Concept and Functions of Feeder Terminal

Basic Concepts of Feeder Terminal

A feeder terminal is a switch monitoring device installed next to the feeder switch. These feeder switches refer to outdoor pole-mounted switches, such as circuit breakers, load switches, and sectionalizing switches on 10kV lines.

Functions of Feeder Terminal

Collection and Processing of Analog Information — Telemetry

The feeder terminal collects AC input voltage, monitors the power supply status on both sides of the switch, and collects analog quantities such as line voltage, the load current and active power, and reactive power experienced by the switch. Generally, the fault current of a line is much greater than the normal load current, so to collect fault information, the feeder terminal must provide a large dynamic input range for current.

Collection and Processing of Digital Information — Remote Signaling

The feeder terminal should be able to collect important status quantities such as the current position of the pole-mounted switch, whether communication is normal, and the completion status of energy storage. If the feeder terminal has microcomputer relay protection functions, it should also perform remote signaling for protective actions.

Receiving and Executing Commands — Remote Control

The feeder terminal should be able to receive and execute commands to control switch closing and tripping, action locking, and starting energy storage. When overhauling line switches, the corresponding feeder terminal should have remote control locking functions to ensure the safety of the operation, avoiding mishaps and severe accidents due to misoperations.

Setting Functions

The feeder terminal should be able to set voltage, current, and relay protection, and the setting values should be able to adapt automatically as the distribution network operation mode changes.

Self-Check and Self-Recovery Functions

The feeder terminal should have self-checking functions and promptly alarm when the device itself fails. It should also have reliable self-recovery functions, being able to reset the system through a monitoring timer to resume normal operation in case of interference-induced malfunctions.

Communication Functions

Besides providing a communication port for communicating with a remote master station, the feeder terminal should offer standard RS232 or RS485 interfaces and connect with various communication transmission devices on both sides to complete communication forwarding functions. A crucial issue is that the communication protocol of the feeder terminal is in urgent need of standardization.

Remote Control Locking and Manual Operation Functions

When overhauling lines or switches, the corresponding feeder terminal should have remote control locking functions to ensure operational safety, preventing severe accidents caused by misoperations. Additionally, the feeder terminal should provide manual switch closing/tripping buttons for manual operations in case of channel failure, avoiding the need to directly operate the switch on the pole.

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