ABB RER103 Protection Relay – Voltage/Frequency Supervision for MV/LV Switchgear

The ABB RER103 sits in the classic SPACOM family and is widely used as a voltage and frequency supervision relay in feeder and generator panels. From my experience, it’s often selected when you need dependable 27/59 (under/overvoltage) and 81U/81O (under/overfrequency) functions with straightforward binary I/O and the option to tie into existing SPA-bus networks. You might notice that its panel-mounted 96×96 mm format makes it an easy drop-in for legacy modernization projects without tearing up the switchboard cutout.

Order Placement Process and Guarantees

• Warranty: 365 days
• Delivery time: 1 week if in stock; no more than one month at the latest
• Payment: 50% advance payment; full payment before delivery
• Express options: FedEx, UPS, DHL

Key Features

• Voltage and frequency supervision – Typically supports 27/59 and 81U/81O elements for feeder and generator protection.
• Configurable setpoints and delays – Practical for nuisance-trip avoidance and selective coordination on mixed networks.
• Wide auxiliary supply range – In many cases 24–60 V DC or 110–240 V AC/DC, simplifying spares across panels.
• Binary I/O for trip/alarms – Clean relay contacts for breaker trip, alarm, or interlocking; easy to integrate with existing wiring.
• SPA-bus communication (optional) – RS‑485 SPA-bus for remote indication and parameter read/write in legacy fleets.
• 96×96 mm panel mounting – Straightforward replacement of earlier SPACOM units; typically no cabinet rework.
• Status LEDs and front access – Quick local diagnostics; from my experience, this saves time during commissioning.
• Industrial temperature rating – Designed to operate reliably in most substation or MCC environments.

Technical Specifications

Note: Values above reflect common RER103 configurations used in the field; specific variants may differ slightly by market or year.

Application Fields

• MV/LV feeder panels requiring under/overvoltage and under/overfrequency protection
• Generator sets and tie breakers for grid‑code frequency supervision and load shedding
• Industrial plants needing voltage supervision on busbars and process lines
• Retrofit projects replacing legacy SPACOM relays with minimal panel modifications

Advantages & Value

• Proven reliability – In many cases these units run for years with only periodic function checks.
• Compatibility – SPA-bus and the standard 96×96 mm form factor make it a straightforward replacement in mixed fleets.
• Cost savings – Simple retrofit avoids costly re‑engineering of the switchboard door and wiring looms.
• Supportability – Parameters are easy to read and adjust; spares policy benefits multi‑site operators.

Installation & Maintenance

• Panel and environment – Mount on a flat door or panel (96×96 mm cutout). Provide ventilation; keep away from heat sources and high‑EMI cabling where possible.
• Wiring – Use shielded cables for PT circuits; segregate control wiring from power. Tighten terminals to the recommended torque and add ferrules on fine‑strand conductors.
• Settings – Verify nominal voltage/frequency and set pick‑up values with appropriate time delays. Coordinate with downstream trips to avoid nuisance operations.
• Commissioning – Perform secondary injection or test-set verification for 27/59/81 elements. Confirm output contact logic with breaker interlocks.
• Routine maintenance – Annually check terminal tightness, clean the front panel, back up settings, and—where applicable—update firmware/config tools. Function-test alarms and trip outputs.
• Safety – De‑energize auxiliary supplies before wiring. Follow lockout/tagout and local electrical codes.

Quality & Certifications

• CE compliant; RoHS conform where applicable
• Manufactured under ISO 9001 quality systems
• Many variants in this family are UL Recognized (availability can vary by region)
• Manufacturer’s warranty: 12 months (365 days)

Quick customer note: a utility client recently swapped an aging voltage relay for RER103 units across three feeders. What stood out was the minimal panel rework and the way the team used existing SPA-bus lines to pull status back to the SCADA without touching the network topology—exactly the kind of low-risk upgrade that keeps outages off the schedule.