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How to measure the zero sequence impedance of 20 MVA DYn11 transformer?
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Why there is a phase shift of 30degree in Dyn11 3 phase transformer?
The phase shift is caused by inductance in the transformer. Any inductance from magnetic flux that fails to link both windings is called leakage flux, and the resulting inductance is called leakage inductance.
How to parallel the Dyn1 and Dyn11 Transformer?
you keep the hv & lv on the dyn11 tx straight in phasing. you then put a cross on any two phases on the hv side of the dyn1 tx, and do the same cross with the phases on the lv side of the tx. for instance lets say we cross a & c phases on the hv & lv sides of the dyn1 tx. now draw a diagram with the four tx, split them up, 2 x dyn1, 2 x dyn11. now on the diagram where you have dyn1 tx, change the the phase plates to read cba left to right, also change the lv side to match. leave the phase plates on the dyn11 tx alone to read abc left to right on both sides. now draw the cables going between them on the hv & lv sides. now if a phase always goes to a phase and b & c phases do the same it will all tie in. prove it to yourself and follow a phase threw all the tx's, do the same will b & c phases. I do it all the time at my job, works every time.
What is the difference between transformer vector group Dyn11 Dyn1 Dyn5?
They all have delta primaries and star secondaries, possibly earthed. The number is the angle of the secondary voltage's lag behind the primary's, expressed as an hour on a clock-face. 11 --> Secondary leads primary by 30 degrees 1 --> Secondary lags primary by 30 degrees 5 --> Secondary lags primary by 150 degrees, making the red secondary voltage lag the yellow primary by 30 degrees (using UK Red/Yellow/Blue phases) Dyn11 and Dyn1 are much more common than DYn5
How change Dyn11 to Dyn3?
DYn1 = Delta connected highside winding, Wye connected lowside winding, neutral brought out, lowside lagging by 30 degrees DYn11 = delta connected highside winding, Wye connected lowside winding, neutral brought out, lowside leading by 30 degrees In a DYn1, the lowside A phase is coupled to the highside A-B leg. In a DYn11, the lowside A phase is coupled to the highside C-A leg. So to convert one to another, you must physically change this coupling, which would require rewiring the internal connections of the transfomer delta.
How can you test ZNyn11 Vector group transformer?
This vector group test is done to confirm whether the vector group provided in the name plate is correct or not and also to confirm that the winding has not been damaged during transport, installation and erection. Taking a particular example, for Dyn11 transformer we have to apply 3~ 400v to the primary, with primary 'U' & secondary 'u' shorted.... then check the voltage across different terminals such as V-v, V-w, W-w, W-v for Dyn11 configuration (V-v = V-w = W-w)less than W-v.... you can compare the results after drawing the vector diagram for the same...... the purpose of shorting the primary U & secondary u is to nullify the phase shift, to obtain a reference vector...
What is DYN11 of a transformer?
It's a description of the some of the electrical properties of the transformer. This is a Delta connected highside (the D), wye connected lowside (Y) that is grounded (N) and there is a 330 degree phase shift between the highside and the lowside (the low voltage is leading the high voltage by 30 degrees).
What is the meaning of DY 11 on a transformer nameplate?
there is no specification of Dy11.. it will be Dyn11.. it is the vector group of the transformer. capital d means primary winding is delta secondary winding is star(y) and the secondary current lags voltage by 30degree this angle when shown in clock will be looking like 11 o clock
Why there is a phase shift of 30degree in Dyn11 3 phase transformer?
The phase shift is caused by inductance in the transformer. Any inductance from magnetic flux that fails to link both windings is called leakage flux, and the resulting inductance is called leakage inductance.
Can a 3-phase DYN 1 transfomer be connected in parallel with a DYN11?
No
How to parallel the Dyn1 and Dyn11 Transformer?
you keep the hv & lv on the dyn11 tx straight in phasing. you then put a cross on any two phases on the hv side of the dyn1 tx, and do the same cross with the phases on the lv side of the tx. for instance lets say we cross a & c phases on the hv & lv sides of the dyn1 tx. now draw a diagram with the four tx, split them up, 2 x dyn1, 2 x dyn11. now on the diagram where you have dyn1 tx, change the the phase plates to read cba left to right, also change the lv side to match. leave the phase plates on the dyn11 tx alone to read abc left to right on both sides. now draw the cables going between them on the hv & lv sides. now if a phase always goes to a phase and b & c phases do the same it will all tie in. prove it to yourself and follow a phase threw all the tx's, do the same will b & c phases. I do it all the time at my job, works every time.
What is the difference between transformer vector group Dyn11 Dyn1 Dyn5?
They all have delta primaries and star secondaries, possibly earthed. The number is the angle of the secondary voltage's lag behind the primary's, expressed as an hour on a clock-face. 11 --> Secondary leads primary by 30 degrees 1 --> Secondary lags primary by 30 degrees 5 --> Secondary lags primary by 150 degrees, making the red secondary voltage lag the yellow primary by 30 degrees (using UK Red/Yellow/Blue phases) Dyn11 and Dyn1 are much more common than DYn5
How change Dyn11 to Dyn3?
DYn1 = Delta connected highside winding, Wye connected lowside winding, neutral brought out, lowside lagging by 30 degrees DYn11 = delta connected highside winding, Wye connected lowside winding, neutral brought out, lowside leading by 30 degrees In a DYn1, the lowside A phase is coupled to the highside A-B leg. In a DYn11, the lowside A phase is coupled to the highside C-A leg. So to convert one to another, you must physically change this coupling, which would require rewiring the internal connections of the transfomer delta.
How can you test ZNyn11 Vector group transformer?
This vector group test is done to confirm whether the vector group provided in the name plate is correct or not and also to confirm that the winding has not been damaged during transport, installation and erection. Taking a particular example, for Dyn11 transformer we have to apply 3~ 400v to the primary, with primary 'U' & secondary 'u' shorted.... then check the voltage across different terminals such as V-v, V-w, W-w, W-v for Dyn11 configuration (V-v = V-w = W-w)less than W-v.... you can compare the results after drawing the vector diagram for the same...... the purpose of shorting the primary U & secondary u is to nullify the phase shift, to obtain a reference vector...
How do you calculation of selecting Neutral Earthing Transformer?
iT IS ISMILAR TO THE GROUND RESITOR CALCULATION FOR TRANSFOMER THE TYPICAL EXAMPLE WAS ANSWERED EARLIER FOR TRANSFORMER DT.19-06-2009 Neutral of transformer can be grounded solidly earthed OR with Neutral Grounded with Resistance. Typical shunt calculations fro 5 MAV 11/6.6 kv transformer neutral are as :_ Transformer rating = 5 MVA Voltage ratio = 11/6.6 KV Vector Group = Dyn11 (6.6 KV ground through Resistor) During Earth fault voltage between Neutral & Earth = 6.6/√3 = 3.81 KV Earth Fault current will be limited to = 5 x 10³ /(√3 x 6.6) = 437.38Amp. N.G.R. value in ohm = V / I = (3.81 x 10³) / 437.38 = 8.71 Ohm Value of N.G.R. is 437.38 Amp, 8.71 Ohm., 10 Sec NGR are inserted On Higher voltage to restrict earth fault current BY SRI
How can you test the vector group DYn11 and vector diagram?
connect the neutral point of the star (secondary) to u phase of primary, and now apply voltage to primary and measure the voltage between V&R, W&B, V&Y and V&B. when you measure voltage b/w 1. V&R the voltage must be maximum, 2. W&B Should be minimum and 3. voltage between V&Y and V&B should be same U.V&W are primary (Delta) R,Y&B are secondary (Star)
What is standby earth fault protection And how it is to be coordinated with transformer primary overcurrent relayin DYn11 tf?
DYn 11 is a Delta HV winding and star lv with theneutral brought out. At primary substations it is usual to have a neutral ct. The ct is a last line of defence operating a standby earth fault relay which opens the lv circuit breaker (11kV). It may have a stage 2 setting in case the lv breaker fails to open which opens the hV side. If there is no local hV breaker it may operate a fault throw switch. This device shorts one phase directly to earth forcing the protection at the remote end to operate.
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
