Electrical reactors are inductive components used to control current, limit fault levels, filter harmonics, or support voltage behavior in power systems and equipment. The right type depends on where it is installed and what problem it must address: an input line reactor, for example, serves a different purpose from a motor-side output reactor or a shunt reactor. For buyers specifying equipment for a low-voltage frequency converter, the key is to match the reactor’s voltage, current, impedance, frequency, and installation conditions to the converter and the wider system. This guide explains the main types, where they are used, and what to check before requesting a quotation.
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This guide is intended for procurement teams, electrical engineers, panel builders, OEMs, and project contractors evaluating electrical reactors for industrial equipment or power systems. It is especially relevant when a project involves a low-voltage frequency converter, motor drive, power factor correction equipment, or a system where current quality and equipment protection need to be considered. The guide provides a purchasing framework rather than a substitute for engineering design. Final selection should be checked against the equipment manufacturer’s requirements and the project’s applicable electrical standards.
An electrical reactor is an inductor designed for use in an AC or DC power circuit. Its winding and magnetic core provide inductive reactance, which influences how current changes and how the circuit responds to harmonics or transients. Depending on its design and position in the circuit, a reactor can limit current, reduce the effect of certain disturbances, or form part of a harmonic-filtering arrangement.
Reactor functions are application-specific. A line reactor is installed on the supply side of a drive, while an output reactor is installed between the drive and motor; neither should be assumed to replace the other. A reactor also does not automatically eliminate harmonics or correct every power-quality issue, so its role should be defined alongside the full system design.
An AC line reactor is connected in series with the incoming supply to equipment such as a frequency converter. It may help limit current changes and reduce the drive’s sensitivity to some supply-side disturbances, subject to correct sizing and system conditions. Buyers should confirm that the reactor is suitable for the drive input and does not conflict with the converter manufacturer’s recommendations.
An output reactor is installed between a frequency converter and a motor. It can be considered where the motor cable is long or where the application requires additional control of the drive’s output waveform and current behavior. Cable length, switching characteristics, motor insulation, and the converter manufacturer’s guidance all affect whether an output reactor is appropriate.
A DC link choke is placed in a converter’s DC circuit. It can contribute to smoothing DC-link current and may be used as part of a drive’s approach to managing current harmonics. Confirm whether the choke is internal to the converter or supplied as a separate component before comparing product quotations.
A detuned reactor is commonly used in series with capacitor banks in power factor correction systems. The reactor changes the circuit’s tuning so that the capacitor-reactor combination is less likely to amplify selected harmonic conditions. Its design must be coordinated with the capacitor rating, system voltage, harmonic profile, and protection scheme.
A series current-limiting reactor is used to restrict current in a circuit, including in some systems where fault-current levels need to be managed. A shunt reactor is connected across a power system and is used in certain network applications to absorb reactive power and support voltage control. These are distinct applications from the low-voltage drive reactors commonly considered by equipment buyers.
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| Application | Reactor to evaluate | Key checks |
|---|---|---|
| Frequency converter supply input | AC line reactor | Drive input rating, supply conditions, impedance, and manufacturer guidance |
| Drive-to-motor connection | Output or load reactor | Motor and cable details, converter output, and installation distance |
| Converter DC circuit | DC link choke | DC current, voltage, mounting, and whether the drive already includes one |
| Capacitor-bank power factor correction | Detuned filter reactor | Capacitor data, harmonic assessment, system voltage, and protection |
| Network or fault-current management | Shunt or series reactor, as applicable | System study, switching conditions, insulation, and equipment coordination |
The table is a starting point, not a final design. A reactor selected only by nominal power can be unsuitable if its current rating, impedance, cooling, or operating conditions do not match the circuit. Where a project includes harmonics, long motor cables, or frequent switching, provide the relevant system information to the engineering team and supplier.
Start by identifying whether the reactor will be installed at the supply input, converter output, DC link, capacitor bank, or power network. State the problem it is intended to address, such as current limitation, drive application requirements, or detuned capacitor-bank operation. This prevents suppliers from quoting different reactor types against the same broad product description.
Prepare the system voltage, phase configuration, rated current, operating frequency, and required impedance or inductance where known. For example, a request may describe an illustrative 400 V, 50 Hz three-phase system, but those values are not universal specifications and should not be copied without checking the actual project. If the required impedance is expressed as a percentage, confirm the reference conditions and calculation basis with the design engineer and supplier.
Describe the ambient temperature, enclosure, ventilation, mounting orientation, altitude if relevant, and expected operating duty. Ask the supplier to state the insulation and temperature-rise basis for the offered design rather than assuming all reactors with the same current rating behave alike. Also confirm terminal style, dimensions, clearances, cable access, and any noise or enclosure constraints that affect installation.
For a frequency converter installation, share the converter make and model, motor ratings, cable length, and any manufacturer instructions relevant to reactors. For a capacitor-bank application, provide capacitor ratings and available harmonic information so the detuned reactor can be assessed as part of the complete arrangement. Review protection, switching, and thermal requirements with the responsible electrical engineer before ordering.
Reactor pricing depends on factors such as electrical rating, core and winding design, enclosure, cooling, terminals, customization, and required documentation. A standard configuration and a project-specific design may have different production requirements, so buyers should compare quotations only after confirming that the technical scope is equivalent. Minimum order quantity and lead time can vary by specification, order volume, and component availability; request current terms for the exact item rather than relying on a general estimate.
For a useful quotation request, provide the datasheet or completed specification, annual or project quantity, destination, preferred delivery terms, and any packaging or inspection requirements. Ask the supplier to identify what is included, what remains to be confirmed, and whether the quoted lead time begins after drawing approval or another milestone. This makes commercial comparisons clearer and helps reduce avoidable changes after order placement.
At ANNEZEE, we support B2B buyers evaluating electrical equipment and reactor requirements by reviewing the application information supplied and clarifying the specification needed for quotation. Share your circuit location, electrical ratings, connected equipment details, quantity, and installation constraints so we can discuss a suitable product scope. Any proposed configuration should be reviewed against your project requirements before purchase.
The right electrical reactor is the one designed for the specific circuit location and operating purpose, with ratings and construction matched to the connected equipment. Begin by distinguishing among line, output, DC link, detuned, current-limiting, and shunt reactors, then verify the electrical, thermal, installation, and commercial details. If you are sourcing a reactor for a low-voltage frequency converter or another industrial application, prepare the system data and request a specification-based review from your supplier. Contact ANNEZEE with your requirements to start a focused product and quotation discussion.
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