Choosing the rating before comparing prices
For a 63 kVA enquiry, ask the project engineer to establish operating demand, diversity and the duty of any significant starting or changing loads. Adding equipment nameplates alone does not select a transformer. For a replacement, share the existing nameplate, actual demand information and the reason for replacement. A higher nearby rating is an alternative to assess, not an automatic upgrade.
63 kVA versus 100 kVA: do not decide from price alone
Keep a 63 kVA and a 100 kVA quotation as separate technical alternatives unless the project engineer accepts both. Compare construction, operating duty and losses on the same basis. No standard load capacity in kW, default voltage ratio or guaranteed motor-starting performance is inferred from the 63 kVA label.
Typical applications: questions, not guarantees
- A commercial-services, institutional or industrial auxiliary-load brief may raise a 63 kVA interest, but none of these applications automatically establishes the correct rating.
- For a replacement, compare actual duty with the existing nameplate and drawings, and explain why the old unit is being replaced.
- List diversity and phase-loading assumptions from the engineer, together with starting or other changing-load information where relevant.
Oil-immersed or dry-type suitability
Oil-immersed and dry-type construction have different installation, cooling and maintenance considerations. OSTL’s dry-type range is confirmed up to 3 MVA, but this does not confirm every rating/voltage/configuration. Ask the engineer and OSTL to assess the site, ventilation, fire strategy, interfaces and project specification. A dry-type label is not a blanket safety, fire-class or approval guarantee.
OSTL manufactures power and distribution transformers within an overall range of up to 10 MVA and up to 66 kV; the exact rating/voltage combination needs confirmation. Dry-type transformers are a confirmed product line up to 3 MVA. The 66 kV company-range statement must not be applied to dry-type products.
Copper or aluminium windings
OSTL confirms copper and aluminium winding options. The material should be selected within the complete electrical and performance design, not treated as a stand-alone promise of loss, efficiency or life. Ask for the product-specific selection and a clearly stated technical offer.
ONAN cooling and CRGO core requirements remain options/requirements to confirm. Neither is asserted as a guaranteed feature of this enquiry rating.
Specifications on request
No guaranteed losses, dimensions, weight, impedance, prices, stock position or default voltage is published for this rating. Request a signed technical schedule and approved drawing for the design offered.
| Topic | What to request or confirm |
|---|---|
| Electrical system | Exact offered rating, HV/LV voltage, phase, frequency, vector group and tapping arrangement. |
| Construction | Oil-immersed or dry-type design, insulation system, cooling, winding material, core and enclosure requirements. |
| Guaranteed performance | Losses and reference conditions, impedance, temperature limits and other agreed duty requirements. |
| Physical and interfaces | Approved dimensions, weight, fluid quantity where relevant, terminal arrangement, drawings and accessories. |
| Standards and acceptance | Applicable standards/editions, current BIS category/rating scope, agreed test/inspection documents. |
| Commercial scope | Quantity, availability/build-to-order terms, price/scope if quoted, delivery destination and confirmed dispatch timeline. |
Clarify the demand assumption
Ask how current operating demand, future allowances and any seasonal duty have been represented. If the brief is incomplete, request a list of missing inputs rather than accepting a standard-voltage or standard-loss assumption.
BIS scope and acceptance documents
OSTL acquired BIS licences in all five major transformer categories in 2020. Request the current licence documents and the applicable product/rating scope; this is not evidence of registration or approval by a utility or procurement platform. Routine tests per IS 1180 / IS 2026 are confirmed; the applicable standard and agreed test/document schedule must be checked for the offered design.
Send a clearer quotation request
- Required kVA/MVA, HV/LV voltage, phase, frequency and transformer construction.
- Application, load schedule/duty, site conditions, interfaces and relevant single-line diagram.
- Specified losses, impedance, temperature requirements and reference conditions, if defined by the project engineer.
- Quantity, delivery state/country, requested dispatch timeline and boundaries for freight, unloading and installation.
Online enquiry submission is not enabled. Contact the Kolkata office by WhatsApp +91 70035 13107, landline 033 4061 3200 or ostltd@hotmail.com.
Related project guidance
Choose your buyer context
See the site and operating questions for six customer segments.
↗TENDER BUYERSReview documents and eligibility
Separate BIS licence scope, technical compliance and buyer-specific vendor status.
↗ALL RATING INTERESTSReturn to the ratings guide
Compare the requested rating interests without assuming approved or stocked models.
↗Losses, winding and cooling: compare the agreed design
Where the applicable distribution-transformer standard specifies EE Level 1, 2 or 3, compare the relevant loss schedule and conditions for the offered rating. A higher applicable level generally sets tighter loss limits, but there is no universal conversion to a BEE star label. A general power duty may need a different loss specification. Obtain the current design-specific loss figures and applicability, not an unsupported efficiency promise.
Copper and aluminium winding options are confirmed. Material selection belongs within the complete electrical and thermal design; neither material by itself guarantees a particular loss, service life or saving. For an oil-filled enquiry, any ONAN requirement must be confirmed in the technical offer; it is not a dry-type cooling label.
Compare offered no-load losses over energised hours and load losses against the actual loading profile at agreed reference conditions. Use the buyer’s tariff and operating inputs; no customer savings or payback is invented here. The EE Level 1 versus 2 versus 3 guide explains the buying questions, and routine-testing guidance helps define acceptance documents.
Company credentials and the offered design
OSTL is ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 certified. Management-system certification, applicable BIS licence scope and purchaser-specific vendor eligibility are different checks. Use quality documentation and the procurement guide to prepare your questions.
Manufactured in Howrah. Enquiries through Kolkata.
OSTL’s manufacturing units are Unit 1, Howrah, West Bengal and Unit 2, Sankrail, Howrah. The corporate office is in Kolkata. Send the exact destination, specification and purchaser’s documents; no regional factory, local stock or universal buyer approval is implied.
For eastern India, use the West Bengal, Odisha, Jharkhand and Bihar pages. The Assam/North-East hub provides the enquiry route for Guwahati and wider NE destinations. Nepal, Bhutan and Bangladesh enquiries need the destination and buyer’s documentary requirements; delivery responsibilities, eligibility and commercial feasibility are agreed for that enquiry.
Contact WhatsApp +91 70035 13107, landline 033 4061 3200 or ostltd@hotmail.com. Use the RFQ checklist or discuss repair and after-sales requirements. Online forms do not create a sent enquiry; use the listed contact channels.