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PTs are high voltage, low current Transformers and so need a relatively high impedance (or burden) load to function accurately. CTs are high current, low voltage (if not open circuited!) transformers and so need a very low impedance load to function accurately.
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What is a c200 current transformer?
This is a class of current transformers, and is a fairly low class. This has to do with what kind of burden can be placed on the secondary. A general rule is a C200 current transformer can supply ~200 volts at full ratio to its' secondary. If the burden (the CT resistance + cable resistance + relay or instrument resistance) times the maximum expected current is higher than 200 volts, the CT is likely to saturate. During multiple fault events, a CT may keep some magnetizing current causing CT saturation to be higher on a reclose event. Typically CT's are sized and their ratios are chosen to minimize saturation when feasible.
What is CT burden in electrical engineering?
CT (current transformer) Burden is the maximum load that the CT secondary can drive (e.g. meters or protection relays) Why do you care about burden when ordering current transformers? The burden is the termination impedance of the measuring instrument. The measuring instrument can be an analog or digital energy meter, a data logger or a recorder. All instruments that use a current transformer to measure line current must terminate the CT with a resistance (impedance in same case which means there is some inductance involved). A CT supplier should be given the burden when ordering. Technically, the total burden for a CT is the internal winding resistance, the connecting lead resistance and the measuring instrument input resistance. Some Ct's are installed a long distance from the measuring instrument and the connecting leads can have a resistance as much as 0.002 ohms per foot (both ways because the current makes a complete round trip). This resistance will cause an error if not taken into account.
What is acceptable ratio error for 5P20 class ct?
A 5P20 CT has a guaranteed error of less than 5% at 20 times it's rated current (in this case 5A, so at 100A), when it's secondary burden is at it's nominal VA rating. The acceptable ratio error has to allow the CT to perform within these bounds to be declared a 5P20 CT.
Where is 5P20 CT used and where is Class PS CT used?
5P20 CT give more accuracy than PS class CT. 5P20 cant be used in unit protection. Class PS CT is a protection class ct. It is used for differtial proction,distance (UNIT)proction.
Why current transformers secondary is always short circuited?
Unless a burden (i.e. meters, relays, etc.) is connected to the CT, current transformers should always be shorted across the secondary terminals. The reason is very high voltages will be induced at the terminals. Think of the CT as a transformer, with a 1 turn primary and many turns on the secondary. When current is flowing through the primary, the resulting voltage induced in the secondary can be quite high, on the order of kilovolts. When a CT fails under open circuit conditions, the cause of failure is insulation breakdown, either at the shorting terminal strip, or at the feedthrough (in the case of oil filled apparatus), because the distances between terminals are not sufficient for the voltages present.
Can a CT drive more than 1 ammeter?
Yes, as long as the burden of these ammeters does not exceed the VA rating of the CT.
What is a c200 current transformer?
This is a class of current transformers, and is a fairly low class. This has to do with what kind of burden can be placed on the secondary. A general rule is a C200 current transformer can supply ~200 volts at full ratio to its' secondary. If the burden (the CT resistance + cable resistance + relay or instrument resistance) times the maximum expected current is higher than 200 volts, the CT is likely to saturate. During multiple fault events, a CT may keep some magnetizing current causing CT saturation to be higher on a reclose event. Typically CT's are sized and their ratios are chosen to minimize saturation when feasible.
What is a ct of burden?
This is not understandable. Please rephrase and resubmit. Be specific
What is CT burden in electrical engineering?
CT (current transformer) Burden is the maximum load that the CT secondary can drive (e.g. meters or protection relays) Why do you care about burden when ordering current transformers? The burden is the termination impedance of the measuring instrument. The measuring instrument can be an analog or digital energy meter, a data logger or a recorder. All instruments that use a current transformer to measure line current must terminate the CT with a resistance (impedance in same case which means there is some inductance involved). A CT supplier should be given the burden when ordering. Technically, the total burden for a CT is the internal winding resistance, the connecting lead resistance and the measuring instrument input resistance. Some Ct's are installed a long distance from the measuring instrument and the connecting leads can have a resistance as much as 0.002 ohms per foot (both ways because the current makes a complete round trip). This resistance will cause an error if not taken into account.
How do you calculate burden resistor fo current transformer?
The method I have seen employed is to estimate the maximum current that will flow in the secondary side of the CT due to fault currents on the primary side, and calculate the total load (resistance) on the secondary side, including the CT resistance, cable resistance (2 way for ground faults, 1 way for three phase and L-L), resistance of any meters/relays connected to the CT. Once this is known, the voltage rise in the CT can be determined to see if the CT is likely to saturate.Alternately, you can determine the VA burden by the above, VA = V*I = (I*R)*I, using Ohm's law.The above answers the question of how to calculate the VA burdon on a current transformer. The VA burden of a CT is determined by the resistivity of the CT, multiplied by the current squared through the secondary. In general, this will be provided by the manufacturer in the form of a CT burden characteristic, developed through testing of the CT in question, not through calculations.
What is acceptable ratio error for 5P20 class ct?
A 5P20 CT has a guaranteed error of less than 5% at 20 times it's rated current (in this case 5A, so at 100A), when it's secondary burden is at it's nominal VA rating. The acceptable ratio error has to allow the CT to perform within these bounds to be declared a 5P20 CT.
Why is burden not used in protection ct?
Generally accuracy at low current values isn't important for protective functions. The burden is taken into account when looking at the saturation curve and available short circuit current to insure the CT doesn't saturate during fault conditions.
Is it ok to have the dot on a current transformer upside down?
You are probably referring to a 'polarity mark'. This is very important if the CT's burden requires current to flow through it in a particular direction in order to work properly. For example, it won't make any difference if the burden's an ammeter. But if the burden is, say, a wattmeter, then it's very important to observe the CT's polarity mark when it is wired, otherwise the wattmeter might read 'downscale' (backwards). It's also very important when the CT supplies protection relays.
What is mean by burden of the current transformers?
The burden on a CT is the sum total impedance connected to the secondary - including the CT secondary winding coil resistance, lead resistance, and any loads attached (relays, meters, etc.).If this is for power calculations and CT saturation in three phase systems, remember you must multiply the lead resistance by two to get the total path resistance.Another AnswerWe use the word, 'burden', to describe the load supplied by the instrument transformer's secondary. This is normally a measuring instrument or protection relay. We use the word 'burden' to distinguish it from the 'load' supplied by the circuit to which the primary winding is connected.
Do CT scans provide a much higher resolution of anatomical detail than do MRI scans?
As we know,Clarity of the image is decided by its Spatial Resolution but not by Pixel Resolution. CT have high Spatial Resolution but MRI have comparable Spatial Resolution to CT&far better Contrast Resolution than CT-So,MRI is the BEST to demonstrate Anatomy,especially in parts containing more soft tissue[Eg:Brain]&CT is the BEST to demonstrate Bony Anatomy.
Is a smaller ct gold better then higher?
No, it's the opposite.
Chances of getting cancer from 3 CT scans?
Radiation exposure from a CT scan is similar to, though higher than, that of a conventional x ray.Although severe contrast reactions are rare, they are a risk of many CT procedures. There is also a small risk of renal failure in high-risk patients
