Dear Mr. Mbrooke
"...I was not aware of breakers that can make trip decision and interrupt in less than a cycle. Can you link me a page? I'm not doubting you- just want to learn
..."
Che. 1. LV ACB and MCCB with "current-limiting" characteristics have been around on the market for more than 25+ years; manufactured in Italy/brand A..., France/brand S...and Germany/S... etc.
2. I made a general comparison (as a rough indication) fuse vs current-limiting breaker; based on 400V with short-circuit 50kArms. These values may differ from different manufacturers. In both cases, if without SCPD, the current would reach 2.3 x 50kArms=115kApack.
a) Fuse
i)Rated 100A; current-limiting to 12kApack; let-through 60 (kA)2s,
ii) Rated 400A; 25kApack; 1000 (kA)2s,
iii) Rated 600A; 35kApack; 2500 (kA)2s.
b) Breaker [current-limiting type]
i) Rated 100A; 0.6kApack; 30 (kA)2s,
ii) Rated 400A; 9kApack; 35 (kA)2s,
iii) Rated 600A; 10kApack; 35 (kA)2s.
3. Observation:
a) fuse technology has little innovation,
b) breaker technology has advanced and there are very much room for innovation.
Che Kuan Yau (Singapore)