ABB RXIIK 4 Microprocessor-Based Negative Sequence Overcurrent Relay

Description

Technical Specifications

Core Electrical Parameters

• Rated Current (Ir): Three standard variants: 1 A, 2 A, 5 A (selectable per model)
• Basic Current (Ib): (0.4 – 1.2) × Ir
• Effective Current Range: (0.03 – 5.0) × Ib
• Frequency: 50/60 Hz (standard); operational range 40 – 70 Hz
• Power Consumption (Per Phase): < 30 mVA (Ir=1A); < 60 mVA (Ir=2A); < 150 mVA (Ir=5A)
• Overload Capacity: Continuous: 4 A (Ir=1A), 8 A (Ir=2A), 20 A (Ir=5A); 1-second peak: 100 A (Ir=1A), 200 A (Ir=2A), 350 A (Ir=5A)
• Measurement Accuracy: ±1% (0 – 40% Ib); ±4% (40 – 300% Ib)
• Reset Ratio: Typical 0.5% equivalent negative sequence current
• Operate Time: < 150 ms; Reset Time: < 130 ms
• I-Alarm Setting: 3 – 30% of Ib, definite time 0 – 100 s
• I-Start Setting: 4 – 40% of Ib, inverse time (K=0–100 s) or definite time (0–100 min)
• I-Trip Time: Inverse time (t=K×(Ib/I-)²) or definite time (0–100 min); reset delay 0–5 s
• Thermal Memory: Settable cooling time 0 – 200 min; block time 10 – 90% of cooling time
• Output Contacts: 5 change-over (CO) contacts; rated 5 A at 250 V AC/DC; 15 A for 1 s
• Auxiliary Supply: ±24 V DC (via external RXTUG 22H DC-DC converter); RXTUG input: 24 – 250 V DC, ±20%
• Binary Inputs: Configurable for blocking/enabling, group selection, reset; 48–60 V or 110–220 V DC

Mechanical & Environmental

• Dimensions: 4U 12C (COMBIFLEX standard)
• Weight: Approx. 1.3 kg
• Mounting: COMBIFLEX panel, 19” rack, or DIN rail compatible
• Operating Temperature: -5 °C to +55 °C
• Storage Temperature: -20 °C to +70 °C
• Humidity: 5% – 95% RH (non-condensing)
• Vibration/Shock: Complies with IEC 60255-21-1, IEC 60255-21-2 (Class 1/2)
• EMC Immission: IEC 61000-4 series, Class 3/4; EMC Emission: EN 50081-2, Class A
• Insulation: Dielectric test 2.5 kV AC; impulse voltage 5 kV; insulation resistance > 100 MΩ at 500 V DC

Standards & Certifications

• Compliance: IEC 60255 series, ANSI C37.90
• Certifications: CE marked, suitable for global utility and industrial applications

Core Functions & Features

1. Negative Sequence Current Protection

• Precise Detection: Calculates and monitors negative sequence current (I-) to identify unbalanced conditions, phase breaks, and unsymmetrical faults.
• Multi-Level Protection: Implements three distinct protection stages: I-Alarm (warning), I-Start (pre-trip), and I-Trip (main protection).
• Thermal Memory: Integrates thermal memory with adjustable cooling time to mimic machine thermal withstand, preventing cumulative damage from repeated unbalance events.

2. Configurable Time-Delay Characteristics

• Definite Time (DT): Fixed, adjustable delay for I-Alarm and I-Trip, enabling precise coordination with system protection schemes.
• Inverse Time (IT): For I-Start and I-Trip, operating time decreases with the square of current deviation (t=K×(Ib/I-)²), providing faster response to severe unbalances.
• Wide Timing Range: Covers milliseconds to minutes, adapting to diverse generator/motor protection requirements.

3. Advanced HMI & Control Interface

• Front-Panel HMI: Menu-driven interface for setting configuration, status monitoring, and fault diagnostics; displays service values and trip information.
• Dual Setting Groups: Two independent parameter sets; active group selectable via HMI or binary input for flexible operation modes.
• LED Indicators: Green (In Service), yellow (I-Start), red (I-Trip) for clear visual status; flash codes for self-diagnosis.
• Binary I/O Flexibility: Configurable binary inputs for function blocking/enabling, reset, and group switching; five programmable output relays for alarms, trips, and status signals.

4. Modular Integration & Reliability

• COMBIFLEX Compatibility: Seamless integration into ABB’s modular protection assemblies (e.g., RAIIK 400) for scalable system design.
• Self-Supervision: Internal watchdog and power-up self-test; continuous monitoring of internal circuits for fault detection.
• High Noise Immunity: Galvanic isolation and robust EMC design ensure stable operation in electrically noisy environments.
• Test Capability: HMI-based output relay testing and binary input verification; compatible with COMBITEST test systems.

Application Scenarios

• Generator Protection: Prevents rotor overheating and insulation damage from unbalanced loads, phase faults, or loss of excitation; critical for cylindrical and salient-pole generators.
• Motor Protection: Safeguards induction and synchronous motors from negative sequence current-induced heating due to unbalanced supply voltages or phase interruptions.
• Transmission & Distribution: Detects unsymmetrical faults and broken conductors in overhead lines and cables; provides backup earth-fault protection in solidly earthed systems.
• Industrial Power Systems: Protects critical motor drives, pumps, and compressors in manufacturing, oil and gas, and petrochemical facilities.
• Power Plant Auxiliaries: Monitors and protects auxiliary motors and transformers in power generation plants against unbalanced operating conditions.
• Renewable Energy Integration: Safeguards wind turbine generators and solar inverter systems from grid-side unbalance events.

Unique Advantages

• Targeted Unbalance Protection: Specifically engineered for negative sequence current detection, offering superior performance over general overcurrent relays for unbalance faults.
• Thermal Modeling: Built-in thermal memory aligns protection with machine thermal capabilities, preventing unnecessary trips while ensuring adequate safeguarding.
• Flexible Configuration: Dual setting groups and wide parameter ranges adapt to various machine ratings and system coordination requirements.
• Easy Operation & Maintenance: Intuitive HMI, front-panel adjustments, and self-diagnosis reduce setup time and maintenance effort.
• System Compatibility: Fully integrates with ABB’s COMBIFLEX platform, enabling comprehensive, multi-function protection schemes.