Power Supply,IPS, RE area

Fully Charged lead acid  Cell Voltage - 2.2 V, Gravity - 1220+/- 5

Discharged lead acid Cell Voltage- 1.85 V, Gravity - 1180+/- 5

Elctrolyte -Dilute Sulphuric Acid

Positive Electrode - PbO2, Negative Electrode - Sponge Pb

Input Voltage of SMR- (160-270) V AC

Initial Charging Voltage - 2.7 V/Cell 

Initial Charging Current- 4% of capacity

Float Charging Voltage - (2.12-2.3) V/Cell

Boost mode equalizing charging - 10% of AH Capacity 

In RE area-

Safety factor -1.5

Safe handling voltage - 400 V 

Induced voltage in underground unscreened cable 

1) On a single line section -for the catenery current of 800 Amps is 116 v/ km.

2) On a Double line section- for the catenery current of 1000 Amps is 95 v/ km

2 m from contact wire - iron mess required 

Iron mess - separate earth less than 10 ohms.

Height of contact wire - 5.55 - 5.75 m from rail level 

2360 mm is distance for signal implantation and OHE mast also

Contact wire and catinary are parallel

Height of Red Aspect -3.65 m.

Quad cable is jointed at every km and every joint should be connected with earth.In case of signalling cables , Armour is earthed in every location box,where it is terminated.

The minimum distance between two working earths must be 3 meter from each other.

Do not connect the Earthing of any block Equipment with any earth provided for other gears.

Induced voltage is normally AC.Earth return voltages are generally DC. 

Do not open keep common battery set for two or more block Equipments.

Do not open the Earthing and connection of any part of block filter unit.

Ensure continuity of Earth bond before opening any insulation joint.

Ensure that max length of track ckt is within limit.

Provide B type choke at both feed and relay ends.

Do not disconnect any OHE bond provided on Single rail track circuit.

Approx 10 V AC will induce into 100m track circuits.

Cross bond is provided at 100m distance in Station Section and at 400m distance in block section.

     In screened cable, two or three layers of metallic Armours are used. Due to this,Any induced voltage in Armour is not likely to reach the copper conductor but cost of the cable will also increase.It protects 50% of induced voltage. 

    In unscreened cable only one layer of metallic Armour is used and Earthing provided at Armour.Cost of unscreened is less compare to screened cable.Now a days only unscreened cables are used in signalling.

Only 6 quad is screened cable used in Railway and three layer Earthing is used.Currently used 6 quad is unloaded and unbalanced cable.

Initial charging and boost charging - Constant current 

Status Monitoring panel in IPS -

At  50%DOD - Start Generator

At 60%DOD - Emergency Start Generator

At 70%DOD- System Shut Down( System feed will cut but all DC DC converters continue till Generator is started.

As per RDSO Specification IRS: S 88/2004 Version 1.0 for LMLA cells - Frequency of topping shall not be earlier than six month.

As per RDSO Specification IRS: S 93/96,VRLA batteries shall be charged at a constant voltage of 2.25 V.

The current rating of Battery Charger= Load current+ AH/10 capacity of cell

As per ACTM para 16.4 to 16.5 of Appendix I

A) If any portion of a signal Post or its fitting falls within 2 meters of a 25 KV live conductor, or any it's metal part, such portion shall be protected by an iron screening solidaly connected to the structure.

If not, a Caution board shall be provided on the signal post at a height of 3 meters above rail level to caution the staff.

Normal height of contact wire is 5.60 m at support.

In tunnels and underneath bridges, contact wire may be as low as 4.58 m.

Normal height of catenary at its highest point is 7.05 m.

Maximum permitted length of direct feed of signal shall be as mentioned below -

Single track - 180 m

Double track - 220 m

In RE area, double line section with uncreened cable, max permissible length of parallelism of DC Circuit using QNA1/ QNNA1 line relay shall be restricted to 2.8 kms.

Distance between The Signal and Mast in front of it - 30 meters








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