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Respondig to S. Ferligul's Aug 28, 11:42pm problem... the formula (in rectangular coordinates) for the 'hook' position as the 'trolley' moves from 0 to twice the load length, is: Y = sqrt [ 2 x L x X - X^2 ], where, Y = hook's vertical position above ground. X = trolley's horizontal...

Responding to Shvetang's Aug 26, 2:58pm and Karen-Shevtang's Aug 29, 12:01pm queries.... the principle is called Armature Reaction. It's easy to say but not so easy to explain, but I will give it another shot. First, let's identify key variables. Neglecting resistances, then: Vt = terminal...

Responding to Shevtang's Aug 26, 2:58 and Ray-Shevtang' Aug 29, 12:01am queries... it ain't easy but I'll try again! Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to markvguy's Aug 29, 12:37am comments & queries.... in the order given: 1) Instrument Transformer Types. Although your question referred to PTs, CTs are included. Of course, both the PT and CT must accurately represent the primary "quantities" they mimic. The operative word is...

To markgvuy... ask the older engineers at GE to describe the supersynchronous motor! They should know... GE "invented" it. Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to Anonymous' Jul 12, 3:31pm query... the following thread may be useful: http://www.control.com/958680065/index_html Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to markvguy's Aug 24, 10:10pm comment... thanks for the accolade (I presume). Now two comments: 1) The Google reference cited by 'markvguy' is an excellent one. It jogged my memory. The most common error in protective relaying is the inattention paid to instrument transformer...

Responding to Anonymous, Aug 24, 1:12am query regarding pf readings: You are probably aware that the lag/lead values are based on the displacement angle between stator (or line) current and terminal voltage. An example might be useful. Consider the case of a single synchronous motor...

Responding to MDR37129's Jul 16, 11:12 pm query: Two excellent references covering AC fundamentals are: 1) One prepared by US Navy personnel: "Basic Electricity" Dover Publications. ISBN 0-486-20973-3. 2) My first EE textbook: "Principles of Electrical Engineering" WH Timbie...

Responding to Mathew Chandy's Jun 27, 11:34 pm query... how is earth-fault relay connected: A) In parallel with 3 line-current CTs? B) In the neutral residual circuit of phase-current CTs that are wye-connected? C) Window or Core-type CT surrounding phase conductors? D) Is restricted...

Responding to Anonymous' Jun 3, 10:31 am query: The information you provided is not clear regarding your load distribution. Under the old hi-leg system one can only presume that the ratio of single-phase load kVA to transformer's kVA capacity, was not too large! That said, I agree with...

Responding to TJ Samouh's Jun 4, 11:11 pm query... perhaps a historical perspective can provide the answer: The calculation method, properly called Symmetrical Components, is a only mathematical "tool!" Early in the history of Electrical Engineering, fault-currents for "balanced", 3-ph...

Responding to Ed's May 22, 10:25 pm query... Yes, at one time polarity had a deleterious effect on DC-operated solenoid coils. (I'll bet that the persons mentioning it were oldER!) Because of material improvements, as well as conditioned-environments, the problem is rare today. The problem...

If you still need definitions or parameters related to load-flow studies, contact me off-list! Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

There is a world of difference separating (excuse the pun) IS and Non-IS cable, as different as apples and oranges: The major differences are related to construction (ex., stranding size), conductor materials (ex., Fe, Cu, Al, T/C), parameters (ex., inductance & capacitance), connections...

Responding to Petrosumit's Apr 19, 11:40pm conditional question: You stated stator current is reduced after the excitation decrease! Therefore, the kW or MW, must have also reduced. Q1) Is the above correct? And, Q2) What does "much below" mean in per-unit or percent of rated value...

Responding to Anonymous' Apr 6 query and Apr 13 comment... Are you certain you looked everwhere? I found info in one of the ANSI / IEEE Stds covering Nuclear Plants! Regards, Phil Corso, PE {Boca Raton, FL, USA} [[email protected]] ([email protected])

Responding to Petrosumit's Apr 19, 11:39 pm question: The stability-limit line is determined by calculating the minimum load-increment that will cause the machine to lose synchronism, i.e, for each correspnding kW and kVAr values. The allowable kVAr range is "usually" larger for a...

Responding to Markvguy's Apr 19, 11:41 pm comment... to whom was your post addressed? If for me, then: 1) The end-turn (end-ring) diatribe in my Apr 16, 8:14 pm post was intended to dispel the perception that end-turn damage was the only concern. (See thread # 1026220640 "ENGR: reverse...

Responding to Solomon's offline post asking for comparison of the Y-Y and D-Y transformer connections: I must apologize for misunderstanding your question. My initial response was aimed at distribution systems related to industrial or bulk-power consumers. The use of Y-Y transformers for...