SARSING:
Since it seems that you are in India, I will say that your frequency is 50 HZ, also, you did not include PF of the motor, or if STAR or DELTA Connection. For best operation limit power to 75 % of maximum motor rated power. 3 phase, Vline=415 volts, Iline=7.4 Amps, 5 HP = 3730 watts 1440 RPM STAR connection Sqrtroot(3) * Vline * I line = Va So Sqrtroot (3) * 415 * 7.4 = 5319 Va per phase I am assuming PF =0.87 Reactive power = Pr = 5319 * 0.87 = 4627 VAR Pr(phase) = 4627/3 = 1543 VAR(phase) Capacitors to be connected in DELTA to STAR motor connection, to reduce the value of the capacitors to one third. I phase= Pr (phase)/Vphase = 1543/415= 3.72 Amps C = I /(2*pi*F*Vphase) = 3.72/(2*3.14*50 Hz*415 Volts) = 28.5 Microfarads Use 30 microfarads per DELTA Leg. 600 Volts AC rated for continuous use. Now, the testing may indicate that the generator may need additional capacitance, some times up to 30 % additional capacitance per phase. It is important not to draw any current in excess of the rating current, ALSO the power rating may have to be reduced further because I am assuming that all 3 phases are loaded equally. Many times is best to get a much greater power motor to attain the desired maximum power and to keep the dissipation of the motor ( generator) below its maximum ----- Original Message ----- From: "sarsing gao" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, March 07, 2005 3:49 AM Subject: [microhydro] (unknown) > > > Dear all, > I would appreciate if somebody could tell me what will > be the capacitor required for an induction motor to be > run as a generator with rating as specified below: > 3-phase, 415 V, 7.4 A, 5 HP, 1440 rpm, Continuos type > induction motor. I would also like to know that in > addition to the excitation current requirement what > are the other requirements to make an induction motor > work as a generator. > Thanks > > Sarsing Gao > > ________________________________________________________________________ > Yahoo! India Matrimony: Find your life partner online > Go to: http://yahoo.shaadi.com/india-matrimony > > > > > > > Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! > > NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way. > > More information on micro hydropower at http://microhydropower.net > > To unsubscribe: send empty message to [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> What would our lives be like without music, dance, and theater? Donate or volunteer in the arts today at Network for Good! http://us.click.yahoo.com/TzSHvD/SOnJAA/79vVAA/FGYolB/TM --------------------------------------------------------------------~-> Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way. More information on micro hydropower at http://microhydropower.net To unsubscribe: send empty message to [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/microhydro/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
