IEEE 741-1997 pdf download IEEE Standard Criteria for the Protection of Class 1E Power Systems and Equipment in Nuclear Power Generating Stations
1.Scope
This standard prescribes criteria that establish protection requirements for Class lE power systems andequipment. It describes the purpose of and the means for obtaining protection from electrical andmechanical damage, or failures that can occur within a time period that is shorter than that required foroperator action. It includes testing and surveillance requirements. It does not include plant physical designrequirements to protect against events such as pipe whip, fire, dropped load, etc.
2.References
This standard shall be used in conjunction with the following publications. When the following standards aresuperseded by an approved revision, the revision shall apply.
ANSI/ISA S67.04 Part 1-1994, Setpoints for Nuclear Safety-Related Instrumentation.
IEEE Std 141-1993,IEEE Recommended Practice for Electric Power Distribution for Industrial Plants(ANSI.
IEEE Std 142-1991,IEEE Recommended Practice for Grounding of Industrial and Commercial PowerSystems (ANSI)
IEEE Std 242-1986 (Reaff 1991), IEEE Recommended Practice for Protection and Coordination ofIndustrial and Commercial Power Systems (ANSI).
3. Definitions
3.1 degraded voltage condition: A voltage deviation, above or below normal, to a level that, if sustainedcould result in unacceptable performance of, or damage to, the connected loads and/or their control circuitry
3.2 loss of voltage condition: A oltage reduction to a level that results in the immediate loss of equipmentcapability to perform an intended function.
3.3 pump runout: A pump flow condition in which the pump is operating beyond its design point due to areduction in the system head. As a result, the pump motor’s brake-horsepower and full load current demandmay be increased.
3.4 service factor (general-purpose alternating-current motor): A multiplier that, when applied to therated power,indicates a permissible power loading that may be carried under the conditions specified for theservice factor.
4. General design criteria
As used in this standard, protection refers to the sense, command, and execute features with their associatedinterconnections (see IEEE Std 603-1991)’ that are provided to minimize equipment damage and any inter-ruption of electrical service resulting from mechanical or electrical failures or other unacceptable conditionsProtection includes equipment required to support the Class lE power system in the performance of itssafety function, and components whose function is to increase the availability and reliability of the safetyrelated equipment. The protection shall be capable of the following:
4Preventing failures in safety systems and equipment from disabling safety functions to below anacceptable level. The protective actions of each load group shall be independent of the protectiveactions provided by redundant load groups (see IEEE Std 308-1991).
bOperating the required devices upon detection of unacceptable conditions to reduce the severity andextent of electrical system disturbances, equipment damage, and potential personnel and propertyhazards.
Monitoring the connected preferred power supply and, where an alternate preferred power supply isCprovided by the design, of automatically initiating a transfer or alerting the operator to manuallytransfer to the preferred alternate power supply.
dProviding indication and identification of the protective operations
ePeriodic testing to verify logic schemes and protective functions.
Being designed in such a way that the availability of protection control power is monitored.gPeriodic testing to verify setpoints. This requirement is not applicable to fuses.
IEEE 741-1997 pdf download
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