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Recent content by Gr8blu

  1. Gr8blu

    Generator with low IR

    Please understand what the test is actually telling you. An insulation resistance measurement is determining the resulting dielectric capability of an insulation system as a result of absorbed moisture INSIDE the insulating material, AND the presence of conductive SURFACE contaminant. Both of...
  2. Gr8blu

    I feel like I wasted 2 years — advice from senior engineers appreciated

    1. One cannot be "on a visa" with an expired passport. When the passport expires, THE VISA EXPIRES THE SAME DAY. Note: most of the time one CAN renew their passport during the period of a visa, if two requirements are met - first, the visa allows it and second, the renewal can be accomplished...
  3. Gr8blu

    Learning NX and building car jack

    For P1-9 I would : 1. Create the cylinder (67 mm length by 54 MM diameter) 2. Add on the 45 x 45 x 33 mm rectangle at one end 3. Locate the correct position and add the two rectangular feet below the cylinder 4. Locate and remove material from the first rectangle to mimic the 20 mm diameter...
  4. Gr8blu

    Learning NX and building car jack

    The P1-17 image has two chamfers. The one at the bottom of the bolt (0.75 x 45 deg) can be created using either a known intersection and an angle (0.75 from end of bolt for example), or by chamfering between two known intersections (each 0.75, since the angle is 45). The one at the top on the...
  5. Gr8blu

    Two-winding equivalent for the three-winding transformer

    See another thread that is currently under discussion ... https://www.eng-tips.com/threads/two-winding-transformer-equivalent-from-a-three-winding-transformer.528343/
  6. Gr8blu

    Small IP68 Fans

    How small is small? The physical casing surrounding a rotating machine that meets IP67 or 68 is going to impose some limitations on minimum volume because to meet the ingress protection rating requires that there is no effective air exchange between the exterior and interior of the casing...
  7. Gr8blu

    Learning NX and building car jack

    Take P1-11 as a simple example. There is a solid cylinder with 20 mm diameter and 45 mm length. Inside the cylinder is a rectangular cutout that runs parallel to the axial center of the cylinder. It is 10 mm wide. Note that there are two assumptions made: 1. the rectangle is actually square...
  8. Gr8blu

    Reactance and Time constant tests for a generator

    The reason for "direct testing" of direct-axis reactances is that it IS pretty much a direct measurement from the data that can be physically tested for. There is also some fairly well-known relationships between the direct axis and quadrature axis values, as there is between positive (direct...
  9. Gr8blu

    Reactance and Time constant tests for a generator

    Most OEMs who manufacture "standard" ratings will have a very capable ability to calculate the expected synchronous, transient, and subtransient reactances for their generator internal geometries and "normal" ratings. Proof of performance is accomplished during the factory acceptance testing...
  10. Gr8blu

    High hydraulic conductivity materials

    @zelgar : 500 in/hr * 2.54 cm/in * (1/3600) hr/s = 0.35 cm/s not 0.055.
  11. Gr8blu

    Easy ways to explain how greywater reuse works?

    Since your post hinted that you're basing comparison or viability on financial criteria (payback period, Net Present Value, Internal Rate of Return) instead of environment (once-through system, for example) then you need to also define a specific duration BEFORE making the comparison. For...
  12. Gr8blu

    High hydraulic conductivity materials

    You're sure about that? 500 in/hr = 1270 cm/hr = 0.35 cm/s. Gravel is one of the more useful materials and ranges between 0.1 and 100 cm/s. Clean sand can get you somewhere in the 0.001 to 1.0 cm/s range. See the wiki table from the following link...
  13. Gr8blu

    VFd parrallel operation

    First - what kind of motor? Squirrel cage induction, wound rotor induction, synchronous, or direct current? Or something else? Chances are the machines are not going to perform exactly the same due to tolerance buildup in material properties and geometry, so there will be some inability to...
  14. Gr8blu

    Alberta Engineering Stamp

    Or at least an engineer registered for Alberta, even if they are physically located elsewhere in the country .....
  15. Gr8blu

    SIPROTEC 7SJ85

    Go to the Siemens relay configurator and copy/paste both product codes into the <search> bar. Step through the configurator and the last page will tell you what the specific sequence means, in (relatively) plain English. If the two descriptions match, chances are good that the relays can replace...

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