6.6 kv. Large Variable Speed Motor "Eating brushes"
6.6 kv. Large Variable Speed Motor "Eating brushes"
(OP)
hi
Just after some fresh ideas on this problem, got 3 of these machine running large freshwater pumps for some reason recently they are going through brushes very quickly, a new set was put in last week 144 brushes, and there already showing signs of major wear, also sparking a fair bit not massively but noticeable I'll post more nameplate details tomorrow.
Brushes are of correct grade, motor current is fine, machines are paired with their own regulators, they are all matched up with right regulator, they haven't been mixed n matched, all connections on motor/brush gear/regulator are good.
Thx
jammyjim
Just after some fresh ideas on this problem, got 3 of these machine running large freshwater pumps for some reason recently they are going through brushes very quickly, a new set was put in last week 144 brushes, and there already showing signs of major wear, also sparking a fair bit not massively but noticeable I'll post more nameplate details tomorrow.
Brushes are of correct grade, motor current is fine, machines are paired with their own regulators, they are all matched up with right regulator, they haven't been mixed n matched, all connections on motor/brush gear/regulator are good.
Thx
jammyjim





RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
This is very interesting and I have a hunch. Are the sliprings only for start? Or is it a doubly-fed machine? Seen similar phenomena in large wind turbines.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
But inside the regulator there is another 3phase stator winding and 3phase rotor winding, I think the rotor turns inside the the stator to increase the speed somehow, had the covers off the regulator to inspect it, and it all looks fine.
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
I know of several machines that *could* fit your description. But I can't make the "no slipring" statement compatible with "brush consumption" AND "AC machine". What kind of beast is this? Pictures? Nameplate?
Any manufacturer?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
The brushgear is adjustable to obtain the variation in speeds.
There are 2 windings on the armature.
Supply to the slip rings,induces voltage to the armature winding,through the brushes to the stator winding.
The movement of the brushgear alters the phase angles to give the speed.
Its complicated to explain without diagrams.
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
BTW, I saw several Schrage motors only a few weeks ago. They seem to survive in textile applications.
OP: Were they running well up till now? Or have they been "sleeping" for a few years and then started again? Other (higher) load?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
https://www.dropbox.com/s/siwakf3i52wnc4p/2014-09-... <---- motor
https://www.dropbox.com/s/pxtrtkym7uftq83/2014-09-... <---- rugulator nameplate
https://www.dropbox.com/s/efue2ymj8lswu6s/2014-09-... <---- regulator
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
High mica segments can cause excess wear.
Just a thought.
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
Still, that's all I can think of. Next step would be to do a detailed check of "Everything"
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
thread237-343881: silicon weather sealant around dc motor brushes/commutators
RE: 6.6 kv. Large Variable Speed Motor "Eating brushes"
Bill
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Jimmy Carter