About Current Transformer

Product description:

A current transformer (CT) is a transformer that is used to produce an alternating current (AC) in its secondary which is proportional to the AC current in its primary.

When a current is too high to measure directly or the voltage of the circuit is too high, a current transformer can be used to provide an isolated lower current in its secondary which is proportional to the current in the primary circuit. The induced secondary current is then suitable for measuring instruments or processing in electronic equipment.

Current transformers are used in electronic equipment and are widely used for metering and protective relays in the electrical power industry. The CT's can be used for measurement purpose, protection purpose or powering an electronic circuit.

CT is made of a soft magnetic laminated or toroidal core, a copper winding and encapsulation. Mainly used in end applications include Energy meters, safety devices, instrumentation, etc.

Nano cores with plastic case & with epoxy coating  CT terminal assembly for energy meter  Nano cores with epoxy coating
Sub assembly for energy meter for block terminal  Current transformer for energy meter or CT with magnet shield or 60A CT or 30A CT or 80A CT or 120A CT or 200A CT  Sub assembly for energy meter with braided wire

Applications:

  • Cores for CTs with Nano-crystalline material
  • Amorphous CT cores
  • Hybrid cores for dc immune CTs
  • Wound CTs as per customer specification
  • Nano/Amorphous cores for Reactors
  • Solar investors
  • High accuracy CTs
  • High efficiency low loss transformers

PML supply wound ribbon cores & CTs in custom casings in material Nano-crystalline and Amorphous. PML also provide CTs with metal shields for magnetic shielding.

Nano crystalline magnetic alloys

Nano crystalline alloys feature is the super fine crystalline structure. The crystal size (nano particles) in these alloys ranges from 1 to 10 NM

Properties of nano alloy depend on the composition, size and number of nano crystals, as well as their relations with the amorphous phase. It has high saturation induction (1.2 T), good thermal stability over a wide temperature range from -60 to 180 °C, a nano crystalline material has excellent characteristics at high frequencies. The alloy is much more economical

Precise annealing allows to adjust the desired properties of the material in a wide range, the shape of the hysteresis loop, the level of permeability, squareness ratio, the specific loss can be varied as per the application requirement.

Amorphous soft magnetic alloys

The common method of producing amorphous alloys in the the form of ribbons is cooling, when a jet of molten metal is sent to the surface of a rapidly rotating cylinder made of a material with high thermal conductivity at a certain speed

The feature of the soft magnetic amorphous alloys in comparison with the crystalline is high content of nonmagnetic elements such as boron, silicon, carbon, phosphorus, and so on which are necessary to maintain the amorphous structure.These elements increase the electrical resistance, increase the hardness, strength and corrosion resistance of amorphous alloys.

Advantages:

Regardless of the application, the use of amorphous and nano crystalline cores when designing inductive components typically provides the following advantages:

  • Lesser weight
  • Lesser losses on the coil due to reduction in number of turns
  • Extended temperature range from -60 to 125 °C
  • More stability of properties and durability
  • High accuracy for measuring devices

Material Properties

Material Properties
Magnetic
Properties
Properties Nano
Crystalline
Amorphous
Bs (Tesla) 1.25 1.56
Br (Tesla) 0.6 ~ 0.7 0.8
μ i(min) at 50Hz and Hmax=0.8mA/cm >80,000 >1100(at 1000Hz)
μ max(min) at 50 Hz >2,00,000 -
Hc(max) (A/m) 0.8 4
Core loss(max)(W/kg) at 50Hz 0.5 0.5
Chemical
Composition
(Atomic %)
%Fe Balance % Balance %
%Cu 1% 0%
%Nb 3% 0%
%Si 13.5% to 15.5% 13.5% to 15.5%
%B 6% to 8% 6% to 8%
Physical
Properties
Curie Temp(°C) 560 410
Density (gmslcc) 7.2 7.2
Resistivity(μ.Ω.cm) 130 130
Working (max allowed temperature in
°C)
130 130