slip rings/comutator 1

[turbinef14]

could some one please tell me why a 415 v three phase
motor has slip rings at one end of shaft and comutator at the other.

 

[Skogsgurra]

It does not sound like a motor. Is there any mechanical load connected to the shaft? Is there a shaft at all?

If no mechanical load is connected, then you have a mono-armature inverter that converts DC into AC. DC is fed into the commutator side and three-phase AC is picked up from the slip rings.

But, there is another possibility. If there are two sets of brushes on the commutator side and the brushes are movable, then you have a Schrage motor. It is an early version of a variable speed drive. It runs directly off three phase and the speed is changed by changing the position of the brushes so that the counter-EMF that is fed back into the rotor (via the slip rings) is changed and in its turn changes the speed of the motor.

 

[turbinef14]

thanks for your help. the motor does have two sets of brushes on the commutator and is used to drive a m/c
one of the brushes was not makeing contact on the slip ring would the motor still run once started and what problem would this have caused. again thak you for your help

 

[jammyjim]

As skog said, it sounds like a variable speed AC motor one end has slip rings the other end has a commutator with two sets of brushes rotaiting in different directions, there is usually a pony motor attactched to the brushgear also , all the ones i have seen were manufactured by a company caller "Anton Piller" im pretty sure they are fed through the slip rings, so if one of your brushes isnt making contact it could cause a problem, maybe the rotor could
"single phase"?

btw, there Very expensive to repair....

 

[turbinef14]

thanks jammyjim there is a seperate motor to drive the brushes on top.it also has a air pressure swith mounted
inside the cover

 

[powerjunx]

turbinef14,

Once, a one carbon brush never making contact on either side on the slip ring definitely the machine is in SINGLE PHASE.

Sequently, a humming sound is heard, it stops from running, overheats and BURN OUT the three phase winding(ROTOR winding with slip ring) or even the adjusting winding (with commutator). Provided, in the event, the protection device fails.

As you cited, a separate small motor atop the carbon brush riggings is use to shift the riggings for speed variation. The shifting of riggings are limited by cam switches or a feedback rheostats that also regulates the small motor from operation.

Another,a small motor is mounted atop the slip rings. it serves as a cooling purposes as a BLOWER. Whenever the blower is inoperational, a pressure switch mounted inside the cover will actuates as it sense a low or no pressure build up. it therefore interlocks the main motor and prevent it from energization.

Furthermore, some brands have OVERLOAD/SHORT CKT RELAY protection on the stator - adjusting winding, and also a micro limit switch mounted on carbon brush holder for monitoring of its presence.

Moreover, everytime id test the machine after a repair/rewinding. i got a tough time in re-setting the brush
riggings to its original setting even a careful marking was done properly prior the dissasemly.

However, it is still can be done accordingly.




ASKING WILL MAKE U CERTAIN..

REGARDS

 

[Skogsgurra]

I had forgotten about this thread when the Schrage motor appeared in thread237-110269. Go there and learn all about it!