Direction of an AC motor revisited

[Michael A. Terrell]

captainvideo462009@gmail.com wrote:

On Friday, June 19, 2015 at 12:19:59 AM UTC-4, captainvi...@gmail.com wrote:
Just wanted to get back to the group about this AC motor that was running in reverse after being disassembled and then put back together. It turns out that reversing the brushes did indeed reverse the direction of the motor. We can't argue with success, but I still don't fully understand why this is so. Can anyone please explain this to me? Thanks, Lenny

I don't have access to the growler any more but can't I use my Simpson? I'm thinking that I should have continuity between each of two segments 180 degrees apart. Is that correct? Lenny

It also test for shorts between coils, usually caused by a short
between segments of the commutator.

https://en.wikipedia.org/wiki/Growler_%28electrical_device%29

 

[whit3rd]

On Friday, June 19, 2015 at 4:01:50 PM UTC-7, captainvi...@gmail.com wrote:

On Friday, June 19, 2015 at 12:19:59 AM UTC-4, captainvi...@gmail.com wrote:
Just wanted to get back to the group about this AC motor that was running in reverse after being disassembled and then put back together. It turns out that reversing the brushes did indeed reverse the direction of the motor. We can't argue with success, but I still don't fully understand why this is so. Can anyone please explain this to me? Thanks, Lenny

I'm just curious, when this plate was moved did all the brushes rotate the same amount, or perhaps just two? Because if you think about that if they all moved the same as a group it doesn't make any sense. Lenny

I think it makes sense. The commutator selects a winding. The rotation of brushes determines
whether winding #1 puts a new rotor N pole CW of the stator's S pole, or winding #2
puts a new rotor N pole CCW of the stator's S pole

 

[Wolfgang Allinger]

On 21 Jun 15 at group /sci/electronics/repair in article 88958a1d-8253-423f-bfd0-1c1b1e17949e@googlegroups.com
<whit3rd@gmail.com> (whit3rd) wrote:

I think it makes sense. The commutator selects a winding. The
rotation of brushes determines whether winding #1 puts a new rotor N
pole CW of the stator's S pole, or winding #2 puts a new rotor N pole
CCW of the stator's S pole

on an AC Motor are no permanent S and N poles ;(
Its because Alternating Current = AC!




Saludos (an alle Vernünftigen, Rest sh. sig)
Wolfgang

--
Wolfgang Allinger, anerkannter Trollallergiker reply Adresse gesetzt!
Ich diskutiere zukünftig weniger mit Idioten, denn sie ziehen mich auf
ihr Niveau herunter und schlagen mich dort mit ihrer Erfahrung!
(lt. alter usenet Weisheit) iPod, iPhone, iPad, iTunes, iRak, iDiot

 

[hrhofmann@sbcglobal.net]

It's good to know Sam Goldwasser is still around, his posts are almost always 100 correct!!!

 

[M Philbrook]

In article <DJHb4JrEQoB@allinger-307049.user.uni-berlin>, all2001
@spambog.com says...

On 21 Jun 15 at group /sci/electronics/repair in article 88958a1d-8253-423f-bfd0-1c1b1e17949e@googlegroups.com
whit3rd@gmail.com> (whit3rd) wrote:


I think it makes sense. The commutator selects a winding. The
rotation of brushes determines whether winding #1 puts a new rotor N
pole CW of the stator's S pole, or winding #2 puts a new rotor N pole
CCW of the stator's S pole

on an AC Motor are no permanent S and N poles ;(
Its because Alternating Current = AC!




Saludos (an alle Vernünftigen, Rest sh. sig)
Wolfgang

Yeah but, it's a series motor so that means it can operate
on AC or DC..

As for the communtator being out by 1.5" or so, that isn't anything
to worry about because in the first short running time that should
smooth out, unless there is some bearing play? You really don't
want that.

Jamie

 

[Wolfgang Allinger]

On 21 Jun 15 at group /sci/electronics/repair in article MPG.2ff115271eb155a4989c33@news.eternal-september.org
<jamie_ka1lpa@charter.net> (M Philbrook) wrote:

In article <DJHb4JrEQoB@allinger-307049.user.uni-berlin>, all2001
@spambog.com says...

on an AC Motor are no permanent S and N poles ;(
Its because Alternating Current = AC!

Yeah but, it's a series motor so that means it can operate
on AC or DC..

The OP didn`t say anything about how the field is connected.
It`s likely, but not necessarily a series motor.!
So how do you know?

There are 3 types of brushed Motors with non permanent fields:

Nebenschluss Motor - shunt wound motor
Reihenschluss Motor - series wound motor
and combinations of them.

Mostly but not all are running with DC and low freq. AC (50/60Hz)
Some need a special wound for running properly with AC.


Saludos (an alle Vernünftigen, Rest sh. sig)
Wolfgang

--
Wolfgang Allinger, anerkannter Trollallergiker reply Adresse gesetzt!
Ich diskutiere zukünftig weniger mit Idioten, denn sie ziehen mich auf
ihr Niveau herunter und schlagen mich dort mit ihrer Erfahrung!
(lt. alter usenet Weisheit) iPod, iPhone, iPad, iTunes, iRak, iDiot

 

[Arfa Daily]

There was a term commonly used years ago which I haven't heard for a long
time. Many commutators would fail because they "threw solder". The point
on the commutator that was soldered to the individual rotor winding had
heated, melted the solder, and "threw" it out of the connection, leaving
that winding either open or intermittent at best.

A friend from my youth was an auto-electrician, and apparently, back then,
this was a common occurrence on starter motors and the like. The term that
he used for the condition was "flung" as in 'it's got a "flung" armature'

I knew what that one meant, but the one that I never got in terms of where
the phrase came from was "drop testing" which I believe referred to the
resistance checking of the armature windings across opposite brass
commutator segments, as described here by someone else.

Arfa