BS IEC 61363-1:1998 pdf download – Electrical installationsof ships and mobile andfixed offshore units —— Part 1: Procedures for calculatingshort-circuit currents in three-phasea.c.

BS IEC 61363-1:1998 pdf download – Electrical installationsof ships and mobile andfixed offshore units —— Part 1: Procedures for calculatingshort-circuit currents in three-phasea.c..
The calculation methods are for use on unmeshed three•phase alternating current systems,
a) operating at 50 Hz or 60 Hz;
b) having any system voltage specified in IEC 60092-201 table 2;
C) having one or more different voltage levels:
d) Comprising generators, motors (both synchronous and asynchronous). transformers. reactor coils, cables. and converter units:
e) having their neutral point connected to the ship’s hull through an impedance (designed to limit the short-circuit current flowing to the ship’s hull);
f) having their neutral point isolated from the ship’s hull.
The calculation procedures are for a three-phase symmetrical short-circuit condition ie. three- phase conductors shorted together, or shorted to the ships hull and for which the short•circuit occurs on all three poles simultaneously. The calculation of short-circuit currents resulting from asymmetric Short-circuit conditions can lead to higher aperiodic (d.c.) components of the short- circuit current and is not considered in this standard.
The calculating formulae and methods described produce sufficiently accurate results to calculate the short-circuit current during the first lOOms of a fault condition. They can be used to calculate the short-circuit current for periods longer than 100 ms when calculating on a bus system to which the generators are directly connected. For time periods beyond 100 ms the controlling effects of the system voltage regulators may be predominant. Calculations ncludlng the voltage regulator effects are not considered in this standard.
The object of this standard is to present formulae for calculating short-circuit currents of the active components of an electrical system and to Indicate how such formulae may be simplified when calculating the short-circuit current at various locations on the electrical system. The calculations give estimates of the prospective short-circuit current when the system’s active components produce their maximum contribution.
The calculating formulae are developed from basic electrical engineering theories relevant to the system components. To simplify the calculation methods yet retain an acceptable level of accuracy in the results, suitable assumptions are outlined and their effects on the calculation results indicated.
This standard provides a calculation procedure. It gives guidance on the interpretation and application of simplifying formulae and the corresponding results when applied to Ihe selection of switchgear. The standard is not intended to provide any other information other than the calculation of the short-circuit current which may flow In the network.
In order to understand the mettods, and consequences of the results, it is assumed that the person responsible for initiating the short-circuit current calculations, is thoroughly familiar with valid electrical engineering fundamentals.
2 NormatIve references
The following normative documents contain provisions which, through reference In this text, constitute provisions of Ibis International Standard. At the time of publication, the edátions Indicated were valid All normative documents are subject to revision, and parties to agreements based on this International Standard 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 60034-4:1985, Rotating electrical machines — Part 4: Methods for determining synchi’onous machine quantities from tests
IEC 60038:1983, IEC standard voltages
IEC 60050(151): 1978, International Electrotechnical Vocabulary (1EV) — Chapter 151: Electrical and magnetic devices
IEC 60050(411)1996. International Electrolechnical Vocabulary (1EV) — Chapter 411: RotatIng machinery
IEC 60050(441); 1984 International Electrotechnical Vocabulary (1EV) — Chapter 441:
Switchgear. controlgear and fuses
IEC 60092-201:1994, Electrical installations in ships — Part 201: System design — Oeneral IEC 60092-202:1994, Electrical installations in ships — Part 202: System design — Protection lEG 609091988, Short-circuit current calculation in three-phase ac. systems
3 Definitions, symbols, subscripts and superscripts
3.1 DefinItions
For the purpose of this International Standard the following definitions and symbols apply.
3.1.1
short cIrcuit
accidental or intentional connection, by a relatively low resistance or impedance, of two or more points in a circuit which are normally at different voltages. 11EV 151 -03-41]
3.12
short-circuit current
over-current resulting from a short circuit due to a fault or an incorrect connection in an electric circuit. [1EV 441-11-07]