Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  • Users: unclebob
  • Content: Threads
  • Order by date
  1. unclebob

    500 HP, 440V motor

    What happens if you try to use a 500 hp motor, rated at 440 V , with a 6-pulse drive, rated at 600 A?
  2. unclebob

    Doble DTA and numbers

    This is an unusual question: from sometime now, I'M having difficulties with Doble and the DTA module. When entering some values (KVA rating, Voltages, Test kV, etc), I can't use commas, or dots to specify decimals. Example: I have a 13,2 kV primary voltage, but I cannot enter 13,2 or 13.2...
  3. unclebob

    Meggering of Dry-type or liquid-filled transformers

    For years I have meggered all transformers at 1000 Vdc for 1 minute. From 600 V thru 120 kV, dry type or oil liquid filled, 1000 V is the voltage, in our maintenance procedure. Now this morning I learn that higher voltages can/must be used. Was I wrong for all these years?
  4. unclebob

    Voltage unbalance on Y-Y trafo

    Hi all. We have a situation where a Y-Y 2500 KVA transformer gives weird voltage readings on the secondary side. Just after the first energization, we take voltage readings, without any load connected. All phase to phase voltages are OK at approx 600 V. But we have A-N =347 V , B-N = 320 V and...
  5. unclebob

    FR3 fluid giving odd megger and Doble results?

    We have some transformers filled with FR3 liquid that we test annually. Problem is, with the aging of the units, the megger values are decreasing and the Doble results are getting worse. DGA doesn't show anything suspect, except that somewhat hi level of ethane (C2H6). These units are on...
  6. unclebob

    Does an O/L exists for a load fed by a PWM signal?

    I have a consultant asking for this. He has an application (ozonation process in water treatment plant) that is fed by a PWM source. He's using a Schneider type LR9F5569 class 20 O/L that trips the moment power is applied on the ozonation equipment. Any suggestion?
  7. unclebob

    Merlin Gerin DA 6000A ACB

    Hello all, I'm looking for informations about this breaker and the trip unit that was installed on. The trip unit I have is a Statipac 100, and Googling this has not been successful. Any help is welcome. thanks Bob
  8. unclebob

    Shouldn't the Tesla car be named Edison?

    After all, it is a dc vehicle, no?
  9. unclebob

    Cable Ampacity Problem

    Hi all, I have a situation where low voltage cables are becoming hot, about 60 C at the hottest point in the gear B phase (middle). Customer wants to know if this is normal. Here's the scenario: We have to feed a 3000 A gear. We have 600V 750 MCM Nual ACWU90 single conductor armored cable...
  10. unclebob

    GEC CTM44 relay

    Good Day. Looking for manuals for the above relay – specifically the explanation of settings and time-curve curves. Thanks!http://files.engineering.com/getfile.aspx?folder=cf5b152d-14cc-4e17-bd0d-5317533aad4e&file=CTM44.pdf
  11. unclebob

    Medium Voltage Power fuses

    Hi all! I'm having a discussion with a consultant about the caliber to use for the primary side of a 5000 kva transformer. I'm using the nominal current to size my fuse. Primary is 25 kV so the nominal current is about 116 A. I'm going with a 150E SM-5 S&C fuse. The consultant wants to use a...
  12. unclebob

    VLF Testing - NETA Specifications

    Good paper on VLF.
  13. unclebob

    What is this symbol?

    Hi all! Please refer to the attachment. This is a 6600 V switchgear, built in the 40's. In it, there are neon ground lamps witch appears to be inductively coupled to the bars. We're wandering what this capacitor-like symbol represents? It is not possible for us to inspect these devices without...
  14. unclebob

    Arc flash protection VS Differential protection

    Hi all! In a 5 kV switchgear, would a busbar differential protection help reducing the Arc Flash Hazard? I think yes. Your comments are welcome.
  15. unclebob

    Frequency Response Analysis (FRA)

    Does anybody here uses this when testing transformers? I have read alot on this subject and found it very interesting. I included a document for those of you who are curious... Any comments are welcome.
  16. unclebob

    Westinghouse Accutrol 700 Drive

    Hello all! I looking for an instruction manual for this drive. Does anyone here have one? Thanks for your help.
  17. unclebob

    Communication Problem RS232

    Hi all! I have to download data into an electronic temperature controler. Its for a 5 MVA dry-type transformer. I need to program fan, alarm and trip temperatures and to make the controler non-failsafe. So I installed the software on my Lap-top and tried communicating. It failed. The Com...
  18. unclebob

    Directional Relay VS Negative-Sequence Relay

    Do these relays do the same thing? SEL literature describes Device Number 67 as Negative-Sequence Relay and ANSI as AC Directional OC Relay. One Hydro-Quebec guy just told me they're not... Your comments please.
  19. unclebob

    Arc Flash Reduction With No Main Breaker

    Here's a paper that talks about Arc Flash reduction solution when no main breaker is present on secondary side of transformer.
  20. unclebob

    Measuring Transformer Ratio Using Doble Ratio Test

    Hi all! This one is for people who use the Doble Test Set (M4000): A customer just bought a new dry-type transformer 2 MVA, 25000 / 600Y347 V. Nothing special... A service group (not us) go there and does the commissioning. They used the Doble Test Set to measure the ratios of the five taps...

Part and Inventory Search

Back
Top