Here we will discuss only line parameters of overhead transmission lines. as we know that transmission are not insulated , Air is use as insulation between 3 phase conductors
Insulators mostly are installed on towers by help of which transmission line passed from one tower to another
Every conductor has its own resistance , As ac current flows in the conductor so magnetic flux will be generated which will link to other conductors also so inductive element is also their in transmission line capacirtive effect is found between two phases or between phase ans earth
Trnasmission line consis of four parameters
Resistance,Inductance,Capacitance,Conductance
RESISTANCE
Resistor is a device which offer opposition to the flow of current
In transmission line their will be some resistance , If a transmission line is divided in equal parts and all parts are equal in size and having same cross sectional area so in this condition resistance of all parts will be same if one part resistance meansured by resistivity method so reisitance of whole line can be find
Resistance also depends on temperature if temprature increase so resistivity of a material will be increased , By increasing cross sectional area resistance can be decreased
TEMPERATURE EFFECT
Frequency increased reisitnace will also be increased
Current density
Current flows in conductir magnetic losses will be produced so as a result resistance will be increased Resistance of a line can be find by two ways
1. Divide total length of line in equal parts
2. Consider only one high value resistance
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