breaker settings

[steve66]

Square D breaker with micrologics trip settings.

Why does the tr go from 0.5 through 8, and then it has a band with 3 labels that all say 16? From my coordination study, I believe I want to set this at 16, but which 16?

Also, I've never been sure - are these switches, or dials? In other words, can I set the tr somewhere between 4 and 8, or is it one or the other?

 

[jim dungar]

Square D breaker with micrologics trip settings.

Why does the tr go from 0.5 through 8, and then it has a band with 3 labels that all say 16? From my coordination study, I believe I want to set this at 16, but which 16?

Also, I've never been sure - are these switches, or dials? In other words, can I set the tr somewhere between 4 and 8, or is it one or the other?



View attachment 11849

First, these should be treated as switches. They are not intended to be infinitely adjustable.

It is not unusual to find an 'in between setting' will cause the breaker to use its lowest setting.

Rather than buying a special switch, it was probably easier to just use the same value for multiple positions.

 

[ron]

This is more of a guess, but I think the dial has a certain number of positions / clicks, and the Long Time Delay (tr) for this trip unit only goes as high as 16 and they had extra space on the dial, so all three "16"s do the same thing.

Many of the other Micrologic trip units have settings after "16" of 20 and 24, but this one stops at "16".

 

[steve66]

OK, thanks for the info.

I thought maybe I was missing something.

I don't ever seem to get shop drawings on the trip units. And trying to find them on the square d website is hit and miss.

 

[jim dungar]

OK, thanks for the info.

I thought maybe I was missing something.

I don't ever seem to get shop drawings on the trip units. And trying to find them on the square d website is hit and miss.

What kind of shop drawings are you looking for?

Instruction manuals would not be included in submittal information unless specifically requested, and then they would likely be skipped.

I have bookmarked this page
http://www.schneider-electric.us/sites/us/en/support/support.page
I like the tabs for FAQ and Downloads.

 

[Jraef]

In IEC world, little details like that always mean something very specific. When the adjustment switch position becomes a solid bar like that, it means that above that setting, you are entering an area that is higher than the final value (16), but is out of calibration and the results might be unpredictable / inaccurate. So if 16sec. is too short of a long time trip delay for you, you can turn it higher, but we (the mfr) take no responsibility for what might come.

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[big john]

In IEC world, little details like that always mean something very specific. When the adjustment switch position becomes a solid bar like that, it means that above that setting...

Do you have a reference for that? Seems like good information to know.

 

[Jraef]

Do you have a reference for that? Seems like good information to know.

Unfortunately no. I learned it when I went to work for Klockner Moeller in the late 70s, they required that I be trained on all the IEC techniques, terminologies and symbols when I started. In typical German fashion, they had this set of about 40 thick binders called "PR manuals" (PR was from the German words meaning roughly Planning Rationalization) full of exacting details about how everyone was to do their job and why, right down to how your desk drawers were to be organized (not kidding). In there, they had some valuable information that I have unfortunately never seen anywhere else, but find useful to this day. How to read IEC symbols and the excruciating details of what the most seemingly obscure marks and letters mean is something that was drummed into my head at the time. Years later when they closed that office, a former co-worker of mine had become the manager and I asked him if I could have those, he refused, he was starting his own panel shop and knew how valuable they were. Years later when I went to work for Siemens I looked for something similar, knowing that another German company would be just as anally retentive about such things. Unfortunately Siemens USA was still more ITE than it was Siemens Germany at that time, so there was nothing I could get my hands on.

But you might try Google now, look for something like "IEC circuit breaker terminology" or "symbols". I know I had found some info a while ago when trying to train people on what the little letters mean, like I_th, I_n, I_u, U_n etc. mean.