rsdoran
Lifetime Supporting Member
I was called to a machine several days ago because the cooling fan for an rewind motor alarmed and kicked out a couple of times. The filter was stopped up so I changed it but in the process of starting that rewinder we heard a loud bang, I lost power to the whole machine. It kicked the main 600 amp breaker feeding the 400amp main for the machine. I found a contactor fused so replaced it, then energized the system again, another loud bang. Closer inspection showed the Digital DC drive had all 6 SCR's blown apart.
Anyway I ordered a new drive and installed it, then did the setup and programming. I went thru a deluge of Alarms, from the drive and HMI/computer interface. The drive would not work. Fuses blew. Upon closer investigation I determine that of the 3 fuses on drive control board that were blowing were part of the Field circuit for the drive. I had Meggered the motor and could not detect a problem.
After talking to the Drive manufacturer I/we determined it had to be in the motor. So I started disconnecting the motor to send it out for checking/repair.
What I found amazed me, the cooling motor fan blades had separated from the squirrel cage assembly, on this system the cooling fan is directly above the terminals for the motor connections. I found half the blades from the fan inside the DC motor..specifically one laying right on top of the connector terminal and TONS of metal shavings all over everything.
This whole thing took several days and isnt resolved completely, the motor is out to shop now but the machine is running.
Guess I am stating this because anything can happen...and drive you nuts trying to figure the why. In this case the original problem was the cooling fan but more major problems happened and I didnt consider the original problem causing it. Ya never know.
Anyway I ordered a new drive and installed it, then did the setup and programming. I went thru a deluge of Alarms, from the drive and HMI/computer interface. The drive would not work. Fuses blew. Upon closer investigation I determine that of the 3 fuses on drive control board that were blowing were part of the Field circuit for the drive. I had Meggered the motor and could not detect a problem.
After talking to the Drive manufacturer I/we determined it had to be in the motor. So I started disconnecting the motor to send it out for checking/repair.
What I found amazed me, the cooling motor fan blades had separated from the squirrel cage assembly, on this system the cooling fan is directly above the terminals for the motor connections. I found half the blades from the fan inside the DC motor..specifically one laying right on top of the connector terminal and TONS of metal shavings all over everything.
This whole thing took several days and isnt resolved completely, the motor is out to shop now but the machine is running.
Guess I am stating this because anything can happen...and drive you nuts trying to figure the why. In this case the original problem was the cooling fan but more major problems happened and I didnt consider the original problem causing it. Ya never know.