IEC 61660-2:1997 pdf download – Short-circuit currents in d.c. auxiliary installationsin power plants and substations – Part 2: Calculation of effects.
This part of IEC 61660 describes a method for calculation of the mechanical and thermal eftects on rigid conductors caused by short-circuh currents in d.c. auxiliary installations in power plants and substations, Such systems may contain the following items of equipment which act as sources, as well as contributing to the short•clrcult currents:
— rectifiers in three-phase a.c. bridge connection for 50 Hz;
— stationary lead-acid batteries;
— smoothing capacitors;
— d.c. motors with independent excitation.
This standard provides a method which has wide application, and which gives results of sufficient accuracy. The calculation method is based on substitute functions, which cause approximately the same maximum stresses in the conductors and the same forces on the supports as the actual electromagnetic force.
The standardized calculation procedures of clauses 2 and 3 are applicable for the electromagnetic effect on rigid conductors and the thermal effect on bare conductors and electrical equipment. respectively.
For cables and insulated conductors, however, reference is made to IEC 60949 and IEC 60986. for example.
Only d.c. auxiliary installations in power plants and substations are dealt with in this standard. In particular, the following points should be noted:
— The calculation of short-circuit currents should be based on IEC 61660-1.
— Short-circuit duration used in this standard depends on the protection concept, and should be considered In that sense.
— These standardzed procedures are adjusted to practical requirements, and contain simplifications with safely margins. Testing or more detailed methods of calculation or both may be used.
— In clause 2 of this standard. Only the stresses caused by shorl.circult currents are calculated. Furthermore, other stresses can exist, such as those caused by dead-load. operating forces, or earthquakes. The combination of these loads with the short-circuit loading should be part of an agreement and/or given by standards, for example erection codes.
The following normative documents contain ptovlslons which, through reference in this text constitute provisions of this part of IEC 61660. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this part of lEG 61660 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60865-1: 1993, Short-circuit currents — Calculation of effects — Part I: Definitions and calculation methods
IEC 60865-2: 1994, Short-circuit currents — Calculation of effects — Part 2: Examples of calculation
IEC 60949: 1988, Calculation of thermally permissible short-circuit currents, taking into account non-adsabahc heating effects
IEC 60986: 1989. Guide to the short-circuit temperature limits of electric cables with a rated voltage from 1.8/3 (3.6) kV to 18/30 (36) kV
IEC 61660-1: 1997. Short-circuit currents in d.c. auxiliary installations in power plants and substations — Part 1: Calculation of short-circuit currents
13 Symbols and units
All equations used In this standard are quantity equations In which quantity symbols represent physical quantities possessing both numerical values and dimensions.
The symbols used in this standard and their exemplary SI units are given in the following lists.
IEC 61660-2:1997 pdf download – Short-circuit currents in d.c. auxiliary installationsin power plants and substations – Part 2: Calculation of effects
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