ABB RXPPK 2H Microprocessor-Based Reverse Power

Description

Technical Specifications

Core Electrical Parameters

• Rated Voltage (Ur): 120 V AC
• Rated Current (Ir): Two standard variants: 1 A or 5 A
• Scale Constant (Is):
  • 1 A variant: 0.1, 0.4, 0.7, 1.0 A
  • 5 A variant: 0.5, 2.0, 3.5, 5.0 A
• Operating Frequency: 50/60 Hz; operational range 45 – 66 Hz
• Operate Setting Range (Iα): 0.3% – 15% of rated current (Ir)
• Compensation Angle (β): ±3° (for system angle error correction)
• Time Delay Stages:
  • Trip t1 (Short Delay): 0 – 4 s (definite time, adjustable)
  • Trip t2 (Long Delay): 0 – 30 s (definite time, adjustable)
  • Hold Time (th) for t2: 0 s or 5 s (prevents reset during power swings)
• Effective Voltage Range: (0.4 – 2.5) × Ur
• Effective Current Range: (0.003 – 1.70) × Ir
• Measurement Accuracy: <2% for current >0.02 × Ir; <5% for current <0.02 × Ir
• Phase Angle Consistency: <0.5°
• Reset Ratio: Typical 80%
• Operate/Reset Time: Typical 100 ms (at 2 × set operate value)
• Overload Capacity:
  • Voltage: 250 V continuous; 300 V for 10 s
  • Current (1 A): 4 A continuous; 100 A for 1 s
  • Current (5 A): 20 A continuous; 350 A for 1 s
• Output Contacts: 3 × Change-Over (CO) dry contacts; Rated: 5 A at 250 V AC/DC; 15 A for 1 s
• Auxiliary Power Supply: ±24 V DC (via external RXTUG 22H DC-DC converter; input: 24 – 250 V DC, ±20%)
• Binary Inputs: 2 × galvanically isolated inputs (48–60 V or 110–220 V DC); for remote reset and Trip t1 block/enable

Mechanical & Environmental Specifications

• Dimensions: 4U 6C (COMBIFLEX standard; 177.8 mm × 42 mm × 200 mm)
• Weight: Approx. 0.7 kg (without RXTUG 22H)
• Mounting: COMBIFLEX panel, 19” rack, DIN rail, or apparatus bar compatible
• Operating Temperature: -5 °C to +55 °C
• Storage Temperature: -20 °C to +70 °C
• Humidity: 5% – 95% RH (non-condensing)
• Vibration/Shock Resistance: Complies with IEC 60255-21-1 (Class 2) and IEC 60255-21-2 (Class 1)
• EMC Compliance: IEC 61000-4 series (Class 3/4 immunity); EN 50081-2 (Class A emission)
• 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 power generation applications

Core Functions & Features

1. Dual-Mode Power Direction Protection

• Reverse Power Detection (Iα>): Operates when active current flows into the generator (I × cos(φ−β−180°) ≥ set Iα), indicating motoring condition.
• Low Forward Power Detection (Iα<): Operates when forward active power drops below the set threshold (I × cos(φ−β) ≤ set Iα), preventing operation at minimal power output.
• High Sensitivity: Detects power levels as low as 0.3% of rated current, critical for large turbo-generators with minimal loss characteristics.

2. Configurable Time-Delay & Coordination

• Two Independent Definite Time Stages: t1 (0–4 s) for fast tripping; t2 (0–30 s) for delayed, secure tripping to avoid nuisance operations.
• Hold Function for t2: 5 s hold timer ensures operation during power swings, preventing premature reset.
• System Angle Compensation: ±3° β adjustment corrects for voltage/current transformer phase errors, ensuring accurate directional measurement.

3. Advanced Blocking & Safety Functions

• Undervoltage Block: Blocks all functions if voltage <40 V (0.4 × Ur), preventing false operation during system voltage collapse.
• Undercurrent Block: Blocks functions if current <0.25% of Ir, avoiding operation at negligible current levels.
• Remote Control: Binary input for remote blocking/enabling of Trip t1 and remote reset of trip indicators.

4. User Interface & Self-Supervision

• LED Indicators: Green (In Service), Yellow (Start Iα), Red (Trip t1), Red (Trip t2) for clear visual status.
• Front-Panel Configuration: Potentiometers and 6-pole DIP switch for on-line setting of Iα, β, t1, t2, and function modes without disassembly.
• Self-Diagnosis: Internal watchdog and power-up self-test; LED flash codes for RAM, ROM, and A/D converter fault detection.
• Test Capability: Compatible with COMBITEST RTXP 18 test switch for safe secondary injection testing.

5. Modular Integration & Reliability

• COMBIFLEX Compatibility: Seamless integration into ABB’s modular protection assemblies (RAPPK) for scalable system design.
• Galvanic Isolation: Full isolation between input, output, and auxiliary circuits for noise immunity and personnel safety.
• Low Power Consumption: Max. 6.5 W (with RXTUG 22H), minimizing auxiliary power requirements.

Application Scenarios

• Steam Turbine Generator Protection: Prevents blade overheating and damage when steam flow is lost, causing motoring.
• Hydro Turbine Protection: Safeguards Kaplan/bulb turbines from axial bearing pressure and mechanical stress during reverse power conditions.
• Gas Turbine & Diesel Engine Protection: Avoids lubrication failure and mechanical damage in prime movers during motoring.
• Generator Decommissioning Interlock: Uses t1 delay to trip field and breaker during controlled shutdown, preventing overspeed.
• Low Forward Power Supervision: Ensures generators operate above minimum power thresholds, avoiding inefficient or damaging low-load operation.
• Industrial Cogeneration Plants: Protects combined heat and power (CHP) units from reverse power damage during grid disturbances.
• Power Station Auxiliaries: Monitors and protects auxiliary generators and motors in power plants against unplanned motoring.

Unique Advantages

• Ultra-High Sensitivity: Detects reverse power as low as 0.3% Ir, unmatched by standard overcurrent relays for large turbo-generators.
• Dual-Mode Flexibility: Combines reverse power and low forward power protection in one unit, reducing panel space and wiring complexity.
• Harmonic & Noise Immunity: Advanced filtering ensures stable operation in polluted power systems with high harmonic content.
• Precise Coordination: Wide time-delay range and hold function enable seamless integration with overall power system protection schemes.
• Easy Maintenance: Front-panel adjustments, self-diagnosis, and test switch compatibility reduce downtime and maintenance effort.