ABB AFS series switches

ABB AFS series switches

Driven by IEC61850 and other Ethernet based communication protocols such as IEC 60870-5-104, switches have found their way into utility networks. Critical applications such as IEC61850 signals or SCADA data can be transmitted via Ethernet networks designed to be robust and reliable. Green field developments are an ideal opportunity to consider such solutions in substation and distribution communication networks.

The AFS650 and AFS670 Family offers many features which are required in the utility environments, including fast protection schemes, redundant power supply and alarm contacts, and enables the stepwise introduction of Smart Grid applications, such as integration of renewable energy sources, advanced distribution automation solutions and similar.

The AFS Family products are compliant to IEEE standards and enhance ABB’s product portfolio for distribution networks, Inplant communication and substation automation applications.

AFS Family at a Glance

−Fully managed modular switches

−Utility grade switches

- IEC61850 and IEEE1613 approved

- Extended temperature rating from -40°C up to 85°C (continuous) as an option

−19” or DIN rail mounting

−FE or GbE version available

−Fast protection scheme in case of link failure

−Automatic topology discovery using LLDP

−Local alarm indication (LED) and alarm contacts

Typical Topology

State of the art substation automation systems use the IEC61850 protocol for communication between IEDs (Intelligent Electronic Device), as well as from IEDs to the station control computer. The IEC61850 protocol transmits different signals, such as GOOSE messages (e.g. interlocking, trip, ...), Sampled Values and Client Server communication via an Ethernet network. Since these are mission critical services, the data packet should reach its receivers with highest security and minimum delay.

Communication networks applicable to substations based on IEC61850 require a network with high availability. Accordingly, the requirements for the communication network include beside IEC61850 specific features, fast network recovery time in case of link failures and high MTBF figures.

As communication equipment has to work in harsh electromagnetically polluted environments, mainly optical connections are used, with distances to be covered of maximum a few 100 meters.

Today’s SCADA Systems for distribution networks often use the IEC60870-5-104 protocol which is based on TCP/IP protocol stack.

The communication network for SCADA systems, which has to transmit real time and mission critical data, requires a redundant network topology and enhanced traffic engineering capabilities.

Besides SCADA data communication, distribution control centers have additional requirements. It might be necessary to provide a telephony system for operational purpose or channels for Renewable Energy (e.g. wind farms).

Since MV networks might be restricted to city areas or larger rural areas, the network design needs to be adapted as per actual requirements. Accordingly communication networks providing L2 Ethernet switching or L3 IP routing might be required. For installation in MV substations extended temperature range and immunity against EMC/EMI is required.

Distances to be overcome are typically in the range of a few kilometers.

Today’s In-plant applications require enhanced Ethernet communication functionality. Various services such as CCTV, public address or access control systems require communication with a central server or operator console.

In-plant communication refers to applications dealing with security of the infrastructure and recovery to normal operation after an incident. Therefore high availability of the communication network and high performance features are required.

Some of the In-Plant applications require significant bandwidth (e.g. CCTV), therefore a proper planning of the network for the initial and future expansion is needed.

To allow supervision and historical analysis it is necessary to synchronize end devices (e.g. cameras) from a central time server.

Product series classification and core parameters

（1） Classification logic and core differences

The AFS series is divided into two core product lines based on installation methods, port size, and functional expansion. Each sub model is precisely adapted to different scenario requirements:

Product series, sub models, installation methods, core structure, port configuration, power specifications, power consumption range, special functions

Compact AFS650/655 DIN rail (optional wall mounted) with fixed port design, metal casing with up to 10 ports (electrical/optical/SFP cage), including up to 3 GbE ports (electrical/SFP/combo) Low voltage: 18-60VDC; High voltage: 48-320VDC, 90-265VAC, supports redundant power supply 12-21W multi-mode/single-mode optical ports optional, suitable for small and medium-sized equipment access scenarios

Rack type AFS670/675 19 inch rack modular design (12 slots, 2 ports/module) up to 28 ports (electrical/optical/SFP cage), supporting FE/GbE, optical ports including SFP cage, SC, ST and other types of low voltage: 18-60VDC; High voltage: 77-300VDC, 90-265VAC, supports redundant power supply (spring clip or connector interface) 10-40W (no PoE), supports PoE power supply (only power type H/Z), high port density, suitable for multi device access in large substations

Rack enhanced AFS677/AFR677 19 inch rack fixed port design, with 16 GbE combo ports (TX RJ45 or SFP slots) in a metal shell, and AFS670/675 10-40W (without PoE). AFR677 adds L3 routing functionality (RIPv1/v2, OSPFv2, VRRP) to adapt to complex backbone network scenarios

（2） Key common parameters

Environmental adaptability: Standard working temperature range of 0-60 ℃, optional -40 ℃ to 85 ℃ continuous working wide temperature version, meeting extreme weather conditions and indoor and outdoor installation requirements of substations; Fanless design+optional conformal coating to reduce mechanical failure points and improve stability in dusty and humid environments.

Switching performance: Adopting a store and forward switching mode, the typical switching delay at a rate of 100Mbit/s is only 2.7 μ s; The MAC address table has a capacity of 8000 entries, supports 4042 VLANs (255 can be enabled simultaneously), and has 4 priority queues to achieve fine-grained traffic management.

Optical port configuration: support multi-mode (MM), single-mode (SM) SFP module and single fiber version, adapt to different transmission distance requirements (multi-mode for substation ≤ hundreds of meters, single-mode for distribution interval kilometers).

Core technical characteristics and compliance standards

（1） Core technological advantages

Fast fault recovery and redundancy mechanism: Supports triple protection protocols - RSTP (Fast Spanning Tree Protocol, IEEE802.1D), MRP (Media Redundancy Protocol, IEC62439), and E-MRP (Enhanced MRP). In the event of a link failure in a ring topology, millisecond level switching can be achieved. Combined with redundant power supply design, it ensures that the communication network has "no single point of failure" and meets the "zero interruption" requirements of power services; Simultaneously supporting sub ring configuration and redundant ring coupling, adapting to complex network topologies.

Full scenario protocol compatibility: Native support for core protocols in the power industry IEC61850 (including GOOSE messages, sampling values, client server communication), IEC60870-5-104 (SCADA system specific), as well as TCP/IP protocol stack related protocols (UDP, TCP, IP, ICMP, etc.); The network standards are compatible with IEEE802.1 series (VLAN, port authentication, topology discovery), IEEE802.3 series (Ethernet, link aggregation, PoE), IEEE1588 (PTP precision time synchronization), etc., achieving seamless integration with intelligent electronic devices (IEDs), RTUs, servers and other terminals.

Security protection system: hardware level supports port disabling and physical isolation; At the software level, it has functions such as IEEE802.1x port authentication, SSH encrypted transmission, SNPv3 encrypted authentication, Radius centralized password management, and multi-level user permission control; Implementing business isolation through VLAN (IEEE802.1Q) to avoid interference from different types of data and ensure the transmission security of sensitive data such as SCADA and control instructions.

Flexible management capability: Supports multi-dimensional management methods - SNMP V1/V2/V3 (compatible with mainstream network management platforms), command-line interface (Telnet), WEB interface (visual operation); Built in LLDP (Link Layer Discovery Protocol) enables automatic topology discovery, while RMON remote monitoring, port mirroring, SFP diagnosis, and other functions facilitate fault location; Configure recovery adapter (CRA), watchdog, and rollback function to quickly restore abnormal configurations and improve operational efficiency.

Value added function expansion: Some models support PoE (IEEE802.3af) power supply, which can provide power for outdoor cameras, wireless APs and other terminals, reducing wiring costs; Support SNTP (Simple Network Time Protocol) to achieve time synchronization of terminal devices such as cameras and IEDs, ensuring the accuracy of timestamps for log and video data; Port rate limitation (in/out direction, kbps step) can prevent high bandwidth services (such as CCTV) from occupying critical communication resources.

（2） Compliance and Certification Standards

This series of switches has passed multiple rigorous certifications in the power industry, ensuring reliability in extreme environments and critical business scenarios

Core industry certifications: IEC61850 approval (power automation communication standard), IEEE1613 approval (electromagnetic compatibility standard for network equipment in the power industry), CSA/UL safety certification.

Electromagnetic compatibility (EMC/EMI): Complies with EN61000-4 series standards (ESD: 8kV contact discharge/15kV air discharge); Surge: Power line 2kV ground/1kV line; Electromagnetic radiation: 35Vpp/m, 80-2700MHz), IEEE C37.90 series standards (high voltage pulse ± 5kV line to ground, electromagnetic field 35v/m, 80-1000MHz), can resist strong electromagnetic interference in substations.

Mechanical reliability: Through IEC60068-2-27 impact testing (15g, 11ms duration, 18 impacts) and IEC60068-2-6 vibration testing (multi frequency, long-term testing), it can adapt to mechanical stress during transportation and on-site installation.

Network protocol compliance: Fully compatible with RFC series standards (such as RFC 791 IP protocol, RFC 793 TCP protocol, RFC 2131 DHCP protocol, etc.), ensuring interoperability with devices from different vendors.

Three typical application scenarios and solutions

（1） Substation automation communication

Scenario requirements: Based on the IEC61850 protocol, communication between IED devices and between IEDs and station control computers is implemented to transmit key data such as GOOSE interlocking signals, trip instructions, and sampling values. Low latency (millisecond level), high availability (high MTBF), and resistance to electromagnetic interference are required, with communication distances typically within a few hundred meters.

Solution:

Hardware configuration: Choose AFS670/675 rack mounted switches (high port density) or AFS650 compact switches (small substations), with multi-mode optical ports as the main configuration (suitable for short distance transmission), and configure redundant power supply.

Network architecture: Pure Layer 2 switching network, using redundant topology (ring or dual link), enabling MRP/E-MRP fast redundancy protocol to ensure ≤ millisecond level switching in case of link failure.

Optimization design: Divide business (such as control signals, sampling values, and operation and maintenance data) through VLANs, set priority queues for QoS, and ensure priority transmission of key data such as trip instructions; Adopting SNMP protocol to achieve centralized network management, LED indicator lights and alarm contacts provide real-time feedback on device status.

（2） Communication between distribution substations

Scenario requirements: Based on the IEC60870-5-104 protocol, transmit real-time SCADA data, while also carrying VoIP voice communication, renewable energy (such as wind power, photovoltaic) data upload and other services; The communication distance is usually several kilometers, and it needs to adapt to different urban and rural environments, requiring network redundancy, high security, and wide temperature operation.

Solution:

Hardware configuration: Select AFS677/AFR677 rack enhanced switch (backbone network) or AFS655 compact switch (terminal access), with GbE ports for backbone network and single-mode optical ports for uplink configuration (suitable for long-distance transmission).

Network architecture: FE/GbE backbone network, using redundant ring topology and enabling MRP/E-MRP protocol; The AFR677 model can achieve multi subnet interconnection through L3 routing functions (RIPv1/v2, OSPFv2), and VRRP protocol ensures routing redundancy.

Security and Management: Enable IEEE802.1x authentication and SSH encryption to ensure secure data transmission; Monitor the status of the entire network through a centralized management system, adapt to AC/DC wide voltage input power supply, and meet the power supply needs of field substations.

（3） In plant communication

Scenario requirements: Support in plant security (CCTV, access control), public broadcasting, equipment monitoring and other business communication, requiring high bandwidth (adapted to CCTV video streaming), convenient equipment power supply (PoE), time synchronization (log/video timestamp), and fast fault recovery.

Solution:

Hardware configuration: Select the AFS670/675 model (camera powered) that supports PoE function, connect the GbE upstream port to the central server, and configure optical ports for transmission links over 100 meters.

Network architecture: FE/GbE backbone network, using star or ring topology, with RSTP protocol enabled to ensure link redundancy; Port rate control prevents video streams from occupying too much bandwidth.

Key function: Implement time synchronization of terminal devices through SNTP protocol; IEEE802.1x port authentication protects the security of outdoor camera access; Quickly restart the device after power failure to reduce business interruption time.

Customer core revenue

Environmental adaptation and reliability assurance: Power grade hardware design, high EMC/EMI anti-interference capability, wide temperature operating range, redundant power supply, and fanless design ensure long-term stable operation in harsh environments of substations, with excellent MTBF (mean time between failures) performance.

Business continuity improvement: The Fast Redundancy Protocol (MRP/E-MRP) enables millisecond level switching of link failures, coupled with multiple security protection mechanisms, to ensure "zero interruption" transmission of critical businesses such as SCADA and IEC61850.

Deployment and operation efficiency optimization: Supports multiple installation methods of 19 inch rack/DIN rail, modular design (AFS670/675) for easy port expansion; Multi dimensional management tools (WEB/Telnet/SNMP), automatic topology discovery, fault alarms, and other functions reduce operational complexity.

Maximizing investment value: Port density can be expanded from 8 to 28, supporting functional extensions such as FE/GbE, PoE, L3 routing, etc., adapting to different scale requirements from small and medium-sized substations to large distribution networks; Cross vendor and cross protocol compatibility capabilities, protecting existing equipment investments and supporting future smart grid application upgrades.