The reactor coil is an electromagnetic component that performs a wide range of protection and control functions in power grids and industrial facilities. It limits short-circuit currents, compensates reactive power, and filters harmonics – making it an indispensable element of modern energy systems. Careful sizing of the reactor coil protects downstream components and significantly extends their service life.
What functions does a reactor coil perform?
Reactor coils generate an inductive reactance that opposes alternating current with a frequency-dependent resistance. This allows currents to be smoothed, switching transients to be damped, and resonances to be avoided. In high-voltage applications, they are used as shunt reactors to stabilize long overhead lines, as arc suppression (Petersen) coils, or as short-circuit current limiters.
Key Characteristics at a Glance
- Current limitation in the event of a short circuit
- Compensation of capacitive reactive power in transmission grids
- Filtering of unwanted harmonics
- Earth-fault suppression in resonant-earthed (unearthed) networks
- Available as dry-type or oil-filled versions
- Linear and non-linear reactors depending on saturation behavior
- Steel or air-gap cores depending on the application
Frequently Asked Questions
How does a reactor coil differ from a transformer?
While a transformer has two or more magnetically coupled windings for voltage conversion, a reactor coil has only one winding. It therefore does not convert voltage but instead specifically influences the behavior of the current flow.
Where are reactor coils most commonly used in practice?
Typical application areas include substations, industrial facilities with non-linear loads, photovoltaic and wind farms, railway power systems, and converter applications. They are also needed for smoothing and filtering in BESS projects.
How is the inductance of a reactor coil calculated?
Inductance results from the number of turns, cross-section, and permeability of the core. In practice, it is designed to match the grid frequency and the required reactance. Where there is a risk of saturation, air gaps are incorporated to keep the inductance stable even at high currents.
How is a reactor coil correctly sized in economic terms?
The decisive factors are the required inductance, the continuous current to be carried, the short-circuit current to be withstood, the thermal requirements, and the desired efficiency. An undersized reactor saturates too early, while an oversized one unnecessarily increases the investment cost and raises ongoing losses.
Do you need a custom-designed reactor coil for your application? Our engineers would be happy to advise you – get in touch with us.