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ANSI Rule of Thumb for Transformer Polarity

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  1. bec51392 is offline NETA Level II Pro Subscriber
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    ANSI Rule of Thumb for Transformer Polarity

    Facing the High Voltage side of a three phase transformer, where is H1?
    Your Answer: In the center
    Correct Answer: Over the right shoulder
    Help: Transformer Polarity Test Procedures - ANSI Rule of Thumb for Transformer Polarity

    "The placement of the bushings in a three-phase transformer is also standardized. The high voltage bushings are arranged H3, H2, H1, and H0 from left to right when facing the transformer from the high-voltage side."

    May just be because I'm sleepy but I don't understand why H1 is over my shoulder. if I'm looking at it why is it behind me.

    According to IEEE 43, at what level may a PI value indicate that insulation is brittle?
    Your Answer: 8
    Correct Answer: 10

    Indications of Brittle Motor Insulation

    According to IEEE Standard 43, when the PI value exceeds 8 it may indicate insulation that is dried out and brittle to the point that it could fail mechanically as well as electrically.
    Reference: NETA World Summer 2004 Tech Quiz #68

    Also IEEE 43 2013 pg 17 second paragraph. 8 not 10.

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    Quote Originally Posted by bec51392 View Post
    Facing the High Voltage side of a three phase transformer, where is H1?
    Your Answer: In the center
    Correct Answer: Over the right shoulder
    Help: Transformer Polarity Test Procedures - ANSI Rule of Thumb for Transformer Polarity

    "The placement of the bushings in a three-phase transformer is also standardized. The high voltage bushings are arranged H3, H2, H1, and H0 from left to right when facing the transformer from the high-voltage side."

    May just be because I'm sleepy but I don't understand why H1 is over my shoulder. if I'm looking at it why is it behind me.

    According to IEEE 43, at what level may a PI value indicate that insulation is brittle?
    Your Answer: 8
    Correct Answer: 10

    Indications of Brittle Motor Insulation

    According to IEEE Standard 43, when the PI value exceeds 8 it may indicate insulation that is dried out and brittle to the point that it could fail mechanically as well as electrically.
    Reference: NETA World Summer 2004 Tech Quiz #68

    Also IEEE 43 2013 pg 17 second paragraph. 8 not 10.
    The question has been asked before, and the intent is that your standing on a GSU type transformer centerline facing secondary. Question should be worded better.

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  5. bec51392 is offline NETA Level II Pro Subscriber
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    Quote Originally Posted by Kalbi_Rob View Post
    The question has been asked before, and the intent is that your standing on a GSU type transformer centerline facing secondary. Question should be worded better.
    Ohhhhhh. See that makes sense but that is absolutely NOT what I thought of. Even so... that makes it more wrong. the question says facing the high side. if you are on top of the transformer, centerline, facing high side, H1 is at your left foot. Xs are over your shoulder.

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    Quote Originally Posted by Kalbi_Rob View Post
    The question has been asked before, and the intent is that your standing on a GSU type transformer centerline facing secondary. Question should be worded better.
    Where did standing on top of the equipment come from? "Over your shoulder" might not be the best term, unless you imagine having an out of body experience and you are standing behind yourself. Maybe it should say "to the far right?"

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    Quote Originally Posted by bec51392 View Post
    According to IEEE 43, at what level may a PI value indicate that insulation is brittle?
    Your Answer: 8
    Correct Answer: 10

    Indications of Brittle Motor Insulation

    According to IEEE Standard 43, when the PI value exceeds 8 it may indicate insulation that is dried out and brittle to the point that it could fail mechanically as well as electrically.
    Reference: NETA World Summer 2004 Tech Quiz #68

    Also IEEE 43 2013 pg 17 second paragraph. 8 not 10.
    We should probably start a new thread for this one but I think the intent was sort of a trick question because IEEE says "exceeds" 8, so the next possible answer would be 10.

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  11. bec51392 is offline NETA Level II Pro Subscriber
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    Quote Originally Posted by SecondGen View Post
    We should probably start a new thread for this one but I think the intent was sort of a trick question because IEEE says "exceeds" 8, so the next possible answer would be 10.
    ehhh yeah I see what you are saying...

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  13. bec51392 is offline NETA Level II Pro Subscriber
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    Quote Originally Posted by SecondGen View Post
    Where did standing on top of the equipment come from? "Over your shoulder" might not be the best term, unless you imagine having an out of body experience and you are standing behind yourself. Maybe it should say "to the far right?"

    Click image for larger version. 

Name:	three-phase-transformer-polarity-left-to-right.png 
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    So did we decide this question just sucks? I am studying for the 3 now and got it again. Messed my head up all over again.

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