Will, and the rest of you fascinated by power distribution, A big synchronous motor allows its power factor to be changed by changing the field current for a given load. The motor can be adjusted to look like a resistive load instead of inductive, or even capacitive to correct plant power factor. Look it up.
Industrial power consumers are charged extra for power factors less than unity because the distribution system must carry more current for the same watts as the power factor departs from unity. Induction motors have inductive power factors because there must be slip between the rotating field and the speed of the rotor. Synchronous motors don't have slip, just phase angle. Zero angle looks like a resistive load, yes? The compressors don't have to run in sync. Best, Bill Hawkins (who heaves a nostalgic sigh just thinking about those fine old engines of progress) -----Original Message----- From: Will Matney Sent: Sunday, June 26, 2011 1:11 PM To: time-nuts@febo.com Subject: Re: [time-nuts] 60 Hz measurement party I quite like your generator description of "huge rotating lumps of copper-ensnarled iron". It brings me back to around 20 years ago, when I was a plant electrician at an older railcar manufacturer. They had huge open-frame synchronous motors, from around the 1930's, that ran their air compressors, and why they used this type of motor is anybodies guess. If I remember right, they were rated at around 200 HP, or so, and were about 8 feet in diameter. The rotor shaft was mounted on huge babbit bearings upon concrete pillars, and about 1/3 of the motor sat in a pit in the concrete floor. I used to have to repair the brushes on the slip rings constantly, until I talked the boss into adding a shunt across the n.o. contacts on the 250 Vdc contactors to quench any arcing. The motors stator itself ran on 4160 Vac. Would the other compressors have to run in sync somehow, as all of them had these motors, just some a little smaller than the others? They drove large single cylinder compressors that fed something like a 6 inch air line (pipe). However, they all did not run at once, and they only did when there was a larger demand for air. Timing is the only thing I can lay this to, and was wondering about it. Best, Will _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.