For a whole factory on a low-voltage three-phase line, choose a three-phase servo stabilizer with an input range that covers your lowest reading on every phase. For one sensitive single-phase machine, choose solid-state: IGBT if voltage falls toward 90V or the machine needs clean power, SCR if voltage stays above 95V and ±5% is enough. Before buying, check your cables and joints — sometimes the voltage drop is inside the factory.
Why is voltage so low at the end of the line?
Factories in industrial areas of Punjab and KPK are often far from the transformer, at the end of a long line shared with many other loads. The voltage falls along the line, and it falls further when everyone runs machines at the same time. The result: motors run hot, machines stall, controllers reset and lights dim when a large motor starts.
Is the low voltage coming from outside or inside the factory?
Check before you buy. Measure voltage at the incoming meter and again at the machine. If the meter reads fine but the machine reads low, the drop is inside: cables too thin for the load, a loose or burnt joint, or an overloaded distribution board. An electrician can fix that, and a stabilizer will not. If the voltage is already low at the meter, the problem is the supply — that is where a stabilizer helps.
Servo vs SCR vs IGBT: how do they compare?
| Servo (SVC) | SCR (thyristor) | IGBT (inverter) | |
|---|---|---|---|
| Output | 220V ±1% | 220V ±5%, stepped | 220V ±2%, pure sine |
| Input range | Standard 150–270V; 30 kVA model from 60V | 95–250V | 90–310V |
| Speed | About 25–30 V per second | About 20 ms | 0 ms rated |
| Sizes Voltec supplies | Single-phase up to 30 kVA; three-phase industrial | 1–10 kVA | 550VA–20 kVA |
| Moving parts | Motor and carbon brush | None in the correction | None in the correction |
Which should I choose for the whole factory?
Servo. Above 20 kVA, and on any three-phase supply, a servo stabilizer is the practical choice today. For three-phase, the Voltec SJW 50 kVA takes 150–260V per phase (260–450V three-phase) and has phase-failure protection, which matters on weak lines where a phase can drop out. Larger units are built to order: see industrial stabilizers and the 50 kVA sizing steps.
If your supply is single-phase and very weak, the 30 kVA servo starts working at 60V and holds 220V ±3% up to 250V. It is single-phase, not three-phase.
Which should I choose for one sensitive machine?
Solid-state. A servo corrects at about 25–30 volts per second, so a sudden drop from 220V to 160V — for example when a large motor starts nearby — takes about two seconds to correct. A CNC controller or laser can reset in that time. SCR reacts in about 20 ms; IGBT is rated 0 ms and works from 90V. Choose IGBT for the lowest voltage and cleanest power; choose SCR when voltage stays above 95V and ±5% is enough. Compare: SCR vs servo, IGBT vs servo.
Can I mix them?
Yes, and many factories should. A servo on the main feed for motors and general load, plus a solid-state unit in front of each sensitive machine, gives each load what it needs.
When will no stabilizer fix low voltage?
If voltage falls below the input range of every option, or the supply simply cannot carry your load, a stabilizer will cut off to protect itself and your machines. Then the fix is on the supply side: a complaint to your electricity company about the transformer or line, or your own transformer for larger loads. Also remember a stabilizer draws more current from the line when it boosts low voltage, so the incoming cable and breaker must be sized for that.