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Foreword
1 General Provisions
2 Terms
3 Emergency Gate， Butterfly Valve， Spherical Valve and Ring Gates
3.1 Automatic control of emergency gate
3.2 Automatic control of butterfly valves
3.3 Automatic control of spherical valves
3.4 Automatic control of ring gates
4 Hydroturbine Generating Units
4.1 Selection， configuration and functions of governors and automatic components
4.2 Automatic control of turbine generator units
5 Reversible Pumped—Storage Units
5.1 Starting methods in pumping mode
5.2 Changeover between different operation modes
5.3 Automatic control for pump starting and condenser starting in pumping direction
5.4 Automatic control from pumping to standstill and from pumping to generating
6 Unit Auxiliary Equipment and Plant Common Equipment
6.1 General requirements
6.2 Automatic control of oil pressure system
6.3 Automatic control of compressed air system
6.4 Automatic control of unit service water supply system
6.5 Automatic control of drainage and dewatering system
6.6 Flood prevention system for powerhouse
6.7 Automatic control of transformer cooling system
7 Excitation System and Electric Braking Equipment
7.1 Selection of excitation system
7.2 Main circuits of excitation system
7.3 Requirements to de—excitation and protection equipment of excitation circuits
7.4 Flashing methods and flashing sources
7.5 Electrical braking
7.6 Requirements to excitation control circuits
7.7 Selection of automatic excitation regulators
8 Synchronization Systems
8.1 Selection of synchronization modes and synchronization points
8.2 Manual synchronization
8.3 Automatic synchronization
9 Black Start
9.1 Methods for black start
9.2 Black start sequence
Appendix A Examples of Unit Start／Shutdown Flow Charts
Appendix B Examples of Control Flow Charts of Unit Auxiliary Equipment and Plant Common Equipment
Appendix C Excitation Source Derivations for Electric Braking
Explanation of Wording in this Code
List of Quoted Standards 

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4.2.15 For the Francis and axial flow units only adopting mechanical braking， the mechanical braking shall be applied when speed drops to 15% to 25% of rated speed in unit shutdown process.The braking jacks shall be reset after unit is stopped.
4.2.16 For the Francis and axial flow units adopting combined braking， a braking mode selection switch should be provided to select electrical braking mode， mechanical braking mode or combined braking mode.
Different braking shall be applied at the following speed.
（1） If electrical braking is selected， the braking shall be applied at 50% to 60% ofrated speed.
（2） If mechanical braking is selected， the braking shall be applied at 15% to 25% ofrated speed.
（3） If combined braking is selected， the electrical braking shall be applied at 50% to 60% of rated speed， and the mechanical braking shall be applied at 5% to 10% of rated speed， in the normal shutdown
or emergency shutdown （due to mechanical faults）.
（4） If combined braking is selected， the electrical braking shall be locked during emergency shutdown （due to electrical faults）， and the mechanical braking shall be applied at 15% to 20% ofrated speed.
4.2.17 For the Francis and axial flow units with thrust bearing high pressure oil system， the thrust bearing high pressure oil system shall be applied when the speed drops to 90% ofthe rated speed. 

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