Dear Mr. Coco_HueHueHue (Electrical)
" Based on my little experience, for example an MCC, when buckets have breakers, it is more expensive than when they have fuses...."
Che. 1. In general, it is true because Breaker is say 30% more than fuse-switch or fuse+mounting base. However, breaker or fuse is only say 15% total cost of the bucket assembly. The bucket frame is the same with the exception of different mechanism for switching the breaker instead of fuse-switch. The bucket size and the other components comprising of contactors +thermal over-load and control transformer etc., the switchboard mechanical structure, busbar assembly remained the same. Therefore, the total additional cost for the whole MCC should not be more than 5%.
2. Breaker besides other advantages also prevents "single-phasing" which is sure to happen which damage motors. A single motor damaged by single-phasing would pay for the additional cost. Not to mention the cost for the production down-time to replace the motor +rewinding cost.
3. It is almost impossible to carry out a thermal scan on the components inside a servicing/fully loaded starter bucket.
Che Kuan Yau (Singapore)