J&D Rogowski coil CTs are optimal for power quality and revenue-grade metering


Engineers previously had to decide if the benefits of using flexible Rogowski coil CTs (current transformers) outweighed the losses in accuracy.

Now, they don’t have to, thanks to the new RGD series of Rogowski Coil, by J&D. Rogowski coil CTs have always had certain advantages, including:

  • Flexibility – they fit into tight spaces and around odd shapes.
  • Ease of installation – they can be installed under load, without the need to interrupt power.

However, previously Rogowski coil CTs were avoided when meter engineers designed for the accuracy standard IEC 61869-2 Class 0.5S and harmonics measuring standard IEC 61000-4-30 Class A due to their limitations. We are pleased to announce a new Rogowski coil that brings together the best of both worlds. With J&D’s perfect-air two-loop shielding technology, meter manufacturers can leverage all the benefits of flexible Rogowski coils while exceeding IEC 61869-2 Class 0.5S and IEC 61000-4-30 Class A. Wide magnetic shielding technology solves the issue of increased errors due to the magnetic field influence from each phase in a 3-phase system.

Figure 1 shows a leading Rogowski coil manufacturer that only meets the IEC 61869-2 Class 0.5 accuracy standard. Note that J&D achieved IEC 61869-2 Class 0.5S accuracy. Perfect-air, two-loop shielding technology reduces harmonics on the secondary output.

Figure 1: Comparing the accuracy class through graphs.
Figure 2: A comparison of the secondary output

Figure 2 shows that the noise caused by an external magnetic field has been significantly reduced on the sine wave of the secondary output. Figure 3 shows that perfect-air two-loop shielding also solves increased errors created when the loop of the flexible Rogowski coil CT deforms in narrow spaces. Deformed loops are common when installing Rogowski coils in tight or uneven spaces.

Figure 3: A comparison of accuracy after the loop is

The new J&D RGD series, which leverages perfect-air two-loop shielding technology, is the best solution to traditional Rogowski coil problems, as evidenced by the data in Figures 1, 2 and 3.

Figure 4: Manufacturers of Power Quality meters and high-quality Revenue-Grade meters.

Figure 4 shows the manufacturers of power quality meters and Revenue- Grade meters with J&D’s new RGD series applied.

These manufacturers include:

• eGauge Systems: The J&D RGD series Rogowski coils have a built-in feature called CTid. CTid, when used with eGauge meters (IEC 62053-22 0.5S) self-identifies the CT to the meter. This feature is available with the eGauge Core (which can handle up to 15 J&D RGD Rogowski coils) or the eGauge Pro (which can monitor up to 30 J&D RGD Rogowski coils). It is easy to utilise CTid features for each rated current used for energy monitoring.

• Continental Control Systems: The J&D RGD series Rogowski coils can be used with the WND Wide Range Modbus revenue-grade meter (IEC 62053-22 0.5S), with a 40mA or 333mV integrator. This solution is optimal for solar power energy metering.

• Power Standard Lab: Whereas not possible with other Rogowski coil options, the PQube 3e has met the IEC 62053-22 0.5S and IEC 61000-4-30 Class A standards using J&D’s RGD series.

The PQube 3e is the optimal solution for power quality monitoring. J&D’s new RGD series is an innovative technology creating the best solution for high-quality revenue-grade and power quality meters.

This article was originally published in Smart Energy International 5-2019. Read the full digimag here or subscribe to receive a print copy here.