Sensitive Circuit Breakers
A couple years back we had to add a UL489 circuit breaker to one of our machines.Â I ended up choosing the Weidmuller 9926 series because it was DIN rail mount, compact (only 26mm wide for double pole), affordable, and readily available.Â The 9926 worked fine in the original machine, which had a fixed panel for the electrical components.
Then another customer required a UL489 circuit breaker in our smaller machine, where the electrical equipment is mounted in a slide-out drawer.Â I made the easy decision, and specified the 9926 series again.Â Â When the first new machine was assembled, the technician noticed that if he hit the side of the electrical drawer, the circuit breaker would trip.
So we did some moreÂ testing and verified a bit ofÂ mechanical shock would cause the 9926Â to trip to the OFF position.Â However, when the electrical drawer was retracted, it was hard to get the circuit breaker to trip, so we didn’t change the circuit breaker.Â But I still wasn’t comfortable with the possibility of shock-induced trips, so I looked at other circuit breakers.
I choose because the ABL Sursum UL series from Altech because the price was within reason, I was able to get a sample to test, and they were impervious to shock.Â The Altech L series were better than the Weidmuller 9926, but I could still get them to trip via hitting them.Â Then I had the challenge of finding space, because the DIN Rail was full, and the ABL UL series was 10mm wider than the 9926, which I solved by finding a narrower power supply.
On my last trip to Excess Solutions, they had a large selection of DIN rail circuit breakers; I couldn’t resist testing them to see how shock sensitive they were; all the ones I tested passed, including models from ABB, Eaton, and Merlin Gerin.
As a side note, I enjoy seeing the where the circuit breakers were made.Â Here, the 9926 takes the prize, because it is made in Lesotho, a country inside of South Africa, by CBi (Circuit Breakers Incorporated).Â The Eaton model was made in Spain.Â I believe (but am not 100% sure) the Altech L series in made in India.Â The ABL Sursum and ABB breakers were made in Germany.CC
Final note: the 9926 series has several pluses, including compact size and competitive price, and we haven’t heard of any problems with them in our machines in the field, but they aren’t a good choice for high vibration environments or other places where they might receive mechanical shock.