IEEE 741-2017 pdf download
IEEE 741-2017 pdf download.IEEE Standard for Criteria for the Protection of Class 1E Power Systems and Equipment in Nuclear Power Generating Stations.
5.1.6 Surge protection
For surge protection of equipment and systems, refer to IEEE Std 141-1993 or IEEE Std C62.23 for electric generating plants. For surge protection of induction motors, refer to IEEE Std C37.96. For guidance on protection of wire-line facilities used for protective relaying and data transfer circuits, refer to IEEE Std 487.
For recommendations in design and installation of’ low-energy, low-voltage signal circuits associated with solid-state electronic equipment, refer to IEEE Std 518-1982.
Surge protection shall be provided to protect the shunt field of dc VAMs. This surge protection may take the f’orm of’a resistor in the motor control center, wired in parallel with the shunt field to provide a discharge path fbr the shunt field’s inductive voltage surges.
For guidance in the application of’ surge arresters to all types of power circuits and equipment, refer to IEEE Std C62.2. Refer to IEEE Std C62.41 for guidance in determining the surge voltage for low-voltage equipment, and to IEEE Std C62.45 to provide guidance for tests that should be used to determine the surge withstand capability of’ the equipment used on low-voltage circuits.
5.2 DC power system
The dc power distribution system shall be provided with coordinated protection. Refer to IEEE Std 946 for dc system design and IEEE Std 1375 for station battery protection. Coordination for dc power system circuits shall include the main bus protective devices and the protective devices used in branch circuits, in switchgear control circuits, in relay and process control panels, and in battery chargers. Care shall be taken to use appropriate correction factors or dc trip characteristic curves for protection devices. The current limiting characteristics of battery chargers shall be considered.
For criteria on isolation and separation of non-Class I E circuits from Class 1 E circuits, refer to IEEE Std 384. Ground detection monitoring shall be provided for ungrounded systems.
Battery chargers shall be provided with current-limiting features or overload protection, reverse current protection, output undervoltage, and overvoltage alarms and/or trips. For additional guidance on the protection of battery chargers, refer to IEEE Std 446.
5.3 Instrumentation and control power system
For guidance on protection for inverters, refer to IEEE Std 446. For information on ground protection practices, refer to IEEE Std 142 and IEEE Std C62.92.3. For criteria for isolation and separation of non-Class IE circuits from Class I E circuits, refer to IEEE Std 384
Where a rectifier-type power supply is used as a source for an inverter, it shall be provided with reverse current protection, current-limiting features or overload protection, and output undervoltage and overvoltage protection.
The instrumentation and control power distribution system shall be provided with coordinated protection. Because inverters and motor generator sets are sources of limited short-circuit current, special attention shall be given to integrating protective device sensitivity and system available fault current. Coordination shall include the protective devices in the alternate supply, inverters, static switches, distribution panels, instrumentation panels and racks, and other equipment powered from the system.
Where an instrumentation and control power bus is supplied by an inverter with current-limiting characteristics and an automatic transfer has been provided to an alternate source with higher available current, this alternate source may be used in order to achieve the previously described coordinated protection.
Ground detection monitoring shall be provided for ungrounded systems.
The instrumentation and control power system shall be provided with undervoltage. overvoltage, and underfrequency protection. Where its power is supplied from a static inverter, overfrequency protection shall also be provided. For recommended practice on alarms and indication, refer to IEEE Std 944-1986.
