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  1. Replies
    12$$
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    1,029

    Check capcitance

    Things to check:
    1. Is there a grounding transformer on that section of isophase? Does that section operate ungrounded when the generator breaker is open? GSU and Auxiliary transformers are...
  2. Could be several reasons: Provide an isolated...

    Could be several reasons:
    Provide an isolated ground source so plant ground faults do not affect utility relaying and utility faults don't trip plant.
    Add impedance to reduce short circuit fault...
  3. Voltage at the VT will still be accurate but the...

    Voltage at the VT will still be accurate but the voltage drop in the wiring to the meter may add errors.

    If the meter draws 10VA or about 0.1 amp (typical for an electronic device's voltage...
  4. Symmetrical Components Example

    For a great visual example of Symmetrical components, search for Alex McAherns Power Quality Teaching Toy (https://www.powerstandards.com/PQTeachingToyIndex.php) and download the simulation.

    It...
  5. Thread: Current Flow

    by rcwilson
    Replies
    68$$
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    9,274

    If you are asking about control wiring diagrams...

    If you are asking about control wiring diagrams try this:

    1. Find the power source and identify the hot and neutral leads/terminals.
    2. Imagine current flowing from the "hot" power terminal to...
  6. Thread: Good Old Daze

    by rcwilson
    Replies
    16$$
    Views
    3,364

    Old Breakers

    I think those large black switches with the horizontal handles are actually circuit breakers. There are three dash pot trip units under each breaker with a linkage up to the trip element. The dash...
  7. Replies
    5$$
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    1,148

    I've seen similar installations at a satelite...

    I've seen similar installations at a satelite base station that was next to commercial TV transmitter towers and on military/defense installations to prevent noise coming into the facility or RF...
  8. Replies
    3$$
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    2,000

    On a couple of power plant construction projects...

    On a couple of power plant construction projects in Canada, the parking lots had "bull rails" with outlets for block heaters fed from DP panels that were equipped with a control system that sequenced...
  9. Replies
    10$$
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    3,241

    The 1960 vintage Surge milkers on my uncle's farm...

    The 1960 vintage Surge milkers on my uncle's farm pulsed or surged every couple of seconds. They did not continuously suck. Maybe the milkers are randomnly in synch and the VFD is responding to...
  10. Correct. Calculate the voltage at the connection...

    Correct. Calculate the voltage at the connection to the heat trace circuit cable. Do not include voltage drop in the heat trace cable itself.

    However, voltage drop along the heat trace cable can...
  11. Replies
    10$$
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    10,932

    If you don't have the transfomer test data, you...

    If you don't have the transfomer test data, you will have to make some assumptions.

    The data you have is the %Z for H-X, H-Y & X-Y. Verify that the values are all on the same base, usually the H...
  12. Replies
    32$$
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    6,569

    Poll: On my first job ( a 60MW power plant) with this...

    On my first job ( a 60MW power plant) with this design build company, we showed home run arrows for most conduit runs with a cable number, no conduit numbers. It was up to the electricians to field...
  13. Replies
    16$$
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    10,226

    IMHO, as reinforced by a client whose...

    IMHO, as reinforced by a client whose transformer failed, the primary protection should clear the transformer before a secondary through fault reaches the damage curve. On a project not...
  14. Thread: is it just me

    by rcwilson
    Replies
    36$$
    Views
    6,662

    Looks like a good design to me. Compare the...

    Looks like a good design to me.

    Compare the amount of copper on the bus work with the metal surface of the fuse. The difference in cross section is pretty significant. To make up for the lack...
  15. Consider zone interlocking protection which is...

    Consider zone interlocking protection which is available on most LV circuit breakers and can be applied to most modern relays.

    The feeder breaker's protection has an output contact or signal that...
  16. You need to get the specific information from the...

    You need to get the specific information from the manufacturer.

    Usually, GSIS switchgear is designed to withstand normal voltage at 1 atmosphere of pressure. At that pressure, the SF6 gas and...
  17. Thread: GE Breakers

    by rcwilson
    Replies
    44$$
    Views
    7,491

    I was doing that work 25-30 years ago on a...

    I was doing that work 25-30 years ago on a combination of existing and new equipment. My 5% figure was a guess. Most failures I recall were high millivolt drop on molded case breakers and tripping...
  18. Thread: GE Breakers

    by rcwilson
    Replies
    44$$
    Views
    7,491

    When I did circuit breaker testing years ago,...

    When I did circuit breaker testing years ago, supposedly following NETA specs, the instantaneous function was tested first. The test set had a pulse feature that pushed current for a short pulse, ...
  19. Welcome to the forum. One reason many of us...

    Welcome to the forum. One reason many of us can't answer your question thoroughly is we don't fully understand the TNC-S and other designations for grounding methods. That system is not used in...
  20. I haven't found a code reference for separation...

    I haven't found a code reference for separation of underground power and communications lines. Utility may have some standards.

    If there are concerns about EMI, use rigid steel conduit.
  21. Isophase bus is used to connect large generators...

    Isophase bus is used to connect large generators to step-up transformers. 1200A-44,000A continuous ratings are available. Large hydro generators use the high ampacity bus. Momentary short circuit...
  22. Replies
    3$$
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    1,104

    Table looks like IEC CT sizing information for...

    Table looks like IEC CT sizing information for various sizes of transformers or services. The CT specification, ratios and 1 A secondaries look like IEC.

    Top row lists the transformer/load size...
  23. Replies
    1$$
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    922

    Old Cutler-Hammer data book: 112.5 kVA 600V...

    Old Cutler-Hammer data book:

    112.5 kVA 600V Dry Type Transformers, Typical Impedance :

    DT-3 150C rise: 6.2%
    DT-3 115C rise: 5.1%
    DT-3 80C rise: 4.3%

    K-4 115C rise: 5.4%
    K-4 80C rise:...
  24. Parallel conductors are assumed to share load...

    Parallel conductors are assumed to share load equally. If 1216 is the amapcity required: 3/phase = 1216/3 = 405.3 A. 4/phase = 1216A/4 =304 Amps. 5/phae = 1216/5 = 243.2 A

    (Verify that 1216 A...
  25. Replies
    3$$
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    1,655

    Faults less than 8,000 A and above 12,000 A will...

    Faults less than 8,000 A and above 12,000 A will be cleared by the tie breaker, as long as other loads on the Main are less than about 1000A. (Tie doesn't see those loads).

    A fault in the 8 -11 kA...
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