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Correction to my earlier Oct 9, 2:19pm comments on the subject... boy, is my face red! Load factor is proportional to the ratio of temp-rise to rated tempe-rise, and not the square of the ratio. Therefore, make the following changes: a) Penultimate sentence in paragraph titled 'Motor'...

Markvguy, you took the second easiest solution, but not the easiest, to determine the number of poles. Unfortunately, your method was not what Ankarao requested. He asked, "How is it done by physical observation?" Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]]...

Responding to N. Lahham's Sep 21 query... have steady-state and dynamic stability assessment studies be done? Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to rajan's Sep 21 comment... having never estimated the cost of a rectifier transformer before, I suggest the following "Guesstimate": 1) Spec Basis. A) 3-winding: delta-primary; delta-secondary; and wye-tertiary. B) Secondary and tertiary windings each provide one-half of the...

Responding to Rajan's Sep 19, 1:07am query... are you sure about the output being 70kV? Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Following is my response to Bruce Durdle's and Michael Griffin's Sep 16 comments. Please bear with me, but it's a 3-parter consisting of a) the Preface; b) the "libelous" comment: and c) continuation of the Technical argument. The Preface. I have always participated in the discussion openly...

For Hilton Lawson... I duplicated the anti-windmilling system described in my Sep 11 response. Although 1-ph instead of 3-ph, one fan was "windmilled" by a second one. The applied DC was 10% of nominal. It was successful. If you want details contact me! Regards, Phil Corso, PE {Boca...

Responding to Paul's Sep 15, 12:42pm query.... do a web search for NEMA Standard No. SG 6-2000! Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to Bruce Durdle's Sep 15 comment... I disagree. Following are my reasons: 1) I answered the question as it related to Class I, Div 1 Areas, which comes under the jurisdiction of the USA NEC. 2) Bruce T. brought up the question of connections To T/Cs. XP enclosures address the...

Responding to Bruce Thompson's Sep 5, query and Bob Peterson's Sep 7, reply.... based on the info provided "should be OK" is libelous: I doubt that the AHJ will approve the installation unless the T/C too, is Certified by an appropriate testing facility for use in either the XP or IS...

Responding to Paul's Sep 14, 12:21am query... if you are referring to protective relaying schemes, then I am familiar with two applications: 1) Carrier-based protective relaying of transmission lines fitted with zone protection. 2) Protective relaying associated with parallel or...

A few off-list questions have prompted revisiting this topic, as well as two related ones, namely, "Current Transformer" (#1026172605) and "Current Transformer Failures" (#1026113301). From the questions asked it is obvious the topic is still in a state of flux (pun intended!) Some...

Responding to Anonymous' Sep, 12:46am query... no, it doesn't make sense! kVA into the transformer's primary must equal kVA out of the transformer's secondary. My questions is, "Where were the currents you mentioned obtained?" 1) From the Generator and transformer nameplates? Or, 2)...

While researching some of the responses to H.Lawson's Aug 20, 12:25pm query... I found a 1974 article describing a solution to your dilemma! Some 20- 60Hp machines were involved. Following are the advantages cited: o Low voltage DC injection to only one phase. o All components located at...

Responding to Shvetang's and Karan's Sep 2 query.... "one picture is worth a thousand words!" Please send me your email address, so that I can forward a sketch of the vector relationships. Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to Anonymous' Sep 5, query and Curt Wollet's Sep 7 comment on a "double-break" application... directionally Curt is right. The 'ROT' is that current increase could be as much as 2 to 3 times the contact's nominal DC rating. But, from a practicality standpoint it is difficult to...

Respondibg to RK Soni's Sep 7, 2:01am query.... unfortunately, there is no CT location. Ground-fault current detection in an ungrounded system is not poassibe. However, ground-fault detection is possible by phase-to-ground voltage monitoring. I suggest you do a search of tte Control List...

Responding to Srinivas' Apr 5, 12:12am query... The following contains= what you seek: ANSI/IEEE Std 422-1986 "Guide for the Design and Installation of Cable Systems in Power Generating Plants" Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to H. Lawson's Aug 30, 12:25pm dilemma... I've never tried this but interlocking implementation should be far less complicated than the system you propose: Rather than the DC source (I don't understand the 1kV bridge comment), resistors, grounding, etc, install a 3-phase variable...

Responding to Anonymous' Aug 29, 10:45pm query.... an interesting, but wide-open question! I'm unaware of specific standards. but some "engineering practices" may be helpful: 1) In the USA pf is ignored, even for short-circuit. However, X/R (lagging pf) ratio's are used to determine...