Large power transformer standing in a high voltage substation

Representative photo. Your order is made to your specification by a verified seller. Photo: “High-voltage transformer 750 kV Трансформатор 750 кВ” by Novoklimov, CC0.

Electrical and electronics · Transformers and switchgear

Power transformer manufacturer in Bangladesh

Looking for a power transformer manufacturer in Bangladesh? Send Roptan the MVA at each cooling stage, voltages, vector group, tap changer and loss limits. We source from a verified maker, check the papers and test results and deliver to your substation.

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Delivered by Roptan

Prefer to deal with suppliers yourself? Post it on the requirement board

Buying power transformers in Bangladesh

A power transformer is the large unit at the heart of a substation or a big plant, stepping one network voltage to another. It is built to order, often with fans, oil pumps or heat exchangers, and an on-load tap changer. Buyers in Bangladesh include utilities, industrial parks and large factories with their own high-voltage supply.

Roptan takes your single-line diagram and specification to a verified power transformer manufacturer in Bangladesh and has every offer priced on the same ratings, taps, fittings and guaranteed losses. We collect the test reports and the drying and oil-filling records, check them against the order, then deliver. Or post the job on our requirement board.

Kinds of power transformer

Oil-immersed, natural cooling

Oil circulates by natural convection through external radiators. Choose it for a steady load and a yard with room for radiators, containment and fire walls.

Oil-immersed, forced cooling

Fans, oil pumps or oil-to-water heat exchangers add one or more cooling stages, each with its own MVA. Choose it where the load has peaks above the natural rating.

On-load tap changer units

The ratio changes while the unit carries load, often through a tap changer on the higher-voltage winding. Choose it where the incoming voltage swings or the loads are voltage-sensitive.

Dry-type units

Windings cast or coated in resin, with no oil, for indoor rooms. IEC 60076-11 covers them up to 72.5 kV; check the seller builds your rating and climate class.

Unitized substations

Transformer and switchgear line-up in one housing, used in industrial plants. Choose it when one seller should answer for both sides and the transformer.

How to specify a power transformer

Rating per cooling stage: Give the MVA at natural cooling and at each forced stage. A unit with fans or pumps usually carries a higher rating with them running than without.
Voltages and vector group: State both voltages and the IEC vector group, which must match the system and any unit it runs in parallel with.
Tap changer: On-load or off-circuit, the range and the step. An off-circuit changer needs the unit de-energised before every change.
Losses and efficiency method: Ask for guaranteed no-load and load losses, and name the efficiency method from IEC TS 60076-20, so offers compare.
Site temperature: State the hottest ambient and the room or yard type. Insulation life roughly halves for every 7 to 10 °C of extra operating temperature.
Protection and gauges: For conservator units, list the gas detector relay, oil level and temperature gauges, and any condition-monitoring facilities you want.

Standards and records for a power transformer

IEC 60076-1: General requirements for power transformers. The 2011 edition added requirements for liquid preservation systems, vacuum, pressure and leak tests on tanks, and condition-monitoring facilities.
IEC 60076-11: Dry-type power transformers up to 72.5 kV. The 2018 edition added climatic classes, a seismic class and handling for altitude.
IEC TS 60076-20: Energy efficiency, as a technical specification. It gives more than one way to define and evaluate an efficiency index, chosen by buyer and maker.
Drying and oil records: The record of drying by self-heating, vacuum or both before oil filling, and written confirmation that the oil is mineral oil free of PCB.

What moves the price of a power transformer

Cooling equipment: fans, oil pumps and heat exchangers add parts, wiring and control.
Tap changer: an on-load changer, which works while the unit carries load, usually adds cost over an off-circuit one.
Core material and losses: lower guaranteed losses, or an amorphous core, usually mean more material in a bigger unit.
Insulation system: a dry-type unit and an oil unit with fire walls and containment carry different installed costs.
Fittings and monitoring: gas relays, gauges and condition-monitoring facilities add to the bill of materials.

Lead times and delivery

Each unit is built to order, so we give no standard time. It usually grows with an on-load tap changer, forced cooling, imported parts, a long drying cycle on a large unit and tests you want to witness. A repeat of a design the seller has already built and tested is usually quicker. Roptan confirms the dates and the terms in the quote.

We deliver anywhere in Bangladesh, with route, crane and plinth agreed before dispatch. The seller installs and commissions the unit. In a substation, switchgear usually sits on both sides of the transformer, so plan both orders together. You receive the routine test reports, the drying and oil records, drawings, manuals and a VAT invoice (Mushak 6.3).

Buying power transformers for export

Liquid-filled units above 10,000 kVA fall under HS 850423; smaller liquid-filled units fall under HS 850422. Your customs broker confirms the line for your market. For an importer we quote FOB Chattogram on an agreed design, with the commercial invoice, packing list, certificate of origin, test reports and drawings.

What we check for this order

Plate against the orderWe check MVA per cooling stage, voltages, vector group and tap range on the plate against your specification.
Drying and filling recordsWe ask for the drying and oil-filling record, since moisture left in the windings invites breakdown under load.
Tank and oil papersWe check the tank vacuum, pressure and leak test results and the PCB-free oil statement before dispatch.
Fittings as quotedWe confirm the gas relay, gauges, fans and monitoring in the quote are fitted and wired.

Questions buyers ask

Do we need an on-load tap changer?

If your incoming voltage swings or your loads are voltage-sensitive, usually yes: it changes the ratio while the unit carries load. An off-circuit changer needs a shutdown for every change. On large units the tap changer is often on the higher-voltage winding, where the current is lower.

Which rating goes on the plate when the unit has fans?

Usually both: a unit with forced cooling carries a rating at natural cooling and a higher one with fans or pumps running. Size the natural rating for your normal load, and ask what the unit can carry if the fans stop.

Can a new unit run in parallel with our old one?

Only if the vector group and voltages match. Send the old unit's nameplate and test report with the enquiry, so the new design matches it.

Why ask for the drying records?

Power transformers are dried for a long period, by electrical self-heating, vacuum or both, before oil goes in. Water left in the insulation can cause corona and breakdown under load. The record shows the step was done on your unit, not just on the design.

How soon will I hear back about transformers and switchgear?

Within 48 hours of a complete requirement, with a price and a delivery date. A requirement is complete when it has the quantity, where it is needed and by when.

Who do I deal with?

With Roptan, when Roptan manages the order: we buy from the verified seller and deliver to you. With the supplier directly, when you post on the requirement board and choose a quote yourself.