Vector Group
Standardized designation of transformer winding connections and phase displacement between HV and LV.
Vector group is the IEC designation for winding connection and phase displacement in three-phase transformers. Letters: Y=star, D=delta, Z=zig-zag. Clock number (0-11) = displacement in 30-degree multiples.
Dyn11: HV delta, LV star, 330-degree lead (most common distribution—delta provides 3rd harmonic path). Yyn0: small distribution. YNd11: power.
Parallel operation requires identical vector groups.
QDTB manufactures all standard configurations, Dyn11 and YNd11 most frequent.
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Related Terms
Three-Phase Transformer
A transformer for three-phase power systems with three winding sets on a common core.
Turns Ratio
The ratio of primary to secondary winding turns directly determining voltage transformation ratio.
Neutral Point
The common connection point of a star (wye) winding where the three-phase voltage vector sum equals zero.
Wye-Delta Connection
A three-phase connection with one star and one delta winding providing phase shift and harmonic isolation.
More in “Design & Engineering”
Altitude Derating
The reduction in transformer capacity and insulation performance required at high altitudes where air density is lower.
Cooling Class (ONAN/ONAF/ODAF)
Standardized codes describing transformer cooling methods: O=Oil, N=Natural, A=Air, F=Forced, D=Directed flow.
Faraday Shield
An electrostatic shield between transformer windings blocking capacitive coupling of high-frequency noise.
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