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What factor cause spill current on external fault in case of transformer differential protection?
Spill current during an external fault in transformer differential protection is primarily caused by the unequal impedance in the transformer windings and the connected power system. When an external fault occurs, the fault current flowing through the transformer can create a differential current between the primary and secondary windings due to their differing voltage drops and phase shifts. Additionally, the presence of harmonics and the effects of CT (current transformer) saturation can further contribute to this spill current, complicating the differential relay's ability to distinguish between internal and external faults.
Why are stripes of iron plates joined instead of using a single block of iron core in a transformer?
To reduce heat generated and eddy current losses in transformer's core during operation.
How to test Excitation Current of a transformer?
To test the excitation current of a transformer, you can perform an open-circuit test, where the primary winding is connected to the rated voltage while the secondary winding is left open. Measure the current flowing through the primary winding using an ammeter; this current is the excitation current. It's essential to ensure the transformer is at the specified voltage and frequency during the test for accurate results. Additionally, record the voltage and power factor for further analysis if needed.
Which loss is maximum in no load transformer?
In a no-load transformer, the maximum loss is typically the core loss, also known as iron loss. This loss consists of hysteresis and eddy current losses that occur in the transformer's magnetic core due to alternating magnetic fields. Since the transformer is not supplying load current, the copper losses (which occur due to resistance in the windings) are minimal or negligible. Thus, core loss becomes the dominant factor during no-load conditions.
What is current voltage transformer?
A transformer is a device that steps up, or steps down voltage. During this process current is also stepped up or down:however, voltage and current are inversely proportional ( meaning an increase in voltage results in a decrease in current and vice versa ) As an example: A step up transformer of 10:1 ratio with 12 volts and 10 amper of current applied to the primary will have ten times the voltage ( 120 volts ) and ten times less current ( 1 amrere ) at the secondary...and a step down transformer with the same turns ratio with 120 volts and 1 ampere applied to the primary will have 12 volts and ten ampere available at the secondary. The electricity supplied into homes and business uses wires carrying very high voltage and low current over long distances, then uses step down transformers to step down the voltage and step up the current. However, in power engineering and protective relaying applications, there are what are called "instrument transformers" which have the specific purpose of providing information to devices (such as relays or meters) about the voltages or currents in the power system. Therefore, there are some differences in construction and connectivity between a Current Transformer (CT) and a Voltage (or Potential) Transformer (PT). A CT will typically have a toroidal core and evenly distributed secondary windings so as to minimize leakage reactance. The primary is typically the main power line conductor, which passes directly through the toroidal core. This type of transformer is specifically for the purpose of measuring current values, and the secondary windings cannot be left open-circuited, or a large voltage will be produce, resulting in dielectric failure (and often an explosion). If a device is not connected to the CT, its secondary must be short-circuited. A PT is connected between the main conductor and ground and can be either wound in the normal way, or the voltage can be taken from a subsection of a string of capacitors (this is called a Capacitive Voltage Tansformer or CVT, and is usually cheaper than the wound type, but is typically not as accurate). This type of transformer measures voltage values, and the secondary winding cannot be short-circuited, as this will produce excessively high currents, resulting in the failure of the PT or the wires it is connected to. A PT can be left open-circuited.
What are the precautions using current transformer and potential transformer?
Secondry of CT should never kept open during functioning
What factor cause spill current on external fault in case of transformer differential protection?
Spill current during an external fault in transformer differential protection is primarily caused by the unequal impedance in the transformer windings and the connected power system. When an external fault occurs, the fault current flowing through the transformer can create a differential current between the primary and secondary windings due to their differing voltage drops and phase shifts. Additionally, the presence of harmonics and the effects of CT (current transformer) saturation can further contribute to this spill current, complicating the differential relay's ability to distinguish between internal and external faults.
Why are stripes of iron plates joined instead of using a single block of iron core in a transformer?
To reduce heat generated and eddy current losses in transformer's core during operation.
How to test Excitation Current of a transformer?
To test the excitation current of a transformer, you can perform an open-circuit test, where the primary winding is connected to the rated voltage while the secondary winding is left open. Measure the current flowing through the primary winding using an ammeter; this current is the excitation current. It's essential to ensure the transformer is at the specified voltage and frequency during the test for accurate results. Additionally, record the voltage and power factor for further analysis if needed.
What types of current transformer?
Current transformer are used for measuring current in a bus bar without disconnecting it by means of ammeter.There are three types 1.bar type current transformer 2.toroidal current transformer 3.wound type current transformer
Which loss is maximum in no load transformer?
In a no-load transformer, the maximum loss is typically the core loss, also known as iron loss. This loss consists of hysteresis and eddy current losses that occur in the transformer's magnetic core due to alternating magnetic fields. Since the transformer is not supplying load current, the copper losses (which occur due to resistance in the windings) are minimal or negligible. Thus, core loss becomes the dominant factor during no-load conditions.
What is the impedance of a transformer?
Impedance (Z) voltage is the amount of voltage applied to the primary side to produce full load current in the secondary side. It is usually listed on the transformer nameplate, expressed as a percent, and measured by conducting a short circuit test.
What is current voltage transformer?
A transformer is a device that steps up, or steps down voltage. During this process current is also stepped up or down:however, voltage and current are inversely proportional ( meaning an increase in voltage results in a decrease in current and vice versa ) As an example: A step up transformer of 10:1 ratio with 12 volts and 10 amper of current applied to the primary will have ten times the voltage ( 120 volts ) and ten times less current ( 1 amrere ) at the secondary...and a step down transformer with the same turns ratio with 120 volts and 1 ampere applied to the primary will have 12 volts and ten ampere available at the secondary. The electricity supplied into homes and business uses wires carrying very high voltage and low current over long distances, then uses step down transformers to step down the voltage and step up the current. However, in power engineering and protective relaying applications, there are what are called "instrument transformers" which have the specific purpose of providing information to devices (such as relays or meters) about the voltages or currents in the power system. Therefore, there are some differences in construction and connectivity between a Current Transformer (CT) and a Voltage (or Potential) Transformer (PT). A CT will typically have a toroidal core and evenly distributed secondary windings so as to minimize leakage reactance. The primary is typically the main power line conductor, which passes directly through the toroidal core. This type of transformer is specifically for the purpose of measuring current values, and the secondary windings cannot be left open-circuited, or a large voltage will be produce, resulting in dielectric failure (and often an explosion). If a device is not connected to the CT, its secondary must be short-circuited. A PT is connected between the main conductor and ground and can be either wound in the normal way, or the voltage can be taken from a subsection of a string of capacitors (this is called a Capacitive Voltage Tansformer or CVT, and is usually cheaper than the wound type, but is typically not as accurate). This type of transformer measures voltage values, and the secondary winding cannot be short-circuited, as this will produce excessively high currents, resulting in the failure of the PT or the wires it is connected to. A PT can be left open-circuited.
Why during loading the voltage get decreased at output?
Output voltage (...of a transformer, for example...) will decrease as it is loaded because of the transformer's internal resistance. As output current increases/load resistance decreases, a larger voltage will be dropped across the internal transformer resistance. This same phenomenon is present in AC and DC systems (such as batteries).
What is impedance of transformer?
The transformer impedance is the amount of voltage applied for transformer during the load test.Answer.I really don't agree with the answer given by the previous user.Impedance is the total vector opposition offered by the transformer to the flow of current i.e the vector sum of its pure resistance (R) and it's inductive reactance (XL). http://en.wikipedia.org/wiki/Electrical_impedanceAnother AnswerThe 'impedance' of a transformer is usually expressed as a 'percentage impedance', which is defined (perhaps rather confusingly!) as the ratio of the primary voltage that will result in the full rated current flowing through the secondary, to the rated primary voltage.
What is MBA in transformer?
MBA in the context of transformers refers to "Magnetizing Branch Admittance," which is a parameter used in electrical engineering to analyze the behavior of transformers. It represents the admittance associated with the magnetizing inductance of the transformer, indicating how much current is required to magnetize the core when the transformer is energized. This parameter is crucial for understanding the transformer's performance, particularly under no-load conditions and during fault analysis.
What is the piv necessary for the diode if transformer?
The pivot necessary for a diode in a transformer circuit is typically the diode's peak reverse voltage (PRV) rating, which must be higher than the maximum voltage seen during the transformer's operation. This ensures that the diode can withstand reverse bias without breaking down. Additionally, the forward current rating of the diode should accommodate the maximum current flowing through the circuit. Proper selection of these ratings ensures reliable operation and prevents damage to the diode or transformer.
