What Is Transformer Voltage Regulation?
Quick answer — Voltage regulation is the change in the secondary voltage from no-load to full load, expressed as a percentage of the no-load voltage. It is caused by the impedance (resistance and reactance) drop in the windings, and it is affected by the load and its power factor. Lower regulation means a more stable voltage; it is improved by a lower impedance, by on-load tap-changing and by the load power factor.
What is voltage regulation of a transformer?
The definition
Regulation = (Vno-load − Vfull-load) / Vno-load × 100. It is the voltage drop from the winding impedance as the load increases.
Causes
The resistance and leakage reactance of the windings drop the voltage under load; the effect depends on the load and the power factor (a lagging load gives a larger drop).
Why it matters
A large regulation means the output voltage falls a lot with load, which can harm the equipment being supplied. On-load tap-changers compensate it, and a lower impedance gives better regulation but a higher short-circuit current.
References & standards
- IEC 60076-1
- IEEE C57.12.00
Related
Related manufacturers
Prolec GE (GE Vernova) · Prolec GE Waukesha · Hitachi Energy USA · Siemens Energy · Eaton · Virginia Transformer Corp
Related components
Technical content is prepared from engineering references, standards frameworks, manufacturer documentation and industry sources. Contractual or compliance decisions should refer to current official standards. TransformerPath Technical Editorial.
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