broken edges of carbon brushes
broken edges of carbon brushes
(OP)
we have four 3300kw, 13.8kv siemens slipring motors in a cement plant, in previous maintenance shutt down one motor was dismantled due to low stator resistance. we take out rotor from stator for stator cleaning, after cleaning motor was assembled and put the motor in service.
after 15 days we took stoppage for inspection and we found that ring#1 red high lighted brushes(see attached image)are broken from edges and their leads are also melted. please see attached file. now repeatedly edges are broken and leads are melting of the same carbon brushes on the ring#1.
i think there is no problem with grade as same brushes are being used for other motors and those are normal.
Brush spring tension has been verified and the springs are constant pressure springs.
slip ring surface is smooth.
no any sparking on these brushes is observed.
please some body can advice me on this issue.
regards,
ahmed
after 15 days we took stoppage for inspection and we found that ring#1 red high lighted brushes(see attached image)are broken from edges and their leads are also melted. please see attached file. now repeatedly edges are broken and leads are melting of the same carbon brushes on the ring#1.
i think there is no problem with grade as same brushes are being used for other motors and those are normal.
Brush spring tension has been verified and the springs are constant pressure springs.
slip ring surface is smooth.
no any sparking on these brushes is observed.
please some body can advice me on this issue.
regards,
ahmed





RE: broken edges of carbon brushes
RE: broken edges of carbon brushes
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: broken edges of carbon brushes
RE: broken edges of carbon brushes
i have checked the wiring, it is ok.
RE: broken edges of carbon brushes
Mike Halloran
Pembroke Pines, FL, USA
RE: broken edges of carbon brushes
I agree with Mike that brushes like mechanically schiped but you should scheck resistor, all contactors and their contact expecialy if part of resistor stay in function after starting of motor.Maybe there is problem. .
Good luck
RE: broken edges of carbon brushes
RE: broken edges of carbon brushes
Your brush wear doesn't look normal and it is certainly due to a mechanical problem. There is no burn marks on the edges.
The mechanical problem might have also caused the cable ripping. I am working for this brush manufacturer. If you need, I can have someone visit your plant.
Let me know if we can help.
Xavier Mlynek
RE: broken edges of carbon brushes
Looks to me like you have two problems, the mounting of the brush holders is not correctly set up. The brushes need to be radial to the commutator. If they run slightly reaction or stubbing (into the toe) vibration and chattering will occur with subsequent breakage. Second problem the brush shunts are being frayed and cut by the Tensator spring, using a suitable insulation on the shunts will negate this. Regards RoyDoug
RE: broken edges of carbon brushes
Bill
--------------------
"Why not the best?"
Jimmy Carter