Feeder Protection Demystified: Understanding SEL 751, GE Multilin 850, and ABB REF615
Overview of Feeder Protection
Feeder protection is an essential aspect of electrical systems, ensuring the safety and reliability of power distribution networks. Different types of feeder protection devices are available in the market, each offering unique features and functionalities to safeguard electrical feeders from various faults and disturbances.
II. Types of Feeder Protection
A. Overcurrent Protection
Overcurrent protection is one of the most common types of feeder protection, designed to trip the circuit breaker when the current exceeds a predetermined threshold. It safeguards against overloads and short circuits, preventing damage to equipment and minimizing downtime.
B. Directional Overcurrent Protection
Directional overcurrent protection is a more advanced form of overcurrent protection that considers the direction of current flow. It ensures selective tripping of circuit breakers based on the direction of fault currents, improving coordination and system reliability.
C. Distance Protection
Distance protection, also known as impedance protection, relies on measuring the impedance of the feeder to detect faults. It offers fast and accurate fault detection over long distances, making it suitable for transmission lines and large feeders.
D. Differential Protection
Differential protection compares the currents entering and leaving the protected zone, tripping the circuit breaker if there is a significant difference. It provides sensitive protection against internal faults within the protected zone, such as winding faults in transformers and motor stator faults.
SEL-751
Feeder Protection Relay
SEL 751 Feeder Protection
A. Overview of SEL 751
The SEL 751 is a popular feeder protection relay manufactured by Schweitzer Engineering Laboratories (SEL). It offers comprehensive protection, control, and monitoring capabilities for distribution and industrial feeders.
B. Features and Capabilities
The SEL 751 features advanced protection algorithms, including overcurrent, directional overcurrent, and distance protection. It also offers integrated arc-flash detection and breaker failure protection, enhancing system reliability and safety.
C. Applications
The SEL 751 is widely used in utility, industrial, and commercial applications to protect feeders against a wide range of faults and disturbances. Its flexible configuration options and customizable settings make it suitable for various feeder protection applications.
D. Pros and Cons
Pros: Robust protection capabilities, advanced features, customizable settings. Cons: Higher initial cost, steep learning curve for configuration and programming.
GE 850 Feeder Protection Relay
GE Multilin 850 Feeder Protection
A. Overview of GE Multilin 850
The GE Multilin 850 is a versatile feeder protection relay manufactured by General Electric (GE). It offers comprehensive protection, monitoring, and control functions for distribution and industrial feeders.
B. Features and Capabilities
The GE Multilin 850 features advanced protection elements, including overcurrent, directional overcurrent, and distance protection. It also offers synchronization, load shedding, and voltage regulation capabilities, enhancing system performance and reliability.
C. Applications
The GE Multilin 850 is commonly deployed in utility, industrial, and renewable energy applications to protect feeders and enhance grid stability. Its modular design and interoperability with GE’s other protective relays make it a versatile solution for various feeder protection requirements.
D. Pros and Cons
Pros: Versatile functionality, modular design, interoperability with other GE relays. Cons: Limited flexibility in configuration, compatibility issues with non-GE equipment.
ABB REF615 Feeder Protection Relay
ABB REF615 Feeder Protection
A. Overview of ABB REF615
The ABB REF615 is a compact and reliable feeder protection relay manufactured by ABB. It offers cost-effective protection and monitoring solutions for medium-voltage distribution feeders.
B. Features and Capabilities
The ABB REF615 features comprehensive protection elements, including overcurrent, directional overcurrent, and earth-fault protection. It also offers voltage supervision, thermal overload protection, and event recording capabilities, providing reliable protection and diagnostics.
C. Applications
The ABB REF615 is commonly used in utility, industrial, and commercial applications to protect medium-voltage feeders and equipment. Its compact design and user-friendly interface make it easy to install and operate in various environments.
Pros and Cons
Pros: Cost-effective solution, compact design, user-friendly interface. Cons: Limited advanced features, scalability for larger applications.
Comparison of SEL 751, GE Multilin 850, and ABB REF615
A. Performance
The SEL 751, GE Multilin 850, and ABB REF615 offer comparable performance in terms of basic feeder protection functions. However, the SEL 751 and GE Multilin 850 stand out with their advanced protection algorithms and features.
B. Flexibility
The SEL 751 and GE Multilin 850 offer greater flexibility in terms of configuration and customization compared to the ABB REF615. They provide extensive options for adapting to specific application requirements and system configurations.
C. Cost
The ABB REF615 is the most cost-effective solution among the three relays, making it a popular choice for budget-conscious applications. However, the SEL 751 and GE Multilin 850 offer superior features and capabilities, justifying their higher initial cost for more demanding applications.
D. Ease of Use
The GE Multilin 850 and ABB REF615 are known for their user-friendly interfaces and intuitive operation, making them suitable for users with varying levels of expertise. The SEL 751, while powerful, may require more extensive training and experience for optimal configuration and programming.
VII. Conclusion
Feeder protection relays play a crucial role in safeguarding electrical systems against faults and disturbances, ensuring the reliability and safety of power distribution networks. The SEL 751, GE Multilin 850, and ABB REF615 are prominent examples of feeder protection relays, each offering unique features and capabilities to meet diverse application requirements. By understanding the differences between these relays, users can make informed decisions and select the most suitable solution for their specific needs.