In 3ph AC motors, starting current varies from 3 to 8 times of normal current ? what   governs 3 to 8 times ?
437857
Given a single motor, the range of current required to start will depend significantly on the load, in addition to this the starting angle of motor will play a big part in the amount of instantaneous current needed to start.  The closer the angle is to the optimum torque the less current needed
80787
it shouldnt mater that much, 3 phase power fires one after another, if all three have the same voltage, amperage, and Hz. the only thing, that i can think of, is to make sure that they are cycling in order. DO NOT CONECT TO MOTOR, if the motor is conected and the wires are conected in the improper order, it will not run backwards, it will cause severe damage, as far as i know. runing backwards would only work in 2 Phase power, Maby. Be carefull when using multi-meters with 3 Phase power, i read on my meter that that source can be unpredictable and very dangerous. A good meter and good judgement can do a lot of help in this situation. I think that if you just guess and hook them all up, and be ready to turn it off quickly, then if it is incorect you just switch your b and c wires and it should work. if you have a meter i think that some power setups have the a and b lines at 115vac and c is higher, MABY! i do not know for sure how to discover for sure what they are, but i dont think that ossiliscopes are the corect tool for the job. good luck
756481
Normally this is a "Restive" not voltage question/answer, and the proper neutral to ground = 2 Megg ohms (min.) this being incorporated in a residential application.\nHigher voltage in let us say a 3-phase utilization this # is on the low side. (assuming a.c. source. d.c. is a completely different animal!
167026
Read this article and the other links inside.\n\nhttp://en.wikipedia.org/wiki/Dc_motor
831663
Variable voltage and frequency drives operate by first converting the incoming ac (typically 50 or 60Hz) into dc.  Then the drive controller uses this DC to generate an AC output that has the proper frequency to turn the motor at the desired speed.  The voltage output is varied depending on the amount of load on the motor.
1105249
8.5x1000=8500 watts.  415 volts.  W=V*A A=W/V\n\nso 8500watts/415 volts =20.48... Amps\n\nthis is the basic relationship between watts volts and amps.  I dont know if the 3 phase motor part would change that answer.
167412
My suggestion would be to use a d.c. motor .  Incorporate the following : A D.C. motor, 2 momentary contact up/down switch, a reversing relay that would switch positive and negative when switching from up to down . Associated micro switches and ice cube relays to sense position and stop motor when destination is reached. Some form of safety clutch,light curtain etc. And a rectifier to convert house hold alternating current to D.C. . An alternative would be a reversing A.C. motor and associated similar controls less rectifier. Similar installation difficulty , my decision a/c vs d/c would be based on price and availability.
805978
Not sure what three things you're looking for, but here are three good ones:\n1. lots of windings\n2. high current\n3. an iron core
478080
Is this for an electric motor or an engine? \n\nNEMA National Electrical Manufaturers Association) has a standard set of starters for electric motors. Try a web search, I bet you will find what you want if you are talking about an electric motor.
423630
As you must be aware, the voltage on an AC line varies sinusiodally with time. ( it goes from 110v to -110v 60 times a second for a standard wall outlet in the US ). that is why it is called Alternating Current.\nhttp://en.wikipedia.org/wiki/Image:Sine_wave.png\n\nA single AC voltage line and a ground line together are a single phase supply. simple.\n\nNow if you take three cables, with voltages varying over them sinusiodally, you have 3 phase supply :). wish it were that simple though. \n\nnow all three sinusoids will reach their peaks simultaneously, and zeroes simustaneously. the instantaneous power on all the lines would be zero at that point. you can avoid this (and is practically more useful to do so) by staggering these sinusoids, so that they reach 0 at different times. the time by which you stagger them is called the phase difference. the standard is to stagger them by 120 degrees as shown here\nhttp://en.wikipedia.org/wiki/Image:Three_phase_voltages.png\n\nthere you are. hope that is cleared up for you :)
1009241
AC stand for alternating current.  AC current can oscillate at whatever frequency (# times per second, usually expressed in Hertz, Hz) you want it to.  However, the power that comes into your house oscillates at 60 in the US and 50 in Europe.  This has to do with the development of electricity.  They had to sync up the phases when they created it and they would do this by hooking up the two sources to lightbulbs that would flash at each peak.  50 or 60 times a second is about the maximum cycle rate visible by the human eye.\n\nPositive and negative current denote which direction electrons are flowing.\n\nNothing will happen if you touch positive or negative current, just don't touch both at the same time.
958490
There is no conversion that takes place in any size 0 through 7 type S starters. They may be attached to another conversion device but that would be defeating the purpose of the conversion device.  It also may be used to connect a 3 phase generator to its load. \nThese switches are simply a coil energized armature that closes three contacts with incremental current ratings per size through a belcrank arrangement.  Overloads may be integral to the device. Through high speed operation and lack of contact bounce, contact life is extended. The coil can be of a wide range of single phase AC voltages or even a DC voltage.\nThat's the most info I can offer based on what you supplied.
129261
Kilowatts  Equations\nDirect Current  =        I x E/1000\nAC / 1phase 115v or 120v =I x E x PF/1000\nAC / 1phase 208,230, or 240v= I x E x PF/1000\nAC 3 phase All Voltages     =    I x E x 1.73/1000\n\nE = Voltage \nI = Amps \nPF = Power Factor
896349
RPM=120*FREQUENCY/P\nRPM=120*50/4\nRPM=1500 RPM.\nnow you want to run motor on 60 hz supply and others parameters same,then\nRpm=120*60/4\nRpm=120*15\nRpm=1800.\nRpm will be increased by 20 %.\nIf the 60 hz is permitted , then you will get 20 % more production.\nWe have lost production what we have expected as we are using 50 hz supply system and machine which we have procured having capacity based on 60 hz capacity!
1068932
To reduce strain on the electrical system when starting the motor (needs that initial "kick" to get it going and would overload most systems).
1027928
Neither of the other answers makes any sense.  \n\nFirst, induction motors or anything for that matter don't "consume" reactive power.  Reactive power is traded back and forth.\n\nSecond, yes, there is an average reactive power component when induction motors run.  This has to do with the fact that induction motors are "inductive" (go figure, huh?).  To produce the needed magnetic field in their airgap and to have high efficiency they have a very large coil that except for a small series resistance is basically and inductor.\n\nInductors of course are reactive.  THe only thing that keeps the motor from being only reactive power is that the shaft output power forces some real power input.  However, some "magnetizing current" is required to run in any case, and there will always be some reactive power except perhaps in very rare circumstances.
480747
just check out the kilowatt of the pump. then apply the formula kw = 1.713 X V X I X PF.\nwhere V = voltage, PF = power factor, I = Amps.\neg:\na 30 kw pump,at 415 volts and 0.8 PF with three phase supply will draw an amps of\nI = 30000/1.732/415/0.8\nI = 52.17 amps.\n\nIn case of single phase motors just remove the term 1.732