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  • Users: sry110
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  1. sry110

    Spinning a de-energized AC motor

    Good Afternoon all, I am working on a drivetrain application where we will have an 11kW, 400V/3-ph/50Hz, 4-pole motor that is 'dragged along' at 120 rpm for a short time period, not to exceed 20 seconds, at initial startup of the system. The motor would be connected to its 400V power supply...
  2. sry110

    Material Selection for Increased Cavitation Erosion Resistance

    Hello All - I am chasing an issue with a torque converter that we use in our mechanical package and I could use some outside advice. The blades in the turbine wheel are exhibiting advanced erosion due to cavitation in the working fluid (ISO VG 32 light turbine oil). The root cause of the...
  3. sry110

    Excessive current at motor startup

    Hopefully this will be a simple one for you electrical guys: I have a 4-pole 3.0kW motor, 380V/3-ph/50Hz, whose data sheet shows D (delta) connection and starting current of 40 Amps. The Customer reports that when they started the motor, it pulled 70 Amps which consequently caused the motor...
  4. sry110

    Soft-start or Variable Speed Drive?

    I am a mechanical guy in need of electrical expertise. I have a motor-driven gear system that has a considerable about of backlash to be taken up before the motor+gear sees the load. When it sees the load, there is a large impact that can damage mechanical components in our system. The impact...
  5. sry110

    Need to reduce impact load due to gear backlash

    I am designing a gear+motor arrangement that will start the driven equipment shaft train from rest ("Breakaway"). The motor is sized such that its 300% starting torque (locked rotor torque) is required to achieve breakaway. There is considerable backlash in the gearbox and inherent to its...
  6. sry110

    Shaft Heating due to Bearing Lube Oil Flow

    I am having a major brain-fart and would appreciate any help. I am looking at an application where I have a 140 lb. carbon steel shaft sitting in a journal bearing that has 1.5 GPM continuous flow of ISO VG32 oil supplied at 131 deg.F. The ambient temperature is -58 deg.F. I want to get the...
  7. sry110

    Basic VFD questions

    I'm considering using a VFD to softly engage a lightly loaded system driven by an AC motor. I have a couple basic questions regarding VFD: 1) Can the VFD be set to control motor speed even if the motor is unloaded? 2) After the speed ramp period expires, can the VFD allow full line voltage...
  8. sry110

    Hub re-balancing after keyway modification...?

    I have a situation where we manufactured and shipped out a steel rigid hub for a high-speed shaft (6000 RPM) with a 3/8" wide x 3/16" deep keyway, but it should have been a 5/8" wide x 5/16" deep keyway. Now the hub is in the Customer's hands and we are trying to find the best way to proceed...
  9. sry110

    Wye-Delta Starter on 6-Lead IEC Motor

    I need some input on wye start / delta run motor starting. I am a gearhead and V=IR is basically the extent of my electrical capability, so please bear with me. First some background: I have a turning gear system consisting of an AC motor, driving into a worm gear speed reducer, and an...
  10. sry110

    Low-pressure Hydraulic Motor

    I have an application where I want to use a hydraulic motor to slowly turn a shaft forward until the clutch on the end of the shaft engages, and the hydraulic motor will then stall out. The torque to turn the shaft is only a couple of lb-ft. The available oil is about 20 psi. We don't need...
  11. sry110

    No-Load Soft Start Operation

    I'm a gear-head dabbling in soft starters and I need help! We make a Turning Gear System which consists of the following: a 7.5 HP AC motor (460VAC / 3-ph / 60Hz, 1800 RPM) driving into a double-reduction worm gear reducer with 173.1:1 overall speed reduction ratio, with a shear pin coupling...

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