Semiconductor soft starter 3RW3 8.7.6 Short-circuit protection and fuse coordinations The DIN VDE 0660 Part 102/IEC 60947-4-1 specification distinguishes between two types of coordination, which are referred to as type of coordi- nation 1 and type of coordination 2. With both types of coordination, the short-circuit to be mastered is reliably deactivated. Differences merely lie in the degree of damage caused to the unit after a short-circuit. Type of coordination 1 The motor feeder may be operable after every short-circuit deactivation. Damage to he soft starter is possible. The circuit-breaker itself always reaches type of coordination 1.
Type of coordination 2 Damage to the soft starter or to any other switching device must not have occurred after a short-circuit; only the short-circuit fusing is destroyed. After renewal of the short-circuit fusing, the actual motor feeder can immediately commence operation again. Maximum short-circuit current All specified fuse designs take a maximum short-circuit current of 50 kA into account, thus ensuring that short-circuits amounting to 50 kA can be deacti- vated without jeopardizing persons and systems Motor feeder: Type of coordination 1 Planning note: The fuseless structure is recommended for motor feeders, i.e.
the combina- tion of the circuit-breaker 3RV and the soft starter 3RW30, thus achieving type of coordination 1. Motor feeder: Type of coordination 1 If a motor feeder is to be set up as "type of coordination 2", the feeder must be fused, i.e. overload protection must be provided for the motor. The following can be used for this purpose: All-range fuse 3NE1, uniting line and semiconductor protection Semiconductor protection fuse 3NE8, for which additional fusing of the line must be provided. Comparison of types of coordination 1 and 2 The variant based on type of coordination 2 calls for higher costs than the one based on type of coordination 1.
This is why the fuseless arrangement (type of coordination 1) is recommended. Advantages are Less components in the control cabinet Less wiring complexity Less control cabinet space Lower price Rev. 08/99 8-45