Recent content by subtech

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    Poly-phase Induction generator

    At what speed does the rotor operate under normal conditions?
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    Distance relay - impedance characteristic question

    This should help you. It gets right at the heart of your question in a relay technician/relay engineer sort of way. http://www.gedigitalenergy.com/multilin/notes/artsci/index.htm I would download the entire book, but in particular you will want chapters 3 & 4. Post again if you need further help.
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    How to find ampacity of 1/2 by 4 copper buss bar

    You may find this interesting http://www.copper.org/applications/electrical/busbar/
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    Torque angle and power factor of generator

    This is best shown with a diagram, but I try to do this with a simple description. Picture the stator windings around the inner circumference of the machine housing, each phase winding has a "reference" mark midway along its distribution. The rotating magnetic field emanating from the rotor...
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    How would the intense light from a massive thunderous lightning storm

    Interesting... http://en.wikipedia.org/wiki/Lightning
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    Why Does Tighter Twisting in Twisted Pair Cable Increase Transmission Rate?

    Look here: http://en.wikipedia.org/wiki/Twisted_pair hope this helps
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    From Israel: what are these recently added transformer discs?

    I did not watch the entire video, but what I saw in the first 2-3 minutes was nothing unusual. The "discs" are insulators as was previously stated by others. The brown colored insulators most likely were manufactured many years ago. (30-50 yrs) They are made from porcelain. The brown color...
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    Understanding Reactive Power Measurement with Wattmeter Configuration

    The wattmeter responds to current that is in phase with the voltage. In your picture, The reference voltage is Y-B. (picture this vector as horizontal, the base of the delta triangle). The current is from phase R. Its vector would be vertical or at 90 deg to the voltage vector. If the power...
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    Optimizing Motor Start Frequency for 13000 Volt Switch Gear

    Your concern about the number of starts per hour for large motors is correct. Overheating of the rotor windings & rotor structure is the primary concern in that case. To say that starting the motor several times in a few hours caused the switchgear to catch fire is a stretch however. A...
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    Trouble Comprehending Rotating Magnetic Fields

    Speaking very generally, when considering single phase motors one should visualise a pulsing magnetic field eminating from the stator windings and not a rotating one. During the positive portion of the cycle, the uppermost stator pole could be likened to the North pole of a magnet. (of course...
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    What is the difference between emf and voltage?

    As previously stated, EMF stands for electromotive force. It is what makes the electrons move from atom to atom. How much electromotive force is present between two points in a circuit is measured in units of Volts. Voltage is a "Unit of Measure" . If you were to apply enough electromotive...
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    Paralleled Generator Protection

    The reverse power relay(32R) s a standard protection feature for most all synchronous generators. It measures and monitors direction of power flow at the generator terminals. Power (watts) from the gen to the system is normal. Power flow from the system into the gen is abnormal and very much...
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    Electrical bonding in high voltage line maintenance

    The arcing you see is ionization of the air beween the chopper and the line thus creating a conductive path. A small amount of current does flow through the arc path to helicopter thus bringing it to the same potential as the line. This current is often referred to as "charging current". It...
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    Question about Coax for Rural Areas w/ Direct TV

    I'm sure there is a reasonable and durable solution to your co-axial cable problem. These people wrote the book on cable and waveguide. Look here: http://www.commscope.com/andrew/eng/index.html
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    Why do 3 phase balanced faults cause such high fault currents?

    It should be remembered that three phase fault current is limited only by the the reactance of the source and perhaps additionally the R and X of any conductors between the source and the fault point. The closer the fault to the source, the higher one should expect the fault current magnitudes...
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