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  1. SSLA

    How to Install Mathcad 15 on Windows 10

    I installed Mathcad 15 m1010 in Windows 7 and later upgraded to Windows 10 and it ran fine under Windows 10 for a year or so. Unrelated to Mathcad, Windows 10 recently developed explorer issues, faulting every few minutes and restarting. Tried everything finally solving the issue by clean...
  2. SSLA

    Tip for Re-Installling MathCad 14 or 15?

    I upgraded from Windows XP to Windows 7 and at the same time moved from MathCad 14 to MathCad 15 to ensure compatibility with Windows 7 and in the hope of a gaining few bug fixes, otherwise MCAD 15 seems to me to be identical to Mcad 14. I went on the Flexnet license server on the PTC website...
  3. SSLA

    Phase-Ground VTs on Delta Transformer

    Folks: We have a project at substation where the transformer have delta secondary windings. The windings supply metal clad switchgear through U/G cable (PILC would be my guess by observation). The metal clad supplies a 13.8 kV distribution system. There is no sign of a grounding reactor at the...
  4. SSLA

    Model Number for CGE Distribution Transformer

    Gentlemen: We have a substation with uses six distribution transformers as bus potential VTs supplying protection, SCADA and revenue metering. The name plates have faded in with time and are nearly illegible. We cannot make out the model number but we can read some data stamped into the metal...
  5. SSLA

    BYM Bushing CT - Manufactured by Siemans or ABB?

    Folks: I have a set of bushing CTs that could be used for revenue metering if previously approved by the regulator. The name plate says they are type BYM part number 72-281-240-011 manufactured by Siemans Power T&D, inc. The regulator has posted approval for type BYM style 72281240011 (same...
  6. SSLA

    Factory tests on three winding transformer not self consistent

    I have a very complete set of factory test records for a three phase, three winding transformer, stepping tansmission voltage down to distribution voltage. There are four load-loss tests in the test pages, each recording impedance voltage and kW loss. The factory carried out the usual H-X...
  7. SSLA

    Is there a "standard" labeling for phases in medium voltage metering?

    Folks: We have just installed metering on a 46kV class subtransmission line with vertical configuration. We assumed the phase layout was A-B-C top to bottom but it turned out to be B-C-A. There is no neutral so we used two element metering, connecting the VT primaries B-C and A-C making the...
  8. SSLA

    Burden Ratings on ANSI Voltage Transformers for Metering

    Folks: ANSI has defined a number of standard burdens (W,X,Y,Z,ZZ and sometimes M). Usually a VT nameplate will list all that it can support e.g. 0.3WXY for a 75 VA unit and 0.3WXYZ for a 200 VA unit. But what does it mean if the name plate on a VT with one secondary lists only one value...
  9. SSLA

    Positive Sequence Resistance of Concentric Neutral Cable

    Folks: I've got metering at the wrong end of some direct buried concentric neutral XPLE cable, three single phase cables, 1000MCM Cu with 1/3 neutral, XLPE, grounded both ends. I need to correct for losses. The load is well balanced so I am focusing on positive sequence current. When I look...
  10. SSLA

    Manual needed for GE MC 65 Phase Shifter

    I am doing a burden study for a revenue meter installation that must include an ancient GE MC65 phase shifter used to convert a watt transducer into a var transducer. I have suggested replacing it but the client has declined. Would anyone know where I could find out what burden the phase...
  11. SSLA

    Definition of Reactive Power

    The IEEE Standard 1459-2000, section 3.1.1.3 defines reactive power as the contour integral of v*di divided by 2*PI. Does anyone know the origins of this definition?
  12. SSLA

    Three Winding Transformer

    Sometimes records of factory test results for a three winding power transformer are only partially complete. Often the other results are available but the kW figures for the X-Y test are missing . A local rule of thumb that seems to have emerged is: kW loss X-Y = 0.85 *(kW loss H-X + kW...
  13. SSLA

    Three Winding Transformer Factory Test Missing X-Y Results

    Folks: I have a three winding transformer, DYY, and need to do some load flow calculations. The T&D book and Blackburn show how to convert the factory test results on winding pairs H-X, H-Y and X-Y into an equivalent Y configuration that can then be analysed. But the factory test report shows...

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