Current transformers on copper busbars inside a panel

Representative photo. Your order is made to your specification by a verified seller. Photo: “Current transformer” by User:FearChild, Public domain.

Electrical and electronics · Transformers and switchgear

Current transformer manufacturer in Bangladesh

Need a current transformer manufacturer in Bangladesh? Send Roptan the ratio, secondary current, accuracy class, burden and mounting. We source metering and protection CTs from a verified maker, check every rating plate against your meters and relays, and deliver.

Verified sellers
Checked before it ships
Delivered by Roptan

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

Buying current transformers in Bangladesh

A current transformer, or CT, scales a large current down to a small standard value, usually 1 A or 5 A, for meters and protective relays, and isolates them from the main circuit. Panel builders, substation contractors, factories and utilities in Bangladesh buy them by the set. Meters on loads above about 200 A are usually fed through CTs.

A CT is small, but a wrong ratio, class or burden makes every reading or trip setting wrong. Roptan takes your schedule to a verified current transformer manufacturer in Bangladesh, has each CT quoted with its ratio, class, burden and the standard it is tested to, and checks the plates before delivery. Or post the schedule on our requirement board.

Kinds of current transformer

Ring or window CTs

A ring fitted over a busbar or an insulated cable, usually dry-insulated in a hard rubber or plastic case. Choose it for LT panels and switchboards.

Bar-type CTs

The primary passes through as a bar with its own terminals, and the body insulates it to earth. Oil-insulated designs with porcelain bushings serve the highest transmission voltages.

Split-core CTs

A hinged core that clips over a cable without disconnecting it. Choose it for temporary monitoring or retrofits; the gap adds error, so it is not normally used for billing.

Core-balance CTs

All three conductors of a cable pass through one ring, so only the unbalanced current reaches the secondary. Choose it to drive earth-fault protection.

Multi-ratio and multi-core CTs

Taps on the secondary give several ratios, and separate secondary windings serve metering and protection from one primary. Choose it when the load may grow.

How to specify a current transformer

Ratio and secondary: State primary and secondary current, for example 800/5 A. The secondary is normally 1 A or 5 A to match the meter or relay input.
Accuracy class: Ratio error at rated current: class 1 is 1 percent, class 0.5 is 0.5 percent or less. Phase error matters too when the CT feeds a power or energy meter.
Burden in VA: The load on the secondary. Typical IEC ratings run 1.5, 3, 5, 10, 15, 20, 30, 45 and 60 VA; add up the meter, relay and lead loads and stay below the rating.
Protection duty: A protection CT must stay accurate at fault currents well above normal. Ask for the knee-point voltage, which matters less for a metering CT.
Mounting and fit: Give the busbar or cable size for a ring CT, indoor or outdoor use, and the system voltage, since insulation changes with it.

Standards and papers for a current transformer

IEC 61869-2: Additional requirements for inductive CTs used with measuring instruments or protective devices. It replaced IEC 60044-1 and IEC 60044-6, so do not accept a report that cites only those, and ask the seller to confirm in writing that each CT is tested to it.
General requirements document: The 2007 general part was withdrawn in 2023 and its replacement is aimed at high-voltage equipment, so ask which document a low-voltage CT's test report cites.
IEC 62053-22: Accuracy classes 0.1 S, 0.2 S and 0.5 S for transformer-operated static meters. Choose the CT class to suit the billing meter it feeds.
Rating plate: Ratio, class, burden and the conditions behind the accuracy. Accuracy shifts with burden, temperature, the tap chosen and nearby fields.

What moves the price of a current transformer

Primary current and window size: a larger ratio or a bigger busbar opening usually means a bigger CT.
Cores and ratios: a second secondary winding or several taps adds copper, core and terminals.
Duty: a protection core sized for fault current and a stated knee point is a different design from a metering core.
Voltage and insulation: a dry ring for an LT busbar is a smaller job than an outdoor CT for a switchyard.
Construction: split-core and core-balance designs are built differently from a plain ring.

Lead times and delivery

No reliable time is published for CTs, so we give no figure. Common ratios for LT panels are often quicker than special ratios, multi-core units, protection cores to a stated knee point or outdoor high-voltage CTs. Imported cores or a large schedule add time. Roptan confirms the dates and any minimum order in the quote.

We deliver anywhere in Bangladesh, loose or fitted in the panel or switchgear they serve. A CT secondary must never be open while primary current flows: it can rise to a dangerous voltage. Ask the installer to keep the secondary shorted or the meter connected. You receive the seller's test record for each serial number and a VAT invoice (Mushak 6.3).

What we check for this order

Plate against the scheduleWe check ratio, class, burden and secondary current on each plate against your CT schedule before dispatch.
Class against the meterWe check that a CT feeding a billing meter carries a class to suit that meter, and that no split-core unit is used for billing.
Standard on the reportWe ask which standard and edition each test report cites, and query a report that cites only a withdrawn one.
Secondary terminalsWe check the terminals allow the secondary to be shorted, so the CT can be wired without an open circuit.

Questions buyers ask

Should we choose a 1 A or a 5 A secondary?

Match the input of the meter or relay you will connect. Then check the burden: long secondary leads and extra instruments add load, and a CT pushed past its rated burden loses accuracy. If the meter sits far from the CT, give the seller the lead length.

Can one CT feed both the meter and the protection relay?

Rarely well. A metering core is accurate in a narrow band around rated current; a protection core must stay accurate at fault currents. A CT with a separate secondary winding for each duty, or two CTs, solves it.

Does every CT meet IEC 61869-2?

Not by default. That part covers inductive CTs for meters and protection, but the general document it was written with is withdrawn and its replacement is aimed at high-voltage equipment. Ask the seller to state in writing which standard each CT is tested to.

What happens if a CT secondary is left open?

It can develop a dangerously high voltage, possibly several kilovolts, with arcing, and the CT can be damaged. Keep the secondary shorted or the burden connected whenever primary current may flow, and never exceed the primary rating, or the core saturates.

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.