Description
REF620E_F NBFNAANNNCC1BNN1X protective device
REF620E_F NBFNAANNNCC1BNN1X Protective Device Introduction
1. Product Overview
REF620E_F with ordering code NBFNAANNNCC1BNN1X is a compact numerical feeder protection and control device designed for medium voltage distribution feeders, ring main units and industrial transformer bays. It integrates protection algorithms, electrical measurement, switchgear control, event logging and communication interfaces into a single panel-mounted unit. The suffix code NBFNAANNNCC1BNN1X defines its specific hardware configuration including I/O layout, communication modules, power supply type, human-machine interface and optional auxiliary monitoring channels. The device is built for indoor cabinet installation with IP20 protection class, and serves as a cost-effective all-in-one solution for radial and loop distribution networks.
REF620E_F NBFNAANNNCC1BNN1X protective device
2. Hardware Structure & Interfaces
The unit adopts standard embedded panel mounting design. The front panel is equipped with an LCD display, navigation operation buttons and multi-status LED indicators. Operators can check real-time electrical values, protection settings, fault records and mimic diagrams locally without external software. LED lights separately indicate power running status, alarm events, protection trip signals and communication failures.
Rear terminal blocks are split into multiple galvanically isolated groups: CT/PT analog input terminals, binary input terminals, relay output terminals, auxiliary power terminals and dedicated communication ports. Analog input circuits isolate field secondary signals from internal logic to suppress switching surges and electromagnetic noise. Multiple passive relay contact outputs are provided for breaker tripping, remote alarm signalling and interlock control, with trip circuit supervision to detect broken trip coil wiring in real time. This model variant reserves standard slots for plug-in communication modules to match different automation system requirements.
3. Key Electrical Specifications
- Auxiliary power supply: Wide-range universal AC/DC input compatible with standard substation control voltages
- Current input: Supports 1 A or 5 A secondary current transformers
- Voltage input: Matches 100 V secondary voltage transformer circuits
- Binary inputs: Multi-channel passive voltage sensing inputs for collecting breaker, disconnector and external fault contact signals
- Output contacts: Isolated dry relay contacts for switching low-power AC and DC control loops
- Signal sampling: High-speed DSP sampling for accurate RMS values, symmetrical component and harmonic calculation
- Operating temperature range: -20°C to +70°C for continuous cabinet operation
- Built-in short-circuit and surge protection for all secondary wiring channels
4. Core Functional Modules
4.1 Feeder Protection Functions
A full set of dedicated feeder protection functions is embedded: three-stage definite-time and inverse-time phase overcurrent protection, directional and non-directional residual earth fault protection, voltage-based earth fault detection, broken conductor supervision, overvoltage and undervoltage protection, and breaker failure backup protection. All protection stages support adjustable time delays and configurable blocking logic to avoid false trips during motor startup, transformer energization or temporary grid disturbances. Automatic reclosing function with customizable sequence and dead time is available for overhead distribution lines. CT and PT circuit failure detection triggers dedicated alarm signals without unnecessary tripping.
4.2 Measurement & Fault Recording
The device continuously measures three-phase currents, line and phase voltages, residual current and voltage, active power, reactive power, apparent power, power factor and grid frequency. It records peak and minimum demand values and accumulates forward and reverse electric energy consumption. An integrated disturbance recorder captures voltage and current waveforms pre-fault and post-fault, while a timestamped event log stores all protection starts, trip operations, switch position changes and internal device alarms for post-fault analysis. Breaker operation counter tracks mechanical switching cycles to assess contact ageing.
4.3 Control & Programmable Logic
Built-in programmable logic eliminates most external auxiliary relays by supporting custom interlock sequences, automatic switching logic and status signal conversion. It provides local and remote control authority for feeder circuit breakers and disconnectors. The trip circuit supervision function monitors the integrity of trip coils and control wiring and generates an alarm once open circuits are detected. Users can edit custom single-line mimic diagrams on the front display to match the layout of the local primary power circuit.
4.4 Communication Functions
Multiple independent communication channels support horizontal inter-device data exchange and vertical connection to upper monitoring systems. Both electrical serial and optical media options are available to resist strong electromagnetic interference in heavy industrial sites. Supported remote operations include real-time data reading, fault waveform download, protection setting group switching and remote status interrogation. The device complies with mainstream substation communication standards to fit common distribution automation architectures.
5. Typical Application Scenarios
- Medium voltage overhead and cable feeder bays in urban and industrial distribution substations
- Ring main units and compact box-type substations for loop network power supply
- Primary side protection of distribution transformers in factory power rooms
- Small industrial power stations and commercial building medium voltage switchgear
- Distribution networks requiring automatic reclosing and multi-layer interlock control logic
6. Basic On-Site Fault Diagnosis
- Power LED off: Missing auxiliary power supply, loose wiring terminals or internal power circuit failure
- Trip LED illuminated: Overcurrent, earth fault, abnormal voltage or breaker failure detected; detailed fault magnitude and timestamp can be accessed via local display
- Communication fault alert: Damaged communication cables, mismatched device addresses or incorrect protocol parameter settings
- Unstable measured values: Poor shielding of CT/PT wiring, insufficient circuit isolation or heavy electromagnetic interference from nearby switching equipment
- CT/PT failure alarm: Open or short circuit in secondary voltage or current transformer loops
