How Does a Transformer Help Control Reactive Power?
Quick answer — A transformer affects reactive power through its impedance (a voltage drop and slight reactive absorption) and, more importantly, through an on-load tap-changer (which changes the voltage and hence the reactive flow), and via a shunt reactor or capacitor on its bus. The transformer regulates the voltage, which controls the reactive power and the power factor in the network, and a tap-changer or a reactor at the substation is used to balance it.
How does a transformer affect reactive power?
Impedance and drop
The transformer impedance causes a voltage drop and a slight reactive absorption, so it affects the voltage and the reactive flow.
Tap-changer and voltage
The on-load tap-changer regulates the secondary voltage, which in turn changes the reactive power flow to the load and the network.
Reactive devices
A shunt reactor (to absorb) or a capacitor (to supply) at the substation, coordinated with the transformer, controls the reactive power and the power factor.
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
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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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