IEEE 741-1990 pdf free.IEEE Standard Criteria for the Protection of Class 1E Power Systems and Equipment in Nuclear Power Generating Stations.
IEEE 741 As used in this document, protection refers tothe sense,command, and execute features withtheir associated interconnections (IEEE Std 603-1980 [18]7 ) provided to minimize equipment dam-age and any interruption of electrical serviceresulting from mechanical or electrical failures orother unacceptable conditions. It includes equipment required to support the Class 1Epower system in the performance of its safety function, andcomponents whose function is to increase theavailability and reliability of the safety relatedequipment. The protection shall: Be capable of preventing failures in safetysystems and equipment from disabling safetyfunctions to below an acceptable level. Protectionin one load group shall not respond to disturbances in a redundant load group.Be capable of operating the requireddevices upon detection of unacceptable condi-tions to reduce the severity and extent of electrical system disturbances, equipment damage, andpotential personnel and property hazards.Be capable of monitoring the connectedpower supply and, where an alternate supply isprovided by the design, of automatically initiatinga transfer or alerting the operator to manuallytransfer to the alternate power supply.Be capable of providing indication andidentification of the protective operations.Be capable of being periodically tested toverify logic schemes and protective functions.Refer to IEEE Std 141-1986 [4] andIEEE Std 242-1986 [6] for recommended practices in application of overcurrent relays, directional relays, differential relays for bus protection,and ground fault relaying.The protection systemsfor the ac distribution system should be coordi-nated in accordance with IEEEstd 242-1986 6.Refer to IEEE Std 142-1982[5] for supplementary information on ground protection practices. If the power distribution systemdesign cannot accommodate paralleling of bussupplies,or if paralleling can be allowed onlyunder certain conditions, interlocks or procedural restrictions shall be provided to restrict such paralleling.Consideration shall be given to thehigher fault current that may exist during parallel operation when selecting protective devices.
Bus voltage Monitoring Schemes.Busvoltage monitoring schemes that are used. fordisconnecting the preferred power source,toaashedding, and starting the standby power sources are part of the protection and shall meet the criteria outlined below. Voltage monitoring schemesthat are used only for alarms do not have to meetthese criteria.Bus voltage shall be aetecteharewerfrom the Class 1E bus to which the standby power source is connected. Class 1E bus voltage monitoring shall not be derived from a non Class 1E bus.IEEE 741 pdf download.