Causes of Ferranti Effect
Ferranti effect basically happens due to the presence of an high charging current because of the capacitance of the transmission line. Although various elements affect the current in the transmission line. However, Ferranti effect happens due to the following three reasons;
- Transmission line capacitance
- Load at the receiving end
- Supply Frequency
Transmission Line Capacitance
The conductors in the transmission line are placed in closed proximity, particularly in underground cables that develop capacitance between them. As a matter of fact, the transmission cable comprises many shunt capacitors and series inductors similarly distributed along the length of the cable. The capacitance increases with an expansion in the length of the transmission line. The capacitors draw a lot of charging current that courses through the entire length of the line. Reactive power is produced by the capacitor and flows in the opposite direction of the source. The inductors in the line consume the receptive power causing a voltage drop across them. The sending voltage is synchronized with the voltage drop. Consequently the voltages add up and the receiving voltage is increased.
Load at the Receiving End
The connected load at the receiving end is another factor that affects the Ferranti effect. The load can be in one of three states:
- No load
- Light load
- Full load
In the no load state, the transmission line only receives a charging current and no load current. The charging current is drawn by the shunt capacitors the line. It produces reactive power that causes a voltage drop across the inductor that is in-phase with the sending voltage and expands the voltage at the less than receiving end.
At the point when light load is connected, there is an very low load current when contrasted with the charging current flowing through the lines. The charging current is naturally leading because of the line capacitance. The capacitor generates reactive power that moves through the inductors which is more prominent than the reactive power consumed by the inductors because of low load current. The voltage drop across the inductors is practically in phase with the source voltage and it is relative to the charging current. As the charging current is higher than the load current, the Ferranti effect happens.
In full load conditions, the load current is higher than the charging current drawn by the capacitor (it is practically steady). Since a large load current is moving through the series inductors, the reactive power consumed by the inductor is larger than the reactive power produced by the capacitor. In this way the net reactive power is negative and the voltage decreases at the less than receiving end.
Supply Frequency
As we know that the Ferranti effect happens because of the reactive power produced in the shunt capacitance of the electrical cables. Anyway reactive power possibly happens if supply voltage and current has some frequency. Since DC has zero frequency, there is no Ferranti effect. The Ferranti effect is more likely to occur in transmission lines that operate at a high frequency.
Ferranti Effect
As we know electricity is generated at power generation plants using huge electromechanical generators by conversion from different types of energy. After that, a long-distance transmission line carries this electrical energy to the end users. In order to maximize the effectiveness of the power transmission and distribution system and ensure the safety of the connected loads and personnel, the electrical power transmission lines require a variety of safety devices and components. The transmission line faces different types of losses and characteristics that influence its efficiency. The Ferranti Effect is one such phenomenon that has a significant impact on the transmission line.
For the most part, we assume that the voltage generally drops in the transmission lines because of the line losses. In a long-distance transmission line with a very low load or no load at all, the Ferranti Effect causes the receiving voltage to be higher than the sending voltage.
In this article, we will be going through the Ferranti effect, First, we will start with the basics of the Ferranti Effect, Then we will go through the Causes of the Ferranti Effect, After that we will go through the Ferranti Effect in Transmission Lines and ways to reduce Ferranti effect, At last, we will conclude our Article with Advantages, Disadvantages, and characteristics of Ferranti effect.
Table of Content
- Ferranti Effect
- Terminologies
- Causes
- Ferranti Effect in Transmission Line
- Ferranti Effect in PI model
- How to Reduce Ferranti Effect?
- Characteristics
- Advantages
- Disadvantages