VFD Selection
Selecting a VFD is not just matching motor kilowatts to a catalogue line. In special purpose machines, the right drive depends on overload profile, acceleration time, torque curve, braking method, EMC constraints, network protocol, and the environmental conditions inside the control panel or machine enclosure.
- Conveyor systems where variable speed control is needed without the cost of a full servo axis.
- Pump and fan applications that require energy-efficient speed regulation and soft starting.
- Machine axes with moderate precision requirements where torque stability matters more than absolute position control.
- Retrofit projects where direct-on-line starting causes mechanical shock or excessive inrush current.
Drive output current, not only nameplate power, must align with the motor and duty cycle. Engineers also check carrier frequency impact, braking resistor requirement, harmonic behaviour, cable length limits, and whether the drive will live in a hot enclosure beside other heat-generating devices. Fieldbus support matters when the VFD must report diagnostics or accept speed references from a PLC network rather than hardwired analog control.
- Sizing only by motor kW and missing overload current demand during startup or process peaks.
- Ignoring braking energy, then discovering the machine cannot decelerate within the required time.
- Placing multiple drives in a compact cabinet without checking thermal rise and spacing rules.
- Using a general-purpose drive where application-specific features like safe torque off or fieldbus diagnostics are required.
- Missing cable shielding and grounding requirements, which later causes communication noise and nuisance trips.
ClusterVise evaluates load profile, voltage, motor data, and cabinet conditions together instead of treating the VFD as an isolated device. It recommends suitable drive families, surfaces accessory requirements such as braking resistors and EMC filters, and keeps those selections tied to the BOM and panel thermal model so downstream changes are visible immediately.
| Item | Selection | Basis |
|---|---|---|
| Motor | 2.2 kW, 400V AC | Constant torque conveyor duty |
| Drive class | 3 kW VFD with overload margin | Startup and jam-clearing headroom |
| Control | PROFINET | PLC speed reference and diagnostics |
| Safety | STO integrated | Safe stop via control system |
| Accessory | Input breaker + shielded cable + EMC grounding | Reliable installation basis |
