IEC 60947-6-1 defines two utilisation categories for transfer switching equipment. PC class equipment is capable of making and breaking short-circuit currents and may also be used to isolate the supply. CC class equipment is capable of withstanding short-circuit currents but cannot be relied upon to break them, so the upstream protective device must clear the fault. The choice affects selectivity, the required conditional short-circuit rating and the maintenance regime.
Source & Authority
This guide is maintained by the engineering team at MOTE Electric, a China-based ATSE manufacturer supplying critical infrastructure projects since 2003. Product specifications referenced are based on IEC 60947-6-1 and internal type-test reports.