Challenge
The gas extraction pump station at a coal mine in Shanxi, China, started its vacuum pumps under load. Every loaded start drew heavy inrush current, dragging down the 10 kV bus — and even the upstream 330 kV substation — into significant voltage dips. The site began experiencing occasional protection trips, interrupting a process that must run continuously to keep mine gas at safe levels.
Solution
We supplied a Xichi CMV-1500-10-G medium voltage soft starter (10 kV class) for the vacuum pump load. Our engineers worked on site with the customer, the motor OEM and the pump manufacturer to implement a two-step fix:
- Restored correct start/stop operation strictly per the equipment manual.
- Re-calculated and re-set the starter’s ramp parameters — peak start current capped at 320 A, ramp time 23 seconds, voltage drop limited to 2%.
The retrofit required no additional hardware: the fix was delivered purely through expert parameter optimization and proper operating procedure.
Results
- Peak starting current limited to 320 A — heavy inrush eliminated
- Bus voltage drop limited to 2% — no more dips on the 10 kV bus or at the 330 kV substation
- Occasional protection trips during loaded starts eliminated
- Gas extraction returned to continuous, reliable operation — no production risk
- No extra hardware cost; commissioning completed through on-site engineering support
FAQ
What is a medium voltage soft starter?
A medium voltage (MV) soft starter is a solid-state motor starting device for 3 kV to 15 kV motors, typically built on SCR thyristor stacks. It ramps voltage to the motor during start, limiting inrush current and reducing mechanical shock, then bypasses to line power during steady-state operation.
How does a soft starter reduce voltage drop and protection tripping at motor start?
Direct-on-line starting can draw 6–8× the motor’s full-load current, dragging down bus voltage and tripping protective relays. A soft starter caps starting current (typically to 2–4× FLC, adjustable) and ramps voltage smoothly over a set time — in this case study, peak current was limited to 320 A and voltage drop to 2%, which eliminated the trips.
Can a 10kV soft starter handle coal mine gas extraction vacuum pumps?
Yes. MV solid-state soft starters are widely used for high-inertia and high-duty loads such as gas extraction vacuum pumps, mine ventilation fans and slurry pumps. The CMV series is a 10 kV-class solid-state starter; for the exact sizing, send the motor nameplate (voltage, kW, full-load current) for a free selection.
Soft starter vs VFD: which is right for a gas extraction pump?
If the pump runs at constant speed and only needs controlled starting, a soft starter is the lower-cost choice (roughly one-third the cost of an equivalent VFD) and is sufficient to solve inrush, voltage drop and water-hammer problems. If the process needs variable flow control, a VFD adds 20–50% energy savings on variable-torque loads. For this project, constant-speed duty meant a soft starter was the right fit. See our soft starter vs VFD comparisons for more detail.
Does the CMV series support remote monitoring / SCADA integration?
For remote monitoring and SCADA integration, confirm the communication option (e.g., RS485 / Modbus RTU) available on the CMV-1500-10-G with our sales engineer — we will specify it in your quotation and propose an upgrade path if required.
What certifications are available for exporting MV soft starters to mining projects?
Export documentation typically includes CE and ISO9001; for mining projects, explosion-proof certification (IECEx / ATEX) depends on the exact model and hazardous-area zone rating. Send us your project country and requirements and we will provide a certification compliance list.
