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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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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.
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 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.
