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  • Users: Jieve
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  1. Jieve

    Evaporation from Tank (Theory Question)

    Assume I have an enclosure, say 4ft x 3ft x 3ft which is closed but not completely airtight. There is a small cylindrical tank of ethanol, say 1.5ft D x 1ft H, with a 1.5 inch pipe sticking out the top, open to the atmosphere (enclosure space). The liquid ethanol level in the tank is about 8”...
  2. Jieve

    PMDC Motor Model with Friction

    I'm trying to model a PMDC motor using manufacturer data and curves. What seems like it should be relatively simple is not adding up, and I'm hoping someone can tell me where I'm going wrong. I've got the no load speed and the rated speed / rated load torque from the manufacturer. From these two...
  3. Jieve

    VFD Line Reactor Saturation

    Some VFD manufacturers provide rated current and saturation current as rms values in the datasheets of their line reactors. VFD input current is, however, not a clean sinusoid, but rather a series of current pulses (4 per cycle with 3-phase input, 2 per cycle with 1-phase input) with peaks that...
  4. Jieve

    VFD Power Conservation

    I’ve been doing some voltage/current measurements on VFDs and have come across a peculiarity that I do not yet fully understand. The specific VFD I’m working with at the moment is a 2hp drive powered by single-phase (240V), with output to a 3-phase 2hp (230V) motor. I’ve looked at both current...
  5. Jieve

    Transient Tank Fill Rate

    I have an application lab testing high pressure pressure sensors using an argon filled welding cylinder as the pressure source. Solenoid valves open and close to feed and bleed into a fixed volume where the pressure is measured, and I need to size the solenoid valves from a selection of...
  6. Jieve

    Spring Natural Frequencies/ Surge Concerns

    We have an application on a test rig where we are applying a load to rotating shaft through a bearing via a linear actuator. The load is applied through a spring setup, similar to a hanging vibration isolator. The max load capability needs to be around 2000lbf, with a total spring constant...
  7. Jieve

    Electrical Enclosure Heating Calculations

    Hello, We are deploying field equipment in standard (rectangular) electrical enclosures and are trying to get an understanding of heating/cooling requirements/modalities with the aim of keeping the components inside the enclosure at a max of 95F. The enclosure manufacturer gives the equation...
  8. Jieve

    Need help with RF CM-Filter Design Problem

    I've only recently started studying EMI and common-mode filtering and need some design advice, so please bear with me. I have an audio circuit project that I am working on, to which I want to add common-mode filtering at the output terminals to prevent any RF (especially in FM range) picked up...
  9. Jieve

    Questionable frame analysis displacement results

    I am using Solidworks to simulate a relatively simple frame. The model consists of beam elements with 3 different cross-sections; the legs are 2” x 1” x 0.095” rectangular tube, the upper and lower rectangular frames consist of 2” x 1.5” x 1/8” angle plug welded to 2” x 1” x 0.095” tube, and...
  10. Jieve

    Cannot reconcile simulation beam stress results with hand calcs

    I am simulating a frame out of 3" x 2" x 1/8" rectangular steel tube and am trying to verify the beam bending stress results that I get from the simulation. Hand-calc methodology: Using the bending moment value at an element node taken from the "list beam forces" table, the cross-section...
  11. Jieve

    Is this a singularity?

    I am modeling a 1/8" plate plug welded to 1/4" tabs that are welded to a relatively rigid frame, and am trying to determine the min plate thickness I can get away with based on the applied plate load. The tab to frame welds are modeled as fixed (overly stiff but approx), plate is modeled with...
  12. Jieve

    Assembly/Drawing Configurations and Mate Best Practices

    Hi, I'm wondering if I can get some input on assembly configuration mating best practices. My process generally goes like this: say I have an assembly with 20 individual parts. All parts are properly mated, but then I decide to change one part completely. I open the part and create a new...
  13. Jieve

    VFD and RCD compatibility

    Hello, We are working on a conveyor system to be used for educational purposes. The system consists of 7 control cabinets: 1 main for power distribution and e-stop circuits, 5 sub-cabinets, each with Siemens PLCs and 1 motor control center. The first component in the main cabinet is a 3-phase...
  14. Jieve

    VFD Motor Parameter Auto-Identification

    Hello, I was wondering if anyone could shed some light on what actually happens during the stationary and rotational motor parameter auto-identification that takes place when commissioning drives. The Siemens G120 units I've been working with apply something like 20V on and off to the motor...
  15. Jieve

    How to get accurate results from thermocouple probes

    I have some very noob basic questions about temperature measurements using thermocouple probes. I recently purchased a fluke 568 and two fluke type K thermocouple probes (1x 80pk-1 bead probe, 1x 80pk-6A exposed junction probe). I am not yet using them professionally, but would like to practice...
  16. Jieve

    Transaxle Bearing Setup Questions

    Hello, A student of ours recently began disassembling a transaxle used in an off-road buggy, and after spending a little time taking a look at how it was designed, I had a few questions about the bearing setup. As I understand it, when a torque is applied to a rotating shaft, the inner rings...
  17. Jieve

    Is this datum hole callout correct? - ISO

    Hello, Quick question - the way I have the hole diameter labeled as datum B dimensioned, with 2x Diam 9 and the Datum referring to the axis of the left hole, is it clear that the LEFT and only the LEFT hole is datum B? I would like to dimension the 9mm hole only once with a 2x callout, but not...
  18. Jieve

    Profile Tolerance for Slots

    Hello Everyone, I have a flat plate with 5 slots in a linear pattern. Primary Datum A is one face of the plate, and secondary and tertiary datums B&C are 2 perpendicular sides of the plate. I would like to use GD&T to locate and orient the slots. I am not so interested in tightening the...
  19. Jieve

    Measurement of a part with position control refinement

    Hello, Question about measurement of a part with a refined position control frame. Assume I have the part whose top view is shown in the picture. The circles on the inside of the part represent exaggerated tolerance zones of 4 hole axes to be drilled into the part. Datum A is the flat face...
  20. Jieve

    ISO Drawing Questions - Views & Hole Callouts

    Hi Guys, 2 Quick Questions: Working to ISO. I have a rectangular part that I am showing in 5 orthogonal views on a 2D drawing. There are a total of 6 holes in the part. 2 are visible in the front view, 2 in the rear view, and 1 on each side view (L & R). The 2 rear holes are 9mm in diameter...

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