In a transmission line, air acts as a dielectric medium between the conductors. When the voltage is applied across the sending end of the transmission line, current starts flowing between the conductors (due to imperfections of the dielectric medium). This current is called the charging current in the transmission line.In other words, we can say, the current associated with the capacitance of a line is known as the charging current.The strength of the charging current depends on the voltage, frequency, and capacitance of the line. It is given by the equations shown below.
For a single-phase line, the charging current
Where, C= line-to-line in farads
Xc= capacitive reactance in ohms
V= line voltage in volts
Also, reactive volt-ampere generated by the line = charging volt-amperes of the lines
For a three phase line, the charging current phase
where Vn =voltage to neutral in volts = phase voltages in volts
Cn = capacitance to neutral in farads
Reactive volt-ampere generated by the line = charging volt-amperes of the lines
where Vt = line-to-line voltage in volts.
Significance of charging current
- It reduces the load current, due to which line losses decreases, and hence the efficiency of the line is increased.
- It improves the power factor of the transmission line.
- Charging current improves the load capacity of the line.
- It improves the voltage regulation of the line because the voltage drop is quite small.
10 thoughts on “Charging Current in Transmission Line”
Easy to understand
in my transmission line trainer, when i energize the line at no load, the voltage at the receiving end is higher than the sending end. is this caused by the charging current? how do you explain this? is this true in the real transmission line?
there is the ferranti effect in your transmission line. because in ferranti effect there are high voltages at receiving end. By using shunt reactors at receiving end of your line you can find your desired voltage.
This is because of ferranti effect,which is high in long transmission line
The effect of line capacitance is to produce charging Current, which has a max value at which end of line???
DISADVANTAGE? And its interfacing with the frequency
It was helpful
Especially significance of charging current
In real life, does this charging current flow between the conductors?