Answer first
Short Answer
Textile production can be vulnerable to brief voltage sags because one drive or control trip may disturb tension, yarn quality, thermal conditions, compressed air, or a coordinated line sequence.
Protection should be based on the first equipment that trips and the minimum process boundary that must remain stable—not simply the total installed plant load.
VFD DC-bus support may fit selected drives, while whole-line protection may be better for mixed loads and shared auxiliaries.
Verified Fujian deployment
Two WS300 systems protecting eight large texturing machines
Chemical Fiber Manufacturer, Fujian, China. Results are reported separately by system through August 24, 2026.
- WS300-66 · June 2026
- 4 machines · 13 sag records · 13 successful ride-through records
- WS300-67 · July 2026
- 4 machines · 5 sag records · 5 successful ride-through records
When This Applies
- A short grid event stops multiple VFD-driven machines.
- Drive trips lead to yarn breaks, tension disturbance, or material loss.
- Air compressors or chillers stop and disrupt several production areas.
- The plant needs to distinguish critical process loads from loads that may safely coast or restart.
Where a Sag Can Become a Production Stop
| Process area | Possible first trip | Assessment question |
|---|---|---|
| Spinning / vortex | Spindle or drafting drive undervoltage | Which drives and controls must remain synchronized? |
| DTY / winding | Tension, take-up, or traverse drive trip | What coast-down behavior produces scrap or yarn breakage? |
| Dyeing | Pump, circulation, temperature control, or PLC reset | How long can flow or temperature depart before the batch is at risk? |
| Compressed air | Compressor drive or control trip | Is receiver capacity enough, and which downstream users are critical? |
| Chilled water | Chiller, pump, or control sequence trip | Which equipment must ride through together to avoid a full restart? |
Calculation Example
If two 250 kW critical drives and 100 kW of required auxiliaries must remain online for 0.4 seconds, the ideal energy gap is (250 + 250 + 100) kW × 0.4 s = 240 kJ, or about 0.067 kWh. Detailed sizing must include actual power at the event, losses, and control reserve.
Alternative Solutions
Selected VFD DC-bus support can be efficient when only specific drives determine process continuity. Whole-line voltage sag protection is considered when controls, heaters, pumps, contactors, and drives must ride through as a group. UPS protection may fit low-power controls, while network or process changes may reduce exposure without protecting the entire line.
Limitations / When Not to Use
- Do not protect only the largest drive if an unprotected PLC, contactor, pump, or tension controller stops the line first.
- Do not use generic textile load assumptions as a substitute for measured site data.
- Long utility outages require a separate backup strategy.
- Quality acceptance criteria must be defined by the plant, not inferred from electrical ride-through alone.
Recommended Architecture
Map the complete stop sequence by machine family, correlate voltage events with drive and PLC logs, and divide the line into protection zones. Start with the lowest-cost zone that preserves product quality and allows continuous or controlled recovery.
Traceable sources
Sources / References
- IEC 61000-4-30: Power quality measurement methods. Measurement and interpretation methods for voltage dips, interruptions, harmonics, transients, and other power-quality parameters. Accessed 2026-08-24.
- IEEE 1159-2019: Monitoring Electric Power Quality. Recommended practice for describing, measuring, and interpreting power-quality phenomena. Accessed 2026-08-24.