Hyderabad and the wider Telangana and Andhra Pradesh belt has a genuinely deep transformer industry — which is good for buyers, and confusing for them too. Price alone tells you very little. These are the checks we would apply if we were on the buying side of the table.
1. Is there a valid BIS licence?
For distribution transformers covered by IS 1180, a BIS licence is not optional. Ask for the licence number and check it. Ours is CM/L-6300036494. A manufacturer who is vague about this is telling you something.
2. Can they test in-house — and will they let you watch?
Routine testing at a third-party lab is slow and easy to skip under schedule pressure. An in-house test bay means every unit is genuinely tested. More importantly, ask whether you can witness the tests. A manufacturer confident in their product will invite you.
- Winding resistance measurement
- Voltage ratio, polarity and vector group
- No-load loss and no-load current
- Load loss and impedance voltage
- Applied and induced overvoltage withstand
- Insulation resistance and oil BDV
3. Are the loss figures guaranteed, with penalties?
Any manufacturer will quote attractive losses. Fewer will put them in the contract with a penalty clause. Insist on it — the difference is paid by you for the next twenty-five years.
4. What actually happens in their factory?
Visit. It takes half a day and it settles most questions. Look for CRGO core cutting done in-house, automated or semi-automated winding, a controlled drying process, and vacuum oil filling. Look at the housekeeping. A works that is chaotic on the day they know a customer is coming is not going to be careful about your core stacking.
5. Do they hold certifications that mean something?
ISO 9001 covers quality management, 14001 environmental, 45001 occupational health and safety. These are process certifications rather than product ones — they tell you the company is run to a system, not that any single transformer is good. Both matter.
6. Can they show you comparable work?
Not a logo wall — specific, comparable installations. If you are building a 200-bed hospital, ask who else they have supplied hospitals for and whether you can call them.
7. What is the real lead time?
CRGO steel and copper availability drive transformer lead times more than factory capacity. Ask what is currently in stock versus what has to be procured, and get the answer in writing.
8. Who comes when it fails at 2 a.m.?
Ask for the service structure by name and location. A manufacturer three states away with a dealer network is a different proposition from a works twenty kilometres from your site.
9. Can they take the whole electrical scope?
Splitting transformer, HT panel, LT panel and cabling across four vendors moves all the interface risk onto you. A single supplier who can do the transformer, the switchgear and the turnkey installation removes an entire category of site problem.
The short version
Ask for the BIS licence number, witness the routine tests, get loss figures into the contract, and visit the works. Any manufacturer worth buying from will welcome all four. We are in Balanagar, Hyderabad, and visitors are welcome most working days.