Ferranti Effect is one of the undesirable phenomena that happens in power systems. Fundamentally it explains the rise in receiving end voltage as compared to sending end voltage due to line capacitance and inductance for a long transmission line i.

Conceptualized by Sir S.

Ferranti in the yearthis effect explained the impact of line capacitance on receiving end voltage under no load or light load conditions. This article discusses an overview of the Ferranti effect. Definition: It can be defined as the rise in receiving end voltage as compared to sending end voltage for a long transmission line under no load or light load conditions. This phenomenon can be explained based on the phasor diagram, mathematical expressions for sending and receiving end voltage and based on reactive power flow in the transmission line.

## What Is the Ferranti Effect?

This is explained individually as follows:. Consider the following equivalent circuit of a transmission line and its phasor diagram. The below figure shows the equivalent circuit of a long transmission line where R, L, C are line resistance, inductance and capacitive respectively. In the equivalent circuit, they are approximated as lumped elements instead of distributed. Now it is to be noted that line resistance, inductance, and capacitance all are directly proportional to the length of the line.

So for a long transmission line, all will have a dominant effect. Let I C be the charging current i. The following figure shows the phasor diagram for the equivalent circuit. Writing simple KVL equation for the above figure we can see that. When represented in the phasor diagram, as shown due to the leading nature of charging current, the vectors QR and PR when added OQ, i. Hence under no-load condition, the line capacitance dominates the line inductance, and the drop across line inductance due to charging current which is leading in nature makes receiving end voltage greater than sending end voltage.

It is be noted that the first half of the right side of equation 1 is also known as an incident voltage which keeps increasing with length of line and the second half is known as reflected voltage which decreases with the length of the line. From a basic analysis of equation 2it is apparent that V R becomes greater than V S. From the fundamentals, we know that, if at a particular node the reactive power generated is more than reactive power absorbed, then the voltage at that particular node becomes higher than the normal value.

From figure Fig 1 a it can be observed that at node A, due to dominant line capacitance since we are considering long transmission line the net reactive power generated is more than reactive power absorbed due to line inductance.

This clearly indicates that the voltage at node A, V R due to no-load condition becomes greater than V Swhich clearly explains the Ferranti effect. The line inductance acts as a sink whereas the line capacitance acts as a source for reactive power.

Further adding to it, the loading at this condition i. Since it is apparent that the Ferranti effect is mostly due to line capacitance, or in other words active power generation, to overcome this effect we need a reactor to compensate the line capacitance. This is known as the shunt reactor which is installed at receiving end side to balance the reactive power.It is a general convention that in an electrical system, the current flow is always from higher concentration or potential area to that of lower concentration or potential area, for compensation which lies within the system.

Practically, it is proven that the voltages at the transmission end are always greater to that of voltages at receiving end because of various line losses which depict the flow of current from supply to load. Ferranti introduced a theory inwhich was declared as an astonishing theory in electrical systems. The basic concentration of the theory was concentrated along medium distant transmission lines or the no-load operation of long-distance transmission lines.

Sometimes the voltages at receiving end are in the level beyond transmission end. This is what the Ferranti effect in a transmission line is known in power systems. The Ferranti effect can be defined as an effect in which the receiving end voltages gets higher at transmission line than that of the voltages at the transmission end. The effect may be occurring because of several reasons such as open circuit at reception end or because of the lighter load at the receiving end.

Whenever an alternating voltage is applied at the line, the current produced is flowing across a capacitor and is known as charging current. The charging current is also given the name of capacitive current. The capacitive current is always increasing in the line whenever the voltages at receiving end are bigger than that of voltages at the transmission end. The Ferranti effect definition can also be illustrated as the effect of voltage collection at the receipting end to be at a higher level than that of voltages at the transmission end.

This kind of effect is generally occurring because of an open circuit or lighter load at the receiving end and may occur because of charging current at the transmission lines. The charging current definition is whenever an exchange voltage is linked, the current is flowing across a capacitor which is then named as the capacitive current.

The charging current is always rising when voltages at the receiving end are greater than the voltages at the transmission end.

### Ferranti Effect

The lines are having two major parameters i. The parameters are considered specifically for those lines having a length of over km. These lines are not having capacitance concentrated at specific points but is distributed over entire line uniformly. By the time when voltages are applied at the transmission ends, the current is drawn through the capacitance of the line which is more than current which is associated with the load. Therefore in light load or no load conditions, the voltages at the receiving end are higher when compared to transmission end and details are also available at Ferranti effect ppt online.

As already discussed in detail how and why Ferranti effect is occurring, following are some additional parameters which needed to be considered as well and can be found in Ferranti effect pdf resources. For the calculation of equations of Ferranti effect, considering a large transmission line having an OE signifying a collection of voltages, OH is signifying flow of current across the capacitor at collection end.

The FE is phasor which is signifying a decrease in voltage through resistance, FG is signifying a decrease in voltage through inductance, OG is also a phasor which is signifying voltages at transmission end in a no-load condition. The following is the circuitry model known as the PI model depicting the entire scenario at no load conditions. In the above PI model, OE is larger than OG and it can be stated that the voltage at reception end is greater than that of voltages at transmitting end and no load conditions are considered.

The following is the Ferranti effect phasor diagram. The equation for a small PI can be deduced as follows known as Ferranti effect equation. This equation is showing that is in negative value which means that the voltages at the receiving end are greater than that of transmission end. This is how the Ferranti effect calculation is undergone.

The Ferranti effect in the power system is a common phenomenon. There are numerous disadvantages for Ferranti effect which affect the performance of the power system.

Therefore Ferranti effect reduction is an important task to achieve i.Ferranti Effect in a transmission Line is reduced using voltage compensation which in turn is accomplished by Shunt Reactor.

Shunt Reactor is just like a Transformer but it has only primary and no secondary. Shunt Reactor is connected to all the three phases i. R, Y and B phase. Figure below shows a Shunt Reactor.

For better understanding we will consider different aspects of Ferranti Effect. A long transmission line can be considered to be composed of a considerably high amount of capacitance and inductor distributed across the entire length of the line.

Ferranti Effect occurs when current drawn by the distributed capacitance of the line is greater than the current associated with the load at the receiving end of the line which occur during light or no load. This capacitor charging current leads to voltage drop across the line inductor of the transmission system which is in phase with the sending end voltages.

This voltage drop keeps on increasing additively as we move towards the load end of the line and subsequently the receiving end voltage tends to get larger than applied voltage leading to the phenomena called Ferranti Effect in power system.

During no load or light load condition, the reactive power generated at a point on the Transmission Line will be more than the reactive power absorbed and therefore the voltage at that point will rise. Mind that during no load or light load condition the line capacitance will dominate to inductance. Ferranti Effect will not be dominating. For a medium length line of km the rise in voltage will be about 9. Thank you! Your email address will not be published.

Notify me when new comments are added. This site uses Akismet to reduce spam. Learn how your comment data is processed. Subscribe to our mailing list and get interesting stuff and updates to your email inbox.C where l is the line length, L and C are inductance and capacitance per unit length. Post a Comment. Ferranti Effect is the rise in receiving-end voltage V R as compared to the sending-end voltage V S of a transmission line.

It was first noticed by Sebastian Ziani de Ferranti on a project involving underground cables in a 10 kV distribution system inand was eventually named after him.

The ferranti effect normally occurs on an energized long line more than 80 km with very light or worst, no load.

However, it can also happen with shorter lines composed of underground cables. Looking at the power quality perspective, long transmission lines and underground cable installations may require protection for overvoltage such as surge arresters when loads are suddenly disconnected.

Ferranti effect is mainly due to the charging current, which is associated with the line capacitance. In addition, these basic points must be noted:. Capacitance is dependent on. Charging current.

Accordingly, ferranti effect occurs only for long lightly loaded or open-circuited energized lines. In addition, the phenomenon becomes more evident with higher applied voltage and underground cables. Ferranti Voltage Rise Factor. At very light or no load, I L can be neglected leaving.

### Ferranti Effect

With resistance neglected, the above equation can then be detailed into:. For example, this factor could be as high as 1. As a result, the receiving-end voltage becomes higher than the sending-end i.

Moreover, it is clear from the equation that the voltage rise factor is proportional to the square of the line length, and consequently the inductance and capacitance. Email This BlogThis! Labels: OvervoltagePower Quality. Newer Post Older Post Home. Subscribe to: Post Comments Atom. I have been working in an electric distribution utility for more than a decade. I handle PQ studies, power system analysis, diagnostic testing, protective relaying and capital budgeting for company projects.

View my complete profile.In electrical engineering, the Ferranti effect is an increase in voltage occurring at the receiving end of a long transmission line,to the voltage at the sending end. This occurs when the line is energized but there is a very light load or the load is disconnected.

The capacitive line charging current produces a voltage drop across the line inductance that is in-phase with the sending end voltages. Therefore both line inductance and capacitance are responsible for this phenomenon. The Ferranti Effect will be more pronounced the longer the line and the higher the voltage applied. The relative voltage rise is proportional to the square of the line length. The Ferranti effect is much more pronounced in underground cables, even in short lengths, because of their high capacitance.

It was first observed during the installation of underground cables in Sebastian Ziani de Ferranti's 10, volt distribution system in An effect as yet not definitely explained, observed in the mains of the Deptford, Eng.

It is observed that the potential difference between the members of a pair of mains rises or increases with the distance the place of trial is from the station.

what is ferranti effect and ferranti effect with phasor diagram

Both capacitance and inductance are responsible for producing this phenomenon. The effect is more pronounced in underground cables and with very light loads. The numerical value of ferranti effect in Chaldean Numerology is: 7. The numerical value of ferranti effect in Pythagorean Numerology is: 1. Word in Definition. Freebase 0. The Standard Electrical Dictionary 0. How to pronounce ferranti effect?

Alex US English. Daniel British. Karen Australian. Veena Indian. How to say ferranti effect in sign language? Numerology Chaldean Numerology The numerical value of ferranti effect in Chaldean Numerology is: 7 Pythagorean Numerology The numerical value of ferranti effect in Pythagorean Numerology is: 1. Select another language:. Powered by CITE. Are we missing a good definition for ferranti effect? Don't keep it to yourself Submit Definition.It can be stated as a factor, or as a percent increase.

It was first observed during the installation of underground cables in Sebastian Ziani de Ferranti 's 10, volt AC power distribution system in The capacitive line charging current produces a voltage drop across the line inductance that is in-phase with the sending-end voltage, assuming negligible line resistance.

Therefore, both line inductance and capacitance are responsible for this phenomenon. This can be analysed by considering the line as a transmission line where the source impedance is lower than the load impedance unterminated. The effect is similar to an electrically short version of the quarter-wave impedance transformerbut with smaller voltage transformation. The Ferranti effect is more pronounced the longer the line and the higher the voltage applied. The Ferranti effect is much more pronounced in underground cables, even in short lengths, because of their high capacitance per unit length, and lower electrical impedance.

Namespaces Article Talk. Views Read Edit View history. By using this site, you agree to the Terms of Use and Privacy Policy.Learn something new every day More Info The Ferranti effect is a term that describes an electrical phenomenon that causes voltage to rise at the end of an alternating current AC transmission line.

This is likely to occur when a transmission line is either very lightly loaded or it is interrupted due to a power outage. The Ferranti effect is named for the electrical engineer Sabastian Zianni de Ferranti, who designed the power station and distribution network for an AC facility in England inshortly after the War of the Currents.

The War of the Currents was the debate between Nikola Tesla, who advocated the use of AC power distributionand Thomas Edison, who advocated the use of direct current DC power distribution. The new construction of the Deptford, England power station first exhibited the Ferranti effect in its AC distribution lines when opened in Observances of the Ferranti effect happen more frequently along buried transmission lines in contact with earth, as at the Deptford power station, rather than along transmission lines strung overhead.

Burying transmission lines contributes to heightened load as it nears the end of its line; and for this reason shunt reactors must be applied to underground lines to stabilize the power flow. As the desired distribution is for stepped-down power voltage at the receiving end of transmission lines versus the raw power voltages at the sending source, the Ferranti effect must be compensated for along the line in order not to avoid delivering excessively high voltage to household or industrial appliances.

The length of the transmission line is also a contributor to the Ferranti effect. Transmission lines produce inductive charges when their load is light, and as these charges build, capacitors must be attached along the length of the lines at intervals to step the power back down.

Using shunt reactors and capacitors in conjunction, and switching on more capacitors along the line as the need arises, keeps voltages more in phase or synchronization between source and line ends. In AC power distribution networks, power factor is a term standing for real power versus apparent power.

## Ferranti effect

Real power is the power in the transmission line that produces the working power to appliances on the receiving end. When compensating for Ferranti effect, the real power needs to be differentiated from apparent power, and the requisite amount of step-down of power should be applied through shunt reactors to provide the counter effect to build-up of voltage. Additionally, line engineers can use the electronic switching on and off of capacitors to make adjustments as needed when monitoring informs of Ferranti effect overloads.

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