Case 1: Indonesia Power Quality Case

Case 1: Indonesia Power Quality Case

Keeping a 500-TPD Indonesian Mill Running: How Power Stabilization and Soft Starts Cut Unplanned Stops

In Indonesia, a customer operating three “Type-25” combined rice mills reported frequent line shutdowns driven by unstable grid voltage. Daily processing targets (500 tons/day) were routinely missed because voltage sags and spikes tripped drives and protection relays. After diagnosis, Starlight implemented an intelligent voltage stabilizer (±10% automatic compensation), re-engineered motor start-up with soft-start modules, and added a one-button emergency stop that shuts down the entire line within three seconds if abnormal conditions are detected. Results: monthly shutdowns dropped from ~12 to ~2; start success rose to 98%; overall efficiency returned to ~95% of normal.

Why this keeps happening in Southeast Asia

Across Southeast Asia’s rice belts, mills contend with: (1) feeder lines that experience regular sags at peak local demand; (2) variable PF (power factor) at facilities where mixed motor loads start together; and (3) long, undersized internal cables compounding voltage drop. For mills running parallel motors (huskers, whiteners, polishers, blowers), inrush currents can be 5–7× FLA (full-load amps). Without controlled start-up and a stabilizer/AVR, protection devices nuisance-trip, and electronic drives reset—multiplying stoppages and scrap. (Regional trend context from your market study.)

Starlight’s engineering response—step by step

1) Power quality survey & load profile. We capture a 7–10-day waveform log (V/I/PF/THD), diagram the single-line, and map each motor’s start sequence and FLA. Outcome: accurate spec for stabilizer kVA and soft-starter ratings.
2) Intelligent voltage stabilizer (IVS) sizing. We select an IVS that:

  • Handles expected sag/swell ±10% compensation continuously.

  • Tolerates transient dips without overshoot.

  • Includes bypass for maintenance and an output within ±1–2% regulation under typical load swing.
    3) Soft-start modules on big hitters. For high-inrush motors (husker main, whitener main, large blowers):

  • Current ramp 3–8s; torque ramp tuned so belts don’t slap.

  • Staggered start logic: 5–10s gaps to avoid compound inrush.
    4) Safety interlocks & a real E-stop. A hardware E-stop that drops a dedicated safety relay shuts the entire line within three seconds. We also wire interlocks so upstream equipment cannot flood downstream sections if a downstream trip occurs.
    5) Operator procedure & training. The best hardware fails without human alignment. Operators learn a standardized pre-start checklist (breaker positions, belt tension, screen cleanliness, air gates) and a post-trip reset protocol to prevent bounce restarts.

The math of ROI: fewer stops, more sellable rice

Every unplanned stop wastes energy, risks kernel breakage from partial-load restarts, and adds off-spec rework. In this case, reducing stops from ~12 to ~2 per month with ~95% efficiency recovery provides:

  • Recovered productive hours: If one stop averages 30–60 minutes of downtime + ramp-up scrap, you regain 5–10 hours monthly.

  • Quality preservation: Controlled restarts reduce sudden mechanical shock on whiteners and polishers, protecting head rice yield.

  • Energy normalization: Voltage sags increase I²R losses; stabilizing voltage moderates heating and lowers kWh/ton.

A practical spec you can copy

For a 500-TPD line operating at 380/400V, 50Hz (typical for Indonesia):

  • IVS rating: sum of simultaneous motor kW ÷ expected PF ÷ IVS efficiency, then add a 20–30% margin for sags and future loads.

  • Soft-start modules: sized at 3–5× motor FLA for ramp duration; include thermal modeling and locked-rotor protection.

  • Protection: electronic overloads with class-20 curves for heavy-duty motors; surge protection (Type II SPD) on MCC incomers; undervoltage trip thresholds coordinated with IVS behavior.

  • Cabling: re-check voltage drop (<3% branch, <5% feeder) at full load and ambient temp.

  • Earthing: <5 Ω system earth; segregate control ground and power earth to avoid nuisance PLC resets.

What changes for maintenance and safety

  • E-stop drills: monthly drills ensure sub-3s cutoff is reliable.

  • Thermal scans: quarterly IR scans of MCC busbars and lugs catch loose terminations that worsen sags.

  • Fan/vent checks: stabilizers and soft-starters dissipate heat—keep filters clean to avoid thermal derating.

  • Spare modules: keep at least one soft-starter of each frame size and one spare IVS controller board.

How Starlight generalizes this solution

We package the above into a Power Quality Kit: properly sized IVS, soft-start modules for inrush-heavy motors, coordinated protection, wiring diagrams, and a start-up SOP. For markets like Indonesia, Philippines, and Myanmar—where the grid is improving but still variable—this kit cuts nuisance trips and stabilizes OEE without the cost and logistics of a complete electrical room rebuild. (Regional adoption and mechanization context.)

Results that matter

This Indonesian mill’s experience—shutdowns down ~83%, start success at ~98%, overall efficiency ~95%—is consistent with what we see when stabilizers and start logic are tuned as a system, not piecemeal.