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Thread: Why do they both trip???

  1. #201
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    Quote Originally Posted by Ingenieur View Post
    you didn't even hear the hoof steps apparently
    why is what you think more important than what I think?
    You have gone on repeatedly and in depth about the breakers possibly not having thermal properties. Yet the answer was easily found because the part number was given by the OP.

    It has been a long thread, but I don't recall that the OP was able to tie a definitive external event, like a power loss or sag, to the tripping of the breakers.

    Blindly turning up breaker Short Time and Instantaneous (magnetic) settings may be becoming 'frowned upon' in today's Arc Flash Incident Energy minded environment.
    FWIW, I have a meeting, later today, where we will likely be discussing the risk to operations, and possible reduced equipment damage, from shutting down a data center rather than letting an arcing fault continue.
    Just because you can, doesn't mean you should.

  2. #202
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    Quote Originally Posted by jim dungar View Post
    You have gone on repeatedly and in depth about the breakers possibly not having thermal properties. Yet the answer was easily found because the part number was given by the OP.

    It has been a long thread, but I don't recall that the OP was able to tie a definitive external event, like a power loss or sag, to the tripping of the breakers.

    Blindly turning up breaker Short Time and Instantaneous (magnetic) settings may be becoming 'frowned upon' in today's Arc Flash Incident Energy minded environment.
    FWIW, I have a meeting, later today, where we will likely be discussing the risk to operations, and possible reduced equipment damage, from shutting down a data center rather than letting an arcing fault continue.
    I do agree that today's focus on arc flash can impact decisions on where to set those, but from equipment protection perspective shouln't maximum settings still be considered protecting the equipment? Not talking about what a VFD or some electronic device may want for line side protection, but just protection of the panelboard, and circuit conductors in general. Different settings for the main VS the branch breakers just adds some selective coordination to the mix so that if a branch trips hopefully the main doesn't trip as well.

  3. #203
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    Quote Originally Posted by Ingenieur View Post
    ..why is what you think more important than what I think?
    Try framing your answers as a question, rather than a whipping stick.

    Quote Originally Posted by Ingenieur View Post
    ...the breakers are set correctly and can't be set higher for some reason
    Why solve the problem right away, when "a Dog and Pony Show" is more fun.

    After all, the customer is paying for the show. Besides, watching gullable forum members boil over is also entertaining.
    Roger Ramjet NoFixNoPay

  4. #204
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    Quote Originally Posted by kwired View Post
    I do agree that today's focus on arc flash can impact decisions on where to set those, but from equipment protection perspective shouln't maximum settings still be considered protecting the equipment?
    I did not say equipment protection.

    The concept is to reduce the amount of damage that results. Why expose an entire data center to voltage fluctuations created during an arcing fault that may last for several seconds?
    Just because you can, doesn't mean you should.

  5. #205
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    Quote Originally Posted by jim dungar View Post
    You have gone on repeatedly and in depth about the breakers possibly not having thermal properties. Yet the answer was easily found because the part number was given by the OP.

    It has been a long thread, but I don't recall that the OP was able to tie a definitive external event, like a power loss or sag, to the tripping of the breakers.

    Blindly turning up breaker Short Time and Instantaneous (magnetic) settings may be becoming 'frowned upon' in today's Arc Flash Incident Energy minded environment.
    FWIW, I have a meeting, later today, where we will likely be discussing the risk to operations, and possible reduced equipment damage, from shutting down a data center rather than letting an arcing fault continue.
    I asked if they did
    the OP said they did not
    the data sheet confirms they do

    turning a CB up from 300% is not an issue nor is it done blindly (I bet no 'study' was done to set them initially, just left as is from the factory)
    they are set too low and is the root cause of his issues



  6. #206
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    Quote Originally Posted by ramsy View Post
    Try framing your answers as a question, rather than a whipping stick.


    Why solve the problem right away, when "a Dog and Pony Show" is more fun.

    After all, the customer is paying for the show. Besides, watching gullable forum members boil over is also entertaining.
    an answer posed as a question s not an answer is it, lol


    I guess if you can milk the cow, milk the cow until you get blood



    turn the breakers up
    'problem' solved, as in there is no problem, other than the cb's set too low



  7. #207
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    Quote Originally Posted by Ingenieur View Post
    (Perhaps you should) "turn the breakers up" (? is more polite)
    Even if harmonics from the LED-lighting subpanel trips those breakers, such harmonics should probably be ignored.

    I'm beginning to doubt adjustable breakers were ever specified for that install, or if they belong there at all?
    Roger Ramjet NoFixNoPay

  8. #208
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    Quote Originally Posted by ramsy View Post
    Even if harmonics from the LED-lighting subpanel trips those breakers, such harmonics should probably be ignored.

    I'm beginning to doubt adjustable breakers were ever specified for that install, or if they belong there at all?
    Makes you wonder why that fancy stuff is specd then never set. Maybe because 10% of $500 is more than 10% of $100 and nobody wants to pay for expertise to set it? Assuming it was never done of course.
    Tom
    TBLO

  9. #209
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    Quote Originally Posted by jim dungar View Post
    I did not say equipment protection.

    The concept is to reduce the amount of damage that results. Why expose an entire data center to voltage fluctuations created during an arcing fault that may last for several seconds?
    I understand that, but isn't that more of a design issue for the data center then it is if the load were primarily across the line connected motors? Cranking those settings up to the max probably isn't that big of an issue for the motors installation when it comes to protection of the equipment.

    OP seems to have some mixture of load types, so his design issues probably fall somewhere in between the motor installation and the data center.

    Add: I guess my main point here is the NEC perspective on these devices is they are there to protect:

    The service conductors from overcurrent

    The feeder conductors from overcurrent

    The branch circuit conductors from overcurrent

    Other items that are a part of the above like switchboards, panelboards etc, from overcurrent.

    Those devices alone should protect those items from severe damage even if set at their maximum magnetic trip - assuming the AIC rating is lower then the available fault current or that downstream devices are series rated with the upstream devices.

    If you want to select a device that also provides extra protection that may be necessary for something like a data center that is optional, or you can use supplemental devices to accomplish that as well.
    Last edited by kwired; 03-22-17 at 11:20 AM.

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