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When a larger voltage is applied to a conductor does the current increase or decrease?
If you increase the voltage applied to a conductor, the current increases.That is, unless you are talking about stepping up the voltage with a transformer with the intent of distributing it over a long distance to a remote transformer, at which point you would step it back down. In this case, the current would decrease. The above answer to the original question remains valid, however, due to lack of information.
What is the reason for using a neutral current transformer on a transformer?
A current transformer is primarily used at the neutral point of a transformer for earth fault protection. A neutral current transformer will measure any ground fault current which will essentially flow from the star point of the transformer. A fault-detection device other devices is connected to the current transformer and, if the fault current exceeds a certain trigger value, the fault-detection device will give a trip command to an earth-fault relay to disconnect the supply of electricity to the transformer.
Why transformer rated in KVA instead in KWH?
VA, or volt-amperes, is a measure of the output of the transformer. VA is also called apparent power. Watts on the other hand, is also called true power. If the transformer feeds a resistive load, then watts are equal to VA, because the voltage and current are in phase. If the transformer feeds a reactive load, such as a motor, then the voltage and current are no longer in phase, and the true power (watts) is less than apparent power. Since the true power, or watts delivered can change depending on the load, it is not very useful as a transformer rating. The VA remains constant irregardless of the load characteristics, and so is a much better indicator of transformer performance.
Why Current Transformer Placed Between Power Transformer and Breaker in Substation?
A current transformer is primarily used at the neutral point of a transformer for earth fault protection.A neutral current transformer will measure any ground fault current which will essentially flow from the star point of the transformer.A fault-detection device other devices is connected to the current transformer and, if the fault current exceeds a certain trigger value, the fault-detection device will give a trip command to an earth-fault relay to disconnect the supply of electricity to the transformer.Additional AnswerCurrent transformers are widely-used in substations to (a) allow the measurement of currents in the high-voltage lines, and (b) to operate protective relays. There are many different types of protective relays, and their function is to disconnect faults by (a) detecting them, and (b) tripping the appropriate circuit breaker(s).
How to calculate fault current for transformer?
The fault current of a power transformer will depend on the following; Transformer Rating (in KVA/MVA) per unit impedence of the transformer (%p.u.) line/phase Voltage (VL/VP) the following formula can be used to find the fault current on the secondary side of a transformer Fault Current = Transformer Rating /(per unit impedance x phase voltage) The Values of Transformer Rating, per unit impedance & phase/line voltage will usually be mentioned on the transformer rating plate / data sheet As an example a 500kVA, 11kV/400V/3-Phase/50Hz transformer with 5% p.u impendence will have the following fault levels on the secondary side Fault level = 500/(5%)=10000kVA S=1.732 * VPP * IP Fault current = 500/(5% x 400 x 1.732) = 14.4 kA Remember to use 3phase voltage!
What is knee point voltage of current transformer?
10 % increase in voltage gives you 50 % increase in excitation current is called knee point voltage. To measure this first demagnetise the CT and apply voltage gradually from secondary keeping primary winding open circuited. while doing this above phenomeneo will be obsesrved.
When a larger voltage is applied to a conductor does the current increase or decrease?
If you increase the voltage applied to a conductor, the current increases.That is, unless you are talking about stepping up the voltage with a transformer with the intent of distributing it over a long distance to a remote transformer, at which point you would step it back down. In this case, the current would decrease. The above answer to the original question remains valid, however, due to lack of information.
What happen if you apply triangular input to transformer?
there will be no neutral point in the circuit and high voltage will be across the transformer coils
If the primary winding of the transformer in the power supply opens what will you observe in the rectified output?
There would be no rectified output. The transformer primary has to be closed to induce a current into the secondary winding. At this point of the secondary the voltage is still AC. This voltage is then applied to the rectification bridge to change it to DC. So you can see how no voltage on the primary, the same as the unit being unplugged, affects the output voltage.
What is the reason for using a neutral current transformer on a transformer?
A current transformer is primarily used at the neutral point of a transformer for earth fault protection. A neutral current transformer will measure any ground fault current which will essentially flow from the star point of the transformer. A fault-detection device other devices is connected to the current transformer and, if the fault current exceeds a certain trigger value, the fault-detection device will give a trip command to an earth-fault relay to disconnect the supply of electricity to the transformer.
What is the point of a step up transformer?
A 'step-up' transformer is a transformer with more turns on its secondary winding than on its primary winding. It's secondary (output) voltage is, therefore, higher than its primary (input) voltage.
Why frequency remains constant in transformer?
First we know that transformer is a statical electrical device that transfer electrical energy from one circuit to another circuit with out change its frequency .....it may be voltage or current is change simultaneosuly or separately .... and point is why does not change the frequency in the transformer because the there is no moving part in transformer....As we know that frequency is depends upon the rotation....
Why secondry of current transformer should not be open?
A current transformer will always attempt to push a ratio of the primary current through the secondary. So if there is primary current flowing, and you open circuit the secondary, the CT will attempt to build up voltage to the point where the correct amount of secondary current can flow through the open circuit (meaning you will get an arc). If it succeeds, you'll have a bright light, and some melted copper, and a very startled person who was unfortunate enough to open circuit the CT. This high voltage can also damage or ruin the CT.
Why transformer rated in KVA instead in KWH?
VA, or volt-amperes, is a measure of the output of the transformer. VA is also called apparent power. Watts on the other hand, is also called true power. If the transformer feeds a resistive load, then watts are equal to VA, because the voltage and current are in phase. If the transformer feeds a reactive load, such as a motor, then the voltage and current are no longer in phase, and the true power (watts) is less than apparent power. Since the true power, or watts delivered can change depending on the load, it is not very useful as a transformer rating. The VA remains constant irregardless of the load characteristics, and so is a much better indicator of transformer performance.
How do you perform no load magnetizing current measurement of transformer?
I am sure there is more than one way of doing this but what I am currently implementing in my own study of I_mag is the following: At no load perform an over excitation test where you vary the input voltage from 0 V and monitor the current flowing through the primary windings of the transformer. Over-excite the transformer until the rate at which current, I_in increases in the primary windings is relatively larger than the change in Vout , across the secondary windings (this is the point of saturation). Plot your results of voltage Vout (y- axis) against current I_in (x-axis) and you should come up with a characteristic B-H curve. (Remember that the B field is proportional to voltage and the H field is proportional to current from magnetic circuits theory) You are then to decide which point on your curve you will regard as the 'knee' point or the point at which the curve starts to deviate from the linear region. This 'knee' point will correspond to your I_mag. While I_in is not necessarily equal to I_mag at no load, at the knee point on your curve these two currents will be approximately equal.
Why Current Transformer Placed Between Power Transformer and Breaker in Substation?
A current transformer is primarily used at the neutral point of a transformer for earth fault protection.A neutral current transformer will measure any ground fault current which will essentially flow from the star point of the transformer.A fault-detection device other devices is connected to the current transformer and, if the fault current exceeds a certain trigger value, the fault-detection device will give a trip command to an earth-fault relay to disconnect the supply of electricity to the transformer.Additional AnswerCurrent transformers are widely-used in substations to (a) allow the measurement of currents in the high-voltage lines, and (b) to operate protective relays. There are many different types of protective relays, and their function is to disconnect faults by (a) detecting them, and (b) tripping the appropriate circuit breaker(s).
How to calculate fault current for transformer?
The fault current of a power transformer will depend on the following; Transformer Rating (in KVA/MVA) per unit impedence of the transformer (%p.u.) line/phase Voltage (VL/VP) the following formula can be used to find the fault current on the secondary side of a transformer Fault Current = Transformer Rating /(per unit impedance x phase voltage) The Values of Transformer Rating, per unit impedance & phase/line voltage will usually be mentioned on the transformer rating plate / data sheet As an example a 500kVA, 11kV/400V/3-Phase/50Hz transformer with 5% p.u impendence will have the following fault levels on the secondary side Fault level = 500/(5%)=10000kVA S=1.732 * VPP * IP Fault current = 500/(5% x 400 x 1.732) = 14.4 kA Remember to use 3phase voltage!
