Part – A : Winding Diagrams Notes by
Part – B : Transformer DC Machine Notes by
Prof. V D Sankarlal,
Single Line Diagram of Substations Notes by
Prof. D Beula
Sir MVIT Bangalore
Notes Credit – VTU Elearning
Transformer [Sample Notes]
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Single Phase and Three Phase Transformers (Core Type)
The elevations of single phase core type transformer and three phase core type transformers are shown in Figure 1. The widths of cores on the two limbs are equal in single phase transformers. The widths of cores of all the three limbs are equal in three phase transformers. The height of yoke may be equal or greater than the width of core, in both cases. The depth of core will be confined to the dimension of circumcircle diameter
Single Phase and Three Phase Transformers (Shell type)
The elevations of single phase shell type transformer and three phase transformer are shown in Figure 2. The width of the extreme limbs will be about half the width of central limb. The depth of the core may equal to about two to three times the width of central limb. The height of yoke may equal to or greater than half the width of central limb
DC Machine [Sample Notes]
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DC Machines form one of the varieties of electrical equipment and are extensively in use in various industrial applications like DC voltage generation, electro- plating, metal extraction, traction, steel industry, paper mills etc. While the performance analysis and design features have been considered already, given the design data, this chapter deals as to how to make drawings of parts, sub assembly and general assembly. The input data for making the CAD drawing may be in the form of wordings, sketches or both.
Te following are the parts of DC machine-
1. Yoke- Housing- Casing
2. Poles- Main Poles- Inter Poles- Compensating Winding
3. Armature and Armature Winding
5. Brush and Brush Holder
8. End Shields
9. Lifting lug
The general appearance (Figure-1), a dismantled view (Figure-2), an exploded view (Figure-3), a general assembly (Figure-4) and a sectional pictorial view (Figure-5) of DC Machine are given below, to familiarize with the various parts and their relative position in the machine-assembly.
Yoke and pole with winding constitute stator and armature with winding and commutator form the rotor. The brush and brush holder assembly is used for supplying or collecting current from/to the machine. The other structural parts are end shields, bearings, fan, foot and terminal board. The drawing of active parts is given prominence. However, knowledge of other parts also, will greatly help in assuming data require for completion of drawing.
Single Line Diagram of Substations
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Electric power is produced at the power generating stations, which are generally located far away from the load centers. High voltage transmission lines are used to transmit the electric power from the generating stations to the load centers. Between the power generating station and consumers a number of transformations and switching stations are required. These are generally known as substations. Substations are important part of power system and form a link between generating stations, transmission systems and distribution systems. It is an assembly of electrical components such as bus-bars, switchgear apparatus, power transformers etc.
Their main functions are to receive power transmitted at high voltage from the generating stations and reduce the voltage to a value suitable for distribution. Some substations provide facilities for switching operations of transmission lines, others are converting stations. Substations are provided with safety devices to disconnect equipment or circuit at the time of faults. Substations are the convenient place for installing synchronous condensers for the purpose of improving power factor and it provide facilities for making measurements to monitor the operation of the various parts of the power system. The substations may be classified in according to service requirements and constructional features. According to service requirements it is classified in to transformer substations, switching substations and converting substations.
(1) Transformer substations: Majority of the substations in the power system are in the type. They are used to transform power from one voltage level to another voltage level. Transformer is the main component in such substations. Transformer substations are further classified into Step-up substations, Primary grid substations, Secondary substations and Distribution substations.
(a) Step-up substations: These substations are usually located at the generating stations. Generating voltage of the order of 11kV needs to be stepped up to a primary transmission voltage level of the order of 220kV or 400kV.
(b) Primary grid substations: These substations are located at the end of primary transmission lines and the primary voltage is stepped down to suitable secondary voltages of the order of 66kV or 33kV.
(c) Secondary substations: The voltage is further stepped down to 11kV. Large consumers are supplied power at 11kV.
(d) Distribution substations: These substations are located near the consumer localities to supply power at 400V, three phase or 230V, single phase to the consumers.
(2) Switching substations: These substations are meant for switching operations of power lines without transforming the voltage. Different connections are made between the various transmission lines.
(3) Converting substation: Such substations are meant for either converting AC to DC or vice versa. Some are used to change the frequency from higher to lower or vice versa for industry utilisations.
According to constructional features substations are classified into Indoor substations, Outdoor substations, Underground substations and Pole mounted substations.
(1) Indoor substations: All equipments of the substation are installed within the station buildings.
(2) Outdoor substations: All equipments such as transformers, circuit breakers, isolators, etc., are installed outdoors.
(3) Underground substations: In thickly populated areas where the space is the major constraint, and cost of land is higher, under such situation the substations are laid underground.
(4) Pole mounted substations: This is an outdoor substation with equipments installed overhead on a H pole or 4 pole structure.
Single Line Diagram
Any complex power system even though they are three phase circuits, can be represented by a single line diagram, showing various electrical components of power system and their interconnection. In single line representation of substation the electrical components such as power transformers, incoming and outgoing lines, bus-bars, switching and protecting equipments, are represented by standard symbols and their interconnections between them are shown by lines. Single line diagrams are useful in planning a substation layout.