Commutators / Split / Slip Rings

[taiga]

I thought I had an idea of what they were until a question from TSSM 2010 threw me off (mind you i havent touched physics since august)

Does anyone have some good definitions for them, their applications, and what would happen without them? I'm having struggling understanding them

[kyzoo]

>.< I just have a pre-memorized definition in my head (pre-memorized from answering the asme question so many times X.x, not rote learning it)

Commutator in a motor:

Commutator reverses direction of current through the coil every half-turn (whenever coil reaches position perpendicular to the magnetic field). Commutator achievse this by alternating contacts between ocil ends and external power supply terminals; thsi results in reversal of magnetic forces acting on the coil, thereby maintaining a torque (and thus rotation) of consistent direction. Without commutator, coil will oscillate about position perpendicular to the magnetic field until it comes to a halt at that position.

Commutator in a generator

Commutator reverses polarity of the output current every half turn (whenever coil reach position perpendicular to the magnetic field), thereby producing a variable DC output current (as coil current switches direction every half turn as well.

[Elnino_Gerrard]

Ims ory what is an OCIl end?

[Chavi]

Split rings = for DC current (reverses the current every half turn, to change the dir. of forces so that the motor keeps spinning is a constant direction)
The graph for this is like a (sin(x))^2 graph. You never get voltage or current below the x axis

Slip rings = AC current. These works with alternators (where a magnet rotates inside a stationary coil) and generators (coil rotates about a stationary magnet). The graph for voltage and current is a simple sin curve. . .

BTW - Commutators and Split rings are only used for DC voltage

hope that helps

[Chavi]

>.< I just have a pre-memorized definition in my head (pre-memorized from answering the asme question so many times X.x, not rote learning it)

Commutator in a motor:

Commutator reverses direction of current through the coil every half-turn (whenever coil reaches position perpendicular to the magnetic field). Commutator achievse this by alternating contacts between ocil ends and external power supply terminals; thsi results in reversal of magnetic forces acting on the coil, thereby maintaining a torque (and thus rotation) of consistent direction. Without commutator, coil will oscillate about position perpendicular to the magnetic field until it comes to a halt at that position.

Commutator in a generator

Commutator reverses polarity of the output current every half turn (whenever coil reach position perpendicular to the magnetic field), thereby producing a variable DC output current (as coil current switches direction every half turn as well.

hahaha. This happened to me too. It's the same question on every third party exam

[kyzoo]

Ims ory what is an OCIl end?

coil end haha

[Elnino_Gerrard]

LOl phew ohkay

[taiga]

Okay so when a question asks me if a Commutator or a slip ring is ideal for a DC supply motor, I immediately call it as a commutator as Slip-Rings are only AC.

But what if it were to ask if a Split ring or a Commutator would be ideal, what would I be looking to say then?

or a Commutator = split ring commutator?

[kyzoo]

Okay so when a question asks me if a Commutator or a slip ring is ideal for a DC supply motor, I immediately call it as a commutator as Slip-Rings are only AC.

But what if it were to ask if a Split ring or a Commutator would be ideal, what would I be looking to say then?

split-ring commutator =D