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  • Users: Uquresh1
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  1. Uquresh1

    Trip/Close Coil Monitor and Voltage drop across coil

    For Trip Coil monitor and Close coil monitor we use a Protection relay Input (high Impedance) wired in parallel to the Tripping relay output contacts, and in series with the Trip/close coil and the 52a/b status. Has anyone ever had issues where the relay input (125VDC control voltage) would not...
  2. Uquresh1

    CT Thermal Rating Factor and CT Class

    If I can't find the CT Thermal Rating Factor TRF (or Rating Factor RF) on the nameplate, is there a way to find that knowing the CT class? In other words, how can I come up with a TRF if I do have the CT nameplate data and saturation curves. Station that I am doing settings for has this 1960s...
  3. Uquresh1

    Old ABB DPU relay - 50 pickup set to 'F'

    What does 'F' mean. I have a settings sheet for a DPU ABB relay. The 50P setting is shown to be 'F'. Does that mean it's OFF.
  4. Uquresh1

    Auto TXFMR and Wye-Gndd/Wye-Gndd TXFMR zero sequence network

    The zero sequence network for an Auto TX and for a Yg/Yg transformer both show that there is no connection to the ground bus (No), which means there will be no 0seq current flowing through that circuit (unless there is a Delta tertiary which does connect to the ground bus in the 0seq network)...
  5. Uquresh1

    Zero Seq. Line Impedance angle higher than Positive Seq. angle

    My transmission line's Zero seq. impedance angle (89 deg)is higher than its positive seq. impedance angle (79 deg). Is this OK?
  6. Uquresh1

    Breaker Column Failure Protection for 500kV Live tank Breakers

    Can someone please explain what Breaker column failure is, and how does this protection work.
  7. Uquresh1

    GE D60 Neg. Seq Directional OC- Offset setting

    I am setting a GE D60 relay and trying to get some clarification on what the intent is for this OFFSET setting and how to set it. I usually use SEL relays. The GE manual doesn't go in detail about this setting. I do not have series compensated lines. Any help would be appreciated. Attached below...
  8. Uquresh1

    Sudden Pressure and Low oil Level TRIPS for < 5MVA Dist. Transformers

    I have a customer that has recently installed a 4.75 MVA distribution transformer (23/4.2kV)that comes on a skid that also has a recloser, regulators, and isolation/bypass switches. I have fuses protecting the transformer on the high-side. The only trips on the transformer were for 63FPX (Sudden...
  9. Uquresh1

    Transformer Case Ground protection for 5MVA Transformer

    I have to implement a Transformer Case Ground protection on a 5MVA Delta (23)/Wye (grounded)(4.2) transformer. The transformer has no high side breaker, only Fuses; Low side has a recloser. I have never used this scheme before.I have included an IEEE excerpt about the TCG protection below. What...
  10. Uquresh1

    Transmission Line Impedances in Matrix format

    A customer provided me transmission line impedance for a 69KV line in matrix format. He got it from ETAP. I am used to of getting impedances in R1+jX1 and Ro+jXo format which is exactly what I input into ASPEN. Can someone please help me with reading or decyphering these matrices to obtain my...
  11. Uquresh1

    PE exam Preparation

    I am planning to take the PE exam this fall in NC, and I was wondering if anyone from NC knows where the PE preparation classes are held. I am in Charlotte, NC. Thanks
  12. Uquresh1

    Fuse Sizing for 3.75/4.68 MVA Transformer 23/4.16kV.

    I have no experience with fuses (other than some fuses on radial distribution lines); I need some help coming up with the fuse size to protect a 3.75/4.68 MVA distribution Transformer. The fuses obviously are on high side (Delta 23kV) and the low side is Wye-grounded 4.16kV. I have looked into...
  13. Uquresh1

    DAL, LTE, STE rating transmission Line

    I have an old relay settings file that is referrring to the 'Winter DAL'rating (given as 32MVA) and has the Inverse Time-overcurrent element pickup set above it. Can someone explain this a little bit. I searched online and I saw apost saying that you shouldnt load the line for more than 5 mins...
  14. Uquresh1

    Transformer Hot spot CTs - How and when to use?

    I have a Virginia Transformer 42MVA 69/13KV. There are two CTs- one on the B phase of High side winding and one on the B-phase Low side winding. These CTs are wired to the Transformer Monitor relay and I am guessing that these are meant for Hot Spot calculations. So, any confirmation on what...
  15. Uquresh1

    Transforner Fan cycle control

    Hey guys, Is it appropriate to turn Stage 2 fans on instead of stage 1 fans juts to keep the wear out of the fans even. Customer wants to toggle between Stage 1 and Stage 2 fans when a signal is received asking for Stage 1 fans to turn on. So when a signal is received for Stage 1 fans, I will...
  16. Uquresh1

    Transformer Grounded Wye - Grounded Wye with Delta Tertiary

    I have a Grounded Wye - Grounded Wye txfmr with delta tertiary (tertiary used for station service). My question is - Do I need a ground relay on the High side? For a Low side ground fault, will my High side see Zero seq current? If it will, would it be the same as what the low side sees? What...
  17. Uquresh1

    How to find Firmware version for a GE relay with a given Serial Number

    I have some GE relays and their Serial #s and want to know how to find which firmware version is in them? I don't have the relays with me, the customer has 'em.
  18. Uquresh1

    Grounded Fuseless Cap bank calculations

    Have a solidly grounded fuseless capbank, and for protection settings I am following the IEEE standard guide C37.99-2000 . I have a double wye connection with 5 strings in each leg of the wye. So 5 in left wye for each phase, and 5 in the right Wye for each phase. I am getting a little confused...
  19. Uquresh1

    Sudden Pressure Blocking for Through-faults

    Is it a good idea to block Transformer Sudden Pressure Relay for through faults. Please explain why or why not. Thanks
  20. Uquresh1

    How to calculate VT Ratio with the given information

    20125/34500GY/115 which Voltage should I use to divide by 115 to get my VT Ratio?

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