Article · Punjab industry
How to size a factory transformer in Punjab
Published 4 November 2026 by Jaybee Industries, Bathinda
Many Punjab factories end up with the wrong transformer. Some are oversized, so they carry high no-load losses all year. Others are undersized and run hot every season. A short method gets you close to the right size before you ask for quotes.
Step 1: List the connected load
Add up the nameplate ratings of motors, heaters, compressors, lighting and HVAC in kW. A Ludhiana knitting unit is mostly motors. A Bathinda rice sheller adds large husk-handling and polishing drives. A cold store is mostly compressors.
Step 2: Apply realistic diversity
Machines rarely all run at full load together. Use your own data where you have it: maximum demand readings from past electricity bills are the best guide. A three-shift textile mill runs closer to its connected load than a one-shift fabrication shop.
Step 3: Convert kW to kVA using your power factor
kVA = kW ÷ power factor. At a PF of 0.8, 400 kW needs 500 kVA. At 0.95 it needs about 421 kVA. Correcting PF with capacitors can therefore cut both the transformer size and the demand charges. Jaybee's main site explains this in power factor and MDI and controlling PF and MDI.
Step 4: Allow for growth, but don't overdo it
Add headroom for expansion you actually have planned. A transformer that runs far below its rating for years still pays its no-load loss every hour. This is where a higher IS 1180 efficiency level or an amorphous core can pay back.
Step 5: Check special loads separately
Induction furnaces, large VFD banks and welding loads produce harmonics and thermal cycling. They need a furnace-duty or specially designed transformer, not just a bigger standard unit.
A quick example
| Item | Value |
|---|---|
| Connected load | 650 kW |
| Observed maximum demand | ≈ 70% → 455 kW |
| Power factor after correction | 0.95 → ≈ 479 kVA |
| Planned expansion | + 15% → ≈ 550 kVA |
| Nearest standard rating | 630 kVA |
Illustrative only. The final rating should come from your measured demand and your consultant or utility requirements.
Next step
Send your load list or last 12 months of bills with the RFQ, and the Bathinda team will suggest a rating and efficiency level. See also how to select a transformer and transformer manufacturers in Punjab.