Overhead crane

[John robertson]

Hello, anyone know why an overhead crane would cut out. It only cuts out when it gets to a certain point in the building. I have IR,continuity test on from control buttons to main panel. Tested windings of the motor all ok. Checked the busbar channel to ensure connectors have not worn down. 7 contactors, 4 were replaced around 2015 i am led to believe, 3 bigger contactors are quite old. Couldnt tell you how old lol. None of the breakers trip and the controls pull in the contactors but nothing happens. No drawings to go by as the manual is from late 70's.

 

[James]

If it is a track and brush for connecting the moving parts, I would look for damage or contamination.

recently been painted? A blob of paint on the conductive track would stop it dead.

 

[John robertson]

Never been painted. The track does seem to be in good condition considering the age. But saying that, it is a very dusty environment would that cause it?

 

[Yozza19]

Could of been zoned out during set up ?
Has it always worked until recently?

 

[John robertson]

It has surely been like this for years but now it has got worse, you think contactors could be starting to go if it has been like that for a while?

 

[James]

If it is always in the same place that it fails, i would be looking very carefully at a bent, damaged, dirty or otherwise failed piece of conductive track.

 

[ipf]

Sounds some kind of contact fault. If you know where it's happening, it's a starting point. It's guesswork for us, though.
It looks like some careful live testing will need to be carried out ....so plenty care needed.

 

[snowhead]

Is it just the travelling that cuts out or does the hook stop rising / falling.?
Is all power it via the Busbars or does it have trailing cables?
Does it stop in the same place with or without weight on it?

 

[John robertson]

Is it just the travelling that cuts out or does the hook stop rising / falling.?
Is all power it via the Busbars or does it have trailing cables?
Does it stop in the same place with or without weight on it?

Everything cuts out, and yes has trailing cables. And always stops at the same place. Control buttons will pull in the contactors they control but nothing happens after that. I did do a IR,continuity etc on cables everything tested ok. And windings of the motor were good too. Cuts out with no weight on it.