Busway Short-Circuit Performance Explained: Icw, Ipk & Fault Level Guide | Yongjin
Understand busway short-circuit performance, including short-time withstand current, peak withstand current, system fault level, protection coordination and how to select the correct busway for a project.
When selecting a busway system, rated current alone is not enough. The busway must also withstand the thermal and mechanical stresses created during short-circuit faults. For this reason, engineers should review short-time withstand current (Icw), peak withstand current (Ipk), system fault level, protection coordination and fault duration before final selection.
Icw represents the RMS short-circuit current that the busway can withstand for a specified period, such as 1 second. It mainly relates to thermal stress in conductors and joints. Ipk, by contrast, represents the maximum instantaneous current peak and is mainly associated with mechanical stress and electromagnetic forces inside the busway.
The required short-circuit performance depends on the system fault level at the busway location. Fault current is usually higher close to transformers and main LV switchgear and may decrease or change further downstream depending on system impedance and configuration.
Busway short-circuit capability must also be coordinated with protective devices such as ACBs, MCCBs and fuses. The objective is to ensure that the busway can withstand the fault until the protection device clears it.
For technical review, customers should provide the SLD, rated current, transformer rating and impedance, prospective fault current, required fault duration, protection device information, busway location and project specification.
Icw means short-time withstand current. It indicates the RMS fault current the busway can withstand for a specified period.
Ipk means peak withstand current. It represents the maximum instantaneous fault-current peak that the busway can withstand mechanically.
No. Rated current applies to normal operation, while short-circuit rating describes busway performance under fault conditions.
Because prospective fault current is often relatively high close to the main power source.
Normally: SLD, transformer data, fault level, required withstand time and protection-device information.
How to Select Busway Rated Current
What Is Icw in Busway?
What Is Ipk in Busway?
Busway Protection Coordination Guide
How to Calculate System Fault Level→
Send Yongjin your SLD, rated current, busway route, number of plug-in points, plug-in box ratings, equipment layout and project specification for preliminary review.