I. Standard Background and Scope of Application GB/T 14285 'Technical Code for Relaying Protection and Security Automatic Equipment' is a national recommended standard that specifies unified technical requirements for the planning, design, configuration, setting, operation and testing of relaying protection and security automatic equipment in power systems. The current version covers the protection of generators, transformers, lines, busbars, shunt reactors, power capacitors and motors at voltage levels of 3 kV and above, and is the core basis for power O&M, digital substation and smart grid construction. For industrial users, the standard also applies to the microprocessor-based protection configuration of distribution systems at 110 kV and below, and is the fundamental specification for judging whether the relaying protection of their own substations is compliant.
II. Detailed Explanation of the 'Four Properties' Indicator System Chapter 3 of the code specifies that relaying protection shall simultaneously meet four basic performance indicators, namely the 'four properties': selectivity, quickness, sensitivity and reliability. Selectivity means that fault clearing shall be limited to the minimum scope, and when the main protection fails to operate, the near backup or remote backup protection shall clear the fault level by level to avoid cross-zone tripping that expands the outage scope; quickness means that the operating time of main protection for lines above 330 kV shall be ≤20 ms, and for near-end faults on 110 kV lines ≤30 ms, so as to ensure system transient stability and equipment safety; sensitivity is quantified by the sensitivity coefficient Ksen, with Ksen ≥2 for transformer main protection and Ksen ≥1.5 for zone I of line distance protection; reliability means that devices operate correctly under faults and do not maloperate under no-fault conditions, with MTBF (mean time between failures) ≥10,000 hours and an annual correct operation rate ≥99.5%. These four indicators constrain each other, and engineering practice must weigh them comprehensively at the system level.
III. Equipment Technical Requirements and Configuration Principles Chapter 4 of the code sets out clear technical requirements for the equipment itself: microprocessor-based protection devices shall have self-check functions, with key circuits (AD sampling, CPU, output relays) having duplicated or triplicated redundancy; devices shall withstand IEC 61000-4 series EMC tests, including 4kV surge, 2kV EFT and 10V/m radiated immunity; communication interfaces shall support IEC 61850 MMS/GOOSE or Modbus RTU/TCP, with sampling synchronization accuracy ≤1us. On configuration principles: lines at 220 kV and above must have duplicated main protection (two independent main protections plus one backup protection); lines at 110 kV and below may use an integrated device combining single main protection and backup protection; transformer main protection shall adopt a dual configuration of differential protection plus gas (Buchholz) protection; busbar protection shall be configured in duplicate and independent of line protection. The FEXLINK SFA multi-element electrical smart monitoring and control device has 27 built-in sub-models covering protection functions such as overcurrent, differential, distance, zero-sequence, undervoltage, overvoltage and frequency deviation, and can carry both main protection and backup protection logic simultaneously, satisfying the code's requirements for redundancy and independence at the architectural level.
IV. Compliant Deployment Application of FEXLINK Products In actual deployments in 200+ customer projects, FEXLINK has developed a compliant deployment methodology based on GB/T 14285. Taking a 110 kV industrial substation as an example: on the 110 kV side of the main transformer, an SFA multi-element monitoring and control device is configured as main protection, with differential protection and gas protection access, operating time ≤25 ms and sensitivity coefficient Ksen ≥2.5; on the 10 kV feeder side, an ESA all-element smart meter is configured as backup protection, with zone I overcurrent operating time ≤50 ms, and zone III overcurrent serving as remote backup, achieving selectivity through the coordination of definite-time and inverse-time characteristics. The SFA simultaneously collects 260+ electrical parameters, uploads them to the station control layer via IEC 61850 MMS, and has a GOOSE trip signal transmission delay ≤4 ms, meeting the code's real-time requirements. The ESA has 10uA-level residual current monitoring capability and can issue early warnings while faults are still forming, forming a 'warning - protection - alarm' three-line defense together with the main protection. All event records carry SOE (Sequence of Events) timestamps with 1 ms accuracy, meeting the code's requirements for fault recording and event tracing.
V. O&M Compliance Key Points Chapter 6 of the code puts forward 12 mandatory requirements for relaying protection O&M. Common compliance points in engineering practice include: first, regular calibration - newly commissioned devices must complete the first comprehensive calibration within 72 hours, followed by at least 1 regular calibration per year; key items include operating value error (shall be ≤5%), operating time error (shall be ≤3%), and circuit insulation (shall be ≥10MΩ); second, setting management - all protection settings must be set by units qualified for power dispatching, and changes must go through the 'setting sheet' approval process; FEXLINK Cloud provides a cloud setting management module supporting version comparison, change approval and one-click distribution, eliminating human errors; third, defect management - device anomalies or alarms must be analyzed within 24 hours and cleared within 72 hours, and serious defects must be immediately removed from service with emergency procedures initiated; fourth, anti-accident measures - the 'anti-accident measures' list issued by the national grid authority must be implemented item by item, such as secondary circuit grounding, anti-open-circuit protection of CT/PT secondary circuits, and moisture protection of protection devices. FEXLINK's 408 national standard rules are built into the edge AI inference engine, enabling automatic compliance self-checks at every device startup and generating visualized compliance reports.
VI. Conclusion and Outlook GB/T 14285 is a benchmark code that cannot be bypassed in relaying protection engineering practice, and its 'four properties' indicator system and equipment technical requirements run through the entire process of power system planning, design and O&M. With the SFA multi-element monitoring and control device and the ESA all-element smart meter at its core, combined with 60+ edge AI algorithms and 408 national standard rules, FEXLINK fully meets the code requirements in four dimensions - hardware redundancy, communication real-time performance, setting management and compliance self-check - helping 200+ customers build compliant, reliable and evolvable digital energy IoT systems. In the construction of the new power system, relaying protection is evolving from 'passive response' to 'active prevention', and FEXLINK will continue to track the revision dynamics of GB/T 14285 and safeguard the safety of every kilowatt-hour with technological leadership.
Key Takeaways Definition: GB/T 14285 'Technical Code for Relaying Protection and Security Automatic Equipment' is a national recommended standard that specifies the configuration, setting, testing and operation management requirements of relaying protection and security automatic equipment in power systems, and is the core basis for relaying protection engineering design. Core principle: The core of the standard revolves around the 'four properties' indicators - selectivity, quickness, sensitivity and reliability: selectivity ensures the minimum scope of fault isolation, quickness requires protection operating time to meet the thermal stability constraints of equipment, sensitivity reflects the ability to perceive faults, and reliability ensures protection devices operate correctly under faults and do not maloperate under no-fault conditions. Applicable scenarios: Applicable to the design, setting, acceptance and O&M of relaying protection and security automatic equipment in the generation, transmission, transformation and distribution links of power systems, covering line protection, transformer protection, busbar protection, motor protection, capacitor protection and other protection objects. FEXLINK capabilities: FEXLINK's SFA multi-element electrical smart monitoring and control device, ESA all-element smart meter, ESF electrical fire monitoring and control device and other equipment support multi-parameter acquisition of residual current, temperature, voltage, current, etc., and SOE event recording, can interface with relaying protection systems to provide auxiliary monitoring data, and support O&M compliance and scheme design.
FAQ Frequently Asked Questions
What is the interpretation of GB/T 14285 'Technical Code for Relaying Protection and Security Automatic Equipment'? GB/T 14285 'Technical Code for Relaying Protection and Security Automatic Equipment' is a national recommended standard that specifies the configuration, setting, testing and operation management requirements of relaying protection and security automatic equipment in power systems, and is the core basis for relaying protection engineering design.
What is the core principle of the interpretation of GB/T 14285 'Technical Code for Relaying Protection and Security Automatic Equipment'? The core of the standard revolves around the 'four properties' indicators - selectivity, quickness, sensitivity and reliability: selectivity ensures the minimum scope of fault isolation, quickness requires protection operating time to meet the thermal stability constraints of equipment, sensitivity reflects the ability to perceive faults, and reliability ensures protection devices operate correctly under faults and do not maloperate under no-fault conditions.
