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Recent content by JB160

  1. JB160

    Calculating solid fan shaft minimum diameter

    The torque called out on the fan rating sheet is 465ft.lbs, That's using a factor of 2. As for attaching the fan & sheave to the shaft are you asking what type of bushing is used? Both ends are keyed also. Thanks, JB
  2. JB160

    Calculating solid fan shaft minimum diameter

    Is there a formula for calculating the minimum fan shaft diameter for a fan that's being driven by an electric motor? Shaft is supported by 2 TAF pillow block bearings and is driven via belts & sheaves. Fan HP Draw: 17.78 Fan RPM: 452 Electric Motor HP: 20 Electric Motor RPM: 1800 Shaft...
  3. JB160

    De-rating AC electric motors for ambient and altitude

    That's supposed to be .00277 in the formula not 00277
  4. JB160

    De-rating AC electric motors for ambient and altitude

    We currently use the following formula to determine if a re-rate of the electric motor is needed. Fan HP = 34.93 Motor HP = 40 Ambient = 110 (((1-(((110))-104)* 00277= .98338 (Since our ambient is over 104 the motor hp is derated by this amount) 40*.98338 = 39.3352 hp We then calculate the...
  5. JB160

    De-rating AC electric motors for ambient and altitude

    I'll elaborate a little more on what it is I'm working on and what it's for. I work for an air-cooled heat exchanger company and some of our units require electric motor drives. We currently have an excel checklist we use to verify/check certain items like design pressure, design temperature...
  6. JB160

    De-rating AC electric motors for ambient and altitude

    I am working on a spread sheet the will de-rate an electric motor if used in high elevations or high ambient conditions. Is there a rule of thumb for de-rating electric motors for use in elevations above 3300' or for use in ambient temps above 104F (40C)? Does it have to be a combo of both...
  7. JB160

    Electric motor help

    Thanks for the info.. BTW.. We use a 1.15 service factor for our motors.
  8. JB160

    Electric motor help

    While doing a run test of an air cooled heat exchanger that uses a 60hp 900 rpm 460V/3PH/60Hz electric motor. The motor was pulling 82 amps as measured on the VFD but the motor at full load is rated for 74.6 amps @ 460 volts. if I calculate the horsepower draw at the 82 amps using the following...

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