The main cause of these voltage surges in power system are due to lightning impulses and switching impulses of the system. But over voltage in the power system may also be caused by, insulation failure, arcing ground and resonance etc. But over voltages occur in the power system due to lightning is very high.
Regarding this, what is an undervoltage trip?
An undervoltage trip device is an optional accessory in a circuit breaker that mechanically trips the breaker when voltage to the terminals drops below a threshhold level. The power for the undervoltage trip does not come from within the breaker, so it must be supplied from an external source.
What is an undervoltage relay?
A relay that has contacts that operate when the voltage drops below a set voltage. Undervoltage relays are used for protection against voltage drops, to detect short-circuit faults, etc.
What is the surge impedance?
The surge impedance is the ratio of voltage and current at any point along an infinitely long line. The term SIL or natural power is a measure of power delivered by a transmission line when terminated by surge impedance and is given by.
What is the meaning of Ferranti effect?
In electrical engineering, the Ferranti effect is an increase in voltage occurring at the receiving end of a long transmission line, above 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.
What is the surge impedance loading?
Surge impedance loading (SIL) of a transmission line is the MW loading of a transmission line at which natural reactive power balance occurs. The following brief article explains the concept of SIL. Transmission lines produce reactive power (MVar) due to their natural capacitance.
Why do we need impedance matching?
In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load.
What is the surge impedance loading of 400 KV line?
Its value is about 400 ohms for overhead lines and about 40 ohms for underground cables. In power transmission at 50/60 Hz it is used to find the Surge Impedance Loading (SIL).and is defined as (V^2/Z), where V= tr line voltage (line to line) in kV and Z=Surge Impedance in ohms and SIL is in MW (mega watts).
What is the corona loss?
Corona is a phenomenon associated with all transmission lines. Under certain conditions, the localized electric field near energized components and conductors can produce a tiny electric discharge or corona, that causes the surrounding air molecules to ionize, or undergo a slight localized change of electric charge.
What is the characteristic impedance?
The characteristic impedance or surge impedance (usually written Z0) of a uniform transmission line is the ratio of the amplitudes of voltage and current of a single wave propagating along the line; that is, a wave travelling in one direction in the absence of reflections in the other direction.
What is the wave impedance?
The wave impedance of an electromagnetic wave is the ratio of the transverse components of the electric and magnetic fields (the transverse components being those at right angles to the direction of propagation). Just as for electrical impedance, the impedance is a function of frequency.
What is the Smith chart?
The Smith chart, invented by Phillip H. Smith (1905–1987), is a graphical aid or nomogram designed for electrical and electronics engineers specializing in radio frequency (RF) engineering to assist in solving problems with transmission lines and matching circuits.
What is the VSWR?
VSWR (Voltage Standing Wave Ratio), is a measure of how efficiently radio-frequency power is transmitted from a power source, through a transmission line, into a load (for example, from a power amplifier through a transmission line, to an antenna).
What is the meaning of return loss?
In telecommunications, return loss is the loss of power in the signal returned/reflected by a discontinuity in a transmission line or optical fiber. This discontinuity can be a mismatch with the terminating load or with a device inserted in the line. Return loss is a measure of how well devices or lines are matched.
What causes return loss?
There are two major causes of RL in a network: discontinuities and impedance mismatches. Discontinuities occur at connections where cable is terminated to plugs or jacks and within the plug/jack connection itself. A discontinuity can also occur if a cable is bent too much, kinked or otherwise damaged.
What is the return loss and VSWR?
VSWR Conversion Chart. Due to mismatches in impedance within the connector, some of the signal is reflected. The ratio of the input to the reflected signal is called the Voltage Standing Wave Ratio (VSWR). This ratio can also be measured in dB, and expressed as Return Loss.
What is the difference between insertion loss and return loss?
In telecommunications, insertion loss is the loss of signal power resulting from the insertion of a device in a transmission line or optical fiber and is usually expressed in decibels (dB).
What is return loss of an antenna?
Return loss, S11, antenna efficiency, and impedance bandwidth. S11 is a measure of how much power is reflected back at the antenna port due to mismatch from the transmission line. When connected to a network analyzer, S11 measures the amount of energy returning to the analyzer – not what’s delivered to the antenna.
What is a db of loss?
Whenever tests are performed on fiber optic networks or cable plants, the results are generally displayed on a meter readout in “dB.” Optical loss is measured in “dB” while optical power is measured in “dBm.” Loss is a negative number (like –3.2 dB) as are most power measurements.
What is s11?
The matrix elements S11,S12,S21,S22 are referred to as the scattering parameters or the S-parameters. The parameters S11, S22 have the meaning of reflection coefficients, and S21, S12, the meaning of transmission coefficients.