VFD Selection
Select VFD power and current rating from motor power/current, load type, overload requirement, and ambient/altitude derating.
Key points
VFD Selection: Select VFD power and current rating from motor power/current, load type, overload requirement, and ambient/altitude derating. Formula: I_VFD ≥ I_e·K_overload/derating | P_VFD ≥ P_e·K/derating. Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. Selecting a VFD by current is more reliable than by power: motor FLA, overload capability, ambient temperature, and altitude all affect usable current. Constant-torque loads (conveyors, extruders, hoists) need heavy-duty 150%/60 s; fan/pump variable torque may use light-duty, but check starting torque.
Inputs
I_VFD ≥ I_e·K_overload/derating | P_VFD ≥ P_e·K/deratingCalculation model (updates with parameters)
| Required VFD current | 24.75 A | I_e×1.10×1.50/降额 |
| Required VFD power | 12.38 kW | 按motorPowerand过载系数估算 |
| Temperature / altitude derating | 1.00 × | Temperature 1.00 × 海拔 1.00 |
| Recommended VFD power rating | 15 kW | 按常用变频器Power档向上取整 |
| Recommended overload capability | 150% / 60s | 恒转矩建议重载型 |
| Motor cable length | 30 m | 常规范围 |
| Voltage / phases | 380 V，三相 | 单相 220V 进线需选单相Input变频器 |
Engineering notes
- Selecting a VFD by current is more reliable than by power: motor FLA, overload capability, ambient temperature, and altitude all affect usable current.
- Constant-torque loads (conveyors, extruders, hoists) need heavy-duty 150%/60 s; fan/pump variable torque may use light-duty, but check starting torque.
- Long motor cables, shielded cables, and parallel motors increase common-mode current and voltage reflection; add output reactors, dv/dt, or sine filters when needed.
FAQ
- What is VFD Selection for?
- Select VFD power and current rating from motor power/current, load type, overload requirement, and ambient/altitude derating.
- What is the formula for VFD Selection?
- Core formula: I_VFD ≥ I_e·K_overload/derating | P_VFD ≥ P_e·K/derating. The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using VFD Selection?
- Selecting a VFD by current is more reliable than by power: motor FLA, overload capability, ambient temperature, and altitude all affect usable current. Constant-torque loads (conveyors, extruders, hoists) need heavy-duty 150%/60 s; fan/pump variable torque may use light-duty, but check starting torque. Long motor cables, shielded cables, and parallel motors increase common-mode current and voltage reflection; add output reactors, dv/dt, or sine filters when needed.