Notes on PSI is a write up that covers some of the basic points on Traction Substation and Traction Switching Stations. To view the same in PDF format click the link below :
Posted by Anup Mohan on Thursday, November 17, 2011,
In :
Design
When you look into a substation layout, say for instance a 132kV Switchyard you would notice that all the equipment installed will be same as the nominal system voltage except for the lightning arrestor. A few days back I found that many of them still have this as unanswered question so as to why is the LA rating chosen lower than the system voltage. So I thought I could share my idea on this with everyone through this post.
When you consider a three phase system, the LA is placed between each... Continue reading ...
Posted by Anup Mohan on Wednesday, November 16, 2011,
In :
Traction
In an Overhead electrification systems, the electricity is supplied by means of electrified wires (live conductors) that run parallel and above the track. These wires are termed as Contact wire. Contact wires can be found attached ( or perhaps supported by ) another length of wire which is termed as Catenary wire.
The electric locomotive uses a Panto-graph, a metal structure which can be raised or lowered so as to make contact with the catenary-contact system and draw current. The return path... Continue reading ...
Posted by Anup Mohan on Friday, November 4, 2011,
In :
Design
The earthing system shall consist of a network of buried conductors forming the earth grid, providing the earthing connections to equipment ground terminals, equipment housings and structures. If the calculated Mesh and Step potentials for this earthing system is less than the attainable mesh and step potentials, then the design is considered to optimum one.
The earth grid shall encompass all of the area of the sub-station within the fencing and also shall extend for approximately one meter o... Continue reading ...
The Earthing of a system is designed with the primary focus being the safety and security of the system by ensuring that the potential on each conductor is restricted to such a value that it is consistent with the level of insulation applied. Most high voltage public supply systems are earthed. Unearthed overhead lines can be found but this may be small as 11kV derived from 33kV mains, where the capacity of earth current is of 4A.
An effective earthing system consists of earth electrodes, buri... Continue reading ...
Posted by Anup Mohan on Thursday, November 3, 2011,
In :
Transformers
Any transformer is rated based on their losses. The losses of the transformer i.e. the Iron loss depend on the voltage and the copper loss depends on the current. Since the loss does not depend on the power factor, a transformer is rated in terms of kVA (kilo-Volt-Ampere).
A transformer is sized based on the load connected to it. There are two types of load, viz. Continuous load and Intermittent load. As the name suggests, continuous load will always be connected with to secondary of the tran... Continue reading ...
