ABB REB670 | Busbar Protection Relay 12ms Trip Time

Description

Key Technical Specifications

• Protection Function: Low-impedance busbar differential protection
• Typical Operating Time: 12ms for internal faults
• CT Inputs: Supports 4 to 24 Current Transformer (CT) inputs per device
• Protection Zones: 2 independent low-impedance differential protection zones
• CT Saturation Requirement: Requires only 2ms of CT non-saturation time for correct judgment
• Communication Protocols: IEC 61850, DNP3, Modbus (supports Process Bus IEC 61850-9-2LE)
• HMI: Large graphical display for local monitoring of currents, angles, and statuses
• Power Supply: Standard substation DC supply (typically 24V-250V DC, verify specific nameplate)
• Mounting: Flush mounting in control room panels
• Configuration: Three-phase and single-phase versions available

Product Introduction

In a high-voltage substation, a busbar fault is basically the worst-case scenario. You need a protection relay that acts in milliseconds, not seconds, or you risk catastrophic damage to the entire switchgear. That is exactly what the ABB REB670 is built for. As part of the Relion 670 series, this Busbar Protection IED is designed to detect internal faults and trip the breakers with a typical operating time of just 12ms, regardless of how many bays are connected to the bus.What makes the REB670 a favorite among protection engineers is its stability during external faults. Even when Current Transformers (CTs) go into severe saturation, this relay uses advanced algorithms to ensure it doesn’t nuisance trip. It features an automatic bay-to-zone allocation, meaning it can dynamically switch CT inputs to the correct protection zone without needing complex external CT switching relays. It is a “fit and forget” piece of kit that handles everything from simple single busbars to complex double breaker arrangements with ease.

Quality SOP & Tech Pitfalls (The Reality Check)

The Lab Report (SOP)
Every REB670 module we ship undergoes a rigorous pre-delivery inspection. We start by verifying the physical integrity of the front HMI and rear terminal blocks. It is then powered up on a secondary injection test set to verify the basic boot sequence and HMI functionality. We check the firmware revision against the order requirements and inspect the communication ports (fiber/copper) for physical damage. Finally, the unit is packed in heavy-duty anti-static and shockproof packaging to survive transit to your substation.The Engineer’s Warning (Pitfalls)
Here is the biggest trap with busbar protection: CT Circuit Openings. If you have a loose connection or an open circuit on one of your CT inputs, the REB670 might interpret the resulting unbalanced current as a massive internal fault and trip the whole bus. The REB670 has built-in CT supervision logic to detect this, but you must configure the thresholds correctly during commissioning. I have seen a plant lose power for half a day because someone forgot to short-circuit a spare CT core, and the supervision settings were left at default. Always double-check your CT回路 (circuits) before energizing.

Installation & Configuration Guide

Phase 1: Pre-Installation

1. Safety First: Ensure all DC control power and VT/PT secondary circuits are isolated.
2. Verify CT Polarity: Before wiring, confirm the polarity of all CTs connected to the REB670. Incorrect polarity is the #1 cause of immediate tripping upon loading.
3. Photo Log: Document the existing DIP switch settings (if any) and wiring diagrams.

Phase 2: Removal & Mounting

1. Unwire: Carefully label and disconnect all CT, VT, binary I/O, and communication cables. Never open a live CT circuit.
2. Extract: Release the mounting clamps and slide the old IED out of the panel.
3. Insert New Unit: Slide the REB670 into the cutout and secure it with the mounting brackets.

Phase 3: Wiring

1. CT Connections: Connect the CT secondary wires to the correct terminals according to the bay-to-zone allocation plan. Ensure tight torque on all screw terminals.
2. Binary I/O: Wire the trip outputs to the respective circuit breaker trip coils.
3. Communication: Connect the fiber optic or Ethernet cables for IEC 61850/Modbus communication.

Phase 4: Power-On & Testing

1. Energize: Turn on the DC auxiliary power. Verify the HMI boots up correctly.
2. Check CT Supervision: Monitor the CT supervision status on the HMI to ensure no open circuits are detected.
3. Secondary Injection: Perform a primary/secondary injection test to verify the differential protection characteristic and trip logic before putting the busbar back into service.

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: Can the REB670 handle CT saturation during a heavy external fault?
A: Yes, absolutely. It is specifically designed to remain stable even when CTs are severely saturated. It only requires a 2ms window of non-saturated CT signal to correctly identify that the fault is external and block the trip.Q: What does the “CT Supervision” alarm mean on the HMI?
A: It usually means the relay has detected an imbalance in the CT secondary circuits, which often points to a loose wire or an open CT circuit. It can also trigger if the load current is extremely low and the sensitivity is set too high. Check your physical wiring first.Q: Can I use this for a double busbar system with a bus coupler?
A: Yes. The REB670 has two independent differential zones and an automatic bay-to-zone allocation feature. It can dynamically track the isolator statuses and assign bays to the correct busbar zone, even during changeover operations.Q: Does it support IEC 61850 Process Bus?
A: Yes, certain variants of the REB670 can be equipped to communicate via IEC 61850-9-2LE Process Bus, allowing it to connect directly to merging units (MUs) instead of hardwired CTs.Q: Is the HMI interface easy to navigate during an emergency?
A: It is very straightforward. The large graphical display shows single-line diagrams, actual switch statuses, and real-time current phasors. You can quickly see which zone is faulted and check the event logs right from the front panel.