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DUCHENG Industrial

VFD MASTER · INDUSTRIAL DRIVE SIZING

VFD Master
Low voltage · Medium voltage · HV projects

Choose the voltage class first, then follow its own selection logic: current and frame pre-selection for LV, complete drive-system configuration for MV, and feasible-architecture triage with vendor-specific engineering for HV projects.

Core principleIdrive ≥ Imotor ÷ Kderating

The current formula runs through all three tracks; the higher the voltage, the more system topology, protection, insulation and reliability matter.

01

Voltage class

Pick the product track first to avoid mixing rules

02

Load profile

Choose the closest machine type

03

Grid & motor

Nameplate current remains the first criterion

04Duty & system checks
Affects derating, topology and accessories
Ready for brand comparisonLow Voltage LV · Live pre-selection

Suggested starting frame

30kW
Rated output current must also be ≥ 43.1 A
Low Voltage LV380 V220–690 V general-purpose products
Duty classNormal Duty ND110% / 60s
Control modeV/f or sensorless vectorQuadratic torque
Peak current45.1 ABased on total motor current
Combined derating100%Temperature × altitude × carrier

System configuration recommendations

Include these beyond the drive itself in the technical agreement and RFQ

2 items
Shielded VFD cable

Use a low-capacitance, symmetrical grounding construction with 360° grounding per EMC requirements.

AC line reactor or built-in DC reactor

Reduces rectifier harmonics and grid impact; first confirm whether the model already has one built in.