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generally tertiary wndng is delta
.if one point of this delta is earthed(through a CT) then it is not a earth fault. thansformer will operate normally. now if a second point(or any point on the delta winding) is earthed (earth fault) then the fault current will be sensed by the said ct.and Transf will tripped. Avradeep Das. email id: avra.wbsetcl@gmail.com
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On a stup down transformer what does the xo symbol mean?
On a step down transformer XO symbol denotes the secondary split phase grounding point. This is also where the neutral of the three wire secondary is connected. The transformer connection is known as a single phase - three wire - with one secondary winding.
What is the purpose of star delta connection in a transformer?
A star winding has a red yellow and blue phases. The centre point of every stay winding is used as d nuetral point. Hence the star winding in a transformer enables a nuetral point.
What is the secondry side of distibution transformer?
There's very little point in having a distribution transformer if its secondary winding isn't connected to a load! So, to answer your question, a 'secondary system' (by which you, presumably, mean 'load'), isn't 'essential' to a distribution transformer, it could just sit there doing nothing!
Why is class A winding insulation is only used in oil filled transformers?
This is because the oil has flash over point at 140 deg.Cl and the winding insulation cannot exceed the flash point of the oil.
What is a current transformer and how can a current transformer be used to extend the range of a wattmeter?
A current transformer (CT) works just like any other transformer. It is important to note it is not referenced to ground. It reflects current flow, not phase to ground voltage, so it attempts to hold current constant, not voltage. There is usually one primary "winding": one large cable through a donut CT, and multiple secondary windings. If a secondary winding is shorted (a wire placed across its terminals), the voltage built up in the secondary will be equivalent to V = I*Z, where I is the secondary current, and Z is the impedance of the secondary winding, usually specified as some flat value plus so many ohms per winding. If too big of an impedance is placed on the secondary, a voltage will build up to the point that the donut CT saturates, resulting in an output wave that has a large amount of harmonics. If the CT is open circuit\'d, voltage will build up until it is high enough to arc over (usually where it should have been shorted). CT\'s can be damaged by open circuiting them, so don\'t do it.
How do you connect an earthing transformer with delta connected secondary?
You have to connect each phase (R,Y & B respectively) of earthing transformer zig zag winding to each phase of power transformer delta secondary respectively. Then the zig zag winding of earthing transformer star point to be earthed.
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.
What does cpe stand for when using transformers?
Centre point earthed
What is vector group YNd11 in transformer?
Vector group means it defines the primary & secondary side connection type of the transformer. It says D for the delta connections (windings connected between two phases) & Y for the star connections (windings connected from each phase to ground). The 11 stands for the phase displacement of the secondary referenced to the primary. Imagine a clock with only an hour hand; at 11 o'clock, the hand is at 30 degrees to the reference (12 c'clock), so the secondary is at 30 degrees to the primary.D or d means delta connectionY or y means star/wye connectionz means zed/zigzag/interconnected star connectionN or n means the Neutral point is accessible in the star connection. This is also sometimes taken to mean that the neutral point is earthed.A number means a phase shift in the secondary with respect to the primary, where the phase is measured in "hours"A capital letter indicates primary winding and lower case secondary. Capital z does not occur as zed transformers are used only for creating an earth on an unearthed system and thus are always on the earthed secondary.Primary is taken to be the higher voltage side, regardless of the direction of power flow.So, Dyn11 means delta primary, star secondary leading the primary by 30 degrees, possibly with an earthed neutral
Why transformer winding are tapped in the middle?
Transformers are not necessarily centre tapped, although some are. In North America, for example, the secondary-side (240-V) of a distribution transformer is indeed centre tapped. It is at this point which it is earthed (grounded) to provide the neutral conductor to a residence's supply. The outer ends of the winding are then at 120 V with respect to that neutral -thus providing the residence with a combination of 230 V and 120 V. Lighting and (120-V) receptacles are then connected between one or other of the outer terminals and the earth terminal, while (240-V) heavy appliances are connected between the outer terminals. European distribution transformers are not connected in this way; they do not have a centre tap secondary.
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.
On a stup down transformer what does the xo symbol mean?
On a step down transformer XO symbol denotes the secondary split phase grounding point. This is also where the neutral of the three wire secondary is connected. The transformer connection is known as a single phase - three wire - with one secondary winding.
What is the purpose of star delta connection in a transformer?
A star winding has a red yellow and blue phases. The centre point of every stay winding is used as d nuetral point. Hence the star winding in a transformer enables a nuetral point.
What is the secondry side of distibution transformer?
There's very little point in having a distribution transformer if its secondary winding isn't connected to a load! So, to answer your question, a 'secondary system' (by which you, presumably, mean 'load'), isn't 'essential' to a distribution transformer, it could just sit there doing nothing!
What is the vantage point in the painting?
The vantage point appears to be in the middle of the road, winding lane.
What is the use of earth transformer?
An earthing transformer is usually associated with three phase supply systems. Earthing of any electrical system at the source is considered by most countries to be the safer practice with regard to personnel and equipment safety. On a three phase system, the neutral would be earthed either directly or through some limiting impedance / resistance. When the neutral point is not available or does not exist with a delta secondary winding of the transformer, a neutral point needs to be created. This is the purpose of the earthing transformer, which could consist of a zig- zag winding, or a two winding star delta transformer where the star winding of correct voltage supplies an accessible neutral point when connected to the supply system.
Why autotransformer can handle more power than conventional transformer?
Perhaps you're referring to the size of the core? Strictly speaking, a 30MVA autotransformer can handle the same amount of power as a conventional transformer. But an autotransformer will be smaller than an equivalent conventional transformer. The reason is an autotransformer essentially has one winding on a core, with one tap including the whole winding, and another tap including only part of the winding. In a conventional transformer, power is transferred from one winding to the other by induction. In an auto, some is by conduction, and some is by induction. Here's an example comparison: Say we have a 10MVA 100kV/50kV 3 winding auto transformer. There are two parts of the winding - the series winding (the section of winding between the 100kV connection and 50kV connection), and the common winding (the section of winding between the 50kV connection to the neutral). If powered at 10MVA (full load), there will be: 10M / (100k * sqrt(3)) = 57.7 Amps flowing into the primary, and 10M / (50k * sqrt(3)) = 115.5 amps flowing out of the secondary So, 57.7A flow into the primary, down through the series winding and out the secondary. At the same time 57.7A flow up from the neutral through the common winding and out the secondary, resulting in a total secondary current of (57.7 + 57.7) = 115.5 (sorry, rounding is making my math look wrong!). Thus, the series winding is handling a total of: (100k - 50k)* 57.7A*sqrt(3) = 5MVA, and the common winding is handling a total of: (50k - 0) *57.7A*sqrt(3) = 5MVA So the series and common windings only have to be made to handle 1/2 the total load(for this example - it is 1/2 because the primary / secondary voltage is 2/1). In a conventional transformer, each winding carries the full load (10MVA), because it operates on induction (no conduction). If the votlage ratio between primary and secondary is too high, there is no real net savings in size (and thus cost), so a conventional transformer is often used. The cutoff point is around 4.
