Description

The ABB 1MRK002247-AH​ is an internal Current / Voltage Transformer (CT/VT) analog input conditioning module—also referred to as a measurement or analog front-end board—designed for installation inside ABB REx670 series numerical protection and control IEDs (REG670, REL670, RET670, REC670). It receives secondary currents from protective CT cores (typically 1 A or 5 A) and secondary voltages from VT/PT secondaries (typically 100 V / 110 V line-to-line or 57.7 V phase-to-neutral), scales and filters them, and presents precision analog signals to the relay’s main A/D conversion stage. The 1MRK002247-AH​ typically supports six CT inputs and two to four VT inputs depending on the relay variant and is a fundamental component for accurate phasor measurement, metering, fault recording, and protection-element operation.h2 Application ScenariosImagine a 220 kV transmission substation where an ABB REG670 distance-protection relay begins reporting slightly skewed apparent-power values and occasional “Metering Channel Error” self-test warnings after years of service. Ratio checks confirm the primary CT/VT secondaries are correct—the issue is traced to aging burden resistors and filter capacitors on the internal analog-input board. Rather than replace the entire IED (which would necessitate reloading the SCL configuration, re-verifying protection settings, and scheduling a protection outage), the protection engineer sources a version-matched ABB 1MRK002247-AH (AH revision). With the DC and VT supplies isolated, the relay lid is opened, the old PCB is disconnected from its backplane header and standoffs, and the new 1MRK002247-AH​ is seated. On power-up the relay passes all self-tests; magnitude and phase-angle accuracy return to specification with no re-calibration required. This scenario illustrates the 1MRK002247-AH‘s vital function: it is the precision gateway between the switchyard analog world and the digital protection algorithm, and a targeted board swap restores measurement fidelity without disturbing commissioned logic.h2

Parameter

*Note: Exact CT/VT channel count, 1 A / 5 A selection method, and terminal block type must be verified against the removed board photo and host device nameplate before ordering.h2 Technical Principles and Innovative ValuesThe 1MRK002247-AH​ is a precision analog front-end—not a standalone meter—engineered to stringent protection-class accuracy requirements.

• Innovation Point 1 – Low-Burden Wide-Range CT Inputs: The 1MRK002247-AH​ uses precision shunt resistors and active buffering to present a very low burden (≤ 0.1–0.2 VA @ 1 A / 5 A) to the CT secondary. This minimizes the risk of CT saturation during high-fault currents and preserves waveform fidelity for sensitive elements such as sensitive directional comparison and harmonic restraint functions.
• Innovation Point 2 – Anti-Aliasing Filtering with Phase-Shift Compensation: Each CT and VT channel incorporates a 2nd-order analog low-pass filter (fc ≈ 1.5–2 kHz) to prevent aliasing before A/D sampling, followed by digital phase-angle compensation in the relay firmware. This dual-stage approach yields Class 0.5 / Class 1 metering accuracy and ≤ ±0.5° phase error across the rated frequency band—critical for distance protection reach accuracy.
• Innovation Point 3 – Transparent Swap with Auto-Calibration Recall: All ratio, vector-group, and phasor-correction coefficients are stored in the relay CPU’s non-volatile memory—not on the 1MRK002247-AH. On replacement, the relay performs an automatic self-calibration / sanity check at power-up and applies the saved correction factors, so measurement accuracy is restored without manual recalibration or re-entry of CT/VT ratios.