A servo stabilizer uses a small motor to move a carbon brush along a variable transformer, which corrects the output voltage smoothly instead of in jumps. In Pakistan, servo-type (SVC) stabilizers cost from about ₨14,000 for 1,000W to ₨288,000 for 30,000W. Here is how servo stabilizers differ from relay types, and when the extra accuracy is worth paying for.
Servo vs relay stabilizer
| Relay (static step) stabilizer | Servo (SVC) stabilizer | |
|---|---|---|
| How it corrects | Switches between fixed transformer taps | A motor moves a brush continuously |
| Output accuracy | Changes in steps, often ±5–10% | Smooth, typically within a few percent |
| Response to slow drops | Clicks between steps | Follows the voltage smoothly |
| Best for | Basic appliances | ACs, motors, clinics, sensitive equipment |
| Price | Lower | Higher, but longer life under heavy load |
When a servo stabilizer is the right choice
- Areas with very low evening voltage. A servo unit keeps correcting smoothly where a relay unit runs out of steps.
- Inverter ACs and compressors. A steady voltage reduces stress on the compressor and the control board.
- Clinics and labs. Equipment such as ultrasound and analyzers needs stable input, ideally with a sine wave UPS after the stabilizer.
- Whole-house supply. Large loads change often, and a servo unit handles that change smoothly.
Servo stabilizer sizes and prices
Our single-phase SVC range starts at the 1,000W unit (₨14,000). The 3,000W and 5,000W units (₨45,000 each) suit 1.5 to 2-ton ACs. The 10,000W (₨108,000) covers most houses. The 20,000W and 30,000W units suit clinics and small hospitals. The full table and a sizing method are in our stabilizer price guide.
Looking after a servo stabilizer
- Install it where air can flow freely, away from dust and direct sun.
- Have the carbon brush and the variac track checked once a year, since they are the parts that wear.
- Do not run it above about 70–80% of its rating for long periods.
- If the motor hunts back and forth constantly, have the control card checked.
Service in Pakistan
We supply servo stabilizers across Pakistan and service them from Lahore. Send us your load list on WhatsApp +92 321 4444595 and we will recommend a size. See all voltage stabilizers.