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Type: Posts; User: paulengr

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  1. Replies
    4$$
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    461

    MCC is not the only way to control motors. The...

    MCC is not the only way to control motors.

    The Code is still NEC 430 for all motors but NEC describes what is necessary, not how.

    Prebuilt combination starters which are essentially an “MCC in...
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    4$$
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    683

    RTDs are a customer decision, nkt warranty. They...

    RTDs are a customer decision, nkt warranty. They are cheap so you get however many you want. Some customers use them, some don't. An overload relay is a calculated heat level in a motor. A...
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    Another gotcha is that the actual trip unit will...

    Another gotcha is that the actual trip unit will trip somewhere between 80% and 100% of rating on a standard breaker but at 100% on a full duty breaker. Some brands trip close to 100%, some at 80%....
  4. A 3 wire motor is a 3 wire motor, period....

    A 3 wire motor is a 3 wire motor, period. Internally it can be delta or wye or any number of crazy winding patterns...just ask a winder to show you their tables and it will make your head hurt....
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    At least with Square D you give them the SCCR and...

    At least with Square D you give them the SCCR and they size accordingly. It's part of the options when the part number is generated.

    Sent from my SM-T350 using Tapatalk
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    FM Global requires 25 feet between transformers...

    FM Global requires 25 feet between transformers if they are mineral oil filled. It drops to zero if they are less flammable fluid. Obviously access matters and although I haven't seen a requirement...
  7. Thread: Training

    by paulengr
    Replies
    3$$
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    1,539

    For thermal imaging the vibration schools often...

    For thermal imaging the vibration schools often do it as a one day class. Just look for vibration certification. Realistically this is more of an apprentice thing though. There are just too many...
  8. Thread: Training

    by paulengr
    Replies
    3$$
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    1,539

    For medium voltage terminations, I know 3M at...

    For medium voltage terminations, I know 3M at least offers training free as long as you supply the materials (not cheap). Otherwise there are cable splices schools for utilities that teach you...
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    Substation battery swap time required

    Have a question about time required to swap a "typical" 60-120 cell, 150 lb./cell substation battery. Haven't had to estimate these before.

    NECA Manual of Labor Units gives an estimate of around...
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    12$$
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    1,570

    LED's are current devices. So normally when we...

    LED's are current devices. So normally when we build a power supply the goal is to regulate voltage while allowing the current to fluctuate as needed. In contrast for an LED power supply the goal is...
  11. Thread: OSHA searches

    by paulengr
    Replies
    7$$
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    981

    OSHA Subchapter S is mostly a simplified version...

    OSHA Subchapter S is mostly a simplified version of an early (1980's) edition of 70E and a similar early version of NEC. For example OSHA requires that you test the meter first and then measure for...
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    That depends on what you mean by "grounded...

    That depends on what you mean by "grounded lines". Transmission lines are designed completely differently from distribution lines. A transmission line is typically 69 kV or higher in voltage. They...
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    I usually design the primary OCP based on the...

    I usually design the primary OCP based on the transformer's inrush rating and try to set it as low as practically possible. That still means it's typically around 150-250% in many cases. The major...
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    The basic issue as pointed out is a question of...

    The basic issue as pointed out is a question of what specific events are you trying to plan for. In many areas the possibility of losing both electrical power AND natural gas simultaneously may be...
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    1. OSHA does not REQUIRE an E-Stop in any...

    1. OSHA does not REQUIRE an E-Stop in any regulation EXCEPT for presses.
    2. BUT if you call it an E-Stop then there are certain requirements that apply, mostly laid out in NFPA 79.

    One of the...
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    NEC has a cutoff of #2 somewhere. Only time I see...

    NEC has a cutoff of #2 somewhere. Only time I see smaller is frequently you may see small bare wires connecting lightning arresters on overhead switchgear such as #4. The small size makes it a fuse....
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    Another consideration is not to oversize the CTs...

    Another consideration is not to oversize the CTs because most relay taps are limited to 1-1.5 on the low end.

    I also suggest using microprocessor relays always. They are much more reliable, no...
  18. NEC is a lousy reference for effective grounding...

    NEC is a lousy reference for effective grounding systems. Note that the quoted section refers ONLY to ground rods and not any other type of grounding. In previous versions of the Code, 25 ohms was...
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    Uh, yeah. Speaking from the industrial side of...

    Uh, yeah. Speaking from the industrial side of things, have you ever actually seen what a Code inspector looks for? Let me put it this way on the memorable things I was cited on in the past:
    1. Not...
  20. On shorts, you have line-line, line-ground, line...

    On shorts, you have line-line, line-ground, line a ground a line, and line-line-line. For medium voltage arcing current is close to bolted faults so that simplifies things. Once we get away from...
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    I do MV work all the time. Most is custom gear. I...

    I do MV work all the time. Most is custom gear. I have used a MV vacuum breaker once as a starter. It works, but...I was using an SEL relay so doubling as a breaker/starter settings was no problem....
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    Electrical installations shall be done in a neat...

    Electrical installations shall be done in a neat and workmanlike manner. That's Article 110. NECA speaks more but this one fails the obviousness test. But you won't get a Code official out there on a...
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    Google assymetrical fault current. During a...

    Google assymetrical fault current. During a fault, a purely resistive load has a symmetrical fault current. A reactive load produces a transient current that is superimposed on the symmetrical one....
  24. Prestrike was a problem years ago and so is...

    Prestrike was a problem years ago and so is restrike. They softened the opening as a result. "Modern" VCB's (those made in the last 20 years) don't do it. Check with Toshiba that made the original...
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    If you go corner grounded, it usually requires...

    If you go corner grounded, it usually requires some training, and you've got to check all of the wiring can handle it. Cost is immaterial but some 480/277 delta-wyes I've encountered used 300 V...
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