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  1. Replies
    2$$
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    55

    Carry a bucket of rats with you in a fiberglass...

    Carry a bucket of rats with you in a fiberglass boat. When you get to the flooded house, throw a rat in the water. If it dies, it's not safe. If it lives, get closer and toss in another rat. Repeat...
  2. Thread: VFD's Tripping

    by Jraef
    Replies
    17$$
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    578

    His concern is "tripping out", which unless he...

    His concern is "tripping out", which unless he returns and discloses the meaning of that, means it is all speculation at this point. But as a general rule, I recommend line reactors on almost all VFD...
  3. Thread: NYC power outage

    by Jraef
    Replies
    8$$
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    417

    What usually happens is that a smaller...

    What usually happens is that a smaller distribution transformer blows up, but the sudden loss of load on the system creates a voltage surge that other transformer tap changers cannot react to fast...
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    Some AHJs have issues with Classified breakers...

    Some AHJs have issues with Classified breakers though, you should ask. The way it works is that all PANELS are ONLY UL listed with the breakers made for it, meaning the same mfr. But BREAKERS can be...
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    As far as changing the heater elements, yes. ...

    As far as changing the heater elements, yes.

    On your 15HP stater, that would be a NEMA Size 2 starter, a 5HP only needs a NEMA Size 0, although some MCC mfrs don't go below Size 1. But...
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    195

    One trick I learned long ago is that if you snap...

    One trick I learned long ago is that if you snap a photo image of the blueprint, then use a digital image editor to converty it to a NEGATIVE image, things that are hard to make out become more...
  7. Thread: VFD's Tripping

    by Jraef
    Replies
    17$$
    Views
    578

    Surge protectors are for high energy rapid rising...

    Surge protectors are for high energy rapid rising spikes on the line, well in excess of the line voltage, as in 10x the line voltage. In addition, most VFDs will have MOVs on the rectifier anyway....
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    6$$
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    179

    Chances are that those buckets were built with...

    Chances are that those buckets were built with MCP (mag-only) breakers and the settings may not work for the new motors.
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    So you seem to believe that a 60A breaker will...

    So you seem to believe that a 60A breaker will trip at less than 60A, that is absolutely untrue. In fact it will not likely trip at 60A for a very long time.

    Breakers are not "80% rated", it's a...
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    I really enjoyed this anecdote from a reviewer: ...

    I really enjoyed this anecdote from a reviewer:


    :slaphead::slaphead::slaphead::slaphead::slaphead::slaphead:

    :lol:
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    5$$
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    It does appear as though you might be in over...

    It does appear as though you might be in over your head here a little by virtue of the nature of your questions and assumptions. It would be best if you could learn at the side of someone more...
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    13$$
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    5x more.

    5x more.
  13. Replies
    8$$
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    250

    Fins-out is the best first step for sure. Move...

    Fins-out is the best first step for sure. Move the majority of the heat out of the box.

    Most large drives have internal stirring fans in their packaging already. Adding more is kind of pointless....
  14. Thread: AB140m

    by Jraef
    Replies
    24$$
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    974

    [Intercom announcement] "Uh Bessie, the system is...

    [Intercom announcement] "Uh Bessie, the system is saying that you are a quart low today. Everything all right girl?"
    [Bessie] "Mooo..."
    [Intercom] "Well, pick it up or we're making a reservation...
  15. Thread: AB140m

    by Jraef
    Replies
    24$$
    Views
    974

    Not sure why the tags would make a difference,...

    Not sure why the tags would make a difference, but there is lots of documented evidence of the Common Mode Noise created by VFDs causing cows to quit producing milk because they can feel a sensation...
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    13$$
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    555

    I see it all the time. Some salesman told someone...

    I see it all the time. Some salesman told someone that they can save buckets of money by installing a VFD, with no clue (from either party) as to how that really works. In the early days, the utility...
  17. Thread: VFD's Tripping

    by Jraef
    Replies
    17$$
    Views
    578

    Yes, line reactors. What a line reactor does...

    Yes, line reactors. What a line reactor does mainly for a VFD is to slow down the rise time of any transients on the incoming line side, so that they don't cause the dc bus to spike up and either...
  18. Replies
    16$$
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    539

    SCCR is measured in amps, not kVA. I'm going to...

    SCCR is measured in amps, not kVA. I'm going to assume you mean 65kA.
    Transformers do not have an SCCR and the PSCC (Prospective Short Circuit Current) of the primary does not pass through to the...
  19. Thread: AB140m

    by Jraef
    Replies
    24$$
    Views
    974

    It's the rate of rise of the inrush current...

    It's the rate of rise of the inrush current that's the issue, not the size of the spike. It can cause the transistors to self-commutate (turn themselves on) when not commanded to, which then cascades...
  20. Thread: GFCI requirement

    by Jraef
    Replies
    3$$
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    234

    Your answer is in 210.8.A.5 (of the 2014 code)

    Your answer is in 210.8.A.5 (of the 2014 code)
  21. Replies
    13$$
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    555

    If it never VARIES the speed, i.e. nobody is...

    If it never VARIES the speed, i.e. nobody is going to tweak that potentiometer and it runs at the same speed all of the time, you would be far better off just using another method of running the fan...
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    12$$
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    494

    NFPA 79 has a color code system for control...

    NFPA 79 has a color code system for control panels. That is a "voluntary" standard, born out of the old "JIC" wiring standards. It's what most people use though.

    Green or Green / Yellow = ground...
  23. Thread: AB140m

    by Jraef
    Replies
    24$$
    Views
    974

    Whew... at least I'm consistent...

    Whew... at least I'm consistent...
  24. Replies
    13$$
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    555

    Typically the problem with a bypass contactor...

    Typically the problem with a bypass contactor system on an air handler run via a VFD is that there is often an issue of supply or makeup air flow based on the modulated blower speed using the VFD,...
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    13$$
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    555

    What is the thermostat doing? Is it just on-off? ...

    What is the thermostat doing? Is it just on-off? If so, why have a VFD? What is going to tell the VFD what speed to run at? Start there before spending time on the rest of the issues.
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