Multi-user access to over 3, medical device standards, regulations, expert commentaries and other documents. Worldwide Standards We can source any standard from anywhere in the world. Learn more about the cookies we use and how to change your settings. Online Tools.
|Published (Last):||15 May 2005|
|PDF File Size:||15.8 Mb|
|ePub File Size:||10.7 Mb|
|Price:||Free* [*Free Regsitration Required]|
The scope of IEC is to describe a method for calculating short-circuit currents in DC auxiliary systems in power plants and substations. Such systems can be equipped with the following equipment, acting as short-circuit current sources:. The data of other equipment may be given by the manufacturer.
This standard is only concerned with rectifiers in three-phase AC bridge connection. It is not concerned with other types of rectifiers. The purpose of the standard is to provide a generally applicable method of calculation which produces results of sufficient accuracy on the conservative side.
Special methods, adjusted to particular circumstances, may be used if they give at least the same precision. Short-circuit currents, resistances and inductances may also be ascertained from system tests or measurements on model systems. In existing DC systems the necessary values can be ascertained from measurements taken at the assumed short-circuit location. The load current is not taken into consideration when calculating the short-circuit current.
It is necessary to distinguish between two different values of short-circuit current:. For more information please refer to the standard itself IEC Each DC source during the fault shall contribute to the total short-circuit current.
The superposition principle is being applied. When one source is observed then the other ones are being disconnected and ignored. The potential DC sources are battery, rectifier, capacitor and machine. The time constant of the battery T B is assumed to be 30 ms.
L BBr is the sum of the battery internal inductance and the line path inductance up to the fault location. Where E C is the voltage of the capacitor terminal before the fault, and R CBr is the sum of capacitor and branch resistance, up to the fault location.
IEC The quasi steady-state current of the capacitor is considered to be 0. The quasi steady-state short-circuit current I kD of a rectifier in three-phase AC bridge connection is:. This equation is valid only if the motor speed remains constant during the duration of the short-circuit fault.
Due to the fact that all non-observed sources at the time are neglected along with their branches it is suggested to use correction factors, which are supposed to improve total results. Each calculated correction factor is multiplied with the partial fault current of the each source, as follows:. IEC Short-circuit currents in d. Jump to: navigation , search. Categories : Calculations Protection. Navigation menu Personal tools Log in. Namespaces Page Discussion.
Search results for “”
According to the IEC 61660
BS EN 61660-1:1997, IEC 61660-1:1997