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  • Users: Robert789
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  1. Robert789

    Sawmill Motor - LRA, Softstart, etc.

    I'm evaluating a customer's request to install a 400 HP motor for de-barking trees at a sawmill on our distribution system. I've calculated the voltage dip due to locked rotor amps of the motor and determined that it would not be appropriate to allow it to start at full voltage (about 5.6% dip...
  2. Robert789

    Power Transformer Inrush Calculation

    I'm looking at the existing protection for a bank of three single-phase, 2500 KVA, 44 KV to 13.2/7.62 KV transformers, connected delta-wye, at a rural substation. Protection for this transformer bank was originally supplied by 125 Amp Southern States Type PF fuses. About 2 years ago (before I...
  3. Robert789

    Leading Power Factor Issues?

    Aside from the associated voltage rise, are there any problems that would likely result from a leading power factor on distribution lines during light load periods? I am planning to add some fixed capacitor banks to a rapidly growing area of our electric system, and would like to add slightly...
  4. Robert789

    Buzzing Capacitor Bank

    We have a pole mounted, 200 KVAR per phase, grounded wye capacitor bank on a 12.47 kV rural distribution feeder. During a recent line patrol, it was reported that an audible hum or buzz could be heard around this bank that was 'similar to, but slightly louder than that of a medium sized three...
  5. Robert789

    Motors Failing - 480 Volt, Three Wire Service

    I work for an electric cooperative. We have a customer who tells me that he has had to replace a three-phase pump motor 5 or 6 times within the last year. The pump is supplied by a 480 volt delta service (three phase, three wire). I have not seen the motor yet (its down in a well), nor was...

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