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Hfzaal... the disturbance you describe becomes the "local-generator connected to the non-infinite bus" scenario! Ignore the action usually mandated, i.e., immediate separation! Instead consider the situation equal to that of dissimilar generators in parallel. Upon a grid-frequency change, the...

Azzam... additional questions: 4) What is time-delay setting of the Ir relay? 5) Has the problem appeared recent, for example, updating of generator's protective relaying system? Phil

Azzam… three follow-up questions: 1) Your original post mentioned the relay tripped under two operating conditions: a) during startup; and b) while synchronized with the grid. Do you have the corresponding V, A, kW, kVAr, and Pf, for the pre-disturbance condition, as well as those during...

Sinu ... is the PSS proposed by the machine supplier, or is it an edict from your Regional Reliability entity? Regards, Phil Corso

Azzam... can you be more specific as to the identity of the "Protective Device Number" that initiated the trips(s)?

GMack... Offhand I'd say it is a misapplication but more info is required: Is the current carred by the contact AC or DC? Regards, Phil Corso

Energy... US Nuclear plants do not use a DCS to control the Nuclear-side of such plants! However, if you want to learn how Nuclear Plant Availability in the US can be increased by at least 100 hours per year, then obtain a copy of the report: Electrical Power Research Institute...

Md. Nubayeed... Shaheed's formula is incorrect because he omitted Efficiency, that is, Nin, which varies with load, but not linearly! CSA's formula covers kWin, that is, it equals: Sqrt(3) x Vin x Iin x PFin, for any load, but that presents a problem. It is not an accurate indication of...

Shaheed... you are closing-in on the fact that the motor is probably a “Permanent” split-phase motor, that is, both Run and Start-windings have equal or near equal impedances! If you want I can provide you with a schematic illustrating a Dual-Action (Up/Down, Increase/Decrease, etc)...

Shaheed... if the motor is indeed a split-phase motor then there are two parallel windings, say, 'Run' and 'Start'! They are distributed around the stator, displaced 90 electrical deg in space, but somewhat less in time. The Start-winding has fewer turns, but a smaller diameter wire than the...

Shaheed: 4) Your original post said that two leads were connected together, and you labeled them as ‘common’! Were they both Black, or were they different in color? 5) Did you happen to measure the currents when you experimented with 12Vdc and 220Vac? 6) Do you know the approximate age...

Shaheed... correction: The first of many problems to overcome is the fact that the typical alternator, used as a synchronous motor, has insufficient starting torque!

Shaheed... the first of many problems to overcome is the fact that the typical alternator has insufficient starting torque! Do you need additional information? Phil

Shaheed: 1) Do you have some idea of the torque (kg(f)-mt) required by the shaft the "stepper" motor is connected to? 2)Why did you assume the motor is 220V, AC? 3) Can you provide the resistance value between the 3-leads? Regards, Phil Corso

Ben, using the procedure I suggested illustrates how the number of speed-torque curve increments can be increased! Thus, materially improving raise/lower speed-control of the crane. In the interest of increasing knowledge, can you provide the resistance measurements obtained with the old...

Ben... this sort of problem can be solved using Symmetrical Components Analysis! Say the resistances of one phase is X ohms!Then the other two phases can be expressed in percent, or per-unit of X. Using Symm Comp, the positive- and negative-sequence values of rotor-current can be determined...

Ben... please provide operating data: a) Line-currents. b) Supply phase-phase voltages. c) Supply phase-ground (or earth) voltages. d) Rotor secondary-currents (per step if possible.) e) Rotor ring-ring voltages. Make sure volt-meter is able to "read" lower slip-frequency. f)...

Hector... is your question, "How is the VAr component transmitted over the HVDC transmission system?" If so, the the answer is simple. It isn't! Capacitors are used at the HVDC station offsetting the VAr, so that only power, i.e., Vdc x Adc is transmitted. Sometimes it is easier to adjust...

Bob... the GSU problem you cited had to do with HV-winding capacitance differences between two existing and the replacement xfmrs! Your problem appears to be different. I presume your GSU HV-side winding (Grid) is Y-connected, and the LV-side (alternator) is Delta-connected! If the...

Jarod... sorry I should have said primary fuse-type and size! Phil Corso