I was wondering as to - what determines the increase in HP of induction motor- Is it size of rotar, Housing, shaft etc... I will highly appreciate for clearing my ignorance.
Thank you so much for this informative video! I have one question: could the laminated rotor disks be made of nickel-plated steel by any chance? The reason why I ask, is because I'm making a squirrel cage motor from scratch, and I cut out disks from nickel-plated steel to make the laminated rotor. The disks have a good attraction to magnets.
Do 3 phase squirrel cage induction polyphase motors need or have starting capacitors? I have a very old Century 1.5 hp motor in my South Bend lathe, that has stopped running in forward, w/o my spinning it by hand. The Reverse operates normally. Thank you for your video, and any help or advise that anyone can give!
@@chrvoje_engineering I'm using this motor in my South Bend Lathe. Again, the Reverse direction works perfectly, I'm only having the "no start" problem in the Forward setting. This motor is only about 55 years old, so it's still just "broken in"! 😉
The following is for 1-phase only: Those old Century motors are started by an offset winding with a centrifugal switch. Two coils and a dual switch in your motor - since it can be reversed. If you have a capacitor on the frame, it doesn't matter. The following still pertains to you. There are two main types of starters - 1) offset windings, and 2) capacitor running on its own dedicated winding. Furthermore, a motor can have a centrifugal switch that cuts out the offset winding at almost full RPM or cuts out the capacitor winding the same way. In addition to that, a motor can LACK a centrifugal switch alltogether, and the offset winding or capacitor winding is always powered. These are usually small, cheap motors which don't need a high starting torque. (An exception - always on capacitor coil motors are used for wide torque band (wide torque range) uses like for compressors, but they have a third starter capacitor start coil (with a special breed 'starting capacitor') that is cut out by a centrifugal switch, and that is for high STARTING torque. Expensive motor.) How a starting offset winding works is that it is wound a pole or two ahead of the main winding usually, and wound with smaller wire. The smaller wire is important, because the rise of current in a winding with large wire is faster than the rise of current (and therefore the development of a magnetic field is delayed) in the smaller winding. So, the two coils of course are energized by the same waveform coming out of the wall, yet the two coils 'fire' (for lack of a better word) in an offset way (meaning develop their peak magnetizm at different times) and therefore simulates a rotating magnetic field. This is perfect for coaxing the rotor to turn because it gives something for it to 'chase'. Cap windings serve the same purpose, but are wound a couple of poles behind the main winding poles, since a cap is an energy storer and thus acts differently from a pure offset starter winding. The only reason why a 1-phase motor keeps runing after startup and any starter coils are turned off - is because the inertia of the rotor brings it around without magnetic assistance where a newly energizing stator pole can 'meet' it. Your Century motor has an open in one of the two offset starting coils. If you see no burning or dark coils, there is a good chance that the contacts for that coil on the centrifugal switch is bad which is an easy fix. Bad luck would be a simple open somewhere in the coil itself. Just disconnect the motor from the mains and use an ohmmeter to check the coils. Look at the switch for which terminals are for the starter coils. If the suspect coil reads infinite ohms or close to it, it is open. If it reads zero ohms, you probably found a contact that has been fried. That would be your answer.
