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Angel... because the generated voltages are 90° apart and the phase loads equal and resistive, the neutral current is the vectoral sum of both phase-currents. Then for 90 Ohm load the phase-current is 120/90 or 1.333 A. Thus the neutral-current is SQRT (2) x 1.333 or 1.88 A. Regards, Phil...

Hydro... in a nutshell, yes! I want to clarify my statement that "... stress is similar to that experienced for DOL-Starting!" At starting a motor produces a starting-torque (also called locked-rotor or breakaway) which is about 150% of its full-load or rated-torque. As motor speed...

Pal... Thanks for the your response. Nic provided some logic comments/details as a guide. But, I’m not sure if you wanted general logic-only information or are you seeking overall strategy/planning involving: A) Placement of the CTs? B) Phase-Fault and Ground-Fault Relays? C) Trip-Relay...

Hydro... the influence a motor's parameters has on its generator-action torque can be seen in the following thread: http://www.control.com/thread/1026155353 The thread covers derivation of a motor's maximum torque, Tm, when operating sub-synchronously! Note the denominator for Tmax...

Hydro... consider the induction motor used in the example above! Its rated sub-synchronous speed as a motor is 2,850 rpm, while as a generator its hyper-synchronous speed is 3,150 rpm. Its speed-torque curve operated as a motor, suitable for DOL-Starting, is similar to its torque-speed-curve...

Pal... does the term "2X87" refer to a specific manufacturer? Regards, Phil Corso?

Hydro... further to my earlier post: Runaway speed can be far greater than your IG's nominal speed rating. And, it is expected when there is a sudden loss of the connection between the IG and its network! However, sudden connection of the IG to its network should never be done if the IG is...

Hydro... what does "5 kW, off-line at runaway speed (~ 1.8 x rated)" represent? Phil

Hydro... 1) If operated off-line as an induction-generator, what is the size of the capacitor connected to the motor's terminals? 2) DO NOT connect the motor to the line while running it at such a high rate of speed! Regards, Phil Corso

GS... the BFW Pump requirement is non-linear, that is it varies as the square of Boiler pressure. Example: for a 2,400 psi plant the BFW power required is (ca) 2.5%; a 5,500 psi plant requires (ca) 6.0%! Regards, Phil Corso

Ken... is your "practices" study limited to Robotic-type machinery, or are SIS (ESD) systems included? Regards, Phil Corso

Petros... the answer is an emphatic YES! However, please clarify your question; are you referring to the generator only or the "Station Bus" to which it is connected! Regards, Phil Corso

Ali Ali... correction to my earlier comment: 1) Nsec/Npri ratio for shorted turn-to-turn condition should be 9.9:1! Phil

Ali Ali... very good question. Essentially there are two ‘negative’ results for the example you cited: 1) The turns-ratio Nsec/Npri will be reduced by one turn, that is, from the normal 10:1 to 9:1. This of course will affect measurement accuracy! 2) More importantly, transformer-action...

Apyzo... do you mean lightning struck an OHV (overhead) transmission line connected to a lower voltage generator via step-down transformer? Regards, Phil Corso

Ekemini... 1) Has the protective rely that operated to clear the cable earth-fault been reset? 2) Has the Electrical Fault-Lockout Relay been reset? 3) If provided has the close-relay circuit supply fuse been checked? 4) Upon meeting all perquisite conditions for synchronization does...

L. Burton... your post is the same as Eric L's in Control.Com Thread http://control.com/thread/1277285012 ! I sent him the general solution covering n-elements/phase arranged as 3-phase, 3-wire delta-load If you want a copy, contact me at [email protected] Regards, Phil Corso

Andy... I suggest you search Control.Com Archive for "ESD" or "SIS" Topics. Regards, Phil Corso

Sd… thanks for the update on your successful transformation! Can you confirm that cable, and not bus-bar was used on both the LV-side and HV-side connections? Regards, Phil Corso

A2A... further to my earlier questions: 7) How about providing Generator parameters? 8) Is Generator operating in Island-mode? 9) Is Generator operating in parallel with another gen'r, or a utility? 10) If in parallel with another Generator, is there load sharing? 11) If in...