First symbol/symbols, capital letters: HV winding connection.
Second symbol/symbols, small letters: LV winding connection.
Third symbol, number: Phase displacement expressed as the
clock hour number.
Winding connection designations
High Voltage Always capital letters
Delta - D
Star - S
Interconnected star - Z
Neutral brought out - N
Low voltage Always small letters
Delta - d
Star - s
Interconnected star - z
Neutral brought out - n
Phase rotation is always anti-clockwise. (international
Use the hour indicator as the indicating phase displacement
angle. Because there are 12 hours on a clock, and a circle
consists out of 360°, each hour represents 30°.
Thus 1 = 30°, 2 = 60°, 3 = 90°, 6 = 180° and 12 = 0° or 360°.
The minute hand is set on 12 o'clock and replaces the line
to neutral voltage (sometimes imaginary) of the HV winding.
This position is always the reference point.
Because rotation is anti-clockwise, 1 = 30° lagging (LV lags
HV with 30°)and 11 = 330° lagging or 30° leading (LV leads
HV with 30°)
Delta connected HV winding, star connected LV winding with
neutral brought out, LV is leading HV with 30°
Dyn11 is vector group notation of tansformer.It means LV
winding,which is star connected (written in small letters
means LV side and vice versa)is 30 degrees lagging by HV
winding which is delta connected.In India we go for +-30
deg connection of transformer.
D = Delta connection at primary,y = Star connection at
secondary and n = neutral point connected at secondary.
Dyn 11 means that the voltage of the secondary star winding
lead the primary phase voltage by 30 degree and it
corresponds to 11 o'clock.
after parallaing two generators current is shooting up in
both the generators.for ex: load is 400 kw..after paralling
and load sharing current in running gen is approx 900 amps
and incoming is 750 amps which is too high when trying
toshift the load current in incoming gen is coming more
than 1300 amps and both getting tripped and making
I hv a question regarding power factor improvement just
after transformer. I request you to reply me plzz. thank
My friend has a small unit of fabrication. in his factory
the main load is a welding machine, lathe machine, grinding
machine. this load is not continuous type. now our
electricity board has installed 16 KVA, 11000/433 V
transformer for our factory. In the energy meter (trivector
meter) at LV side of transformer, i hv seen power factor
value of 0.15 only when only 3 KW load was flowing. Further
electricity board has suggested to install 4 KVAR capacitor
at LV side after energy meter. Now my question is that if
we permanantly install and switch on 4 KVAR capacitor after
energy meter, during some load on transformer and also
without any load on transformer, wht will be the power
factor shown in energy meter?i dont want to get any penalty
by electricity board, so plz suggest me if i can
permanantly install and switch on the 4 kvar capacitor or
not at LV side of transformer just after energy meter?
Thank you again and awaiting for ur positive reply soon.