High Accuracy Current Transformer
High Accuracy Current Transformer

The high accuracy current transformer (CT), which has very low phase error (phase shift) and ratio error (current error) for measurement, usually has a good linearity core inside and a winding coil with a large number turns. Although 0.1 class CT is most popular, we can also provide current transformers of 0.05 class stipulated by the Chinese National Standard, which have phase error of 4′ when input is 5% of rated current, or even higher accuracy class. When DC offsets exist in the circuit, it’s better to choose our DC immune type current transformers, which are made of amorphous & nanocrystalline composite cores.

Plastic case with epoxy resin fixing is the most common type of encapsulation for our high accuracy CT, as it provide good protection for the coil. Insulation tape wrapped CT has the advantage of flexible for pilot production, as no plastic mold is required. Due to the sophisicated winding technology and high grade CT cores we made ourselves, we can provide compact size toroidal current transformers with excellent linear output, high sensitivity and low measurement error. For high precision industry electricity meter, our heavy current type CT with big through-hole is more suitable. We can also manufacture customized current transformer for clients’ special requirements.

High Accuracy Current Transformer


  • A variety of encapsulations, with or without DC immunity
  • Plastic box with epoxy resin vacuum potting, or double insulation wrapped
  • Through hole or busbar type, easy to fix and install
  • High linearity over the whole current range
  • Accuracy up to 0.05 class, low phase error
  • Meet the standard IEC 60044-3, JB/T10665
  • Customized current transformer available
  • Quick prototype development and sampling


  • Energy meters, smart meters
  • Electrical measuring instruments
  • Electrical protective devices
  • Current sensing modules
  • Electronic power meter
  • E-Mobility charging station
  • Current measuring
  • Ammeter
  • Unbalance current
  • Converter
  • Smart grid
  • Power supply
  • Instrument component
High Accuracy Current Transformer

Ratio Error and Phase Error

Ratio error (or 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 Class0.01In0.05In0.2InIn2In3InImax
0.05 8422222

Basic Parameters

Description High Accuracy Current Transformer
Structure Of WindingToroidal
PhaseSingle, Three
Input / Output10~600A/1~40mA
Max. Current10~600 A
Turns Ratio1:1000~25000
Burden (Rb)5~100 Ω
Accuracy Class0.05/0.1/0.2 Class
Core InsideDC Immune Dual Core
EncapsulationPlastic Case, Double Insulation
Busbar TypeNone
Mounting MethodScrew Fixing, Through Hole
ApplicationMeters, Instruments
Accept CustomizedYes


High Accuracy Current Transformer
High Accuracy Current Transformer
Model (Part Number)Input/OutputCurrent Rating(A)Turns RatioID(Hole) (mm)OD(Dist.) (mm)HT (mm)

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

High Accuracy Current Transformer