Load and Equipment
- Load type: Centrifugal compressor
- Rated voltage: 10 kV
- Motor rated current: 52 A
- Motor poles: 4-pole
- MV soft starter model: CMV-750-10
Centrifugal compressors are large, high-inertia MV machines. Starting one directly at 10 kV draws 6–7 times rated current, causing a deep voltage dip on the MV bus, disturbing other loads, and applying a torque shock to the compressor train. A CMV series medium-voltage soft starter (3–6–10 kV) (see the full medium-voltage soft starter range) was selected to control the start.
Commissioning Settings
Parameter | Set value | Purpose |
Initial voltage | 45% | Breakaway torque for the centrifugal compressor load |
Current limit | 3.5× rated current | Caps MV inrush and keeps bus voltage dip within limits |
Start (ramp) time | 15 s | Smooth acceleration without torque shock |
Result
The 52 A, 4-pole motor accelerates smoothly under current-limited soft start: the 10 kV bus stays stable and the centrifugal compressor train reaches rated speed without a start shock.
