Third Edition of IEC 60909-3 Addresses Short-Circuit Currents in Three-Phase AC Systems
April 15, 2009 // Published as a news service by IHS
The International Electrotechnical Commission (IEC) released the third edition of IEC 60909-3 - Short-circuit currents in three-phase alternating current (AC) systems - Part 3: Currents during two separate simultaneous line-to-earth short circuits and partial short-circuit currents flowing through earth.
It specifies procedures for calculation of the prospective short-circuit currents with an unbalanced short circuit in high-voltage, three-phase AC systems operating at nominal frequency 50 hertz (Hz) or 60 Hz.
The third edition of the standard also includes an annexed redline version that shows all changes from the previous edition, according to the IEC.
The ability to withstand maximum short-circuit currents, including their thermal and mechanical effects, concern all electrical apparatus and equipment.
Thus, short-circuit calculations are important for the electrical manufacturing industry, industrial power plants and power utilities to ensure safe design of components and systems to prevent damage of equipment and interruptions of public electric supply systems. The safety of involved personnel and third parties is also at stake, according to the IEC.
The standard was developed by IEC Technical Committee 73: Short-circuit currents.
Source: International Electrotechnical Commission (IEC).