Overhead Equipment – Section Insulator

Last updated on April 5th, 2015 at 06:18 am

Section Insulator is a device installed along with the contact wire for insulating two elementary sections where the pantograph of the locomotive negotiates smoothly and maintaining the current continuity. It is used in crossover, turnouts, maintenance pits and  yard line, etc. During movement of locomotive pantograph, it first passes over the runner and smoothly glides to the contact wire on the other side without the break of continuity. Section insulator restricts the speed to 70 Kmph therefore, its usage is limited on slow speed lines and avoided on the mainline.

Section insulator is used to isolate a elementary section requiring maintenance, breakdown attention, etc. and maintaining the OHE supply to other line for smooth flow of traffic. In order to avoid accidental movement of locomotive bridging the section insulator and charging the elementary section, OHE block in the elementary section is taken with traffic block as well. 

 Sectional insulators should be so located that the following conditions are fulfilled.

1. At location of section insulator, the axial distance between the catenary and contact wire shall not be less than 450 mm in the case of single-wire section insulator and 600 mm in the case of a double wire section insulator without increasing the encumbrance at the supports beyond 1.40 m.
2. The section insulator is to be located beyond the point where the center distance between the two tracks is equal to or more than 1.65 m.  If the section insulator is erected with the free ends of the runners away from the center of the turn out this distance may be reduced to 1.45 m.
3. The stagger of the contact wire at the location of the section insulator should normally be zero, but in no case should it exceed + 100 mm. 
4. On loops, the section insulator shall, as far as possible, be located close to the first support of the overhead equipment for the loop.
5. The preferred location of section insulator on main running track is 2 to 10 m from the support in the direction of traffic, though its provision on the main line should be avoided.
6.  In double line section, the runners should be in the trailing direction.