Line Reactors / Inductors
A line reactor (input/AC line choke) is a three-phase series inductor installed between the supply and a VFD, rectifier, soft-starter or other non-linear load.
Overview
A line reactor (input/AC line choke) is a three-phase series inductor installed between the supply and a VFD, rectifier, soft-starter or other non-linear load. It limits the rate of current rise, buffers the drive from voltage transients, notching and sags, and reduces harmonic current drawn from the line — a 3–5% impedance reactor typically cuts input current THD from roughly 80–100% down to about 35–40%, improving true power factor and protecting both the drive's DC-bus capacitors and upstream equipment. The same construction used on the drive output (as a load reactor) limits dV/dt and reflected-wave stress on motor cables and windings. ACE manufactures these as dry-type, naturally-cooled, copper- or aluminium-wound reactors on laminated silicon-steel cores, rated to the drive's full-load current with impedance specified as %Z (Uk). Buyers choose ACE for reactors sized to the actual operating current so the rated impedance is delivered where it matters.
Specifications
| Impedance (%Z / Uk) | typically 3% or 5% (line buffering vs. harmonic mitigation) |
|---|---|
| Rated current (A) | matched to VFD/drive full-load current (FLA) |
| Inductance (mH) derived from %Z, current and frequency | |
| Voltage class | 230 / 415 / 480 / 600 / 690 V up to ~1140 V |
| Frequency | 50 / 60 Hz (400 Hz on request) |
| Phases | three-phase (single-phase on request) |
| THD reduction | input current THD reduced to ~35–40% at 3–5% Z |
| Insulation class | up to Class H; temperature rise to spec |
| Cooling | natural air (dry type); Mounting: panel / floor; Enclosure: open IP00 or enclosed |
| Applicable standards | IEC 60076-6, IEEE-519, UL/IS as required |
Applications
- Input (line-side) protection and harmonic reduction for VFDs / AC drives
- Output (load-side) reactors limiting dV/dt and reflected-wave on long motor cables
- Soft-starter and rectifier-bridge input buffering
- Reducing voltage notching and nuisance tripping between multiple drives
- DC-bus capacitor and semiconductor protection in drive systems
Frequently asked questions
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