Introduction Substations are the points in the power network where transmission lines and distribution feeders are connected together through circuit breakers or switches via busbars and transformers. This allows for the control of power flows in the network and general switching operations for maintenance purposes. The first step in designing a power substation is to design an earthing and bonding system. The earthing system also guarantees equipotential bonding such that there are no dangerous potential gradients developed in the substation. Mesh Voltage: This is the maximum touch voltage that is developed inthe mesh of the earthing grid. A grid layout with particular conductors is then analyzed to determine the effective substation earthing resistance, from which the earthing voltage is calculated.
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What is Renewable Energy Certificate? Power transmission and distribution in densely populated urban areas is a great challenge because of land availability and low noise and electromagnetic limitations. With the development in technology and enough improvement in substation design, Gas Insulated Substations are finding increasing use because of their safety, reliability, less space requirement and enhanced life.
Factors affecting the Layout and Design of a substation: The physical layout and the design of the substation are governed by: 1. The number of incoming and outgoing feeders existing and proposed 2. Existing and expected load demand on the substation, 3. Soil resistivity, 4. Expected fault levels at 33 kV and 11 kV level , 5. Climatic conditions, such as temperature, altitude, rainfall etc.
The standard layout guides for the general arrangement of the equipments, structures, bus-bars etc. The general specifications of a substation cover the details of the major equipments and other items to be supplied.
The tender for a particular substation clearly indicate these specifications. The tender specification also has the reference drawings, which indicate the schematic of major connections and form the part of the specification. Suitable provisions can be made in the switchyard depending upon the local condition and locations so as to facilitate transportation of heavy equipments, especially power transformers.
While carrying out the substation construction all the labour regulations, safety codes and measures must be followed. There must be provision for 2 additional 11 kV outgoing feeder for load enhancements in future.
The number of 33 kV incoming feeder may be one or two depending upon the requirement. The various arrangements for the 33 kV incoming and outgoing lines may be according to the standard practice adopted by the electricity board.
Control Panels: All the control and equipments needed to monitor and remote control the vital equipments such as transformers, circuit breakers, feeders etc. In these control panels, relays, meters, and instruments are mounted as per the drawing arrangements.
Relays: Relays are the sensing device which sense the abnormal condition in any power system and accordingly give alarm and trip signal to circuit breaker.
Earlier electro-mechanical relays were used which are now being replaced. The relays used in modern substation are of microprocessor based numerical relays with overload, earth fault and short circuit protection. They should be of the burden more than the minimum burden mentioned and of accuracy class 0. Earthing of a Sub-station: The earthing of a substation is of prime importance for the satisfactory operation of protective devices and for the safety of equipments and personnel.
All equipments must have separate earthing and in the numbers given in the manual. These earths should be well connected to each other and should form a grid.
The resistance of the earthing should be maintained at the required minimum value. There should be satisfactory drainage facility in the yard so that accumulation of rain water should not take place. Yard should be covered with granite metal to prevent the growth of grass and weeds, formation of mud etc. Inspection is necessary before dispatch, delivery at site, installation, commissioning, putting into operation and handing over the equipments.
What is a Electrical Substation – Definition, Layout, and Uses of Substations?
December 13, By Dave Leave a Comment In the modern era, the need for electrical power has increased at an enormous pace. To fulfill the required demand, huge power is needed to be delivered; hence bigger generating stations are to be designed. The electrical power generating stations may be generating electrical energy from water, atomic, thermal, or renewable sources solely contingent on the accessibility of resources and areas where these power stations are built. The areas where power stations are built might not be nearby load centers where the load is consuming power. Therefore transmitting generated power to the load center is of great importance. There is a need for larger high voltage transmission networks for the purpose of transmission. Usually, power is generated in lower voltage levels and is economical for its transmission in high voltages.