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Don't know what happen on motor that use for pump

thread237-3591

Don't know what happen on motor that use for pump

Don't know what happen on motor that use for pump

(OP)
I have some problem in  water pump group motor in  my factory. I must be change a motor's bearing every 1-2 month because the shock pulse value exceed standard value
(~35db). I check everything and found
     1.  The grease (type shell R3) in Brearing non-drive  change to liquid status
          temperature on flange ~80 C.
     2.  Electric Current on ground's cable has  ~16 Amps(150 Hz). We not connect this          cable to ground system but we connect this cable to the copper ground rod.
     3.  My group motor has 10 motors (200 , 90 , 132 Kw).       

RE: Don't know what happen on motor that use for pump

Do you happen to have connected the motor stator to the motor rotor, for example a copper jumper from the motor stator to the shaft slip rings, additionally installed? There may be an electrical current flowing from the motor stator to the motor rotor via the motor bearings. Large electrical rotating machines have this grounding feature designed and installed. A possible measurement by an ammeter between the motor stator and motor rotor shaft could reveal an approximate amount of current flowing from the motor stator to the motor rotor via bearings under assumption that the copper connection has much lower resistance than the electrical path via the motor bearings.

RE: Don't know what happen on motor that use for pump

If these are driven by VFDs you have induced bearing current.   Check ou thease people.
http://www.teleport.com/~sgsi/

RE: Don't know what happen on motor that use for pump

amphan
   Jbartos and bjc have highlight most probable cause. If these are not the case decouple the motor from the pump and run, measure voltage and currents and spm again without the pump (or intermediate transmision bearing) connected.
   Is it just one motor on the skid or the whole group giving problems?
   are the pumps allowed to "cavitate" this can cause you some strange spm readings.
   Also consider that if your ground connection  resistance is up a little and you are pumping sea water or such then a real good earth will be the process via bearings and pump rotor

   keep us posted
regards Don

RE: Don't know what happen on motor that use for pump

Amphan.
I send you a little cuestions that probably help you.
1- begin easy.
¿It´s only one motor that have the problem?
in case "yes"- The other motors have the same grease???
Discard lubrication problem.
Check the geometric line between the motor and the pump ;and the torque adjust of the mounting bolts .
Try to get an acelerometer and send us the values.

2- The electric problems leave in the bearing a very little holes, if you measure this you found a high frecuency. this is cause of the bearing balls beating in front of the hole edges.

3- low frecuency it´s a typical response from desbalance it might be mechanical or electric, in the electric case c ould be that any bars of the squirrel rotor are broken.

4- if you have the same problems in all motors change the grase i recomend you  "LE" lubrication enginers monolec type.

keep au posted
Regards.


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