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Responding to SNA's Aug 8, 2005, 4:43pm comments... more info please: 1) Does the star-delta transformer have a tertiary winding? 2) Is the star side of the star-delta transformer earthed? 3) Where do you "see" the current flow to earth you mentioned? Primary? Or secondary? Regards...

Responding to SNA's Aug 5, 11:38pm query... "ungrounded" delta-systems are actually "grounded" by system capacitance. If there is no intentional short-to-ground, then, all three terminals should measure (ph-ph) / sqrt(3) to ground. However, when one phase is grounded, then the other two...

Responding to Anonymous' Aug 5, 8:46pm query... formula has been provided! See the Jan 27, 2005, 2:43pm reply to this thread: http://www.control.com/102620547/index_html Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to Anonymous' Jul 31, 4:52pm comment(?)... checkout threads: o 1026187617 and, o 1026205467 Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to Dave Downunder's query about the missing link... "a" @ Lat51.48°N (Greenwich, England) is used for Hp in SI units, while "a" @ Lat45°N (Someplace, France) is used for metric horsepower Ps or Cv. (In fact there is a third designation, Ch.) Here's a trick to jog your memory...

Responding to Ravi's Jun 29, 7:45pm query... before I toss my BGE into the PSH please provide the following: 1) Manufacturer - All the same? Different? 2) Motor - Rating & speed? 3) Construction - Vertical? Horizontal? 4) Bearing type - Ball? Roller? Sleeve? 5) Control mode -...

Replying to Anonymous' Jul 25, 11:10pm comments... you are right! But before revealing the answer to you I ask for your patience... this is a 3-parter for trivia buffs! For homework I asked my physics students to research "horsepower!" A popular website was...

Responding to Stefan's Thu, Jul 21 query... based on previous discussion covering poer factor correction (PFC) the size proposed is much too large. A) Sizing Criteria. If the motor is started conventionally, then following are my recommendations in descending order of priority: 1) Contact...

Responding to Anonymous' Tue, Jul 19, 6:43pm query: Before a meaningful answer can be given specific detail is requred Q1) Normal demand and pf? Duration of max demand? 15 minutes? 15 hrs? Q2) Starting kVA to Hp ratio? Q3) Is the existing transformer equipped with alternate coolng...

Responding to Rajan's Tue, Jul 19, 6:41pm comments: I disagree with your comment about the open-circuited secondary: Unless the primary and secondary windings are separated by a grounded electrostatic shield, the two windings will be capacitively coupled. If the secondary is left...

Responding to Joe Hohn's Jul 16 reply... all is not lost: Change the sign in the height terms for each interval from (-) to (+) Then, divide the total sum of intervals by Tn. Changing subtraction to addition yields the area of a trapezoid for each interval. It also gives the triangular...

Responding to Joe Hohn's Thu, Jul 14, 5:09pm comments: A) I want to apologize to Tong for my earlier reply. It was way, way off base. B) Joe your formula has several errors: 1. It addresses only the triangle segment of each interval area. 2. The rectangular segment (if any) is...

Responding to Anonymous' Thu, Jul 14, 6:42pm comments: 1) As long as the connected burden (load) doesn't exceed PT capability, then the stated accuracy will not be compromised. For example, suppose the 3 PT's are connected to a protective relaying circuit. Presumably the secondary circuits...

Responding to Anonymous' Tue, Jul 12, 6:51pm query: A1) Are you talking about the Burden Rating (capability) of one is different than the other two? Or, the actual burden (load) of one is different than the other two? A2) Depends on what the PTs are used for, and their circuit...

A small, albeit important technical correction of William Hinton's Sun, Jul 12, 2005, 3:20pm comments: Your observation regarding phase-angle (displacement) between primary phase-to neutral and secondary phase-to-neutral voltages for the Yy case is correct. But, the same cannot be said for...

Responding to Krishna's queries: Q1) Why is vector group important? A1) Because it determines the phase angle displacement between the primary (HV) and secondary (LV) windings. Q2) If the vector-group is changed from Yd11 to Yd1, how will it affect generator synchronization? A2) The...

Responding to Blackbomb77's query: Because the driving pressure slightly exceeds ambient, one can assume the air is incompressible. Thus, the flow rate is proportional to the area x sqrt(2 x DP / rho). Applying Bernoulli's "common" equation, I converted area, pressure-drop, and density...

Responding to Paul Karnopp's comments: Does your comment mean that you haven't heard about similar strange behavior of AC circuits? Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Revising Flyer's Jan 17, '05 post: Maxim Integrated Products Inc, announced the development of a Variable-Resistor IC which can mimics a Pseudo-Logarithmic scale output to a linear input. Free samples are available. Go to: http://www.maxim-ic.com Regards, Phil Corso, PE {Boca Raton...

Responding to P. Wakhae's Apr 25 query: Such 'test' instruments are readily available from utility service or maintenance organizations! Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])