- Which material has highest skin depth?
- What is proximity effect and skin effect?
- How can skin and proximity effect be reduced?
- Is skin effect good or bad?
- What is GMR and GMD?
- What is GMD and self GMD?
- What happens if the separation between the three phases of the transmission line is increased?
- Why bundled conductors are used in EHV line?
- How does bundled conductors reduce corona?
- Which type of copper wire will have highest tensile strength?
- What is self GMD?
- What is the value of self GMD?
- How can we reduce Ferranti effect?
- Where is the strain type insulators used?
- What is the most common cause of failure of overhead line insulators?
- Why do insulators have skirts?
- Why is the wavy structure of pin insulators used?
- How many types of insulators are there?
- Which insulator is used in overhead lines?
- What material is used for overhead power lines?
- Which insulator is used on dead ends of medium voltage line?
- Which insulator is used in dead end?
Which material has highest skin depth?
Even NIST and CRC do not fully agree on bulk resistivity values for materials as well-known as copper and aluminum. Most common conductors used in cabling have a relative permeability of very near unity (1)….Conductor Bulk Resistivity & Skin Depths.
| Material | Aluminum |
|---|---|
| Chemical Formula | Al |
| Relative Permeability μ/μ0 | 1 |
| Skin Depth (µ[email protected]) | 81.9 |
| 25.9 |
What is proximity effect and skin effect?
Skin effect is the tendency for high-frequency currents to flow on the surface of a conductor. Proximity effect is the tendency for current to flow in other undesirable patterns—loops or concentrated distributions—due to the presence of magnetic fields generated by nearby conductors.
How can skin and proximity effect be reduced?
How to reduce Proximity Effect? The proximity effect can be reduced by using the ACSR (Aluminum Core Steel Reinforced) conductor. In ACSR conductor the steel is placed at the centre of the conductor and the aluminium conductor is positioned around steel wire.
Is skin effect good or bad?
The skin effect is a usually undesirable effect which occurs when using AC signals. It causes the outer surface – the “skin” of the wire – to be used more than the inner surface for carrying current – engineers say the surface has a higher “current density”, or amperes per meter squared.
What is GMR and GMD?
GMD & GMR stands for Geometrical Mean Distance and Geometrical Mean Radius. In GMD we take the Geometrical Mean of distances between the strands of two Transmission Lines while in GMR, Geometrical Mean of distances between the stands of a single composite conductor are calculated.
What is GMD and self GMD?
Mutual GMD is defined as the distance from one end of the conductor to the other end. 8. Define self GMD. Self GMD is defined as the limit of geometrical mean of the distance between all the pairs of elements in that area as the number of elements increase without limit.
What happens if the separation between the three phases of the transmission line is increased?
5) What happens if the separation between the three phases of the transmission line is increased? a. The inductance will increase and capacitance will remain unchanged.
Why bundled conductors are used in EHV line?
A bundled conductor reduces the reactance of the electric transmission line. It also reduces voltage gradient, corona loss, radio interference, surge impedance of the transmission lines. As the surge impedance gets reduced due to bundling the conductor, the surge impedance loading, of the conductor gets increased.
How does bundled conductors reduce corona?
Bundled conductors per phase reduces the voltage gradient in the vicinity of the line. Thus reduces the possibility of the corona discharge. (Corona effect will be observed when the air medium present between the phases charged up and start to ionize and acts as a conducting medium.
Which type of copper wire will have highest tensile strength?
Which type of copper wire will have highest tensile strength ? (C) Hard drawn. (D) Protect conductors against short circuiting….172 .
| Q 1- 15 | Q 16- 30 |
|---|---|
| Q 91- 105 | Q 106- 120 |
| Q 121- 135 | Q 136- 150 |
| Q 151- 172 |
What is self GMD?
In order to have concept of self-GMD (also sometimes called Geometrical mean radius; GMR), consider the expression for inductance per conductor per metre already derived in Art. Inductance/conductor/m. In this expression, the term 2 × 10-7 × (1/4) is the inductance due to flux within the solid conductor.
What is the value of self GMD?
Therefore, The self GMD method is used to evaluate Inductance only. Important points: The inductance of the hollow conductor is less when compared to the solid conductor. A bundled conductor reduces the reactance of the electric transmission line.
How can we reduce Ferranti effect?
Ferranti effect can be reduced by installing shunt compensation devices at receiving end. The compensation device is a shunt reactor which is connected in parallel with the transmission line. It reduces the voltage level by absorbing the reactive power. Running the transmission line with higher load.
Where is the strain type insulators used?
A strain insulator is an electrical insulator that is designed to work in mechanical tension (strain), to withstand the pull of a suspended electrical wire or cable. They are used in overhead electrical wiring, to support radio antennas and overhead power lines.
What is the most common cause of failure of overhead line insulators?
flashover
Why do insulators have skirts?
A porcelain cap and pin disc insulator is shown in Fig-A. Also in Fig-B is shown a glass disc insulator. In the porcelain insulator the somewhat umbrella like upper part called skirt is glazed and smoothened so that when it rains the dust and salt deposited on it are easily washed away.
Why is the wavy structure of pin insulators used?
Right Answer is: C Wavy structure of pin insulator increases its flashover voltage. Wavy structure of pin insulator depends on the variation of voltage. So, when we increase the voltage, the structure of pin insulators also increases. Also known as sparkover voltage.
How many types of insulators are there?
5 types
Which insulator is used in overhead lines?
porcelain
What material is used for overhead power lines?
Overhead power lines commonly use conductors in which the basic material is drawn with hard aluminium or its alloys containing magnesium and silicon. However, due to the insufficient durability of aluminium, non-ductile, bare, steel-aluminium conductors marked as AFL are used.
Which insulator is used on dead ends of medium voltage line?
Strain type insulators
Which insulator is used in dead end?
STRAIN TYPE INSULATORS When there is a dead end of the line or there is corner or sharp curve, the line is subjected to greater tension. In order to relieve the line of excessive tension, strain insulators are used. For low voltage lines (< 11 kV), shackle insulators are used as strain insulators.