Servo voltage stabilizers, 5 kVA to 500 kVA
5 kVA to 500 kVA, air or oil cooled, correcting to ±1% output. The right first fix when the MIDC feeder swings all day and the equipment keeps tripping on undervoltage.
- Capacity range
- 5 kVA – 500 kVA
- Configuration
- 1φ and 3φ (balanced or unbalanced)
- Input range
- 340–480 V (3φ) · 170–270 V (1φ). Wider to order.
- Output
- 415 V ±1% (3φ) · 230 V ±1% (1φ)
More views of the Servo Voltage Stabilizer
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By rating and configuration
Each of these is a distinct build, not a filter on one page.
Oil Cooled Servo Stabilizer
From 100 kVA up, and anywhere the ambient is hot or the air is dirty, oil cooling is the right call. The windings and the variac sit in transformer oil, which carries heat out far more effectively than forced air and keeps abrasive dust off the carbon brush track.
View specs 5 – 100 kVAAir Cooled Servo Stabilizer
Lighter, cheaper and with nothing to test annually. Suited to clean indoor environments — commercial buildings, clinics, offices, light industrial units and telecom sites.
View specsAnd when it’s the right answer
A servo stabilizer uses a motorised variable transformer and a buck-boost winding to hold the output within a tight band while the input wanders. It is a mature, repairable, electromechanical solution and it remains the most cost-effective answer to one specific problem: an input supply whose voltage is wrong but whose continuity is fine.
That is the everyday condition on industrial feeders around Pune. Voltage sags through the morning shift as the estate loads up, climbs at night, and swings when a large motor next door starts. Equipment does not fail dramatically — it just trips, runs hot and wears out early.
Understand what a stabilizer does not do: it gives you no backup. If the feeder drops, the load drops. Where the supply is both dirty and unreliable, the correct specification is a stabilizer upstream of a UPS, and we will tell you when that is the case rather than selling you the larger stabilizer.
Choose a stabilizer when the problem is voltage, not continuity, and when the load is large — a 200 kVA stabilizer costs a fraction of a 200 kVA UPS and needs no battery room.
An isolation transformer removes noise and gives galvanic separation but does not correct voltage. Different problems. They are often installed together.
Relay-type stabilizers correct in coarse steps and are fine for a household. A servo corrects continuously to ±1%, which is what three-phase industrial loads need.
Where these get installed
- Machine shops and CNC installations
- Textile and processing plants
- Electroplating shops
- Cold storage and ice plants
- Hospitals and diagnostic centres
- Petrol pumps and commercial buildings
- Telecom sites
Full specification
Typical values for the standard build. Every unit is configured to order — the figures on your general arrangement drawing are the ones that apply.
| Capacity range | 5 kVA – 500 kVA |
|---|---|
| Configuration | 1φ and 3φ (balanced or unbalanced) |
| Input range | 340–480 V (3φ) · 170–270 V (1φ). Wider to order. |
| Output | 415 V ±1% (3φ) · 230 V ±1% (1φ) |
| Correction speed | 20–30 V per second |
| Efficiency | > 98% |
| Waveform distortion | Nil — no waveform modification |
| Cooling | Air cooled to 100 kVA · oil cooled above |
| Duty | Continuous, 100% rated |
| Protection | HV/LV cut-off, overload, single phasing, surge |
| Enclosure | IP21 indoor · IP55 / outdoor to order |
| Bypass | Manual bypass switch standard |
Sectors that buy this
CNC & Machine Shops
A CNC controller that resets mid-cycle scraps the job and can crash the tool. On MIDC feeders that is a voltage problem far more often than an outage problem.
Electroplating & Surface Finishing
Deposit thickness is current × time. If the current wanders, the coating varies — and you find out at the salt-spray test, not on the line.
Cold Storage & Food Processing
Compressor motors are unforgiving of low voltage, and the stock in the chamber does not care whose fault the outage was.
Hospitals & Diagnostics
The load list in a hospital is not one load. Theatres, imaging, ICU and the server room each need a different answer, and the specification has to hold up in an NABH audit.
Pharmaceutical & Life Sciences
In a GMP environment a power event is not only a downtime cost — it is a deviation, an investigation and potentially a lost batch.
Servo Voltage Stabilizer — questions we get asked
Anything not covered here, call us — most of it is faster to answer on the phone.
What is the difference between a servo stabilizer and a UPS?
A stabilizer corrects voltage but provides no backup — no supply in, no supply out. A UPS carries the load through an outage on battery. If your equipment trips because voltage is low, you need a stabilizer. If it goes down because the power fails, you need a UPS. Plenty of sites need both, in that order.
Oil cooled or air cooled servo stabilizer?
Air cooled is standard up to about 100 kVA — cheaper, lighter, no oil to test. Oil cooled is used above that and in dusty or high-ambient environments, because oil carries heat away far better and the windings run cooler, which is what determines service life. Oil units need a dielectric strength test on the oil roughly every two years.
How do I size a servo stabilizer?
Total the connected load in kVA, add 20–25% headroom, and check the widest voltage swing you actually see rather than the nominal. Also check whether your load is balanced across the three phases: if it is not, you need an unbalanced (independent-phase) stabilizer, which regulates each phase separately. Getting that wrong is the single most common specification error we see.
Does a servo stabilizer save electricity?
Sometimes, indirectly. If your incoming voltage regularly runs above 415 V, resistive and lighting loads draw more power than they need to, and holding the output at 415 V trims that. Anyone promising you a fixed percentage saving is guessing — the honest answer depends entirely on your voltage profile and load type.
Where we supply and attend
Servo Voltage Stabilizer units are built at our Pune works and delivered, installed and commissioned across the city and the industrial belt around it.
Outside these areas we contract individually against distance, and we will tell you honestly if the response time you need is not one we can hold to. All areas served
After it’s installed
We service what we build, and what everyone else builds too.