24. SPD,EI

Earth is a Equipotential surface.

All power equipments along with suitable SPDs are to be connected to Earthing having earth Resistence less than 1 ohms.

LPZ ( Lightening Protection Zone)-

Outer Zone

LPZ 0- Zone where the threat is due to unattenuated lightening electromagnetic field.

LPZ 0 is sub divided into 

LPZ 0A- Zone where threat is due to direct lightening.

LPZ 0B - This Zone is protected against direct lightening.  Internal system will be subjected to partial lightening surge current.

Inner Zone - 

Area inside structure 

LPZ 1- 

Zone inside structure where magnitude of surge current is reduced due to multiple parallel paths and isolating surfaces and or by installing SPDs.

LPZ 2..n -

Zone inside structure where magnitude of surge current may further reduced  by current distribution and isolating surfaces and or by installing SPDs.

Surge Protection Device -

Class A -

 This is provided with an external lightening conductor on top of the building, connected through a down conductor to ground ( Earth). By this arrangement 50% of lightening energy is connected to ground.

Class B - ( Stage 1 Protection)

  Provided at input of Power Supply equipment.

(Power line protection at distribution level) against Lightening Eletro - Magnetic Impulse ( LEMP) & other higher surges provided at power distribution panels.

This is the first stage of protection provided before the equipment at mains distribution panel is called class B type.This device is spark gap type and operate on arc chopping principle and designed to handle pulses of 10/350 micro seconds.

It can handle 100Ka current between Neutral and Earth.

50 Ka current between all three phases  and neutral.

It is provided with a 63 Amp fuse in phase line. 

Class B SPD is connected between all three phases and the neutral also between neutral and earth.

Max protection is less or equal to 2.5 kv.

Class C- ( Stage 2 Protection)

(Power line protection at Equipment level)

This is second stage protection. This type of protection is provided against low voltage surges at equipment input level connected between phase and neutral.

This device is single high capacity variable ( MOV) which has following additional features.

Failure Indication when device failed.

Thermal disconnection of device when it starts having high leakage current due to aging/ handling several surges.

Potential free contact for remote monitoring 

A number of MOVs in no case to be provided in parallel.

MOV is surge suppressor.

Response time of Class C is less than 25 n seconds

Class D- ( Stage 3 Protection)

Provided at Indoor and field equipment.

Protection for power/ Signalling/ data lines

 All external power/ Signalling/ data lines (AC/DC) shall be protected by using class D type SPD. It consists of Varistors/ Suppressor diodes and Gas discharge tube with voltage and current limiting facilities.

      Note- if power/ Signalling/ data lines ( AC/ DC) are carried through overhead wires or cables above grounds to any nearby building or any location outside equipment room,additional protection of Class C type shall be provided at such locations for power supply lines and Class D type for signal/ data lines.

MOV and Gas discharge tubes are used in Class D protection.

SPD in IPS-

    IPS is provided with class B and Class C, two stage protection.  Coordinated type B and C arrester shall be provided in a separate enclosure adjacent to each other in IPS room.This enclosure should be wall mounting type.

EI shall be shall have provision of accomodating 15% of I/Os in future.

During the alterations of stn yard only Application logic will be changed. 

Capacitor microphone and carbon microphone require polarizing voltage.

Ribbon, Dynamic and Crystal microphones do not require any external voltage 

All object controllers are connected through OFC  only to EI.

Executive Software of an EI system is common to same model of same OEMs.

Changeover of EI system shall be done from Main to Hot Standby and vice versa once in Monthly under supervision of Sectional SSE/JE.

In an EI system, Protocol Converter is used to interface between EI and Datalogger.

Vital Output of EI - 

Signal - HR, DR, UGR, COHR,HHR

Point - NWR, RWR,PCR 1, PCR( Point power Control)

Crank Handle - CHYR

Siding Control - KLYR

LC gate - LXYR

Vital Input of EI -

Signal- DECR, HECR,RECR, CO_HECR, UECR

Point - NWKR, RWKR

Track Circuit - TPR

Crank Handle - CHCR

LC gate - LXCR

SMCR

Non Vital Input of EI

Signal - GN

Point - WN

Siding - KLN

Gate - LXN

Crank Handle - CHYN

All route buttons

Common point Buttons - NWWN, RWWN,EWWN

Signal cancel Button - EGGN

Route Cancel Button - EUUYN, EUYN

Slot Buttons- GSBN, GSRBN

Panel/ PC key 

Non Vital Output of EI -

All the indications

Pre Commissioning check list of EI will be verified by field ADSTE/DSTE and countersigned by SrDSTE or Dy CSTE.

System Architecture-

Two out of two Hardware Architecture with identical hardware and identical or diverse software.

Important points of EI

1) Only approved application logic with specified checksum shall be used in the EI system and this data and checksum shall be version controlled and preserved by Railway 

2) The input and output cables shall be twisted to minimize EMI and EMC effect.

3) EI system shall be installed closer to Operator Room, preferably adjacent room.Track crossing should be avoided between main EI system and operator room.

4) Clean and dirty wiring shall be clearly segregated and routed in different enclosures/ladders and where this is not feasible, a minimum distance of 150 mm between clean and dirty wiring shall be maintained. 

5) If clean and dirty cables  need the cross at any place, then wiring should be arranged at perpendicular to each other.

6)  Indicative type surge protection devices of appropriate class and rating  shall be installed for all copper based external interface ports.

7) The connectivity between EI and sub system like Control Terminal,Control panel and object controller shall be planned with OFC cable to avoid damage due to surge and lightening.The OFC shall be provided in redundant manner to avoid failure due to cut/ damage in one location/ path.

8) Executive Software of an EI system is Common to same model of same OEM.

9) Changeover of EI system shall be done from Main to Hot Standby and Vice Versa once in on Month under Supervision of Sectional SSE/JE when there is no train movement.

10) Protocol Converter is used as interface between EI and Datalogger.

150 mm - Distance between clean and Dirty cables in EI installation.

3m - Minimum distance between two earth pipes.

Object Controller ( OC)-

Object controller is the equipment which drives the field function through conventional relay or directly through its own electronic circuitry.It also takes input from field.

Object controller are used as slave unit of Main system.

OC and Main system can be connected by copper cable or OFC or wireless.

Both Hardware and Software of Object controller must meet SIL 4 standards.

OC should be placed at maximum distance of 15 Kms from CIU.

Each OC is independent from Other.

Hardware used in EI -

Input cards - All the field relay contacts are connected to these input cards.

Field inputs - ECRs,TPRs,NWKRs etc

Panel inputs - GNs, UNs, NWN, RWN etc

Read back inputs - HR DR WNR WRR

Opto couplers are provided to isolate field optically from the system in input cards.

Processor Card -

Called central processing unit card of the system.

Provided with microprocessor,RAM,ROM,EPROM,EEPROM memory etc.

System software consists of the following 

1) Executive Software programmed in system EPROMs

2) Application Software programmed in Data EPROMs.

During EI alteration Data EPROMs are to be replaced with new Data EPROMs as per new table of control.

For EI alterations EI Complier software is used.

Executive Software-

Common to all EIs for the same company manufacturing 

Factory installed software 

Cut off Vital supply voltage to output relays in case of unsafe failures.

Application Software -

Specific for each station.Different for different stations.

As per table of control of specific station.

Can be installed at site by signal engineer.

Vital Output -

DR HR WNR WRR CHYR  KLR  LXYR

Vital Input -

DECR HECR RECR UECR Co HECR NWKR RWKR TPR KLCR LXCR

Non Vital Input -

GN  UN WN  CHN  LXN

Non Vital Output -

DGKE  HGKE  RGKE

EI shall have provision of accomodating 15% of I/Os in future.

No of physical ASR Relay is zero in EI.

As per RDSO Specification in big yards MTBF of all vital modules shall be more than 1 Lakh.

RDSO Specification for EI in big Yard ( More than 200 routes) - RDSO/SPN/203/2011

System availability ( operational Availability of Complete system) shall be 99.98% or better.

AC may be provided in PI/RRI having more than 100 routes.

FAT-

Performed with computer Simulation

Control table ( including Negative Testing)

Cross table ( Also known as Square sheet testing)-Conflicting movement testing.

SAT -

Logic and interlocking Testing:

1. Control table ( including Negative Testing)

2. Cross table ( Also known as Square sheet testing

Table )

Interface and Equipment function test

1. Intercommunication test between sub racks

2. Correspondence test.

EI system back up data of Minimum 10 lakhs or one month data.

TSAA - Technical System Application Approval 

Both Cyclic time and response time must be less in EI system.

As per GOI RB  letter 2021/ Sig/ 25 - Conf/5/ SSC dated 26.05.2021

Upto 100 routes - Centralized/ Distributed EI  Can be provided with approval of CSTE.

100 to 500 routes -Distributed EI

More than 500 routes - RRI with Metal to Metal or Distributed EI

TSAA upto 200 routes - PCSTE approval required. TSAA must be prepared as per TAN.

Power Supply Arrangement for EI-

1) Input 110 V DC from IPS room to EI rack shall be provided with duplicate cable so that voltage drop is less than 1 volt.

This 110 v DC is directly given from EI to battery.

110 DC is connected to reliable UPS recommended by OEM,to get 50 V DC or 24 V DC or any other desired voltage by OEM.DC DC Converters shall be used in N+1 Configuration.

Reliability Parameters-

1.MTBF

2.Failure Rate 

3. Failure probability .

Maintainability  Parameters-

1. MTTR

2. Time for replacement 

3. Time for preventive maintenance 

Warm Standby Arrangement of EI - Only one system will switch on.

In EI system RTC of CPU system should be updated with external data logger.

NWR and RWR connected to read back.

10 Second- Time taken in EI to take longest route and display lowered signal