A few days ago the motor on my compressor stopped working.
It died right about when the outside temp was around 41ºC and the compressor has been running on and off at least 20 times during that day. My compressor is in an external enclosure and when I went to check what had happened I noticed the 240V 6" enclosure venting fan had been manually switched off! I figure I must have accidentally knocked it off as the switch is in the middle of my metal rack and it has happened before.
The VFD indicated the motor had a short and sure enough when I checked two of the unconnected coils had a ~10Ω resistance between them (should be open circuit). On opening up the motor it was clear that it had overheated. That 4kw motor had cost me $35 so I was not that fussed but I must put some sort of cover over that switch.
So, off to gumtree again where I found a Toshiba motor that had been on an Ingersol compressor. The owner had swapped out the 3P motor for a SP motor as he did not have 3P at his place. The motor is an open frame type (end caps have cast grill openings) "well used", but it meggered and checked out resistance wise OK. What surprises me is this thing has no external fan, just the short stubby fins attacked to one end of the rotor as usually found on grinder rotors.
The other thing that surprises me is that in between the end cap opposite the pulley, and the main body of the motor, is a large circular disc.
IMG_6270.jpg
This disc seems to effectively seal up one end of the motor so I can't see how it allows any sort of air flow through the motor.
My gut feeling is to leave the disc out and add a 6" 240V fan to the outside of the end cap to help cool the motor?
The compressor is well out of the way so no one except me is going to access the actual compressor
Can anyone see anything wrong with this idea.
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Electric motor question
