Engineers have a mission to choose CTs immune to DC for power quality measurement of distributed power HV/LV transformers that are easily affected by DC.
J&D has provided a solution for meter engineers by releasing new current transformers, the ARCT-M Rogowski coil CTs and the IACT series split-core CTs.
1. ARCT-M Series, new split-core type DC immunity flexible Rogowski coil CT benefits:
1) Perfect Dual Air-Core Technology with precision instrumentation integrator applied by proprietary auto-zeroing technology: Proprietary auto-zeroing technology achieves very good linearity for a wide measurement range and better magnitude and phase response. There is also low offset voltage, near-zero offset and gain drift, excellent linearity, and exceptionally low-noise density that extends down to DC.
2) Its small profile and light weight allow it to be used on conductors in tight spaces where rigid CTs simply will not fit.
3) It performs 0.5S Class accuracy standard as revenue-grade, complying with IEC61869-2 and ANSI C57.13 standards even though the loop of the Rogowski coils are distorted in the tight space. Additionally, it meets IEC61000-4-30 Class A power quality meter certification standards.
4. Accuracy is not only a question of the position of the primary conductor in the loop but also of orthogonality, how the primary conductor corsses the loop, how it is located versus the Rogowski loop axis at 90º, 45º, 0º, or 180º(See Figure 1). Here, the ARCT-M loop is immune to this phenomenon and this has no impact on its accuracy thanks to the J&D patent.
2. IACT Series, new split-core type DC immunity CT benefits:
1) Advanced Offset Cancelling Technology(AOCT): J&D’s new hybrid technology removes DC offset with a combination of zero-drift operational amplifier IC and high permeability perm-alloy cores, giving enhanced precision to current output signals.
2) The IACT Series is a closed-loop compact and lightweight CT applied by AOCT technology which enables accurate AC current measurement even under DC current effects.
3) DC tolerance: IACT is immune to DC, so it can measure clean AC current.
4) It is possible to check if the clasp is locked with just a simple click sound and it can be installed easily.
5) Accuracy of 0.5S is satisfied and IEC61869-2 certification standards are satisfied.
6) IACT Series supports IEC61000-4-30 Class A power quality device certification standards.
7) Plug & Play: Provides RJ12 port for easy connection to the meter.
8) Output: 50mA/100mA
3. JAGUAR IoT(iMC785) Revenue-Grade Power Quality Meter
JAGUAR IoT meter is a revenue-grade power quality meter optimized for distributed resources that have already been, or will be, installed by using ARCT-M Series Rogowski coil CTs and JPS Series split-core CTs. Three current transformers are designed to be optimized for IEC61000-4-30 Class A & IEC61557-12 and for revenue-grade level, while quickly installing CTs in distributed power supply together with JAGUAR IoT meters.
J&D has cooperated with Iskraemeco in Slovenia to realize a specialized power quality meter for distributed resources with Iskraemeco developing the power quality measurement part of the JAGUAR IoT meter, and J&D developing the CTs for power quality measurement.
The current inputs of the device can be connected in different ways, depending on the selected CTs.
At this time, the ARCT-M Series Rogowski coil(333mV output) is equipped with a high-precision amplification integrator so it can be used for high precision calculation in a wide range from low to high current and shows accurate power quality readings.
In addition, the JPS Series split CT(100mA output) is designed with consideration of harmonic effects and can be used for precision rate calculation in a wide range from low to medium current and shows accurate power quality readings.
The JAGUAR IoT(iMC785) meter is a perfect solution for the power quality measurement of distributed energy resources.