What are the various types of OHE Railway Insulators used in Railway Industry?

Why are rail tracks insulated?

The rails of a train track are its most fundamental component. They are at the front of the train and are responsible for distributing the weight of the cars to the sleepers. It ought to be consistently smooth with low friction. At present, in automatic block zones or on electrified railways, each pair of rails serves as both a signal line for the track circuits and a loop line for locomotive traction. Therefore, insulation of rails is required to prevent stray current interference. Rail lines typically make use of insulators and insulated rail junctions. The ductile iron shoulder is protected from wear caused by direct contact with the rail, and electricity is insulated, thanks to the insulators. They are often set up between the rail and the sole plate.

OHE Railway Insulators in railway traction have a dual purpose: they insulate the live conductor from the ground and they support it mechanically.

The constant movement of trains on the railway lines causes vibrations that subject insulators to mechanical shocks. Railway Insulators, moreover, are constantly exposed to shocks caused by pantograph movement.

As a result, the integrity of the insulators is crucial to the safe and dependable functioning of any overhead electric traction system. There is a growing obligation to guarantee not only the reliability but also the availability of power supply for traction load on the Indian Railways' expanding electrified network.

Disruptions to traffic flow can occur when porcelain insulators fail for any number of reasons, including flashover or mechanical fracture (from either normal stress or vandalism/accidents). Replacement of the Railway insulator typically results in a 2- to 3-hour outage. Because of their improved contamination and pollution performance and reduced flashover rates compared to porcelain insulators, composite insulators are increasingly being used in the electrical power sector around the world.

The Indian Railways use millions of Railway insulators, but only a small fraction of them are composite insulators for its 25 kV a.c. single phase traction network that includes around 45,000 kilometres of electrified track.

Types of OHE Railway Insulators: - Stay Arm Insulator:

Insulator known as the Stay Arm Insulator is a component of the Cantilever Assembly that is a part of the horizontal member and which seperates the Stay Tube from the structure where it is attached with the Cantilever. Insulator also forms part of the Stay Tube.

• Bracket Insulator:

Insulator that is part of the inclined member of the Cantilever Assembly (from which the Overhead Traction Conductors are strung) and that is known as the Bracket Insulator. It serves to separate the Bracket from the structure where the mounting of Cantilever is done.

• 9-Tonne Insulator:

The Insulator, also known as a 9-Tonne Insulator, is typically utilised as a Strain Insulator for the purpose of anchoring conductors; however, this application is not the only one for which it is suitable. In addition, it can be positioned vertically to serve as a support for 25 kV Feeder Wire.

• Section Insulator:

In a typical setting, the term "section insulator" refers to the insulating component of a piece of equipment known as a Section Insulator Assembly. This equipment is employed for the purpose of isolating the adjacent areas of traction lines mounted overhead that are associated with distinct Elementary Electrical Sections. It does this by offering a continuous and smooth route, both mechanically and electrically, for the passage of the pantograph used by electric rolling stock.

Which material is used in OHE Railway Insulator?

Porcelain and glass are the two materials that are traditionally utilised in the production of railway insulators. This is due to the fact that both of these materials offer excellent insulating and weather-resistant capabilities. However, they have a number of drawbacks, including the fact that they are cumbersome, have a low resistance to impact, and have poor electrical withstand properties, particularly in dirty or polluted environments. In order to address these limitations, the development of composite insulators was carried out and eventually implemented across the Indian Railways in locations that are prone to pollution.