It improves both intrinsic errors in low current and errors occurred by external vibration and shock with strong durability and minimum tolerance on cutting cross section of core. Main applications are sub metering, power meter, PLC (Programmable Logic Controller), energy automation and etc.

Measuring Principle
The core placed around the current bus is provided with a secondary winding (N turn), in which electromagnetic induction caused by AC electricity to be detected (I) induces secondary current (I/N).
The core material of J&D AC CT is saturated by the over current owing to the conductor, the linearity of secondary output current will be distorted and or the error of phase angle will be caused.
Before using of J&D AC CT, please refer to data sheet.
J&D recommends the best solution from our AC CTs for your measuring application.


J&D DC CT provides non-contact detection of DC current.
The DC CT has two types of split-core & solid-core design with various utility, high reliability & cost-effective solution for precise current measurements.
The rated current range is 5A to 30,000A DC and secondary output value is 4V/5V/10V/333mV DC & 4-20mA, Instantaneous DC current.

Measuring Principle of Open-Loop Technology
Open-Loop Hall effect technology creates magnetic flux from the input primary current and its magnetic flux couples a proportional low voltage, which amplify before being output.

Measuring Principle of Closed-Loop Technology
The secondary current is generated by transferring the proportional voltage of the hall sensor originated by the magnetic flux from the primary current.
The feedback of the compensating current via the secondary winding closes the loop, where by this current is an exact representation of the primary current.


The J&D ACVT of compact voltage transformers are designed for applications where AC voltage signals must be transformed accurately into a lower AC voltage signal for micro-processor based circuits.
The ACVT of toroidal core, PCB voltage transformers are designed specifically for integrating products which require exceptionally accurate primary signal transformation when exposed to harsh environmental operating conditions.
ACVT model is designed and manufactured to meet the specific working conditions of the client’s specific application.


J&D DCVT offers a comprehensive range of accurate, reliable and galvanically isolated devices to measure DC voltage from 10V to 1500V across a range of technologies.

Measuring Principle of Closed-Loop Technology
When a primary Voltage (electrical potential) is applied to a primary wire, current flows through the wire and generates an electrostatic field. By mounting a Hall Sensor device within this electrostatic field, current is then induced into the sensor material of the device. This field then acts to induce a secondary current through the material of the Hall substrate material. This secondary current flows through an external resistor developing a secondary current into the secondary winding. This secondary current in turn produces a Voltage across the wire that is proportional to the current in the primary wire. By placing an amplifier within the Hall Effect transducer, we increase the current by amplifying the signal and converting it into a secondary current (Is). Therefore, the secondary current (Is) is exactly proportional to the primary current at any time. Output (Vm) is detected measured between the secondary current (Is) and an electrostatic potential developed across a measuring resistor (Rm).

Measuring Principle of Isolation Amplifier Technology
Our Isolation Amplifier Technology Voltage Sensors – iSaST EVS series begins with an internal resistor network. This network measures DC Voltage by directly contacting both the Positive High Voltage (+HT) and the Negative High Voltage (-HT). This Voltage signal is transmitted to the secondary side of the sensor through an insulated transformer that isolates the Primary High Voltage from the Secondary Low Voltage. The resulting signal is then converted through an amplifier into either a current or a Voltage signal. Therefore the circuit converts a primary Voltage into a secondary current or Voltage that is proportional to the input.



J&D AC RCT provide non-contact detection of AC current
The AC RCT is clamp type of air-core design with various utility, high reliability & Cost-effective solution for precise current measurements.
The rated current range is 100 to 50000A AC and secondary output value is 0-5/10 V or 4-20 mA DC and 1A/5A/333mVAC/Instantaneous AC voltage.

Rogowski coil is designed as open type and flexible sensor which can be installed to conductor easily. There are two terminals on end of coils and it is designed lead wire spiral coil from one end to other end which is returned through center of coil. To provide optimizing trans-mission, length will be chosen by rated current measuring range. Primary current induced proportional voltage from output of coil. This technology supplies very high sensing on primary current changing value.
Electronic integrated circuit need to be changed from voltage signal to output signal which is proportional versus input current. Rogowski coil is possible to accurate mechanism and linearity sensing by additional electronic component and integrator circuit


Rogowski coil feature
Rogowski coil has better frequency reaction than normal current transformer, due to low inductance and non-magnetic core. It also doesn’t use saturation core, so it is very accurate on high primary current. These kind of sensors are better to apply specially on power measuring system which has high current or fast changing current. To measure high current, normal current transformer is usually big and heavy. In contrast, Rogowski coil is small and light, so it is simply installed as advantage.

Rogowski coil technology
The AC CT have two types of sprit-core & solid-core design with various utility, high reliability & Cost-effective solution for precise current measurements. The rated current range is 5 to 2400A AC and secondary output value is 0-5/10 V or 4-20 mA DC & 0.1A/1A/5A/333mVAC/Instantaneous AC current



J&D AC JCP provide non-contact detection of AC current
The AC clamp on current probes are based on AC transformer principle with various utility, high reliability & Cost-effective solution for precise current measurements.
The rated current range is 5 to 1000A AC and secondary output values are 0-5/10 V or 4-20 mA DC & 0.1A1A/5A/333mVAC



J&D JCP provide non-contact detection of DC or AC current
To supply great property against electric jamming, it needs equivalent winding. This kind of performance is up to Rogowski manufacturing process. Other main points are positioning conductor in loop and consider opening clip from external conductor’s sensitivity.
Clamping clip makes sure of high symmetry on both end of coils and accurate mechanism overall. New technology in this field, as special hardware and electric property, possibly makes better accuracy and strong tolerance on conductor’s position. Conductor’s positioning error is not good as ±3% at 50/60Hz generally, but on the other hand, new Rogowski coil has error lower than ±0.5%.