Introduction
The ABB REJ603 REJ603BB401NN3XE Grounding Protection Relay is a compact, self-powered protection device engineered for secondary distribution networks, Ring Main Units (RMU), and unmanned substations. Designed under ABB’s Relion® protection philosophy, this relay delivers dependable overcurrent and earth-fault protection without requiring an external auxiliary power supply.
Built for modern utility and industrial environments, it ensures stable operation even in remote installations where system reliability is critical. Its self-sufficient CT-powered architecture makes it a highly efficient and maintenance-friendly solution for feeder protection applications.
Technical Specifications
The REJ603 series is designed with a strong focus on operational reliability, compact engineering, and flexible configuration for various distribution network conditions.
| Parameter | Specification |
|---|
| Model | REJ603BB401NN3XE |
| Type | Self-powered feeder / grounding protection relay |
| Power Supply | Current Transformer (CT) energized |
| Frequency | 50/60 Hz ± tolerance |
| Protection Functions | Overcurrent (3-stage), Earth-fault (2-stage) |
| Operating Principle | Non-directional protection |
| Mounting | Panel / switchgear mounted |
| Communication | Optional (variant-dependent) |
Applications
The ABB REJ603 REJ603BB401NN3XE is widely deployed in:
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Ring Main Units (RMU) in medium-voltage distribution systems
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Secondary distribution substations
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Industrial power distribution networks
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Utility feeder protection systems
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Remote or unmanned substations without auxiliary power supply
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Transformer feeder and cable protection systems
Its self-powered design makes it especially valuable in infrastructure where maintenance access is limited or reliability demands are high.
Applications
Advantages
The REJ603 grounding protection relay offers a balance of engineering simplicity and industrial-grade performance.
Key advantages include:
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Fully self-powered operation reduces wiring complexity
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Reliable protection even in auxiliary power failure conditions
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Compact footprint suitable for space-constrained switchgear panels
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Fast commissioning with pre-configured protection logic
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High stability during transformer energization due to inrush detection
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Flexible coordination with upstream and downstream protection devices
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Robust design suitable for harsh electrical environments
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Minimal maintenance requirements over lifecycle operation
Technical FAQs
1. Does the REJ603 require an external power supply?
No, it is powered directly through current transformers (CTs).
2. What protection functions are included?
It includes overcurrent and earth-fault protection with multiple stages.
3. Can it operate in unmanned substations?
Yes, it is specifically designed for remote installations.
4. Is it suitable for RMU applications?
Yes, it is widely used in Ring Main Units.
5. Does it support inverse time characteristics?
Yes, both definite time and inverse time curves are supported.
6. Can it detect earth faults internally?
Yes, via vector summation or optional CBCT input.
7. What is the mounting type?
Panel-mounted for switchgear integration.
8. Is it compatible with IEC standards?
Yes, it supports IEC-based protection curves.
9. How compact is the device?
It has a width of 96 mm and a depth of 150 mm.
10. Is it suitable for transformer protection?
Yes, it includes features for feeder and transformer protection coordination.
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