3-Phase Servo Voltage Stabilizers
Servo-controlled automatic voltage stabilizers that hold output within a tight band for 3-phase industrial loads under wide input-voltage swings.
About 3-Phase Servo Voltage Stabilizers
A servo voltage stabilizer keeps the output voltage of a three-phase supply steady when the incoming voltage swings. A voltage-sensing circuit drives a servo motor that moves the brush on a continuously variable auto-transformer, adjusting the voltage until the output is back at the set value. Because it corrects continuously over a wide band, it suits whole-plant and machine-line supplies on weak or fluctuating feeders.
Microtech supplies three-phase servo stabilizers from Jindal Electric, Power Star and Globe Rectifiers. Published listings show the range clearly: Globe offers LT servo voltage controllers from 30 kVA to 7500 kVA with a 350–460 V input window and 400 V output, and HT automatic voltage controllers from 300 to 7500 kVA that correct an 8–12 kV input to 11 kV. Jindal lists oil-cooled three-phase units with input windows such as 330–470 V.
We check your actual input voltage range and load type before recommending a rating and cooling type, and install and commission the unit.
Key specifications
| LT ratings | 30 kVA to 7500 kVA (Globe Rectifiers LT servo voltage controller) |
|---|---|
| Typical input window | 350–460 V (Globe) or 330–470 V (Jindal), model-dependent |
| Output | 400 V, 3-phase (Globe LT controller); set to site requirement |
| HT voltage controller | 300–7500 kVA, 8–12 kV input, 11 kV output (Globe Rectifiers) |
| Cooling | Air-cooled or oil-cooled |
| Correction | Servo motor driving a continuously variable auto-transformer |
Features & benefits
- Holds output steady across wide input-voltage swings
- Three-phase correction for whole-plant and machine-line supplies
- Oil-cooled versions for high ratings and hot, dusty sites
- HT automatic voltage controllers for 11 kV incomers
- Copper-wound models available
- Sized against measured input range and load profile
Where it’s used
- Textile, plastic and packaging machinery
- CNC and machine-tool shops
- Hospitals and diagnostic equipment rooms
- Commercial buildings and hotels
- Cold storages and food processing
- Plants at the tail end of long rural feeders
3-Phase Servo Voltage Stabilizers — FAQs
Air-cooled or oil-cooled servo stabilizer?
Air-cooled units are lighter and suit smaller ratings in clean indoor rooms. Oil-cooled units handle higher ratings and dusty or hot environments better. We recommend based on rating and site conditions.
What input voltage range should the stabilizer cover?
It should cover the lowest and highest voltage you actually see at the incomer, with some margin. We log or measure your supply before choosing a model; published windows such as 330–470 V or 350–460 V vary between makes.
Can the voltage be stabilised on the 11 kV side instead?
Yes. HT automatic voltage controllers correct the 11 kV supply before the transformer, which suits large plants with many LT feeders. Globe Rectifiers lists HT controllers from 300 to 7500 kVA.
Servo or static stabilizer – which do I need?
A servo stabilizer is economical for wide, relatively slow voltage swings on a whole-plant supply. Loads with sudden steps that need very fast correction may suit a static stabilizer. Tell us the load type and we will advise.
