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Panth... if your question is intended just for information, that is, nothing you intend to do in the near future, then I suggest you refer to either the USA ANSI/IEEE Xfmr Standard, C57 or your country's own standard. They contain Charts and Tables covering short-time, recurring, overloads for...

Darren... If you send me a simple SLD (Single-Line-Diagram) or even a hand-drawn sketch, I may be able to provide additional trouble-shooting ideas! Phil ([email protected])

Darren… presuming the 3 ph-ph voltages are those at the bus to which the generators are all connected, as well as the Ph-N and Ph-Pe, then the Voltage-Unbalance-Factors, VUF, are less than 0.2%! Additionally, the Ampere-Unbalance-factor, AUF, for the three line-currents you cited, is about 3%...

Darren... further to my earlier response; at hi-load when the Current "displays" indicated zero: 3) were there any indications that any of the gen-sets were in distress? 4) were you able to confirm, via a Clamp-on ammeter, that the currents were, indeed, zero? Phil

Darren... please provide a tabulation of current and voltage measurements, during light and heavy load conditions, for Gen-Set, as follows: 1) Currents: Ia, Ib, Ic, In, and Ipe! 2) Voltage: Vab, Vbc, Vca, Va-n, Vb-n, Vc-n, Va-pe, Vb-pe, Vc-pe, and Vn-pe Regards, Phil Corso

Ha... you have not indicated the location of the crane, so the following comments pertain to a USA installation! The National Electric Code (NFPA-70) is the most widely adopted code in the US! Caveat... one of the most salient requirements concerns system-earthing (grounding) and bonding...

VenKat... my response is the same as the one given to Shaheed on Jun 2nd! If you have an AC supply available to "Start the generator" then why isn't it enough to "Charge the battery?" Phil

Charz... there is a way to "investigate" the transient phenomenon, Ferroresonance! A good first-step is to recognize when L and C parameters are connected in series, or parallel! First, the prefix "ferro-" refers to phenomenon involving electrical apparatus containing a magnetic-core, hence...

Venkat... is your query similar to Shaheed's? That is do you want to power the Generator with an AC source so that it, the generator, can be used to charge the battery? Regards, Phil Corso

Charz... additional questions related to Harmonic and Ferroresonance potential: 6) How is the 6.6kV transformer earthed? 7) How are 6.6kV system monitoring and protective PTs configured? Regards, Phil

Sudheer... I suggest you search the Control.Com Archive for like threads. You will find that most posters suggest grounding the shield at the panel-end, rather than the instrument-end, and never both-ends simultaneously! Regards, Phil Corso

Charz... following are the results of my review of your situation: 1) The voltage at the motor, during a DoL start, is approximately 87%! 2) The voltage at the motor, during an AT start, is approximately 95%! 3) PFC capacitors should not exceed 50-75kVAr! 4) A series-reactor reduce...

Ebrahim... no! Opposite direction is intended to enhance air-flow, hence heat extraction from the slip-ring/brush interface! Regards, Phil Corso

Charz... re your query, I will respond shortly! Phil

Charz... what is the motors rated voltage? Phil

Santanu... Is vibration frequency in sympathy with rotor-rpm or rated line-frequency, if the two are different? Regards, Phil Corso

Samual... Is vibration frequency in sympathy with rotor-rpm or rated line-frequency, if the two are different? Regards, Phil Corso

Maatallah... Is vibration frequency in sympathy with rotor-rpm or rated line-frequency, if the two are different? Regards, Phil Corso

Sumeet... My interpretation of your question is, "A Loss-of-Excitation (LoE) event occurring while the machine is already responding to a Prime-Mover failure (LoPM) is worse than the LoPM, itself!" If my interpretation is correct, then it is not worse because "typical" protective relaying...

Charz... can you provide detail: 1. Often the connecting cable is sufficient to reduce inrush current to a capacitor-bank! 2. How do you know you will have harmonics? 3. Insure that the shunt capacitance does not result in resonance, that is, inductive-reactance should not be close to...