Product pictures Product Overview: Emerson UNI4402 Parameter Specification Brand Emerson / Control Techniques Part No. UNI4402 Series Unidrive M400 Type AC Variable Frequency Drive (VFD) Application & Fault Scenarios System: Emerson UNI4402 Unidrive M400 AC drive used in conveyors, pumps, fans, compressors, packaging machines, and general manufacturing automation for motor speed control. Typical Faults: IGBT module failure → OC/OH trip, drive won't restart DC bus capacitor