MCCB Magnetic elements

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You are not telling me anything I do not already know, it just seems you are derailing this thread as usual. It seems you do not even read threads from the start and enjoy jumping in the middle and taking things off track.
 
zog said:
You are not telling me anything I do not already know, it just seems you are derailing this thread as usual. It seems you do not even read threads from the start and enjoy jumping in the middle and taking things off track.
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Agreed that it seems that way but I'm guessing this is an instance of trolling that occurs naturally due to Haja's disposition rather than an intentional attempt to derail the conversation.

He is of course right in his most recent statement (mainly since it was copy/pasted directly from the referenced document). But the statements have no relevance to what you and Jim correctly claimed. If the inst. component of the OCPD reacted as a vertical line and did not stretch to the right, that would imply that fault currents that are greater multiples of rated current than the vertical line would not cause the OCPD to react, which is of course ridiculous.
 
To go back to the original question that Zog posted, others stated correctly that the components used in manufacturing result in the differences. I agree that this is a great contributing factor to being difficult to series rate different breakers.

In the context of coordination studies, that is what makes studies of existing facilities so challenging (interesting). At times the adjustments could be made to the settings of the OCPD to make the coordination selective to an acceptable degree, although there's usually some degree of miscoordination somewhere in the system. Other times the IT curves just don't work out and replacement is necessary.
 
skeshesh said:
To go back to the original question that Zog posted, others stated correctly that the components used in manufacturing result in the differences. I agree that this is a great contributing factor to being difficult to series rate different breakers.

In the context of coordination studies, that is what makes studies of existing facilities so challenging (interesting). At times the adjustments could be made to the settings of the OCPD to make the coordination selective to an acceptable degree, although there's usually some degree of miscoordination somewhere in the system. Other times the IT curves just don't work out and replacement is necessary.
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Thanks, and to add to that just because a curve coordinates in software that does not mean the actual breakers will due to the allowed tollerances. The series testing project I just finished up showed exactly that and I was puzzled with the results, but I think Jim answered it right on post #2, I was just curious to what the specifics of the different materials and designs used.

(Suprised Jraef has not chimed in here yet, seems right up his alley)
 
zog said:
it just seems you are derailing this thread as usual. It seems you do not even read threads from the start and enjoy jumping in the middle and taking things off track.
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Your main question is 'why the max clearing time for some breaker types (INST) is the same as current increases while other types show some inverse time characterstics in the INST range'.
My intention is to explain that only.For that purpose,I first wanted to clarify how it is impossible that true INST range can have inverse time response.But if such an approach of mine trolls you i.e excites only unpleasant feelings in you,it is sure sign to me that I must stop,because I want to enjoy my technical deliberations with the OP . Do you enjoy my technical deliberation or not?
 
zog said:
Thanks, and to add to that just because a curve coordinates in software that does not mean the actual breakers will due to the allowed tollerances. The series testing project I just finished up showed exactly that and I was puzzled with the results, but I think Jim answered it right on post #2, I was just curious to what the specifics of the different materials and designs used.

(Suprised Jraef has not chimed in here yet, seems right up his alley)
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I intended to chime in as it was an interesting topic. After reading post #8, I went elsewhere. So, my answer to post #25 is, NO.
 
zog said:
The series testing project I just finished up showed exactly that and I was puzzled with the results...
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Is it possible for you to share the results in some detail? Unless you already have in another thread; I was unavailable for a little while and did not manage to keep up with the posts.
 
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