Help needed regarding a synchronus motor allowing a grab unit to drop.
Help needed regarding a synchronus motor allowing a grab unit to drop.
(OP)
Good morning ladies and gentlemen,
I have been having an issue with one of the machines in our manufacturing plant. The piece of machinery in question is a grab unit. The issues we are having are that it is suddenly dropping during running, sometimes it only drops an inch but it has been seen to have dropped up to 36 inches. It doesn't happen all of the time and is very intermittent.
The grab weighs approximately 1000Kg maybe slightly more and it is lifted with a chain drive arrangement which is run by a Bosch-Rexroth synchronous motor and gearbox with the motor brake rated at 32NM.
I was doubtful about the motor being faulty as it is only 4 months old but the grab has been reworked and made slightly heavier than before. I am curious whether the added weight means the brake may not be rated high enough anymore of whether it is simply a motor fault. Any ideas or suggestions on either option would be appreciated please, I have not really done any motor torque work since college which was more years ago than I would like to remember.
Thanks all.
I have been having an issue with one of the machines in our manufacturing plant. The piece of machinery in question is a grab unit. The issues we are having are that it is suddenly dropping during running, sometimes it only drops an inch but it has been seen to have dropped up to 36 inches. It doesn't happen all of the time and is very intermittent.
The grab weighs approximately 1000Kg maybe slightly more and it is lifted with a chain drive arrangement which is run by a Bosch-Rexroth synchronous motor and gearbox with the motor brake rated at 32NM.
I was doubtful about the motor being faulty as it is only 4 months old but the grab has been reworked and made slightly heavier than before. I am curious whether the added weight means the brake may not be rated high enough anymore of whether it is simply a motor fault. Any ideas or suggestions on either option would be appreciated please, I have not really done any motor torque work since college which was more years ago than I would like to remember.
Thanks all.





RE: Help needed regarding a synchronus motor allowing a grab unit to drop.
https://www.researchgate.net/publication/276949903...
RE: Help needed regarding a synchronus motor allowing a grab unit to drop.
999/1000 Not the motor.
Bill
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"Why not the best?"
Jimmy Carter
RE: Help needed regarding a synchronus motor allowing a grab unit to drop.
" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
RE: Help needed regarding a synchronus motor allowing a grab unit to drop.
RE: Help needed regarding a synchronus motor allowing a grab unit to drop.
RE: Help needed regarding a synchronus motor allowing a grab unit to drop.
Jraef could be right.
Why don't you check if you have a power factor trace or some kind of record from the motor feeder!
Power factor and the impedance undergoes for a rapid change during pole slip.
How about motor protection - does it include load jam protection, pole slip protection etc.!
Rompicherla Raghunath