Product Core Brief
- Model: RXPPK 2H, Full OEM part number: 1MRK001615-AA
- Brand: ABB Hitachi Energy
- Series: Classic COMBIFLEX modular secondary protection relay system
- Core Function: Microprocessor-controlled two-stage directional reverse power relay, specially designed for synchronous generators (thermal, hydro, gas turbine units). It detects reverse power flow (power fed back from grid to generator) and low forward power operating conditions to prevent prime mover damage (turbine runaway, steam turbine blade erosion, water turbine reverse rotation). The AA variant is the universal standard version supporting both 1A and 5A secondary CT ratings, with two independent definite time delay stages for graded anti-reverse-power protection and distributed generation anti-islanding blocking.
- Product Type: COMBIFLEX plug-in modular reverse power protection relay
- Key Specs: Two independent definite time protection stages; adjustable operate current range 0.3%–15% of rated CT secondary current; two time delay tiers (t1: 0–4 s, t2: 0–30 s); built-in standby hold timer for stage 2; software selectable 1A / 5A CT input; wide universal AC/DC auxiliary supply; multiple independent Form-C alarm/trip relay contacts; standard COMBIFLEX 19-inch rack withdrawable drawer structure
- Note: Still active production for conventional COMBIFLEX generator relay panel renovation; factory-sealed new relays and fully bench-load-tested surplus units are widely supplied for thermal power plants, hydropower stations, combined cycle power plants and industrial self-generation unit maintenance retrofits.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Full OEM Article Code | RXPPK 2H 1MRK001615-AA |
| Measuring Principle | Directional reverse power detection via combined CT & VT secondary signals |
| Rated CT Secondary Compatibility | Software switchable 1 A / 5 A secondary current |
| Operate Current Setting Range | 0.3 % ~ 15 % of nominal CT rated current, continuous fine adjustment |
| Protection Stage Layout | Two fully independent definite time delay stages (Stage 1 t1, Stage 2 t2) |
| Stage 1 Time Delay (t1) | Adjustable range: 0 s ~ 4 s, fast-stage warning/alarm |
| Stage 2 Time Delay (t2) | Adjustable range: 0 s ~ 30 s, slow-stage generator trip |
| Standby Hold Timer (Stage 2) | Configurable hold time 0 s / 5 s; timer will not reset immediately after reverse power disappears during hold period |
| Auxiliary Control Supply | Wide-range universal AC/DC power supply (90–250 V AC/DC) for standard substation cabinet control power |
| Output Contacts | Multiple independent Form-C silver-plated changeover relay contacts: stage 1 light alarm, stage 2 generator main trip signal to breaker control circuit & DCS/SCADA |
| Front Panel Status Indicators | Green RUN (normal operation), yellow START (reverse power detected), Red STAGE1 ALARM, Red STAGE2 TRIP LED indicators |
| Mechanical Mounting | Standard COMBIFLEX plug-in drawer for 19-inch relay rack installation |
| Continuous Operating Ambient Temp | -10 °C ~ +55 °C inside control cabinet; storage temperature: -40 °C ~ +70 °C |
| Humidity Class | <95% RH non-condensing, indoor substation control room rated |
| PCB Treatment | Anti-corrosion conformal coating for long-term stable operation |
| Compliance Standards | IEC 60255 protection relay standard, KEMA fully type-tested, CE & RoHS certified |
Product Introduction
The RXPPK 2H 1MRK001615-AA is a dedicated dual-stage reverse power protection relay within ABB’s COMBIFLEX modular relay portfolio, serving as mandatory backup protection for all grid-connected synchronous generator bays.
Core Functional Advantages
- Two-Tier Hierarchical Reverse Power Protection LogicStage 1 (short delay 0–4 s) acts as a light alarm function: it detects minor short-duration reverse power flow and sends warning signals to DCS without tripping the generator unit, allowing operators to adjust turbine valve load in time. Stage 2 (long delay 0–30 s) executes critical generator trip when sustained heavy reverse power occurs, cutting off the generator from the grid to protect prime mover equipment from severe mechanical damage. The built-in hold timer prevents false stage 2 reset caused by transient power fluctuation.
- Universal 1A/5A CT Compatibility (AA Standard Variant)The AA hardware version supports software switching between 1A and 5A CT secondary ratings without internal circuit modification, compatible with all small, medium and large capacity generator CT configurations, simplifying spare parts inventory management for power plant maintenance teams.
- Core Anti-Damage Protection For Generator Prime MoversReverse power happens when the generator loses driving torque (steam cutoff, water flow interruption, gas fuel loss), turning the generator into a synchronous motor and drawing power from the grid. Long-duration reverse power will lead to turbine blade abrasion, runner reverse rotation and serious mechanical failure. RXPPK 2H accurately identifies this abnormal operating condition via directional power vector calculation and implements graded alarm-trip logic.
- Additional Distributed Generation Anti-Islanding ApplicationIt can also be deployed for PV/wind distributed generation grid interconnection bays, detecting low forward power loss-of-mains conditions to trigger DG disconnection and avoid off-grid islanding hazards.
The plug-in COMBIFLEX drawer design enables rapid unit replacement without full cabinet secondary circuit rewiring, fully compatible with COMBIFLEX system accessories including RXDS 4 four-circuit CT/VT test disconnect switches, RXIDK overcurrent relays and RXEDK voltage relays, forming a complete generator secondary protection system solution.
QA & Testing SOP (Transparency Building)
- Incoming Visual Inspection: Cross-check full part number RXPPK 2H 1MRK001615-AA and serial number against ABB power system spare parts database to reject counterfeit mismatched relays; inspect front current/time adjustment potentiometers, internal directional measuring PCB, silver-plated relay output contacts and conformal coating for burn marks, salt corrosion or mechanical deformation; record serial numbers and production batches for full traceability.
- Full Performance Bench Linkage Test: Mount RXPPK2H on standard COMBIFLEX 19-inch test rack, supply matched universal AC/DC auxiliary power, input synchronized CT current and VT voltage signals to simulate forward power and reverse power flow; run 24-hour cyclic testing covering stage 1 short delay alarm, stage 2 long delay trip, standby hold timer function, 1A/5A CT mode switching and directional power vector calculation accuracy, verify no false operation under normal forward power fluctuation simulation.
- Electrical Insulation Test: Use insulation resistance tester to confirm isolation resistance ≥ 10 MΩ between CT/VT measuring circuits, auxiliary power and relay output contact circuits; test chassis ground continuity resistance below 0.5 Ω.
- Setting Record Backup: Photograph front panel current/time adjustment dial definitions and rear COMBIFLEX plug terminal CT/VT/power wiring pinout for field commissioning reference.
- Final QC Packaging: Wipe relay housing with anti-static microfiber cloth, cover all front adjustment terminals and rear plug connectors with insulating dust caps, place the unit into independent ESD shielding bag, attach unified printed QC test tag with technician ID and full 24-hour cyclic test runtime timestamp, then pack into foam shockproof carton for long-distance power plant transportation.
Installation Pitfalls & 4-Step Replacement Guide
Common Installation Hazards
❗ CT Open-Circuit Safety Risk: Before extracting the RXPPK 2H relay, fully activate the CT shorting links of the matched RXDS4 test switch to avoid lethal high open-circuit voltage on CT secondary loops during disassembly.❗ VT Polarity & CT Phase Sequence Mismatch: Incorrect CT/VT wiring will reverse power vector calculation, leading to permanent protection misoperation (no trip during actual reverse power or constant false alarm under normal forward load); strictly follow original photographed wiring sequence.❗ CT Rating Switch Setting Error: Fail to toggle internal selector to match on-site 1A or 5A CT will cause power measurement calculation deviation and protection threshold drift.❗ Auxiliary Power Polarity Reversal: Reverse positive/negative DC auxiliary power wiring will instantly damage internal directional measuring microprocessor circuits.❗ ESD PCB Damage Risk: Wear certified anti-static wrist strap during all disassembly and installation work; bare hand contact with internal measuring chips permanently impairs directional power calculation accuracy.
4-Step Plug-in Relay Replacement Guide
- Pre-install Preparation: Lock out and tag out the generator cabinet auxiliary power supply, engage CT shorting links via RXDS4 test switch, wear ESD wrist strap, photograph rear COMBIFLEX plug terminal wiring of CT measuring circuits, VT voltage circuits, auxiliary power and stage1/stage2 alarm/trip output contacts.
- Removal Operation: Unlatch the COMBIFLEX drawer locking handle, pull the old RXPPK 2H relay fully out of the fixed rack base socket (the base wiring remains permanently hardwired to cabinet secondary circuits). Retain the base socket if undamaged; only replace the base if terminals show burning or corrosion.
- Installation & Wiring: Insert the new RXPPK 2H 1MRK001615-AA module into the original COMBIFLEX base socket and push fully to lock the drawer handle; adjust internal CT rating selector switch to match on-site 1A/5A CT specification; re-terminate all CT, VT, power and control wiring strictly following photographed terminal sequence.
- Power-on Commissioning Test: Restore cabinet auxiliary power, input rated forward power CT/VT signals to verify no alarm/trip output; simulate reverse power flow signal to trigger stage 1 short-delay alarm, then sustain reverse power to verify stage 2 long-delay generator trip function, confirm standby hold timer operates normally, check stable alarm/trip signal transmission to DCS/SCADA system.
FAQ
Q: What is the core application difference between RXPPK 2H and other COMBIFLEX relays like RXIDK / RXEDK?A: RXPPK 2H is a directional power measuring relay dedicated to generator reverse power protection, relying on both CT and VT signals to calculate power flow direction. RXIDK is pure overcurrent protection (only CT input), RXEDK is pure voltage supervision (only VT input); they cannot realize reverse power directional detection and cannot replace RXPPK 2H for generator bays.
Q: What is the difference between RXPPK 2H and single-stage RXPPK 1H relays?RXPPK 1H only has one single definite time stage, limited to simple reverse power trip without hierarchical alarm function. RXPPK 2H provides two independent time delay stages with hold timer logic, realizing graded early warning + critical shutdown protection, which is mandatory for large-capacity generator main protection coordination.
Q: Can the plug-in RXPPK2H be hot-swapped under energized cabinet power?Not permitted. The relay connects to live CT and VT secondary measuring circuits as well as auxiliary power loops; extraction under energized conditions will generate abnormal voltage surge and permanently damage internal directional measuring hardware. Full auxiliary power lockout and CT shorting via RXDS4 test switch are required before replacement.
Q: What warranty applies to stocked RXPPK 2H 1MRK001615-AA modules?Factory-new original COMBIFLEX relays carry 12-month official ABB manufacturer warranty covering directional power measuring circuits, time delay logic and silver-plated relay output contacts. Bench-tested surplus modules provide 6-month functional warranty; damage caused by CT open-circuit voltage surges, CT/VT wiring polarity error, power polarity reversal or ungrounded ESD handling voids all warranty terms.
Q: Has ABB discontinued RXPPK 2H series production?No formal EOL notice has been issued. RXPPK 2H AA universal variant remains standard supply for conventional COMBIFLEX generator relay panel renovation projects. New digital substation power plant projects adopt REG670 generator protection IEDs with built-in reverse power algorithms instead of discrete COMBIFLEX plug-in relays.
Q: What typical faults indicate a defective RXPPK 2H 1MRK001615-AA relay?Common failure symptoms: Constant false reverse power alarms under normal generator forward load (directional measuring circuit drift), no stage 2 trip output when sustained reverse power occurs, time delay deviation exceeding factory tolerance range, failure of standby hold timer function, unstable power vector calculation leading to random alarm flickering.
