GB/T 21066-2007
Electrical installations of ships and mobile and fixed offshore units.Procedures for calculating short-circuit currents in three-phase a.c. (English Version)

Standard No.

GB/T 21066-2007

Language

Chinese, Available in English version

Release Date

2007

Published By

General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China

Latest

GB/T 21066-2007

Scope

This standard specifies the calculation method of short-circuit current that may occur in AC power installations of marine or offshore installations. This calculation method is applicable to the non-grid three-phase AC system with the following characteristics: a) The operating frequency is 50 Hz or 60 Hz; b) It has the system voltage specified in Table 2 of GB/T 7358-1998; c) It has One or more different voltage levels; d) including generators, motors (asynchronous and synchronous), transformers, reactor coils, cables and converter units; The system neutral point is connected to the hull; f) has a neutral point insulated from the hull. This calculation method is applicable to the three-phase symmetrical short-circuit state, that is, the three-phase wires are short-circuited together, or the short-circuit with the hull causes the three-phases to be short-circuited simultaneously. The calculation of the short-circuit current caused by the asymmetrical short-circuit state will result in a relatively high non-periodic (DC) component of the short-circuit current, which is not considered in this standard. The calculation formula and method described in this standard can accurately calculate the short-circuit current in the first 100 ms of the fault state. When calculating a busbar system directly connected to a generator, these formulas and methods can also be used to calculate the short-circuit current for periods greater than 100 ms. When the time period exceeds 100 ms, the control role of the system voltage regulator may be dominant. Calculations in this standard do not take into account the effects of voltage regulators. The purpose of this standard is to give the calculation formulas for the short-circuit current of active components in the power system, and to indicate how to simplify these calculation formulas when calculating the short-circuit current at different locations in the power system. The calculations give an estimate of the prospective short-circuit current, taking into account the maximum influence produced by the active components of the system. Calculation formulas are derived from basic electrical engineering theory related to system components. In order to simplify the calculation method, but at the same time maintain the accuracy of the acceptable results, suitable assumptions are listed and the influence of these assumptions on the calculation results is stated. This standard provides a calculation method. This standard provides guidance on the interpretation and application of the simplified formula and the corresponding results when using the corresponding results for the selection of switchgear. This standard does not provide any information other than the calculation of the short-circuit current in the network. In order to understand the calculation method and results, it is assumed that the person working on the short-circuit current calculation is fully familiar with the principles of electrical engineering.

GB/T 21066-2007 Referenced Document

• GB/T 7358-1998 Electrical installations in ships--System design--General
• IEC 60034-4:1985 Rotating electrical machines; part 4 : methods for determining synchronous machine quantities from tests
• IEC 60038:1983 IEC standard voltages
• IEC 60050-151:1978 International Electrotechnical Vocabulary. Part 151 : Electrical and magnetic devices
• IEC 60050-411:1996 International Electrotechnical Vocabulary - Chapter 411: Rotating machines
• IEC 60050-441:1984 International Electrotechnical Vocabulary. Part 441 : Chapter 441: Switchgear, controlgear and fuses
• IEC 60092-202:1994 Electrical installations in ships; part 202: system design; protection
• IEC 60909:1988 Short-circuit current calculation in three-phase a.c. systems

GB/T 21066-2007 history

• 2007 GB/T 21066-2007 Electrical installations of ships and mobile and fixed offshore units.Procedures for calculating short-circuit currents in three-phase a.c.