A miniature current transformer(CT) is an important component for energy meters, power measuring devices, and other instruments. Usually, there’s at least one coil in a CT. The busbar, which the primary current comes through, can be fixed properly in the through-hole of the coil. Then, we have a busbar built-in current transformer. The busbar type current transformer can be directly installed in a device or instrument, while the through-hole type current transformer require a primary wire or connect bar come through its hole.

Miniature current transformer plays an important role in the circuit of an electric energy meter (or electricity meter), the device that measures the amount of electric energy consumed. As a current transducer, the current transformer provides safe galvanic separation between the primary current and winding coils. Xianyu provides a wide range of miniature current transformers suitable for energy measuring. We provide DC immune current transformers with amorphous & nanocrystalline composite cores inside, or normal miniature current transformers without DC tolerance, which have a more favorable price.


  1. Fe-based Nanocrystalline / Amorphous / Silicon Steel Cores Inside
  2. Electric energy measurement error introduced by DC Immnue CT is less than 3%
  3. Accuracy 0.02/0.05/0.1/0.2 Class, low phase error, high linearity over the whole current range, safe galvanic separation, high dynamic range
  4. Variety kinds of encapsulation, busbar or through-hole type, easy to fix and install
  5. We produce the critical parts ourselves, accept ODM / OEM, and provide free samples
  6. Meet the requirements of standard IEC 62052, IEC 62053, IEC 62059, GB17201, JB/T10665
  7. Used for electrical measuring instruments, electrical protective devices, current sensing modules, and so on

Typical Products.


Model ( Part Number )Input/OutputCurrent Rating (A)Turns RatioID(Mounting Hole) (mm)OD(Dist.) (mm)Height (mm)
MC30-10A5(30)A/5mA301:1000Φ4.9Φ17 (12.7)9.5
MC40-20A5(40)A/2.5mA401:2000Φ7Φ23.5 (18.5/15*10)13
DMB60-25A5(60)A/2mA601:25002-Φ5.2Φ33 (15)31
DPB60-25A5(60)A/2mA601:25002-Φ5.3Φ30.6 (16)18.3
MC80-20A10(80)A/5mA801:2000Φ8Φ31 (20*9)19
DI80-25A10(80)A/4mA801:25002-Φ6.2Φ33.5 (21)21.8
DSB80-25A10(80)A/4mA801:25002-Φ6.4Φ32 (22.5)22
MPB80-25A5(80)A/2mA801:25002-Φ6.532 (18)30
MSB100-10A5(100)A/5mA1001:10002-Φ7.4Φ28 (32.5)18
MSB100-25A5(100)A/2mA1001:25002-Φ5.2Φ26 (16)14.5

The above data are selected from some popular models we produce. Please contact us for detail datasheet. We can also design some special current transformers to meet customers’ requirements.

Manufacturing Process

Magnetic Core Inspection

Usually, the production process of a current transformer starts from a magnetic core. There’s a few different kinds for magnetic cores for variety of current transformers. The amorphous & nanocrystalline dual cores are used for DC immune current transformers, the nanocrystalline single cores are used for normal miniature current transformers, the zero phase current transformers may need silicon steel cores or nanocrystalline cores, the split current transformers usually need ferrite cores.

These magnetic core should be tested before coil winding. The induction value must be within the upper and lower limitation.

Coil Winding

When we get the qualified cores, we’ll make coils by automatic winding machines. The cores should be fixed properly and the enamel wire length and gauge should be considered in advance.

Coil Inspection

Every winding coil should be inspected before further processing. If the coil is a defect one, we must remove it from the production lines. Otherwise, extra material and labor will be wasted.

Coil Assembly

As the secondary, the coils should be connected to lead wires, as the enamel wires are not strong enough. For PCB type current transformers, the pins replace the lead wires, and therefore, the enamel wires should be connected these pins.

After the coil is ready, for different types of CT, there’s different process. For plastic case CT, we put the coil inside a plastic case. Then, fill the case with liquid epoxy resin which will become harden within one or two days. For insulation tape wound coils, we’ll wrap the coil by hand.


For each piece of CT, we should test the current error and phase shift. The test result should meet the State Standard or the customers’ requirements. According to GB/T 10665 of China, the required current error and phase shift for different accuracy class of miniature current transformer is as below. Our high accuracy current transformers usually have accuracy class of 0.1 or 0.05, and the cost will be higher than normal type.

Current Error +/-(%)
Accuracy Class0.01In>=0.05In
Phase Shift +/-(‘)
Accuracy Class0.01In0.05In0.2InIn2In3InImax

Packing & Shipment

After inspection, qualified products will be placed to small paper boxes and then put these boxes inside cartons. For some occasions, we’ll use plywood case or pallet to protect these cartons from damaging during long transshipment.


Q: I’m interested in your current transformers. Can we start from a small order?

A: Yes, we accept trail orders of small quantity. We fully understand the risk to shift to a new supplier.

Q: Can you deliver some samples for test?

A: No problem. We always provide free samples to our customers, but the express fee will be paid by receivers.

Q: Why cannot find the current transformers I wanted in your website?

A: Considering the loading time, we only presented a few popular current transformers in our webpages. Please tell us the parameters you wanted, and we’ll select some suitable ones from our products database for you. We can also design some new ones according to your drawing and specification.

Q: What is your terms of payment?

A: We accept T/T, L/C. For trial orders, we also accept Western Union, Paypal.

Q: Do you test each piece of the current transformers before delivery?

A: Yes, we have 100% test of critical parameters, such as current error, truns ratio error, phase shift error and so on.