Secondary Equipment in Distribution Rooms refers to devices including DTU terminals, relay protection devices and background communication systems, which work alongside primary high and low voltage main equipment in the power distribution hub to perform power distribution, equipment management and fault protection and maintain safe, stable and intelligent operation of the distribution network.
Secondary Equipment in Distribution Rooms work in tandem to complete data acquisition, fault protection, remote monitoring and command transmission. They enable unattended operation, precise maintenance and rapid fault handling, greatly boosting the overall efficiency of the power distribution system.
Secondary equipment including DTU terminals and various power protection relays is the core guarantee for safe, efficient and intelligent operation of modern power distribution rooms.
Overview of Core Secondary Equipment in Distribution Rooms
Secondary equipment in distribution rooms is mainly categorized into three groups: data acquisition terminals, relay protection devices and background communication equipment. With clear division of responsibilities and coordinated operation, they form a complete distribution automation management and control system. The key information of major equipment is summarized as follows:
| Equipment Name | Core Functions | Installation Location | Primary Role |
|---|---|---|---|
| Distribution Terminal Unit (DTU) | Three-remote data acquisition, fault detection, logic control, data storage | Ring main units and switchgears in distribution rooms | On-site data collection and local intelligent management & control |
| electrical protection relay | Protection against short circuit, overload, ground fault, undervoltage and overvoltage; fault tripping and alarm | High-voltage compartment switchgears | Isolate faults rapidly to protect equipment and power grid |
| electrical scada system | Protocol conversion, data uploading, command issuing, clock synchronization | Communication panels and main control background in distribution rooms | Establish communication links between on-site equipment and dispatch master station |
Detailed Introduction to Core Equipment
Distribution Terminal Unit (DTU)
As the core front-end device for intelligent distribution rooms, the DTU is specially designed for 10 kV distribution network switching stations and ring main units. It features high stability and high integration to adapt to complex on-site power operation scenarios.Classified by application requirements, DTUs fall into two types: centralized DTU and distributed DTU.
The DTU terminal undertakes full-cycle data collection and intelligent logic control, serving as the fundamental data source for automatic operation of distribution room secondary equipment.
Main Functions
It supports three-remote functions (telemetry, telesignalisation and remote control), and collects real-time operational data such as busbar voltage, line current, power and switch status. The device accurately detects phase-to-phase short circuits, zero-sequence overcurrent, overload and other faults.
It can independently realize fault location, isolation and power restoration in non-fault areas. It also features local data storage and power-off data retention to ensure the integrity of operational and maintenance data for subsequent fault analysis and routine inspection.
Communication Characteristics
Equipped with multiple interfaces including Ethernet and RS485, the DTU is compatible with mainstream power protocols such as IEC 104 and Modbus. It aggregates data from protection devices, measurement & control units and electric meters within the station, and transmits all data to the background master station in a unified manner.
Electrical Protection Relay
Secondary Equipment in Distribution Rooms includes electrical protection relays, which act as the safety barrier of distribution rooms.
These devices provide targeted protection for primary equipment such as power lines and switchgears to prevent fault propagation and subsequent grid accidents.
Reasonable deployment of protection relays and controls builds a layered and reliable safety protection system for the entire distribution network.
Core Protection Logic
It is configured with basic protection functions including instantaneous overcurrent protection, time-delay overcurrent protection, zero-sequence earth fault protection, overload protection and undervoltage protection. A professional three phase protection relay is adopted to monitor the operating state of three-phase power lines in real time.
When equipment operates abnormally, the device executes instantaneous tripping, time-delay tripping or audible & visual alarms according to fault types. It cuts off faulty circuits promptly to avoid equipment burnout and widespread power outages, ensuring the stable operation of healthy circuits.
Electrical scada system
Regarded as the “nerve center” of the distribution room, the background communication system consists of communication management units, industrial switches, time synchronization devices and monitoring background software. It realizes full-coverage data interconnection and remote management of all on-site equipment.
The background communication system ensures stable and real-time data interaction between on-site secondary equipment and remote dispatch terminals, supporting intelligent remote operation and maintenance of distribution rooms.
Data Transmission Functions
It collects data from DTUs, protection devices and measurement & control units within the station and completes protocol conversion. It transmits real-time operational data and fault information to the power dispatch master station, and accurately issues remote switching commands and parameter setting instructions.
Monitoring and Time Synchronization Functions
Cooperating with the SCADA monitoring background, it realizes data visualization, limit violation alarms, event logging and automatic report generation. Supported by GPS/Beidou time synchronization devices, it ensures unified time for all equipment in the station.
The overall time error is controlled within 1 ms, fully meeting the high-precision requirements for fault traceability and accident analysis of the power grid.
Collaborative Operation Logic of Equipment
During normal operation, DTUs collect real-time operational data from on-site equipment and transmit the data to the monitoring master station via the background communication system, realizing 24-hour remote real-time monitoring of the distribution room.
Once faults occur on the power grid or equipment, the protection device acts immediately to isolate faults and send out fault signals synchronously. The background system summarizes all operating data and fault information, and triggers real-time alarms.
Operation and maintenance staff can quickly locate, troubleshoot and resolve problems based on the recorded data. This collaborative working mode comprehensively improves the safety, stability and intelligence level of distribution room operation.
The coordinated operation of DTU terminals, electrical protection relays and background communication systems forms a complete intelligent operation and maintenance system for distribution room secondary equipment, which is widely applied in modern power distribution automation projects.
