Electronics in breakers

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Basically thinking this:





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mbrooke said:
What do the screws to the left and right access? Looks like there is some type of cover for something?
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The screws provide access into the breaker case, for the addition of accessories like shunt trip and auxiliary contacts.

There are no electronics in that particular Square D breaker, but it is no longer in production.
The trip adjustment simply changes the spacing of the magnetic trip armature.
 
jim dungar said:
The screws provide access into the breaker case, for the addition of accessories like shunt trip and auxiliary contacts.

There are no electronics in that particular Square D breaker, but it is no longer in production.
The trip adjustment simply changes the spacing of the magnetic trip armature.
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Thanks! Same for for Larry Fine :)


My apologies for doubting everyone.
 
GoldDigger said:
Just curious why you are so eager to avoid electronics in breakers? EMP effects?
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Question- how do electronic breaker respond to a 3 phase fault in front of them or when being powered up into a 3 phase fault? I'd imagine the voltage collapsing to near zero would prevent them from operating.
 
Jraef said:
Yes. In a nutshell once you get to 1000A and above, the requirement for GF trip has pushed everyone to use ETUs (Electronic Trip Units). Years ago you would add an external GF trip unit to an old T-M breaker, but that meant the mfrs had to support inventory for two different versions of the same frame and once ETUs became cheap, it made no more sense. With some mfrs that philosophy has now drifted down into lower frame sizes so even if you order a non-adjustable trip, you are still getting an ETU without an adjustment means. It varies from one mfr to another though.

In the coming years we will see this more and more in new equipment as the old NEMA molded case breakers become obsolete and the mfrs become more and more global in focus. Rules that apply outside of North America called RoHS (meaning Reduction of Hazardous Substances, referred to as “rohass”) mean that the fiberglass reinforced plastic used in our old style breakers can no longer be used because it cannot be recycled. Newer breaker designs use different materials but required new frame engineering, leading to incompatibility with some older designs. So although we will still see the older designs made for decades into the future here in North America because of the installed base, it will be relegated to retrofit use and become very expensive. What we already have started seeing is new gear being designed and built to only use the new versions of breakers with no options for the older ones. How that relates to the original question is that many of these newer designs will have ETUs starting at 250A frames as standard.
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Doing research it seems to start once you get over 200amps- correct observation?



With that said- can fixed trip standard thermal magnetic breakers coordinate with fused switchboards?
 
And adjustment dials such as this automatically indicate electronics, correct?



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Forgive the basic questions- I've never taken on of these larger frames to pieces.
 
Ok, last question- but how do these dials work? What are they attached too? I can't see semiconductors in a 1970s FPE breaker.



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