Short-Circuit Impedance (%Zsc)
Transformer impedance measured with one winding short-circuited, determining fault current and regulation.
Short-circuit impedance (%Zsc) is impedance as % of rated voltage to circulate rated current with one winding shorted. Affects fault current, regulation, parallel compatibility.
Components: resistance and reactance. In large power transformers, reactance dominates (90-95%). Parallel operation requires matching (within 10%).
Typical: small distribution 3-4.5%, large distribution 4.5-6%, power 8-18%, GSU 12-20%.
QDTB precisely controls impedance through optimized winding geometry, verified by factory measurement.
Related Products
Related Terms
Impedance (%Z)
Total opposition to current flow in a transformer as a percentage, determining fault current and voltage regulation.
Leakage Reactance
Reactance from magnetic flux not linking both windings, a major component of transformer impedance.
Fault Current
The extremely high current during a short circuit that transformers must withstand mechanically.
Voltage Regulation
The change in secondary voltage from no-load to full-load as a percentage, indicating voltage stability.
More Terms Starting with “S”
Step-Up/Step-Down Transformer
Transformers increasing (step-up) or decreasing (step-down) voltage levels based on the turns ratio.
Substation
A facility housing transformers, switchgear, and protection for voltage transformation and power routing.
Shielded Winding
A transformer winding with shielding to reduce surge voltage stress and improve impulse distribution.
Solar Transformer
A transformer optimized for solar PV plants handling inverter harmonics and variable loading.
More in “Performance Parameters”
Core Loss
Power dissipated in the transformer magnetic core due to hysteresis and eddy currents, also called iron loss or no-load loss.
Copper Loss
Power lost as heat in transformer windings due to electrical resistance, proportional to the square of load current.
Efficiency Class (IE1-IE4)
International classification for transformer energy efficiency, IE1 (standard) to IE4 (premium) with progressively lower losses.
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