Ek's Home   |   Forum   |   Chat   |   Electrical Links   |
	Subject - 250hp Synchronous motor CaApprentice If a 250 hp synchronous motor failed to synchronize, what part would you check first? What part in a synchronous motor generally requires the most frequent attention? Ryan_J Do you want us to take the test for you? lctrc789 Well let's see the armortisseur winding, the discharge resistor. Just to start but their could be even a few more that could cause you problems. frenchelectrician most common source is slip rings for dc exicter field so i suggest to check it out the dc suppy center unless it is self contanted then check the didoe gimzo on the rotor shaft that one of few common thing and other thing is check the current to the field if too much or too little current it will " step off line " and it will kick out motor overcurrent relay or devcies but there are quite few diffrent way to deal with it PEI Geez ! You have to be as old as I am to have ever seen 1 of these machines, but they are neat. Realize they are not started as a synchronous motor (isn't that what the amortisseur windings were for?), so there is a relay type device that monitors the currents to be sure they are in phase and it kicks in - and if I remember right the field excitation is applied at that point. Then you can adjust, over-excite or under-excite, to make it appear capacitive for power factor correction. My company's synchronous motor drove a reciprocating 5000 cfm air compressor - 16-inch diameter pistons and all. I would say whatever that relay type device was would be the reason it never reached synchronization. Also, ours had excitor motors that generated DC, later models used solid state devices to deliver DC. I would say keeping the slip rings cleaned and smooth or the brushes in the excitor motor would have been the most frequent maintenance item. The slip rings if I remember were where the excitation voltage was applied. They are a pair, exposed, about 2-foot in diameter, sharing the same concentric shaft as the motor. Lastly, I can't believe this is on a test unless you are taking a stationary engineers license. This is old technology, and too expensive to bring back.