Description
ABB REX521GHHGSH51G Feeder Protection Relay for Medium-Voltage Switchgear
The ABB REX521GHHGSH51G is a draw-out feeder protection and control relay from the proven REX 521 series. It’s typically used on MV feeders, ring-main units, and industrial incomers where fast overcurrent/earth-fault protection, breaker failure logic, and autoreclose are expected. From my experience, it’s a reliable fit for utilities and plants modernizing legacy panels without a full redesign, especially when you need stable IEC 60255-class performance and straightforward HMI operation.
Company’s Order Placement Process and Guarantees
- Warranty: 365 days
- Lead time: typically 1 week if in stock; no more than one month at the latest
- Payment: 50% advance payment; full balance before delivery
- Express delivery options: FedEx, UPS, DHL
Key Features
- Feeder protection package (50/51, 50N/51N) – Time and instantaneous overcurrent plus earth-fault protection for MV feeders.
- Breaker failure protection (50BF) – Trips upstream device if the local breaker does not clear, reducing fault energy.
- Autoreclose (79) – Single- or multi-shot reclosing for overhead lines to improve SAIDI/SAIFI in many cases.
- Disturbance and event records – COMTRADE-compatible oscillography and time-stamped events help speed up post-fault analysis.
- Programmable logic – Flexible interlocking and scheme logic to match site standards without extra relays.
- Metering and supervision – RMS current, demand, breaker wear counters, and self-supervision of internal hardware.
- HMI with LEDs and keypad – Clear front-panel navigation for local operations; you might notice it’s very approachable for field teams.
- Proven communications – SPA-bus and IEC 60870-5-103 over serial; optional LON/Modbus depending on the card set.
- Withdrawable design – Draw-out unit simplifies commissioning and maintenance; test blocks make isolation safer.
Technical Specifications
| Brand / Model | ABB REX521GHHGSH51G |
| HS Code | 8536.49.00 (Other electrical relays) |
| Power Requirements | Auxiliary supply H51 variant: typically 80–265 V AC/DC; burden usually < 20 VA |
| Operating Temperature | -5 to +55 °C (typical for REX 521 series) |
| Signal Input/Output Types | CT inputs: 1 A / 5 A; residual/ground input supported. Binary inputs: typically 24–250 V DC (variant dependent). Output relays: Form C contacts for tripping/alarms. |
| Communication Interfaces | Rear serial (RS-485/RS-232) with SPA-bus and IEC 60870-5-103; front service port; optional LON/Modbus depending on option boards. |
| Installation Method | Panel flush mounting in a withdrawable (draw-out) case; terminals in the fixed case for safe isolation and testing. |
| Dimensions & Weight | Typical REX 521 draw-out case; depth ≈ 215–240 mm; weight ≈ 5–6 kg |
Related or Supporting Products
- ABB REF615 – Modern IEC 61850 feeder protection; ideal replacement when migrating to digital substations. More protocol options and advanced HMI.
- ABB REM615 – Motor protection if the application involves large drives rather than feeders.
- ABB REF620/630 – For more complex schemes and bay control; typically used where additional logic and I/O density are needed.
- Communication accessories – SPA-bus to gateway converters or RS-485 to fiber media converters for longer runs and EMC robustness.
- Test blocks and isolation plugs – To support secondary injection and maintenance on draw-out relays.
One thing I appreciate is how tolerant the REX 521 is to mixed fleets. In many cases it drops neatly into existing cabinets, keeps SPA/103 links alive, and gives you time to plan a wider IEC 61850 rollout. Feedback we hear from maintenance teams: “the draw-out chassis made fault isolation faster than our older fixed relays, and the autoreclose logic needed minimal tweaking.”
Installation & Maintenance
- Environment and cabinet: Install in a dry, vibration-free switchboard with adequate ventilation. Maintain clearance for draw-out operation and front access.
- Wiring: Use shielded, twisted pairs for CT/VT secondaries and serial comms. Properly short CTs before any disconnection. Ground shields at one point only.
- Protection settings: Validate pickup/time curves (50/51, 50N/51N) against system fault studies. Check breaker failure and autoreclose interlocks carefully.
- Tools: Configuration is typically performed using ABB CAP 505 for REX 521. Keep a baseline settings file and event time sync consistent across bays.
- Routine checks: Annual secondary injection (or after network changes), visual inspection of terminals, clean the front panel, and verify trip circuits and LEDs.
- Firmware and records: Where applicable, keep disturbance records archived (COMTRADE). If firmware updates are available for your variant, schedule during outages.
- Safety: De-energize auxiliary supplies when removing the draw-out unit. Observe CT shorting procedures and local lockout-tagout rules.
Quality & Certifications
- Conformity: CE marked; type-tested to IEC 60255 protection relay standards.
- RoHS: Typically compliant for later production; legacy units may vary by year.
- Manufacturing: Produced under ISO 9001 quality systems by ABB.
- Warranty: 365 days warranty from our side for the supplied unit.
If you’re replacing an existing relay, send a photo of the rating plate or the complete option string. The “H51” power supply and the communication card set can vary slightly between builds, and matching these up front usually makes commissioning a same-day job.
Reviews
There are no reviews yet.