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Raul, please provide rated current, applied volts, nameplate RPM, and actual RPM, if available! Regards, Phil Corso

Fred, if the question is related to your previous 29-Sep-08 (08:24) query, the answer is no! Furthermore, the X-axis of a CT's excitation-curve is not indicative of loss. The 300:5 CT you mentioned has a secondary-winding resistance that is less than the resistance of a one with a lower...

What has your instrumentation revealed? Phil Corso ([email protected])

Responding to Bruce's 18-Nov-08 (15:17) query... the circuit you seek is used all over the world: It can be found anywhere a ship is connected to shore-power. Typically, it consists of a sequence or rotation detector, and a reversing controller or contactor. On some of the more frugal...

Responding to Michael's 15-Nov-08 (23:50) query... search the Control List Archives for the following threads: o http://control.com/thread/1026157812 o http://control.com/thread/1026209342 o http://control.com/thread/1026211569 o http://control.com/thread/1026245378 Regards, Phil...

Responding to Riolyn's 30-Oct-08 (18:24) query... Look at Control.com's: http://control.com/thread/1026157812 Regards, Phil Corso ([email protected])

Randhir, 1) While a higher impedance will result in an increase in percent regulation, it doesn't necessarily increase losses. 2) 10% is usually the preferred maximum limit, but manufacturers can go higher. 3) I agree % Z is a trade off between economics and performance, but aren't most...

James, your answers are usually level headed. So, I am puzzled about your suggestion to use a VSD, when a trip-free circuit can be implemented using two auxiliary relays. Regards, Phil

Adding to my 06-Nov-08 (22:43) response: 1) Phase-to-ground fault-current is not always greater than the 3-phase case. 2) Fault-current asymmetry has more to do with the L/R ratio of the total fault path impedance between the source and the point of fault. This affects closing or making...

Responding to Shaikh's 06-Nov-08 (06:11) query... there are two types of electrical faults; symmetrical and unsymmetrical. Solution of the former is simple because it is a balanced 3-ph system that can be represented as a single-phase series circuit. A solution of the latter is not as simple...

Responding to Fluoronator's 05-Nov-08 (11:08) query: See Control List thread #1026215647. It describes the electrically-trip-free or X-Y scheme, or anti-pumping circuit frequently used for control of circuit breakers. Regards, Phil Corso ([email protected])

Responding to Points [2] & [3] in Narayanan's 03-Nov-08 (01:52) query: Typically a transformer's impedance is sufficient to withstand maximum fault exposure. Also, for most manufacturers, 20% is considered an upper limit. However, voltage-regulation will suffer and non-normal or additional...

Raj, this query is a repeat of your 24-Sep-08 post. In response, several questions were asked regarding measurements that could be used evaluate the problem. Your reply to those questions will be helpful. Regards, Phil Corso ([email protected])

Abby, The capacitor provides the inductive current needed by the motor. It is connected to the motor terminals, thus connecting it in parallel with both the main and auxiliary windings. Regards, Phil ([email protected])

Abby, The capacitor is necessary to supply the inductive requirement of the motor. For the split-phase case, it shoud be connected across the two supply leads! Phil Corso

Shahvir, how about providing details: 1) What is meant by 'some'? 2) Manufacturer? 3) Voltage 4) Type? 5) Size? 6) Environment? 7) Duty? 8) Earth-fault detection? 9) Age? 10) All fed by same feeder? Regards, Phil corso ([email protected])

Tsk, tsk CSA... had you obtained a copy of my paper most of the questions and complaints, noted in your 23-Sep-08 (09:55) post, would have been addressed some two years ago. Regards, Phil (Note, no !s)

Finally, a voice of experience! Phil Corso

Rob, You are being charged by the utility because the calculation for power is equal to: P = |V|x|A|xPF where, |V|= Magnitude of Phase-to-Phase current. |A|= Magnitude of Line current. PF = Cosine of theta, the angle between V & A. Let's say that PF for an...

Shahvir and Blackstoneboy: I'll gladly provide any information requested. Just contact me with your full name, company or school affiliation, and your location. The offer stands for anyone requesting information. Phil ([email protected])