DC Immune Current Transformer

DC Immune Current Transformer
DC Immune Current Transformer
DC Immune Current Transformer

DC immune current transformers are used for circuit where there is direct current (DC), as well as sine alternating current (AC). We provide different encapsulations, from plastic casing to insulation tape wrapping. Due to its compact size, our toroidal current transformer usually have a through-hole big enough for the primary wires in most applications. DC immune current transformers with built-in or removable bus-bars (or busbars) can be easily fixed and assembled in meter cases. As high permeability nanocrystalline & amorphouse composite cores are used inside, Xianyu’s DC immune current transformers have very good linearity and very low phase shift.

Due to our design of sophisicated structure, we can provide a special type of DC immune current transformer, which can work properly under strong magnetic field. The winding coil inside is usually protected by a metal shield, thus, it can be applied to anti-tamper or anti-theft electricity meters. The built-in or removable busbar is an optional, which make it can be easliy assembled inside the case of energy meters or other electrical devices.

According to customers’ requirements, we can provide 0.05 or 0.1 class high-precision CTs or economical type CTs. If there’s very low DC in the circuit, normal AC miniature current transformer (without DC immunity) is another good choice. Due to our automatic winding machines, we can provide very competitive price under large-scale production.


  • A variety of encapsulations
  • Amorphouse & nanocrystalline compsite core inside
  • High linearity over the whole primary current range
  • Accuracy up to 0.05 or 0.1 class, low phase error
  • Meet the standard IEC 62053, JB/T10665


  • Electrical measuring instruments
  • Electrical protective devices
  • Current sensing modules


  • Meet the requirements for current transformer in the International Standard IEC185 and State Standard GB1208-97.
  • Suitable for single phase or three phase smart meter / watt-hour meter under 50/60 Hz industrial frequency electric current supply system.

Current error and phase error limits

Current error ±(%) in the following currents

Accuracy Class0.01In≥0.05In

Phase error(′) In the following currents. Note: When current is 0.2In~Imax, phase error(δe ) is the average of δmax and δmin; When current is i, the phase error of i is the difference of betweenδi and δe. (△δi=δi-δe)

Accuracy Class0.01In0.05In0.2In1In2In3InImax

Basic Parameters

  1. Insulation level: while put the secondary winding to ground and input 3kV voltage (RMS value) between primary and secondary winding for 1 minute, the leakage current is 1mA, no breakdown, no arcing or spark.
  2. Insulation resistance: under test voltage of 500VDC, the resistance value between primary and secondary winding of current transformer is ≥1000MΩ.
  3. Impact voltage test between primary winding and secondary winding: put 6kV current between primary winding and secondary winding for 10 times, there’s no breakdown, no arcing or spark.
  4. Overload requirements: put 30 times Imax current impact of half a cycle under rated load, the current transformer has no breakdown, no arcing or spark.
  5. Temperature increase: work continuously for 30 min, while ambient temperature is 40°C , primary current is 100% Imax, the temperature increase of current transformer’s case is less than 25°C .
  6. DC immune requirements: assemble the current transformer to the energy meter and input current of Imax/1.414, the tolerance of energy meter is less than 80% of what specified in the State Standard GB/T17215, i.e, 2.4%.
  7. Anti-magnetic Performance (optional): up to 300mT, special structure is required.

Technological requirements

  • Winding coil: the secondary winding coil is connected by black/red lead wires. The winding coils are fixed by epoxy resin, which should be mixed evenly, clear and no air bubble.
  • Outward appearance: the trade mark is clear and exact, no dirty material in the surface of current transformer. The gauge, length and position of lead wires should be follow the drawings.
  • The operating temperature of current transformer is -40~70°C , relative humidity in house is no more than 98%(at 25°C), and there’s no harmful gases and other harmful media in the air.
  • The entire transformer complies with UL94 V-2: After two 10s burn tests on the sample, the flame is extinguished within 60s and there is a burning off.

Packing and shipment

  • Packing: suitable paper boxes and cartons, plywood case is optional, strong enough for anticollision, antiseismic, antimoist, make sure the current transformers are protected well during shipment.
  • Inner and outer packaging marks: the product model, company name or trademark, date of manufacture or batch number and quantity are clearly indicated on the product.
  • Shipment: vibration, damping, impact, and rain or snow should be avoided during transportation.
  • Storage: under the condition of good packaging, store the current transformers on the shelves of the warehouse, the stacking height should not exceed 3 layers, and should avoid direct sunlight.
  • The storage place should be clean, the ambient temperature is 0~40°C, the relative humidity is not more than 80%, and the air should not contain harmful materials enough to cause corrosion of the current transformer.
  • The storage period is 2 years.