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Waiphyo... If the Generator is "Y" connected, then absence of an Hz measurement indicates that Leg of the "Y" is disconnected... perhaps at the terminal block! What are the three Line-Line, three Line-Neutral, and three Line-Earth, voltage measurements? Regards, Phil Corso

Diaa... the free-ist site is Control.Com Archives... as suggested by the ModSquad. For example,"Cross-Compensation", alone brings up 22 threads. And Iso-Mode some 55! Regards, Phil Corso

Paru... What is primary-winding? Delta or Wye?

Doobs... Four more questions: 1) What type of Neutral Contactor is being used? 2)What is Utility Xfmr kVBA rating? 4)What is Genset KW or kVA rating? 5) Interrupting-Duty of Swgr? Phil

Doobs I sent the SLD illustrating why the Genset GFP trips to you. With the 'Neutral' contactor closed the system becomes a 3-loop symmetrical network and the Genset neutral-current is the sum of its contribution to load neutral-current and its ground-path current. With the contactor open...

Paru... If primary-winding is Delta-connected, and each load is 1.00 per-unit, then, primary supply current distribution is 1.00 : 1.00 : 1.74 If primary-winding is Wye-connected, neutral status must be known. Phil

Barindra... By using the Open-Delta, or Vee, analogy, you lose the impact of a circulating-current in the Delta-winding. Phil

Paru... Clearly, circulating-current will flow in the Secondary delta-winding. Primary winding-currents, as well as Supply line-currents will change. If you want to know the magnitude of the problem please provide the Primary-winding configuration, i.e., Wye or Delta. Regards, Phil Corso

I agree with Roy. Situation is similar to Control.Com Thread: http://www.control.com/thread/1450358265 Regards, Phil Corso

To all requesting additional info... Doob mentioned that the Genset GFP measures the sum of phase-currents L1, L2, & L3, but Neutral-current is not measured. Instead it's taken as the 'residual' or unbalanced sum of phase-currents. Of course with the Neutral-contactor open, its share of...

Lakmalp... you have missed an important fact. When the connection between the Genset's neutral-terminal and the Load's Neutral-bus is open-circuited (via the single-pole contactor), the Utility-neutral and Genset-neutral are still connected. Note the line labeled "E" at the bottom of...

Gentlepeople... in conclusion, the GFP operates falsely because of current imbalance: Consider the GFPs. Whether it's provided using the residual-connection method (3-Phase CTs) or the window-type method (encompassing all 4 phase and neutral conductors), an error always exists. The...

Miquel, The nameplate % impedance is the result of adding both primary and secondary impedances. Regards, Phil Corso

Barindra, your comment "because the current will divide into two path" is exactly what I said in my 22-Dec post, point b). So, you do understand me after all. However, you still haven't explained false tripping of the Genset's ACB. Phil

ModSquad... I did send the OP's schematic to those that requested it! Regards, Phil

Barindra... You concluded that the closure of the neutral-contactor is meaningless, except when only the Genset is carrying load. Please explain, then, the false tripping of the Genset's ACB. It is my conclusion that it will will occur if the utility's Xfmr is 'Energized', but its ACB is...

Jameelrahman... I'm pretty sure that CSA meant to say that regardless of rotor-type, i.e., salient-pole or cylindrical, it is not physically possible to change the number of poles a generator has. Thus, the only possible approach would be to alter rotational velocity (rpm). But, that...

Mike... can you identify a pattern with regard to which/when Gen's are tripping? How about identifying protective-relaying action(s), if any? Regards, Phil Corso

Gentlepeople... if anyone would like a schematic drawing illustrating my concerns, contact me at: [email protected] <b>Moderator's Note:</b> you might want to give them the original as well so they can compare them.

Barindra... I didn't ask for a "what if" situation. The PRESENT situation is that the two neutrals are now CONTINUOUSLY connected together via the earth-block or earth-bus. Thus, both sources will contribute to an Earth-fault. Isn't the purpose of "Neutral-Switching" to insure that only one...