2% Above Sync

The correct solution is to maintain 2% above synchronous speed. That's 1836 rpm. at 61.2 cps. Once you drop below synchronous speed you will loose all power. The capacitors will loose their saturation and drop off line. The battery is only used as a component for bench testing. If you were to use a battery in the working system that means it must be maintained and have extra circuitry to cut in and out at the proper times. Capacitors need no maintenance and operate automatically. The 61.2 cps. just means that your motors will run slightly faster @ 2% (frig, washer, dryer, etc.) no harm will be caused here, your local utility maintains 60 cps. at + or minus 2%. You will need to extract 8 hp. from the water wheel. That's the data plate rating + 60% 5 hp. + 3 hp. = 8 hp from the water wheel.

Offered by Jay.

Why 2%? I am thinking that one could turn on two fans one much stronger and faster than the other. If the stronger fan blows the weaker fan in such a way as to tend to speed up the blade faster than it would normally turn (with the 60 cycle source tuning it as a motor), then to me this slower motor will resist being speeded up and start to flow current back into the 60 cycle source. Thus becoming a generator. This I believe to be true of almost any motor DC or AC. Am I wrong?

Offered by Mike.

Mike, in this instance I was speaking of a stand alone application, using capacitors only for self excitation. If the above condition were to take place you would have a 5 hp. motor trying to drive a 5,968 watt load (8 hp. water wheel X 746 watts per hp. = 5,968 watts). This would most definitely trip any protection circuitry or burn the motor up. Most usually in applications of this nature two phases are used to supply 120 volt ac. line current for the home while the remaining phase is used to charge battery storage banks. You are unable to drive a three phase motor on a single phase line without modifications.

Every time you introduce a load in a circuit that the internal resistance of the alternator or generator increases in proportion to the load. This in turn lowers the rpm (this is how electric motoring brakes work). You must maintain an rpm near the upper gross deadband (the maximum output capable of any given alternator or generator before damage will occur). This is why motors have data plates. In a stand alone system you will have loads going on and off continuously and need this 2% to handle the ups and downs in current draw.

Offered by Jay.