Unbalanced Load
Unequal three-phase loads causing unequal currents, neutral current, and zero-sequence effects.
Occurs when three-phase loads are unequal in magnitude or PF. Results in unequal currents, voltage drops, zero-sequence currents.
Effects: increased losses from stray flux in tank, localized hot spots, neutral current requiring adequate sizing, potential core saturation in three-limb designs.
IEC specifies zero-sequence limits. Five-limb cores or zig-zag handle unbalanced better. Utilities limit to 5-10%.
QDTB designs with appropriate core configurations and tank shielding for expected unbalanced conditions.
Related Products
Related Terms
Zero Sequence Current
Current components equal in all three phases flowing through neutral/ground during unbalanced or fault conditions.
Neutral Point
The common connection point of a star (wye) winding where the three-phase voltage vector sum equals zero.
Three-Phase Transformer
A transformer for three-phase power systems with three winding sets on a common core.
Eddy Current
Circulating currents induced in conductive materials by changing magnetic fields, causing energy losses in transformers.
More in “Operating Conditions”
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