LS DR Line/Output Reactor

The LS DR Series Line and Output Reactor is a three-phase dry-type iron-core inductor designed for installation on the AC supply input or motor output side of variable frequency drives, providing harmonic current attenuation, EMI suppression, dV/dt limitation, and protection against supply voltage notching and transient overvoltages. The DR3-0250 is a 3% impedance input line reactor sized for 250 A continuous service at 380–480 V AC, 50 Hz, housed in an IP20 ventilated enclosure suitable for motor control centre mounting. At 3% impedance, the reactor reduces the peak input current demand of the drive rectifier, limiting supply harmonic distortion (THD-I) from the drive to approximately 25–35% compared to 40–50% without a reactor — providing a cost-effective first-step harmonic mitigation measure where the full performance of an active harmonic filter is not required. The reactor's 150% overload current rating for 60 seconds matches the overload capability of the connected VFD, ensuring the reactor does not limit drive overload performance.

When used as an output reactor on the motor side of a VFD, the DR series limits the dV/dt (rate of voltage rise) of the PWM output pulses to below 500 V/μs, protecting standard motor winding insulation from premature breakdown caused by voltage reflection on long motor cables. This is particularly important in Saudi Arabian applications where motor-to-drive cable runs frequently exceed 50 metres in large process plant motor control centres, and where motors may not be specified to inverter-duty winding standards. The reactor also acts as a radio-frequency interference (RFI) choke, attenuating the high-frequency emissions conducted along motor cables that can couple into instrument signal cables running in the same cable tray — a common problem in petrochemical and process plant environments.

Line reactors and output chokes are specified as standard items in ARAMCO and SABIC electrical engineering standards for VFD installations, and their use is increasingly required by SEC network operators to limit the harmonic impact of large industrial drive loads on the distribution network. In Saudi Arabia's industrial cities and process plants, where motor control centres often contain dozens of drives of varying sizes connected to a common bus, individual line reactors on each drive provide the most cost-effective approach to meeting aggregate harmonic distortion limits without system-level active filters. The DR series is also specified for UPS system input isolation and battery charger input current smoothing at telecoms and data centre installations.

Razz Middle East supplies DR series line and output reactors for all standard VFD current ratings from 10 A to 1000 A in both 3% and 5% impedance versions. Sizing calculations for specific VFD models and cable run lengths are provided by our engineering team, including dV/dt and harmonic compliance assessments. SAR pricing with duty-paid delivery for stock items is available, and custom reactor specifications for non-standard ratings or higher impedance values are available on extended lead times. All DR reactors carry a two-year warranty.