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Recent content by dewone

  1. dewone

    Electrical Cable Bend Radius

    The cable manufacture will give the min bend rad for the cable in the cut sheets. This varies per cable type, insulation, and thickness. I'd use the manufactures spec. If ABS has a more stringent spec use that. Again you will need to know cable material, and gauge if it has one.
  2. dewone

    MV(20kV) Vacuum circuit breaker and surge arrester

    I've seen them on the breaker, and on the load side in the cells.
  3. dewone

    breaker trip on ground fault

    How do you know the GF tripped you. On the first version of SST there are no indicators, on the second design there are indicators. Makes that an easy call. Is the SST a four wire, or the 3 wire.
  4. dewone

    Transformer Yoke and Frame

    The yoke connection can also be a high resistance grounding point, a neutral or four wire connection point, or simply grounded direct: low resistance ground. Depends on how your using the transformer.
  5. dewone

    High Voltage Connections for Dummies

    Hope this helps you figure the how. When you apply your stress cone or the build up of insulation. You first gap the cable by peeling the layers back down to the conductor. So from the end of the conductor where you crimp on the connection back, you peel so many inches of insulation to the semi...
  6. dewone

    TESTING of 1250kVA TRANSFORMER

    If it was properly stored. Oil sample, megger, turns ratio, and test any devices on the unit ie. pressure vacuum, oil level, temp gauge fan start, alarm, trip... Should give you a good indication of weather to energize. Had it been just shoved aside. The above plus Doble testing.
  7. dewone

    transformer mothball- keep in place for a few months

    Be sure to place a nitrogen blanket on the unit. Also keeps out moisture with out a heat source. For an extended period of out of service. Drain oil, and blanket with nitrogen. SphincterBoy has the other precaution covered ground all bushings.
  8. dewone

    Oil analysis results

    Maybe try a Fault metal test ASTM D-3635icp, and a Corrosive Sulfur test ASTM D-1275. Agree with the above retest DB on your own just to compare. Is this a conservitor type trans or sealed with a top air space.
  9. dewone

    Cleaning High Voltage Lightning Arresters

    For the tuff dirt. I use collinite No 240 with a scotch brite pad, then buff with clean rag to a sparkleing waxed finish. You can reach Collinite at 315-732-2282 (Happen to have can on my desk now)!
  10. dewone

    TRANSFOMRER TEMPERATURE READING VS TEMPERATURE RISE

    In most cases the alarm contacts are set @ 75C and shut off at 85C
  11. dewone

    Noisy Tranformer - Bad core laminations?

    Well alot good info has been discussed and without an electrical solution I suggest. Placing rubber under the transformer mounts to reduce the noise transfer to the floor that will help reduce the total amount of noise in the room.
  12. dewone

    Big motor starting

    Can the motor be Wye, Delta connected. Six leads in the condulet.
  13. dewone

    Utility distribution feeder reclosing timing

    Typical reclose times are like 7-10 seconds after trip. 3 Shots then lockout. Schemes I've seen anyway.
  14. dewone

    Acceptable Leakage current value at dielectric Withstand test

    Contact the cable manufacture for the amount of time per lengh, test voltage, and allowable leakage current.
  15. dewone

    Performing "retorque" of bolted electrical bus connections

    Checking the torque with a torque wrench should not yeild the tensil of the bolt any greater than the original torquewas set to by the manufacture. It should be re-torqued to the same value. You are only ensuring it hasn't vibrated loose. I can understand where someone over torqued a bolt and it...

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