It is a method which breaks short circuit current with both upstream and downstream circuit breakers. For example, in the case that short circuit current at secondary side of a downstream circuit breaker exceeds breaking capacity of the downstream circuit breaker, an upstream circuit breaker works backup protection and break short circuit current. The advantage of this method is economical ,compared with selective coordination.
On the other hand, the disadvantage is that power supply for other downstream circuit breakers which are connected with same upstream circuit is not available, either.
Combinations of cascading are described in our general catalog. We have selected good combinations based on breaking tests.