Key Technical Specifications
| Parameter | Specification |
|---|---|
| Auxiliary Voltage | 110/120/220/240 V AC (85…110% variation) |
| Total Operate Time | ≤2.5 ms (HSO1, HSO2, TRIP3) |
| Output Type | 2x High-Speed IGBT (HSO1/HSO2), 1x Relay (TRIP3) |
| Sensor Input | Optical Fiber (Ring/Radial) or Lens Sensors |
| Max Fiber Length | 60 m (no splices), 50 m (1 splice), 40 m (2 splices) |
| Overcurrent Blocking | Adjustable 3-phase or 2-phase + Neutral |
| Expansion Ports | 2x RJ45 ports (up to 5 extension units per port) |
| Quiescent Power | ~9 W |
| Operating Power | ~12 W |
| Operating Temp | -35°C to +80°C |
Product Introduction
Arc flashes don’t wait for maintenance windows, and neither does this relay. The ABB REA101-AAA is the central brain of the REA 10 series, sitting in the switchgear panel waiting to catch a light signature before the copper melts. I’ve installed dozens of these in medium-voltage switchgear, and they do exactly one job: look for light, check for overcurrent, and trip the IGBTs in under 2.5 milliseconds. It’s not a multi-function relay trying to be a meter; it’s a dedicated arc guard.Engineers specify this module because the IGBT outputs eliminate the mechanical delay of standard relay contacts. When you have a fault, you need that breaker open now, not 10ms later. The built-in overcurrent blocking is a lifesaver, too—it stops camera flashes or welding arcs from tripping your main feeder just because someone was doing maintenance nearby. One thing to keep in mind: this specific revision is extremely sensitive to fiber optic bend radius. Keep it above 50 mm, or you’ll be chasing phantom faults all weekend. Otherwise, it’s a solid piece of kit.
Quality SOP & Tech Pitfalls
We don’t just box these up and ship them. Every REA101-AAA goes through a strict pre-shipment protocol. First, we do a visual and counterfeit check on the PCB and connectors. Then, it goes on our dedicated arc relay test rack for a live power-up and optical input simulation. We verify the IGBT trigger times using an oscilloscope and check the overcurrent blocking thresholds. Finally, we log the firmware version, perform an insulation resistance check with a Fluke 1507, and seal it in anti-static packaging.Here is the reality check: Do not skip the fiber routing check. I once saw a panel where the tech zip-tied the optical fiber too tightly against a sharp metal edge. The arc sensor worked perfectly during testing, but three months later, a minor vibration caused a micro-fracture in the fiber. The relay locked out, and they had a minor arc event that damaged a busbar. Also, verify your DIP switch settings against the old unit before pulling the power. I’ve seen guys swap these and forget the fiber loop configuration, turning a redundant ring into a single point of failure.
Installation & Configuration Guide
- Pre-Installation: ⚠️ Lock out and tag out the auxiliary power. Wait 60 seconds for the internal capacitors to discharge. Take a high-resolution photo of the old module’s DIP switches and fiber routing before touching anything.
- Removal: Label every fiber and RJ45 cable. Release the DIN rail clips gently; the plastic gets brittle after years of heat cycling. Do not yank the fiber connectors—pull by the boot.
- Installation: Copy the DIP switch settings exactly. This prevents 90% of startup communication errors. Seat the REA101-AAA firmly on the DIN rail and ensure the grounding tab makes solid contact with the panel.
- Power-On & Testing: Apply 110-240V AC auxiliary power. Watch the LEDs: Power (green) should be solid, and Fault (red) should be off. Use the front panel buttons to run a manual lamp test and verify the IGBT outputs trigger the breaker test circuit. Download the configuration via Optolink if required.
Compatible Replacement Models
| Model | Compatibility Tier | Notes |
|---|---|---|
| REA101-AAAG | ✅ Drop-in Replacement | Identical specs, but uses glass fiber Optolink connectors instead of plastic. Verify your cable type before ordering. |
| REA101-CAA | ⚠️ Software Compatible | Uses 24/48/60V DC auxiliary supply instead of AC. Requires rewiring the control power and verifying logic. |
| REA103-AA | ❌ Hardware Mod Required | This is an extension unit, not a central unit. Cannot replace REA101-AAA without adding a new central unit. |
Frequently Asked Questions (FAQ)
Can I hot-swap the REA101-AAA while the panel is energized?
No. Absolutely not. This module handles the auxiliary supply and trip circuits. Pulling it live will cause an arc in the connector and potentially trip your upstream protection. Always de-energize first.Why does my relay keep locking out after a fiber replacement?
You probably exceeded the bend radius or used the wrong splice type. The REA101-AAA runs a continuous self-test on the fiber loop. If the light loss exceeds the threshold, it locks out to prevent false tripping. Check your routing and ensure you didn’t kink the cable during the swap.Will this work with my older REA 101 from the 90s?
Maybe, but check the suffix. The REA101-AAA is the standard AC version. If your old unit has a different suffix (like -CAA or -AAAG), the hardware might be compatible, but the fiber connectors or voltage ratings could differ. Send us a photo of the nameplate, and we’ll confirm.How do I know if the IGBT outputs are actually working?
You can’t test them with a standard multimeter because they are solid-state. You need to use the built-in test function via the front panel or the configuration tool to trigger a simulated trip and measure the voltage drop across the output terminals with an oscilloscope. If you don’t have one, hire someone who does.Is the overcurrent blocking really necessary?
Yes. Without it, a welder working 20 feet away with the cabinet door open can trigger your main breaker. The REA101-AAA requires both light AND overcurrent to trip (unless configured for light-only in specific zones). It’s the difference between a nuisance trip and a real fault.What happens if I lose one of the RJ45 extension links?
If you’re running a ring topology, the relay will reconfigure and keep working on the remaining link. If you’re running a radial (daisy-chain) setup and lose the middle link, everything downstream goes blind. Always design with redundancy if possible.
