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Type: Posts; User: beanland

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  1. Replies
    5$$
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    394

    PCOC

    I agree, this is a POCO issue. Most POCO do not allow unsealed or accessible wireways on the utility-side of the service disconnect. If the PV AC is fed by a panel breaker, then the POCO has no say....
  2. Good Luck

    I did some digging for various lugs and connectors and do not see any easy way to make room for 5 more conductors, it looks like all the spare room has been used up. I think you are looking at a...
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    29$$
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    2,331

    YGyg vs. Dyg

    Issues to consider:
    (1) If the inverter needs to properly sense line-ground voltage to properly implement anti-islanding, you will need to use a YGyg transformer. If you use a Dyg transformer, you...
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    14$$
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    776

    10kA or more

    Be careful assuming 10kA. As suggested by others, if this transformer serves multiple services, it can be large and thus, have a high fault current. For a single home, a 25kVA is fine but these are...
  5. Thread: %IZ vs %Z

    by beanland
    Replies
    3$$
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    300

    One and the same

    %IZ and %Z are the same. When a transformer impedance is measured and scaled to be on a per unit basis, it is expressed as a %. IZ is the voltage rise created by a short circuit of one winding and...
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    14$$
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    1,589

    DC

    I assume this is a DC combiner? It is not unusal to have several strings using PV Wire in air come to a DC combiner and leave as a single circuit using THWN in EMT or PVC.

    You cannot just...
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    28$$
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    1,889

    Upsize EGC

    I agree that upsizing to a larger conductor for the 1000ft run to lower the voltage drop is not a problem and solves the issue. However, NEC requires that the EGC be upsized if the conductors are...
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    5$$
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    1,147

    40C

    40C is 104F, as hot as a spa, but that is the breaker ambient.

    Wire rated for 75C would be at 167F, hot enough to cause skin burn if touched for more than a few seconds, but still within its...
  9. Thread: Motor Calc.

    by beanland
    Replies
    15$$
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    770

    Ugly's

    My Ugly's says a 125Hp 460V motor is 156A. So, would seem 125% is appropriate since there is no other data about the application.
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    11$$
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    821

    Brief Load

    I worked on a clinic with an x-ray a few years ago. The thing is that given how brief x-ray load is, it does not count toward continuous loading; nothing ever has time to warm up. BUT, the generator...
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    0$$
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    347

    LFMC Cover Options

    The most common LFMC uses a PVC jacket. When used outdoors, the PVC-jacket rapidly deteriorates from the UV radiation, indoors it is fine. I have looked into options and see that TPU-covered LFMC is...
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    39$$
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    1,941

    Delta-wye

    The simple answer is no. A delta to wye transformer must have primary fault protection up to 225% and secondary overload protection up to 125%. A line ground fault on the wye side appears as a...
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    19$$
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    2,126

    AHJ acting as Utility Manager?

    I am a little confused. You mention AHJ. That generally refers to the electrical inspector who enforces the NEC and building codes for the governmental jurisdiction. The utility may have concerns...
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    4$$
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    410

    Overcurrent Protection and Inrush

    I agree with the others. A 150kVA transformer when energized at 208V has a 416A full load current. A 125% OCPD would be 600A (next size up). This is unlikely to have inrush problems. (You can go to...
  15. Uncancelled Magnetic Field

    Any time you have a conductor with current flowing there is a magnetic field created. If you have multiple phases, these magnetic fields can cancel. Anytime you have a magnetic material and a...
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    7$$
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    521

    Agree

    I agree. Options are to corner ground the delta, center side ground the delta (240/120V), or add a zigzag bank.

    With only 3 wires and a 3-pole contactor, welding of ONE pole cannot be detected...
  17. Sinusoidal Loads

    Without knowing the harmonic content of the loads, it is not possible to compute the result. If the 100A load is entirely 3rd harmonic, the load could be 300A on the neutral. If we assume essentially...
  18. Pulling Calculations

    First rule, iso-phase, one phase per conduit, never do it with metal conduits. With metal conduit, always 3-phases each conduit. But, where PVC is used, the choice to use one larger conduit versus 3...
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    21$$
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    2,419

    Bluebeam REVU

    I have used REVU with its electrical toolbox to directly create PDFs. Not as powerful as CAD but less expensive and easier to learn.
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    13$$
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    1,192

    Radial vs. Looped

    Radial lines are simple, overcurrent devices are in series, protection can be fuses. System cost is kept lower. The disadvantage is that faults can create large outages.

    Looped lines, even a...
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    7$$
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    810

    Voltage Rise

    You indicate that only one end of the shield is grounded and the other is not. You also say it was one of the open shields that shows signs of damage. There will be standing voltage on the open...
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    2$$
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    759

    89 = Switch

    Don't you love lingo. An "89" device is a switch. An "89L" would typically be a line switch but the "L" is arbitrary. I read this as they want all sources of power labeled. If you label the...
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    4$$
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    1,028

    UL508A and UL1741

    I need to have a protective relay panel built to comply with utility interconnection requirements that will interface with a photovoltaic system; it is designed as backup protection to trip the main...
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    21$$
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    1,565

    MVA/Z is not X/R. It does not work that way. Z =...

    MVA/Z is not X/R. It does not work that way. Z = sqrt(r^2 + x^2) MVA and Z are independent.
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    21$$
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    1,565

    LOL

    I look forward to seeing your answer. Enjoy your anniversary!
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