Guide · 6 min read
How to Choose the Right Servo Stabilizer (kVA Sizing Guide)
How to size a servo stabilizer: work out your load in kVA, allow headroom, pick single vs three phase and air vs oil cooling.
Start with your load
Sizing a stabilizer means matching it to the total load it will feed. Add up the power ratings of everything that will run through it. Ratings in watts can be converted to VA, and 1000 VA is 1 kVA. If your equipment lists amps and volts, multiply them to get VA.
Add headroom
Never size a stabilizer to exactly your load. Allow roughly 20–25% extra capacity so the unit isn't running at its limit, and so you have room to add equipment later. Motors and compressors also draw a large surge at start-up, which the stabilizer must handle.
A quick rule of thumb: total your connected load in kVA, then add about a quarter again for headroom and start-up surge. When in doubt, share your load list with us and we'll size it for you.
Single phase or three phase
If your premises are supplied on single phase (typical for homes and small shops), you need a single-phase stabilizer. Three-phase premises need a three-phase unit — balanced if the load is spread evenly across phases, or independently-corrected (unbalanced) if some phases carry much more than others.
Air-cooled or oil-cooled
For moderate loads in clean indoor spaces, air-cooled units are lighter and easier to maintain. For heavy loads that run continuously, or hot environments, oil-cooled units manage the heat far better and last longer under strain.
Match the voltage window
Stabilizers are built for an input voltage range — the band of mains voltage they can correct. If your supply routinely drops very low or spikes very high, tell us, because you may need a wider correction range than a standard unit provides.
Related products
Still deciding? Send us your requirement and we'll recommend the right stabilizer and quote it.
Answers
Related questions
What size stabilizer do I need for my home?
It depends on which appliances run through it. A whole-home single-phase setup with AC units often falls in the 4–10 kVA range, but the right size comes from your actual load. Send us your appliance list for a firm recommendation.
Can one stabilizer cover my whole factory?
Often yes — a suitably sized three-phase unit can protect the whole installation. Very large or uneven loads may be better served by an unbalanced three-phase model, or by units on specific lines.