Foreword

This code was revised by the Northeast Electric Power Design Institute of China Power Engineering Consulting Group Corporation from GB 50062-92 Design Code for Relaying Protection and Automatic Device of Electric Power Installation，in response to the Notice on Printing and Distributing the Preparation and Revision Plan Regarding National Standards for Engineering Construction of 2004 （Jianbiao［2004］No.67）issued by the Ministry of Housing and Urban-Rural Development of the People's Republic of China.

This code is organized into fifteen chapters and two appendices，mainly including:General，General Provisions，Generator Protection，Power Transformer Protection，3-66kV Transmission Line Protection，110kV Transmission Line Protection，Busbar Protection，Power Capacitor and Reactor Protection，Protection of Motors of 3kV and Above，Automatic Reclosing Devices，Automatic Switch-in Devices for Standby Power Supplies and Equipment，Automatic Low-Frequency and Low-Voltage Load-Shedding Device，Synchronization closing，Automatic Excitation Regulation and De-excitation，as well as Secondary Circuits and Associated Equipment.

The revisions made mainly include the following:

1.The applicable scope is extended from generators rated 25 MW and below to generators rated 50 MW and below；

2.Protections for transformers grounded via a resistor and grounding transfomers are supplemented；

3.Protections for shunt reactors are supplemented；

4.Automatic low-frequency load shedding device is changed into automatic low-frequency and lowvoltage load shedding device；

5.Contents about synchronization closing and disconnection from the grid are curtailed into'synchronization closing and the contents about disconnection from the grid are deleted；

6.Automatic excitation regulation and de-excitation are supplemented；

7.Secondary circuits and the associated equipment are supplemented.

This code is administered by the Ministry of Housing and Urban-Rural Development of the People's Republic of China and the Northeast Electric Power Design Institute of China Power Engineering Consulting Group Corporation is responsible for the interpretation of specific technical details.During the implementation of this code，the interests concerned are expected to seriously summarize the experiences and refer any comments and suggestions for modification or supplementation to the Northeast Electric Power Design Institute of China Power Engineering Consulting Group Corporation at the address:Renmin Street No.4368，Changchun City，Jilin Province，Postcode 130021，for reference in the future revision.

Main drafting organization and drafters of this code are as follows:

The code is drafted by the Northeast Electric Power Design Institute of the China Power Engineering Consulting Group Corporation.

The leading authors of this code:Li Yanshan，Wang Ying，Zhang Fusheng，Liu Gang，An Liqun，Fu Guang and Wei Xianan.

This code is translated by SUNTHER Translation & Solutions under the authority of China Electric Power Planning & Engineering Association.