SCC CARD IN CEL SSDAC

 Signal Conditioning Card  (SCC)

1) There are two SCC cards in SSDAC. 

2) SCC 1 is connected to TX 1 and RX 1 coils.

3) SCC 2 is connected to TX 2 and RX 2 coils.

4) SCC 1 generates carrier signal 21 KHz and feed it to TX 1 Coil. RX 1 receives this signal and send back to SCC 1 Card.

5) SCC 2 generates carrier signal 23 KHz and feed it to TX 2 Coil. RX 2 receives this signal and send back to SCC 2 Card.

When there is no train there is a phase difference of 180 degree between the signals of TX and RX coil.

This phase shift can be monitored by means measuring 2.2 V DC if there is no wheel on device.The range is 2.0 to 2.5 volts.

If this voltage is in the range,it means that SCC card is transmitting correct frequency, receiving  correct frequency and phase difference between  Tx and Rx are 180 degree.

If during installation of SSDAC you are not getting this 2.2 V DC, reverse the RX Cable polarity in Location box for getting the same.

When you place Dummy wheel on the track device the phase difference between signals of Tx and Rx coils becomes almost zero and  this voltage should be less than 0.7 volts DC.

SCC card demodulates the signal received from Rx.

After Demodulation, it produces a 5 volt digital pulse which is forwarded to both MLB 1 and MLB 2 for processing. 

There is no point to check this 5 Volt anywhere in unit or in Location Box.At the time of failure ,we can not check whether SCC Card is forwarding this 5 volt to MLB Cards or not.


Comments

Post a Comment

Popular posts from this blog

CRS , CST and PCE sanction

  Validity of CST sanction   is six months .Required when we are doing any changes in existing interlocking.e.g commissioning of BPAC Validity of CRS and PCE sanction are same (01 year). PCE sanction is required only for closing the LC gate.Earlier it was with CRS, now delegated to PCE. ESP,SIP,SWRD,PD and SWR required to be attached with PCE sanction.  CRS sanction is must when do any change in interlocking,e.g.any new line is opened. Validity of CRS sanction is 01 year. CRS permission is required in following cases. a) Additions/extensions or alterations to the existing block, Signalling and interlocking installations b) Change in Block, Signalling and Interlocking installations. c) New stations temporary or permanent. d) Interlocking of level crossings, catch siding and slip sidings etc. CST Sanction   CST Sanction required in following works 1) Provision of Telephone at already Manned level crossings. 2) Provision of electrical & mechanical lifting barrier including emergency
Read more

Railway Establishment and Stores

  Max LAP approved one time - 180 days .( if available in his account). Max LHAP approved one time - 24 months ( if available in his account). Leave not due - Max 360 days in service. Can be sanctioned on medical grounds  Compensatory casual leave granted to Group C &D employees other than supervisory staff for attending on Sundays and holidays. Special casual leave    It is sanctioned for participation in sporting events/events of national importance,for scouting duties and family welfare. Special casual leave can be granted in following cases. Administration of operative society members. Participation in scouts . Participation in sports activities  Participation in railway union activities etc In bandh,curfew and national calamity. A railway Servant,who has taken CL for half a day on the afternoon of a working day due to unexpected sickness or compelling grounds and he has no CL at his credit, may as an exception to general rule,be permitted to combine half a day’s CL with regu
Read more

Telecom

                                                    Basics of Telecom Mobile Communication   Emergency Communication  Emergency Communication is provided by following means a) Emergency Socket b) 5/25 Watt VHF sets c) GSM - R ( very less percentile) d) Mobile phones available with driver, guard and staff. Disadvantage of above mode of Emergency Communication - Section controller is not able to contact train crew in moving train It can be initiated only in static condition SOS facility is not available Weight of emergency control phone is fairly heavy. GSM - R is used at very less percentile. To avoid these Shortcoming MTRC ( Mobile train radio communication) is implemented. Accidents, unusual situation, robbery in train, Locomotive failure and chain pulling etc. Features of MTRC  - Driver to Control Guard to Control Driver to station master Driver to guard Guard to train crew Train crew to gateman of gates enroute. MTRC uses GSM-R technology. MTRC has been designed on EIRENE ( European
Read more