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What is zero sequence impedance in transmission line?
In symmetrical components, there are three types of impedances - positive sequence (balanced), negative sequence (unbalanced), and zero sequence (ground). In a transformer, positive and negative are equal. Ground impedance is determined by the (same factors as the) positive sequence and is based on the flux paths available through the transformer core that can induce ground current.
What is zero sequence impedence?
Zero sequence impedance indicates a homopolar symmetrical component. It is a term used in electrical engineering within a three-phase system of linear combinations.
How do you derive negative sequence impedance of an earthing transformer for 11 KV delta connected 10 MVA source transformer?
Negative sequence and positive sequence are the same for a transformer. You would derive using the same connections as done to calculate the positive sequence impedance. Usually the test report will give positive, and often zero sequence impedances (sometimes left off, depending on the type of transformer as the zero sequence sometimes is the same as the positive sequence). The negative sequence is never given to my knowledge, because it is redundant and unnecessary test.
How calculate zero phase sequence capacitance of transformer?
In my experience, the zero sequence of transformers is not calculated, it is directly tested following ANSII/IEEE guidlines for Z1no, Z2no, and Z1ns tests (for three phase, three winding transformers). Rough estimations of zero sequence impedance can be determined based on the positive sequence and core form of the transformer. A Shell type core will have a zero sequence of ~100% the positive sequence because the flux stays in the core / follows the same path as it does for positive sequence currents. For a core type, the zero sequence will be ~80-90% typically, because the flux must travel outside the core. This is for three winding transformer.
Does ideal amplifer has zero output impedance?
Yes
Which device has its characteristics very close to that of an ideal current source?
A: A current source can be defined as a zero impedance source. A battery is essentially a zero impedance since it can provide lots of current with zero volts out
Is a voltage source a zero or infinite impedance?
Obviously it's not infinite impedance--that would mean it soaks up all the voltage. It can't be zero impedance either...that would be a superconductor, and there aren't many of those around. Voltage sources have impedance, but it's not infinite. Sometimes the impedance of the source is critical--radio frequency amplifiers have to be impedance matched to their transmitting antennas if you don't want to burn them out.
What is the impedance reactance 22 mva power transformer?
A transformer this size will usually come with a test report which will give this information. Depending on the configuration, it may give zero seqence and positive sequence impedances.
Relation between kva and fault level?
There isn't enough information here. Available short circuit fault level can be given as a KVA value for different types of faults, but I assume the questioner is looking for a relationshiop between (transformer?) KVA and available short circuit current - If my assumption is correct, there is no direct correlation without knowing the transformer positive and zero sequence impedances. If these are known, you can assume the source impedance is infinite, and calculate the maximum short circuit current through the transformer as follows: lowside fault current for a 3 phase fault on the lowside of the transformer: lowside kV (line to line) / (1.732 x per unit positive sequence impedance x scalar to real impedance), where scalar to real impedance is equivalent to lowside kV (line to line) ^2 / base kVA. For a L-G fault, do the same with zero sequence impedance.
Why the resistance of a current source is zero?
It isn't. The internal impedance of a current source is high. In an ideal one it would be infinite. A voltage source, however, has a low internal impedance, ideally zero ohms.
What are the factors that affect the difference between the computed values and measured values?
-- rounding errors in computation -- non-ideal components, such as diodes with finite reverse resistance, inductors with resistance, power supplies with non-zero internal impedance, wire with inductance, etc.
Why for a random series the autocorrelation between two observation is close to zero?
A non-zero autocorrelation implies that any element in the sequence is affected by earlier values in the sequence. That, clearly violates the basic concept of randomness - where it is required that what went before has no effect WHATSOEVER in what comes next.
