocking

(VPR & PPR )

To Reset Boxin SM ’s Room

To Reset Boxin SM ’s Room

Station 1 Station 2

Block Section

Communication Channel

SSDAC in a single line Block Section

SSDAC 2

To BlockInterlocking

(VPR & PPR )

SSDAC 1

Model No.

Communication

Power Consumption

Reset Voltage

Casing

Dimension SSDAC DACF-710P (L*B*H)

Dimension Vital Reset Box VR-721 (L*B*H)

Dimension Reset Box RB-259 (L*B*H)

ITU-T V.21, 300bps, Full Duplex

<50W @ +24VDC

+48VDC

Mild Steel (CRCA)

360mm*330mm*138mm

320mm*250mm*160mm

280mm*255mm*168mm

DACF710P

Ÿ Block WorkingŸ Track CircuitingŸ Intermediate Block SignallingŸ Auto Block Signalling

Ordering Information:

Item

SSDAC

Axle Detectors

Vital Relay Box with PR & Reset Relay

Reset Box

Surge Voltage Protection Device

Model No.

DACF-710P

AD-711

VR-721

RB-259

SV-121

S. No.

4.

1.

2.

3.

5.

CEL make DAC-E1 or DAC-RS232 can be used with SSDAC for other media & redundancy in communication channel. For more details kindly refer to the individual product brochure of DAC-E1 / DAC-RS232.