Electric Traction | State the function of following: (i) Feeding post (ii) Sectioning & Paralleling Post (iii) Sub-sectioning Post (iv) Elementary Section

(i)Function of Feeding post:

1) Feeders connected to two sets of bus-bars which are used to maintain supply to OHE in case of failure of one of them or when under maintenance.

2) The 25 kV CB of feeding post are controlled from RCC of railway.

(ii)Function of Sectioning & Paralleling Post:  

1) Sectioning and paralleling post consists of two paralleling interrupters used to parallel OHE of up and down tracks, one on the side of neutral section. 

2) Two bridging interrupters are normally kept open unless emergency feed is required. It should only be closed after taking special precautions to warn the drivers to drop the pantograph when passing the feeding post up to which feed is extended. This is necessary because no neutral section is provided in front of feeding post except on an insulated overlap. 

3) Each substation feeds two sections.

4) Supply to each section is controlled by one CB.

(iii) Function of Sub-sectioning Post:

1) This facilitates isolation of faulty section. 

2) At some stations with large yards change over switch is sometimes provided so that supply may be divided either from OHE of one subsection or other.

3) There is no interrupter for paralleling the up and down track line.

(iv) Function of Elementary Section:

1) To ensure rapid isolation of fault on OHE and facilitate repairs each subsection is further divided into elementary sections. 

2) Adjacent elementary subsections are separated by insulated overlap bridged by isolators which are manually operated on no load.