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  • Users: FreddyNurk
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  1. FreddyNurk

    VSD versus motor sizing, oversized VSD

    A question came up today regarding VSD sizes versus motor size. Case in context, drive is an existing unit, something like a 150kW, brand name unknown. For various reasons the consideration of using existing VSD with a much smaller motor, say 11kW. In theory, this should work, with the...
  2. FreddyNurk

    Periodic Testing of Dry Type Transformers

    I'm aware that different scopes of transformer testing have been covered here previously, and am also aware that there can be quite a number of factors involved in choosing a testing regime. I'm interested in the feasibility of testing such as tan delta / dielectric loss angle for smaller dry...
  3. FreddyNurk

    Type Tested options to IEC60439 for 1kV DC Systems

    I'm aware with greater interest in arc flash issues, fault withstand and safety that there is more of a progression to use of Type Tested and Partially Type Tested assemblies, at least as far as typical AC LV Switchboards are concerned. However, has anyone come across equivalent arrangements...
  4. FreddyNurk

    AS2067 (1984) Circuit & Wire Identification - Replacements?

    At a number of workplaces I've been employed at, AS2067's Table D1 was used for cable and wire identification, and for substations and generator cubicles it suited the purpose reasonably well. It didn't do much for process plants or factory automation though. With the revision of AS2067 in...
  5. FreddyNurk

    Hypothetical - exceeding switchboard ratings

    Within my employer there has been some recent discussions regarding ratings of some of our equipment, and instances whereby that rating may be exceeded. To this end, a couple of considerations occurred to me, and I'm curious to hear others' views on it. Situation: Board previously certified as...
  6. FreddyNurk

    Solar Hybrid Reverse Cycle Air Conditioners

    Not strictly a work related question, but more of a curiosity, and if theres likely to be a sensible answer, its here. I've seen a number of advertisements recently regarding 'Solar Hybrid Reverse Cycle Air Conditioners'. Usual sort of thing, various quotes on efficiency improvements over...
  7. FreddyNurk

    Voltage Regulation & Sensing - Prime Power Generators

    Folks, My current employment consists of looking at isolated grid prime power stations, normally powered by diesel generators of sizes ranging from 50kW up to about 1.5MW, with various configurations onsite. We normally use Basler SR4 AVRs for our larger stations, with a few Stamford units...
  8. FreddyNurk

    Fault Levels & Breakers - Isolated Grid

    Recently there has been some discussion here regarding fault levels and equipment withstand ratings, as shown in threads such as http://www.eng-tips.com/viewthread.cfm?qid=251289. As part of a review of drawings at an isolated power station that we run, I've come across a particular station...
  9. FreddyNurk

    Use of contactors as circuit breakers

    Folks of Eng-Tips, I've got an interesting situation thats come up in amongst site drawing reviews for something completely unrelated. We manage the upgrades and installation for a number of remote (i.e. isolated grid) power stations in Australia. Its come to my attention recently that some of...
  10. FreddyNurk

    Four Quadrant Power meter and Readings

    I'd recently been called in to look at the metering setup (indicative only, not for tariff purposes) for a processing plant. They'd had a number of 4 quadrant power meters fitted to various feeders, including the incomer for the site, and a couple of the larger feeds to the site. Anyway, the...
  11. FreddyNurk

    Roof height for arc vent on MV switchgear

    Hello all, I have an interesting situation at a site where I am supervising the construction of a mineral processing plant. WE have an incoming 22kV 3 phase supply and an 8 cubicle MV distribution board, with the bus being rated at 1250A continuous, and 25kA 3 second fault rating. After...
  12. FreddyNurk

    Transformer commissioning and testing

    We have a startup processing plant that is in the process of being constructed, and has not yet reached commissioning phase. As part of the plant, a number of second hand transformers were purchased, with varying condition. I believe that it is appropriate to arrange for these to be tested...
  13. FreddyNurk

    HV 22kV Cable runs

    Hello all, As part of a project for a processing plant we've been asked to assess the legality / other considerations for running a HV cable at around 600mm above ground in a cable tray, part of which is running directly under the floor of the control room. Cable has not yet been run as the...
  14. FreddyNurk

    Use of transformers outside of nameplate voltage.

    Hello all, we've been brought in to an interesting construction job, for a minerals processing plant. The whole job appears to have been run as a D&C plant, with the appropriate design documentation stored in a hard to access mental archive. Part of our scope is assessing the design intent and...
  15. FreddyNurk

    QA and adherence to procedures

    After a recent unexpected changing of employers in recent months, I've found myself faced with somewhat of an interesting situation. My main intention in raising the issues below is more or less to encourage discussion of such things, as I'm sure its not just my workplace that has these issues...
  16. FreddyNurk

    Multi Needle process (4-20mA) meters

    Hello all, I have a client that wants a standard (DIN96, 90 degree movement) meter that has capability to accept two 4-20mA signals and have the pivot point for both meters in the corner, i.e. stacked one on top of the other. The reason for this is we wish to display both a setpoint as well as...
  17. FreddyNurk

    AutoCAD compatible schematic editor

    After much searching and asking of numerous questions around the office, it has come to looking for new software packages that would allow us to automate some of the more tedious tasks for schematic editing, such as wire and part numbering and automated parts list generation. Which brings me...

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