Back to smartelemfg Home
Contact us Merchants settle in
Back to smartelemfg Home
Home -Differential protection relay
GWZC-9913 FO Line Diff Relay(87L)
GWZC-9913 FO Line Diff Relay(87L)
GWZC-9913 FO Line Diff Relay(87L)

Applicable Scope:This FO Line Diff Relay is designed for 132kV and below non-grounded/low-resistance grounded systems. It provides primary (differential) and backup (overcurrent/zero-sequence) protection with integrated monitoring. Supports switchgear or panel mounting, using dedicated/multiplexed fiber channels with 2048kbps E1 interface for substation and distribution applications.

Product functions(ANSI):87L | 50/51 | 51 | 50N/51N | 51N | 81U | 49 | 79 | 60 | 60 | 60 | 60/51 | 94 | 21

Communication functions:Supported Protocols:​​IEC 60870-5-103 (over Ethernet) | MODBUS RTU (via RS-485) | IEC 61850 (Ed.2 or Ed.1, as applicable)
​Interfaces:​​2× Ethernet Ports​ (IEEE 802.3 compliant, 10/100 Mbps) | 2× RS-485 Ports​ (ANSI/TIA-485-A standard, galvanically isolated)

Other functions : Support time synchronization via communication message, SNTP (Simple Network Time Protocol) time synchronization, and IRIG-B time synchronization. Support the dot matrix printing function with serial port communication. Support the fault recording function

Product Introduction Technical Parameter Size

FO Line Differential Relay Introduction

          This FO Line Diff Relay is suitable for non-effectively grounded or low-resistance grounded systems with voltage levels up to 132kV. It provides primary protection (optical fiber pilot differential) and backup protection (overcurrent, zero-sequence, etc.) for transmission lines and feeders, while integrating measurement and control functions.

          The FO Line Diff Relay supports decentralized installation in switchgear cabinets or centralized panel mounting. It uses dedicated optical fiber or multiplexed channels as pilot communication media and is equipped with a 2048kbps E1 interface. Suitable for substations, distribution networks, and similar applications, it ensures selective protection while meeting remote monitoring requirements.

FO Line Differential Relay Protection Functions(ANSI)

1.Fiber-Optic Line Differential Protection (ANSI 87L)
2.Three-Stage Phase Overcurrent Protection (ANSI 50/51)
3.Inverse-Time Phase Overcurrent Protection (ANSI 51)
4.Two-Stage Zero-Sequence Overcurrent Protection (ANSI 50N/51N)
5.Inverse-Time Zero-Sequence Overcurrent Protection (ANSI 51N)
6.Underfrequency Load Shedding (ANSI 81U)
7.Overload Alarm (ANSI 49)
8.Three-Phase Single-Shot Reclosing (ANSI 79)
9.Bus PT Broken Wire Alarm (ANSI 60)
10.Line PT Broken Wire Alarm (ANSI 60)
11.CT Broken Wire Alarm (ANSI 60)
12.PT Broken Wire Overcurrent (ANSI 60/51)
13.Independent Tripping Circuit (ANSI 94)
14.Fault Recording (ANSI 21)

FO Line Differential Relay Protection Working Principle

1.The GWZC-9913 FO Line Diff Relay incorporates three key components:
          ①.power frequency variation current differential element,
          ②.phase current differential element,
          ③.zero-sequence current differential element.
          All three elements can implement phase-segregated differential logic.

2.Fiber Optic Channel
          Dedicated fiber optic channels shall be prioritized when the fiber core quantity and transmission distance permit. When power requirements cannot be met, multiplexed fiber optic channels may be adopted.

2048kbit/s dedicated fiber optic channel


2048kbit/s multiplexed fiber optic channel

Related products More
GWZC-9916 Bus differential protection relay
GWZC-9916 Bus differential protection relay
detail
GWZC-9884 Generator Differential Protection Relay(87H | 87 | 87A)
GWZC-9884 Generator Differential Protection Relay
detail
GWZC-9826 Main Transformer Differential Protection Relay(87H | 87 | 87A)
GWZC-9826 Main Transformer Differential Protection Relay
detail
GWZC-9833 Motor Magnetic Balance Differential Protection Relay (87M)
GWZC-9833 Motor Magnetic Balance Differential Protection Relay
detail
GWZC-9821C Transformer Differential Protection Relay (87H | 87 | 87AL)
GWZC-9821C Transformer Differential Protection Relay
detail
Technical Knowledge More
Wireless Temperature Monitoring System for Substations
Wireless Temperature Monitoring System: Application in Switchgear​
This article introduces the application of wireless temperature monitoring systems in high-voltage and low-voltage switchgear. The configuration of the wireless temperature monitoring system varies across different equipment. If you need a customized wireless temperature monitoring solution for your project, please visit our website for more information.
2025/09/08
GWZC-9804 Arc Flash Protection Relay
Switchgear Arc Flash Protection System Configuration Scheme
This article introduces the configuration scheme for a switchgear arc flash protection system. Busbar arc flash protection monitors the busbar compartment and trips the incoming breaker, while feeder arc flash protection monitors the circuit breaker compartment and cable compartment to trip the feeder breaker. A proper arc flash protection system configuration scheme can effectively protect personnel and equipment safety. For information on a reliable arc flash protection system configuration scheme, please visit our website.
2025/09/04
Arc Flash Protection Relay
Arc Protection Working Principle and Decision Process
Arc Flash Protection is a specialized safety system engineered to rapidly detect and mitigate destructive electrical arc flash faults. Unlike conventional overcurrent protection, it utilizes a combination of light and current sensors to identify an arc flash event within milliseconds. By triggering a circuit breaker to isolate the fault incredibly fast, Arc Flash Protection significantly reduces the explosive energy released, safeguarding personnel from severe injury and preventing extensive damage to electrical equipment like switchgear. This makes it an indispensable defense layer in industrial, commercial, and utility power systems.
2025/09/03
GWZC-9913 FO Line Diff Relay(87L)
Inquiry Consultation
产品表单
Inquiry Consultation
+86-17621210051
+86-17621210051
+86-17621210051
+86-17621210051
home product email
live chat
my