In modern industrial facilities, Variable Frequency Drives (VFD) are widely deployed to control pumps, fans, compressors, and conveyors. However, high-speed IGBT switching generates severe harmonic distortion and steep voltage rise rates (dv/dt) that can destroy motors and disrupt nearby automation.
Input Reactors (ACL Series) – Protecting the Drive and the Grid
Installed between the AC power supply and the input terminals of the inverter, ACL input reactors fulfill three vital roles:
- Suppressing Grid Voltage Surges: Absorbs high-voltage switching surges and lightning transients from the incoming grid, preventing rectifier diode breakdown.
- Mitigating Harmonic Distortion: Reduces input current total harmonic distortion (THDi) by smoothing the pulsating DC bus charging currents.
- Improving Power Factor: Raises the fundamental displacement power factor of the drive system from ~0.75 to ~0.90+.
Output Reactors (OCL Series) – Protecting the Electric Motor
When the distance between the VFD and the motor exceeds 30 to 50 meters, cable parasitic capacitance and high-frequency PWM pulses create wave reflection phenomena, doubling the peak voltage at the motor terminals. OCL output reactors:
- Limit Steep dv/dt Voltage Spikes: Dampens voltage rise rates to protect motor stator insulation against premature inter-turn dielectric failure.
- Reduce Motor Operating Temperature & Noise: Filters high-frequency carrier ripple, lowering acoustic hum and iron eddy-current heating.
- Suppress Cable Leakage Current: Prevents nuisance ground fault tripping on long cable runs.
AIKEY Power manufactures complete CKSG, ACL, and OCL series reactors with vacuum-impregnated H-class insulation for heavy industrial motor drive systems.