Transmission Line Distance Protection
ED7-D

The ED7-D series IEDs provide one integrated platform for the protection, control and monitoring of transmission lines up to 765 kV with the latest in communication technologies. The IEDs are based on long-term field experience and focusing on the challenges our customers face.

Devices are used as main or backup protection of the line and automatic control of the line breaker.

The device offers the following capabilities: distance protection, directional earth-fault protection with high-frequency intertrip or teletripping, current protections, automatic control of one circuit-breaker, auto reclosing (single-phase or three-phase), automatic unload at current overload and circuit-breaker failure protection functionality.

Front panel

Large graphic display is designed to show the information necessary for the user

16 electronic switches are used to enable/disable relay protection functions directly from the device front panel. Each electronic switch is fitted with LED indicator. They can be assigned to any program switch in IED logic circuit

The user assigns available versions:

32 LEDs with electronic switches,
48 LEDs w/o electronic switches.

These LEDs light up, when certain protections actuate. They can be freely configured for any internal logic signal

The following buttons are provided on the IED front panel:

alarm reset
local/remote control
circuit-breaker control functional buttons
selecting group of settings
keyboard

USB port for PC connection for setting up and configuring IED parameters

Rear view

Up to 96 binary inputs and output relays in total. Binary inputs have no common contact

IED has up to 16 analog inputs in various configurations

IEDs have several communication interfaces (RS-485, FOL, Ethernet (electrical/fiber-optic), 1PPS) and can be integrated into automation system of any enterprise

ED7-D protection function	ANSI code	For lines with three pole operated CB	For lines with single pole operated CB

Distance protection	21
Power swing blocking	68
Remote tripping	85
Earth-fault protection	50N/51N/67N
Overcurrent protection	50/51
Directional overcurrent protection	67	O
Inrush detector	INR
Automatic switch onto fault logic	SOTF
Undervoltage protection	27
Residual overvoltage protection	59N
Overvoltage protection	59
Negative sequence overvoltage protection	47
Phase Discontinuity Protection	46BC
Built-in communication interface for protections		O	O

Tripping logic	94
Trip circuit supervision	74TC	O
Breaker failure protection	50BF
Synchrocheck, energizing check and synchronizing	25	O
Autorecloser (3 Phase)	79	O
Autorecloser (1 Phase)	79SP
Lockout	86	O
Fuse Failure / VT Supervision	60
Circuit breaker control / Supervision	52	O
CT Supervision		O	O
Open-phase protection		O

Three-phase Measurement
One-phase Measurement
Fault locator	21FL

Disturbance recorder
Event recorder
Self-test function

— basic functions

O — optional functions

Application

Used as protection on double-end, three-end (including with three-way supply) and dead-end overhead transmission lines

Distance protection

Distance protection is implemented in five zones with blocking in case of swings and malfunctions in voltage circuits. The first zone protects against all types of short circuits, the zones from second to fifth protect from phase-to-phase short circuits

Distance protection zones blocking in case of voltage swings

Two blocking algorithms can be used:

by change rate of negative and positive sequence currents
by change rate of resistance phasors

Directional earth-fault protection

Directional earth-fault protection includes six stages. Current relay (instantaneous overcurrent) responds to linear currents. Protection functions offer acceleration capabilities: using a parallel line, during energizing test, real-time protections and using high frequency channel

Circuit-breaker control automation

Circuit-breaker control automation receives closing and opening commands, offers control and latching of circuit-breaker position, protection against multiple CB closing

Auto reclosure

The voltage on the buses and the line (absence, presence or synchronism of voltages) is monitored when auto reclosure (single or double) is started. The circuit-breaker making mode supports both monitoring and synchronism detection

Overcurrent protection

Overcurrent protection is implemented as two-stage protection with combined voltage-controlled start. Overcurrent protection current relay responds to phase values

Circuit-breaker failure protection

Circuit-breaker failure protection implements an individual function principle. Moreover, it is possible to arrange a universal circuit-breaker failure protection according to the diagram with a dual start, as well as according to the diagram with auto check of circuit-breaker serviceability

Self-test and test mode

Devices feature an advanced self-test system, ensuring continuous monitoring of hardware and software serviceability

Operation conditions

Devices operate at increased air humidity (≤ 80%), high positive and negative ambient temperatures (from -5 to +55 °C)

Data communication protocols

Supporting all modern protocols, communication standards (IEC 61850-8-1, IEC 61850-9-2LE, IEC 60870-5-103, Modbus RTU (with optional converter) and time synchronization protocols (SNTP, PPS (electrical and optical), PTPv2 (for SV))

Specification	Value

Rated alternating current, A	1 or 5 (selected via software)
Rated frequency, Hz	50
Rated AC voltage, V	100
Rated auxiliary DC voltage, V	110; 220

Operational voltage range	-20 % … +10 %
Interruption, ms	up to 150

Maximum continuous air temperature, °C	+55
Minimum continuous air temperature, °C	-5
Upper humidity value, %	80
Ingress protection (IP) degree	IP40 — front panel IP20 — rear panel

Permissible overload of current inputs, continuous	2 * I_r
Permissible overload of current inputs, 1s	100 * I_r
Burden at I_r, VA	0.2
Permissible overload of voltage inputs, continuous	1.5 * U_r 1.8 * U_r for open delta
Burden at U_r, VA	0.2

Rated voltage	(1–300) VDC (1–400) VAC
Continuous current, А	5
Switching capacity of contacts (making current)	up to 30 А for 0.20 s
Maximum operation time, ms	10

Transmission Line Distance ProtectionED7-D

Display

Electronic switches

Two-color LEDs

Functional control

USB port

Binary inputs and output relays

Analog inputs

Communication ports

Functions

Features

Specifications

Transmission Line Distance Protection
ED7-D