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How do you derive negative sequence impedance of an earthing transformer for 11 KV delta connected 10 MVA source transformer?
Powercarekhedekar
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.
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∙ 13y ago
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What is the difference between neutral earthing resistance and solid earth?
The star point of a primary*-transformer's secondary winding is frequently connected to earth via an impedance, in order to limit the return current in the event of an earth fault close to the transformer. The impedance may be a resistor or an inductor, (choke) depending on the nature of the earth return. In general, if the earth resistance is low, then resistive earthing is used; if the earth resistance is high, then inductive earthing is used.(*e.g. 33/11 kV)For resistive earthing, the transformer secondary's star point is often connected to the centre electrode of a galvanized-steel tank which is solidly earthed. The tank is then filled with water, and it is the resistance of the water that provides the required resistance to earth. The actual resistance of the water is modified to the desired value by dissolving sodium carbonate into the water while measuring its resistance. The solution has a negative temperature coefficient of resistance, which means that, in the event of an earth fault, as the fault current increases, the increasing temperature causes the resistance of the water to decrease, thus accelerating the response time of the protective system.
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 current series feedback?
The current series feedback is a negative feedback in which the output current feeds back a proportional voltage back to the input terminals in series with the input signal. Here the output impedance as well as the input impedance increases as both are connected in series.
What is standard earthing of electrical equipment?
i have a question? in the earthing system should we connect the negative pole of supply to the earth for example a +24 power supply?
Why does a three phase transformer not short itself out when the phases are connected through the transformer?
I asked this very question to my professor in electronics 101 in college! He explained to me the load side of the transformer if not connected to any load is open. This is a great resistance to completing the circuit. This is transferred to the primary side of the transformer as a great resistance thus no current flow.
What is negative grounding?
The term, 'negative ground' or 'negative earth' refers to the system of chassis-grounding, or chassis-earthing, used in vehicles. With this system, the negative terminal of the battery is directly connected to the metal parts of a vehicle, while the positive terminal is connected to the various electrical devices (lamps, etc.) using insulated conductors. The vehicle's metal parts ('chassis') then act as the return conductor to the battery.
What is the conjugate impedance for 5 20 degrees?
Conjugate impedance for 5 20 degrees is 5 - 20 degrees. (5 and negative 20 degrees)
Advantages of negative feedback amplifier?
Most practical amplifier circuits use negative feedback for the following practical benefits: Stabilization of voltage gain, decreasing output impedance, increasing input impedance, decreasing distortion, increasing bandwidth.
Explain the working principle of center Tapped transformer full wave rectifier?
Explain the working principle of center Tapped transformer full wave rectifier? A center tapped transformer full wave rectifier is a type of rectifier circuit that converts alternating current (AC) to direct current (DC) using a transformer and diodes. The working principle of this circuit is based on the use of a center tapped transformer. A center tapped transformer is a transformer with a secondary winding that has a center tap, which is connected to ground. The primary winding of the transformer is connected to the AC source, and the secondary winding is connected to the load resistor and the diodes. During the positive half-cycle of the input AC voltage, the upper end of the secondary winding is positive with respect to the center tap, and the diode connected to this end conducts. At the same time, the lower end of the secondary winding is negative with respect to the center tap, and the diode connected to this end is reverse-biased and does not conduct. The current flows through the load resistor in the direction of the arrow. During the negative half-cycle of the input AC voltage, the lower end of the secondary winding is positive with respect to the center tap, and the diode connected to this end conducts. At the same time, the upper end of the secondary winding is negative with respect to the center tap, and the diode connected to this end is reverse-biased and does not conduct. The current flows through the load resistor in the opposite direction of the arrow. As a result, the output voltage across the load resistor is a pulsating DC voltage that alternates between positive and negative values but has a DC component. The ripple voltage of the output is lower than that of a half-wave rectifier since it rectifies both half-cycles of the AC input voltage. The advantage of using a center tapped transformer in a full-wave rectifier circuit is that it allows the output voltage to be double the voltage of a half-wave rectifier using the same transformer.
What condition you get negative regulation for transformer?
When its load has a leading power factor.
What is bridge rectifier with digram?
The four diodes connected together as a diamond. A.C. comes in to the ones with the opposite cathode bands. One banded (cathode) and one non-banded (anode) end tied together. The D.C. goes out the places where the cathode bands are the same being v+ and where the anodes are is negative. It is between the transformer and the caps for the D.C. voltage. The transformer is connected to a packaged bridge and has "S" where the A.C. comes in and "+" and "-" where the D.C comes out.
What is the different between series and parallel connection?
In parallel connection all the positive terminals are connected with positive of the source and all the negative terminals are connected to negative of the source. Whereas in series connection one positive terminal is connected to the negative of another, like wise it goes on and finally the positive end is connected to the negative of the source.
