Advancing Motor Timing pros/cons/ accel efficiency

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Advancing Motor Timing pros/cons/ accel efficiency

Mark Hanson-2

Hi Jeff etc;
Yes, my previous experience with Prestolite and a tranny is neutral is best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral when installing it so it always has run in neutral.  I would think that 20% reduced torque with a given current means 20% *less* efficiency and a bad thing.  My max RPM's is 3K (with 4-speed tranny) so I'm certainly not running this motor very fast where i think advanced timing would be needed.  So I'm inclined to leave it alone as i don't see how advancing the timing for 3K rpm operation would have a positive effect (at that speed) and have a negative effect starting off.
Best Regards,mark
Message: 8
Date: Mon, 5 Nov 2012 10:33:14 -0800 (PST)
From: Jeff Major <[hidden email]>
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
To: Electric Vehicle Discussion List <[hidden email]>
Message-ID:
<[hidden email]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Mark,

Brushes arc primarily due to voltage, current and RPM.? Any, or combinations, can cause excessive arcing when too high.? I personally think that most times the advance is too far.? But if that is where it is drilled, I'd do it for the voltage you're running.

Advancing the brushes weakens the field in effect and therefore reduces the torque per amp of the motor while increasing the RPM per amp.? On a 4 pole motor, if you rotate (advance) the brushes 90 degrees, you reverse rotation.? 45 degrees would give you zero torque.? So you lose about 2 percent per degree.? That is just an approximation because it is not linear.? But it is not unreasonable to expect 20 percent lower torque at a given current with a 12 degree advance.

The other thing is:? What is your starting point?? Was your motor set on neutral when installed?? I recall you doing test on the Prestolite motor assuming it was neutral to start and it was manufactured with a 4.5 degree advance.

Most cases will benefit from the advanced brushes and improved commutation even at the expense of torque if you have the transmission.? Just use a lower gear.? If you don't run a transmission, think hard about it because reverse on the motor with advanced brushes can be damaging.

See ya,

Jeff M
     
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Re: Advancing Motor Timing pros/cons/ accel efficiency

Jeffrey Jenkins
Mark Hanson-2 wrote
Hi Jeff etc;
Yes, my previous experience with Prestolite and a tranny is neutral is best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral when installing it so it always has run in neutral.  I would think that 20% reduced torque with a given current means 20% *less* efficiency and a bad thing.
Nope - 20% less torque is offset by 20% more RPM (for the same current and voltage, respectively).

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Re: Advancing Motor Timing pros/cons/ accel efficiency

Jeff Major
In reply to this post by Mark Hanson-2
Hi Mark,

As JJ says, the torque loss is offset by RPM increase as happens with field weakening, so it is not a direct hit on efficiency.  The efficiency curve will be altered with brush advance (and with field weakening).  At some load points it may increase a bit and other loads decrease.  Proper advance should not result in significantly lower motor efficiency.  Going too far with advance or retardation may result in adverse effects on the efficiency by actually shifting shorted coils (those being commutated) under the main field flux.

And I told you that advance compensates for altered commutation due to high current, high voltage and/or high RPM.  In your case, it is not 3000 RPM I would be concerned about, it is the system voltage and current limit.  You said it was drilled for 12 degrees, right?  Off hand, I think about half that would be better for you.  If you're smelling or hearing the brush arc going uphill, I'd give it that 6 degrees.

Regards,

Jeff M



________________________________
 From: Mark Hanson <[hidden email]>
To: "[hidden email]" <[hidden email]>
Sent: Tuesday, November 6, 2012 9:55 AM
Subject: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
 

Hi Jeff etc;
Yes, my previous experience with Prestolite and a tranny is neutral is best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral when installing it so it always has run in neutral.  I would think that 20% reduced torque with a given current means 20% *less* efficiency and a bad thing.  My max RPM's is 3K (with 4-speed tranny) so I'm certainly not running this motor very fast where i think advanced timing would be needed.  So I'm inclined to leave it alone as i don't see how advancing the timing for 3K rpm operation would have a positive effect (at that speed) and have a negative effect starting off.
Best Regards,mark
Message: 8
Date: Mon, 5 Nov 2012 10:33:14 -0800 (PST)
From: Jeff Major <[hidden email]>
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
To: Electric Vehicle Discussion List <[hidden email]>
Message-ID:
<[hidden email]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Mark,

Brushes arc primarily due to voltage, current and RPM.? Any, or combinations, can cause excessive arcing when too high.? I personally think that most times the advance is too far.? But if that is where it is drilled, I'd do it for the voltage you're running.

Advancing the brushes weakens the field in effect and therefore reduces the torque per amp of the motor while increasing the RPM per amp.? On a 4 pole motor, if you rotate (advance) the brushes 90 degrees, you reverse rotation.? 45 degrees would give you zero torque.? So you lose about 2 percent per degree.? That is just an approximation because it is not linear.? But it is not unreasonable to expect 20 percent lower torque at a given current with a 12 degree advance.

The other thing is:? What is your starting point?? Was your motor set on neutral when installed?? I recall you doing test on the Prestolite motor assuming it was neutral to start and it was manufactured with a 4.5 degree advance.

Most cases will benefit from the advanced brushes and improved commutation even at the expense of torque if you have the transmission.? Just use a lower gear.? If you don't run a transmission, think hard about it because reverse on the motor with advanced brushes can be damaging.

See ya,

Jeff M
                         
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Re: Advancing Motor Timing pros/cons/ accel efficiency

gtyler54
I found a pretty good explanation that will help those who have never looked
at this before,
http://www.cedengineering.com/upload/DC%20Generators%20and%20Motors.pdf

page 1-9 talks about interpoles etc. I think the important thing is, the
reaction of the flux and the amount of brush advance needed is not directly
influenced by RPM. It is directly related to current in the armature,
reading this document we can see why. Only thing, I have limited experience
with DC motors, last course I did on them was in the '60's. I have never
seen or heard of a SERIES DC motor with interpoles, in a way, the normal
poles are like interpoles because they are also in series. My reasoning
tells me that if you advance the brush timing the right amount the timing
should be right at all loads, currents and RPM's? In a shunt motor they are
in series so that as the current increases and rotates the flux path they
turn it straight again, and as this is caused by the current the current
through the interpoles, varying with this current produces the right amount
of counter rotation to correct it as the current varies.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 5:16 a.m.
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hi Mark,

As JJ says, the torque loss is offset by RPM increase as happens with field
weakening, so it is not a direct hit on efficiency.  The efficiency curve
will be altered with brush advance (and with field weakening).  At some load
points it may increase a bit and other loads decrease.  Proper advance
should not result in significantly lower motor efficiency.  Going too far
with advance or retardation may result in adverse effects on the efficiency
by actually shifting shorted coils (those being commutated) under the main
field flux.

And I told you that advance compensates for altered commutation due to high
current, high voltage and/or high RPM.  In your case, it is not 3000 RPM I
would be concerned about, it is the system voltage and current limit.  You
said it was drilled for 12 degrees, right?  Off hand, I think about half
that would be better for you.  If you're smelling or hearing the brush arc
going uphill, I'd give it that 6 degrees.

Regards,

Jeff M



________________________________
 From: Mark Hanson <[hidden email]>
To: "[hidden email]" <[hidden email]>
Sent: Tuesday, November 6, 2012 9:55 AM
Subject: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
 

Hi Jeff etc;
Yes, my previous experience with Prestolite and a tranny is neutral is
best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral when
installing it so it always has run in neutral.  I would think that 20%
reduced torque with a given current means 20% *less* efficiency and a bad
thing.  My max RPM's is 3K (with 4-speed tranny) so I'm certainly not
running this motor very fast where i think advanced timing would be needed. 
So I'm inclined to leave it alone as i don't see how advancing the timing
for 3K rpm operation would have a positive effect (at that speed) and have a
negative effect starting off.
Best Regards,mark
Message: 8
Date: Mon, 5 Nov 2012 10:33:14 -0800 (PST)
From: Jeff Major <[hidden email]>
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
To: Electric Vehicle Discussion List <[hidden email]>
Message-ID:
<[hidden email]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Mark,

Brushes arc primarily due to voltage, current and RPM.? Any, or
combinations, can cause excessive arcing when too high.? I personally think
that most times the advance is too far.? But if that is where it is drilled,
I'd do it for the voltage you're running.

Advancing the brushes weakens the field in effect and therefore reduces the
torque per amp of the motor while increasing the RPM per amp.? On a 4 pole
motor, if you rotate (advance) the brushes 90 degrees, you reverse
rotation.? 45 degrees would give you zero torque.? So you lose about 2
percent per degree.? That is just an approximation because it is not
linear.? But it is not unreasonable to expect 20 percent lower torque at a
given current with a 12 degree advance.

The other thing is:? What is your starting point?? Was your motor set on
neutral when installed?? I recall you doing test on the Prestolite motor
assuming it was neutral to start and it was manufactured with a 4.5 degree
advance.

Most cases will benefit from the advanced brushes and improved commutation
even at the expense of torque if you have the transmission.? Just use a
lower gear.? If you don't run a transmission, think hard about it because
reverse on the motor with advanced brushes can be damaging.

See ya,

Jeff M
                         
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Re: Advancing Motor Timing pros/cons/ accel efficiency

Jeff Major
Hello George,

Interpole series motors are used for reversing applications and where dynamic, plug, or (dare I say it?) regenerative braking is used.  Brush advance doesn't work in these spots. 

Interpoles in shunt and compound motors work better than the brush advance because they vary strength with load and the sweet spot for commutation varies with load.

Contrary to what your referenced article says and what you state, interpoles do not counteract armature reaction.  Compensating or pole face winding do.  And interpoles do not shift (rotate) the main field flux.  The interpole by virtue of the mmf from the comm coil (interpole winding) manipulates the flux in a small interpolar region where the neutral plane was before it was shifted by the armature reaction.  This may seem picky.  But that is because most here are concerned with series motors where armature reaction is not a big factor in performance.  With shunt machines, armature reaction can cause serious loss of torque or regulation.  There you will find interpoles do nothing to counteract this and they must use compensating windings and sometimes series field windings.

Regards,

Jeff M



----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List' <[hidden email]>
Cc:
Sent: Tuesday, November 6, 2012 6:30 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

I found a pretty good explanation that will help those who have never looked
at this before,
http://www.cedengineering.com/upload/DC%20Generators%20and%20Motors.pdf

page 1-9 talks about interpoles etc. I think the important thing is, the
reaction of the flux and the amount of brush advance needed is not directly
influenced by RPM. It is directly related to current in the armature,
reading this document we can see why. Only thing, I have limited experience
with DC motors, last course I did on them was in the '60's. I have never
seen or heard of a SERIES DC motor with interpoles, in a way, the normal
poles are like interpoles because they are also in series. My reasoning
tells me that if you advance the brush timing the right amount the timing
should be right at all loads, currents and RPM's? In a shunt motor they are
in series so that as the current increases and rotates the flux path they
turn it straight again, and as this is caused by the current the current
through the interpoles, varying with this current produces the right amount
of counter rotation to correct it as the current varies.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 5:16 a.m.
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hi Mark,

As JJ says, the torque loss is offset by RPM increase as happens with field
weakening, so it is not a direct hit on efficiency.  The efficiency curve
will be altered with brush advance (and with field weakening).  At some load
points it may increase a bit and other loads decrease.  Proper advance
should not result in significantly lower motor efficiency.  Going too far
with advance or retardation may result in adverse effects on the efficiency
by actually shifting shorted coils (those being commutated) under the main
field flux.

And I told you that advance compensates for altered commutation due to high
current, high voltage and/or high RPM.  In your case, it is not 3000 RPM I
would be concerned about, it is the system voltage and current limit.  You
said it was drilled for 12 degrees, right?  Off hand, I think about half
that would be better for you.  If you're smelling or hearing the brush arc
going uphill, I'd give it that 6 degrees.

Regards,

Jeff M



________________________________
From: Mark Hanson <[hidden email]>
To: "[hidden email]" <[hidden email]>
Sent: Tuesday, November 6, 2012 9:55 AM
Subject: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency


Hi Jeff etc;
Yes, my previous experience with Prestolite and a tranny is neutral is
best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral when
installing it so it always has run in neutral.  I would think that 20%
reduced torque with a given current means 20% *less* efficiency and a bad
thing.  My max RPM's is 3K (with 4-speed tranny) so I'm certainly not
running this motor very fast where i think advanced timing would be needed. 
So I'm inclined to leave it alone as i don't see how advancing the timing
for 3K rpm operation would have a positive effect (at that speed) and have a
negative effect starting off.
Best Regards,mark
Message: 8
Date: Mon, 5 Nov 2012 10:33:14 -0800 (PST)
From: Jeff Major <[hidden email]>
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
To: Electric Vehicle Discussion List <[hidden email]>
Message-ID:
<[hidden email]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Mark,

Brushes arc primarily due to voltage, current and RPM.? Any, or
combinations, can cause excessive arcing when too high.? I personally think
that most times the advance is too far.? But if that is where it is drilled,
I'd do it for the voltage you're running.

Advancing the brushes weakens the field in effect and therefore reduces the
torque per amp of the motor while increasing the RPM per amp.? On a 4 pole
motor, if you rotate (advance) the brushes 90 degrees, you reverse
rotation.? 45 degrees would give you zero torque.? So you lose about 2
percent per degree.? That is just an approximation because it is not
linear.? But it is not unreasonable to expect 20 percent lower torque at a
given current with a 12 degree advance.

The other thing is:? What is your starting point?? Was your motor set on
neutral when installed?? I recall you doing test on the Prestolite motor
assuming it was neutral to start and it was manufactured with a 4.5 degree
advance.

Most cases will benefit from the advanced brushes and improved commutation
even at the expense of torque if you have the transmission.? Just use a
lower gear.? If you don't run a transmission, think hard about it because
reverse on the motor with advanced brushes can be damaging.

See ya,

Jeff M
                         
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|
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|
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Re: Advancing Motor Timing pros/cons/ accel efficiency

gtyler54
Are there any examples of series motors with interpoles on internet?

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 3:04 p.m.
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hello George,

Interpole series motors are used for reversing applications and where
dynamic, plug, or (dare I say it?) regenerative braking is used.  Brush
advance doesn't work in these spots. 

Interpoles in shunt and compound motors work better than the brush advance
because they vary strength with load and the sweet spot for commutation
varies with load.

Contrary to what your referenced article says and what you state, interpoles
do not counteract armature reaction.  Compensating or pole face winding do. 
And interpoles do not shift (rotate) the main field flux.  The interpole by
virtue of the mmf from the comm coil (interpole winding) manipulates the
flux in a small interpolar region where the neutral plane was before it was
shifted by the armature reaction.  This may seem picky.  But that is because
most here are concerned with series motors where armature reaction is not a
big factor in performance.  With shunt machines, armature reaction can cause
serious loss of torque or regulation.  There you will find interpoles do
nothing to counteract this and they must use compensating windings and
sometimes series field windings.

Regards,

Jeff M



----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List'
<[hidden email]>
Cc:
Sent: Tuesday, November 6, 2012 6:30 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

I found a pretty good explanation that will help those who have never looked
at this before,
http://www.cedengineering.com/upload/DC%20Generators%20and%20Motors.pdf

page 1-9 talks about interpoles etc. I think the important thing is, the
reaction of the flux and the amount of brush advance needed is not directly
influenced by RPM. It is directly related to current in the armature,
reading this document we can see why. Only thing, I have limited experience
with DC motors, last course I did on them was in the '60's. I have never
seen or heard of a SERIES DC motor with interpoles, in a way, the normal
poles are like interpoles because they are also in series. My reasoning
tells me that if you advance the brush timing the right amount the timing
should be right at all loads, currents and RPM's? In a shunt motor they are
in series so that as the current increases and rotates the flux path they
turn it straight again, and as this is caused by the current the current
through the interpoles, varying with this current produces the right amount
of counter rotation to correct it as the current varies.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 5:16 a.m.
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hi Mark,

As JJ says, the torque loss is offset by RPM increase as happens with field
weakening, so it is not a direct hit on efficiency.  The efficiency curve
will be altered with brush advance (and with field weakening).  At some load
points it may increase a bit and other loads decrease.  Proper advance
should not result in significantly lower motor efficiency.  Going too far
with advance or retardation may result in adverse effects on the efficiency
by actually shifting shorted coils (those being commutated) under the main
field flux.

And I told you that advance compensates for altered commutation due to high
current, high voltage and/or high RPM.  In your case, it is not 3000 RPM I
would be concerned about, it is the system voltage and current limit.  You
said it was drilled for 12 degrees, right?  Off hand, I think about half
that would be better for you.  If you're smelling or hearing the brush arc
going uphill, I'd give it that 6 degrees.

Regards,

Jeff M



________________________________
From: Mark Hanson <[hidden email]>
To: "[hidden email]" <[hidden email]>
Sent: Tuesday, November 6, 2012 9:55 AM
Subject: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency


Hi Jeff etc;
Yes, my previous experience with Prestolite and a tranny is neutral is
best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral when
installing it so it always has run in neutral.  I would think that 20%
reduced torque with a given current means 20% *less* efficiency and a bad
thing.  My max RPM's is 3K (with 4-speed tranny) so I'm certainly not
running this motor very fast where i think advanced timing would be needed. 
So I'm inclined to leave it alone as i don't see how advancing the timing
for 3K rpm operation would have a positive effect (at that speed) and have a
negative effect starting off.
Best Regards,mark
Message: 8
Date: Mon, 5 Nov 2012 10:33:14 -0800 (PST)
From: Jeff Major <[hidden email]>
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
To: Electric Vehicle Discussion List <[hidden email]>
Message-ID:
<[hidden email]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Mark,

Brushes arc primarily due to voltage, current and RPM.? Any, or
combinations, can cause excessive arcing when too high.? I personally think
that most times the advance is too far.? But if that is where it is drilled,
I'd do it for the voltage you're running.

Advancing the brushes weakens the field in effect and therefore reduces the
torque per amp of the motor while increasing the RPM per amp.? On a 4 pole
motor, if you rotate (advance) the brushes 90 degrees, you reverse
rotation.? 45 degrees would give you zero torque.? So you lose about 2
percent per degree.? That is just an approximation because it is not
linear.? But it is not unreasonable to expect 20 percent lower torque at a
given current with a 12 degree advance.

The other thing is:? What is your starting point?? Was your motor set on
neutral when installed?? I recall you doing test on the Prestolite motor
assuming it was neutral to start and it was manufactured with a 4.5 degree
advance.

Most cases will benefit from the advanced brushes and improved commutation
even at the expense of torque if you have the transmission.? Just use a
lower gear.? If you don't run a transmission, think hard about it because
reverse on the motor with advanced brushes can be damaging.

See ya,

Jeff M
                         
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Re: Advancing Motor Timing pros/cons/ accel efficiency

Morgan LaMoore
The Warp 11 HV has interpoles.

On Fri, Nov 9, 2012 at 12:51 PM, George Tyler <[hidden email]> wrote:

> Are there any examples of series motors with interpoles on internet?
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf
> Of Jeff Major
> Sent: Wednesday, 7 November 2012 3:04 p.m.
> To: 'Electric Vehicle Discussion List'
> Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
>
> Hello George,
>
> Interpole series motors are used for reversing applications and where
> dynamic, plug, or (dare I say it?) regenerative braking is used.  Brush
> advance doesn't work in these spots.
>
> Interpoles in shunt and compound motors work better than the brush advance
> because they vary strength with load and the sweet spot for commutation
> varies with load.
>
> Contrary to what your referenced article says and what you state,
> interpoles
> do not counteract armature reaction.  Compensating or pole face winding
> do.
> And interpoles do not shift (rotate) the main field flux.  The interpole by
> virtue of the mmf from the comm coil (interpole winding) manipulates the
> flux in a small interpolar region where the neutral plane was before it was
> shifted by the armature reaction.  This may seem picky.  But that is
> because
> most here are concerned with series motors where armature reaction is not a
> big factor in performance.  With shunt machines, armature reaction can
> cause
> serious loss of torque or regulation.  There you will find interpoles do
> nothing to counteract this and they must use compensating windings and
> sometimes series field windings.
>
> Regards,
>
> Jeff M
>
>
>
> ----- Original Message -----
> From: George Tyler <[hidden email]>
> To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List'
> <[hidden email]>
> Cc:
> Sent: Tuesday, November 6, 2012 6:30 PM
> Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
>
> I found a pretty good explanation that will help those who have never
> looked
> at this before,
> http://www.cedengineering.com/upload/DC%20Generators%20and%20Motors.pdf
>
> page 1-9 talks about interpoles etc. I think the important thing is, the
> reaction of the flux and the amount of brush advance needed is not directly
> influenced by RPM. It is directly related to current in the armature,
> reading this document we can see why. Only thing, I have limited experience
> with DC motors, last course I did on them was in the '60's. I have never
> seen or heard of a SERIES DC motor with interpoles, in a way, the normal
> poles are like interpoles because they are also in series. My reasoning
> tells me that if you advance the brush timing the right amount the timing
> should be right at all loads, currents and RPM's? In a shunt motor they are
> in series so that as the current increases and rotates the flux path they
> turn it straight again, and as this is caused by the current the current
> through the interpoles, varying with this current produces the right amount
> of counter rotation to correct it as the current varies.
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf
> Of Jeff Major
> Sent: Wednesday, 7 November 2012 5:16 a.m.
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
>
> Hi Mark,
>
> As JJ says, the torque loss is offset by RPM increase as happens with field
> weakening, so it is not a direct hit on efficiency.  The efficiency curve
> will be altered with brush advance (and with field weakening).  At some
> load
> points it may increase a bit and other loads decrease.  Proper advance
> should not result in significantly lower motor efficiency.  Going too far
> with advance or retardation may result in adverse effects on the efficiency
> by actually shifting shorted coils (those being commutated) under the main
> field flux.
>
> And I told you that advance compensates for altered commutation due to high
> current, high voltage and/or high RPM.  In your case, it is not 3000 RPM I
> would be concerned about, it is the system voltage and current limit.  You
> said it was drilled for 12 degrees, right?  Off hand, I think about half
> that would be better for you.  If you're smelling or hearing the brush arc
> going uphill, I'd give it that 6 degrees.
>
> Regards,
>
> Jeff M
>
>
>
> ________________________________
> From: Mark Hanson <[hidden email]>
> To: "[hidden email]" <[hidden email]>
> Sent: Tuesday, November 6, 2012 9:55 AM
> Subject: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
>
>
> Hi Jeff etc;
> Yes, my previous experience with Prestolite and a tranny is neutral is
> best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral
> when
> installing it so it always has run in neutral.  I would think that 20%
> reduced torque with a given current means 20% *less* efficiency and a bad
> thing.  My max RPM's is 3K (with 4-speed tranny) so I'm certainly not
> running this motor very fast where i think advanced timing would be
> needed.
> So I'm inclined to leave it alone as i don't see how advancing the timing
> for 3K rpm operation would have a positive effect (at that speed) and have
> a
> negative effect starting off.
> Best Regards,mark
> Message: 8
> Date: Mon, 5 Nov 2012 10:33:14 -0800 (PST)
> From: Jeff Major <[hidden email]>
> Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
> To: Electric Vehicle Discussion List <[hidden email]>
> Message-ID:
> <[hidden email]>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi Mark,
>
> Brushes arc primarily due to voltage, current and RPM.? Any, or
> combinations, can cause excessive arcing when too high.? I personally think
> that most times the advance is too far.? But if that is where it is
> drilled,
> I'd do it for the voltage you're running.
>
> Advancing the brushes weakens the field in effect and therefore reduces the
> torque per amp of the motor while increasing the RPM per amp.? On a 4 pole
> motor, if you rotate (advance) the brushes 90 degrees, you reverse
> rotation.? 45 degrees would give you zero torque.? So you lose about 2
> percent per degree.? That is just an approximation because it is not
> linear.? But it is not unreasonable to expect 20 percent lower torque at a
> given current with a 12 degree advance.
>
> The other thing is:? What is your starting point?? Was your motor set on
> neutral when installed?? I recall you doing test on the Prestolite motor
> assuming it was neutral to start and it was manufactured with a 4.5 degree
> advance.
>
> Most cases will benefit from the advanced brushes and improved commutation
> even at the expense of torque if you have the transmission.? Just use a
> lower gear.? If you don't run a transmission, think hard about it because
> reverse on the motor with advanced brushes can be damaging.
>
> See ya,
>
> Jeff M
>
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> Checked by AVG - www.avg.com
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|
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Re: Advancing Motor Timing pros/cons/ accel efficiency

Lee Hart
On 11/9/2012 1:49 PM, Morgan LaMoore wrote:
> The Warp 11 HV has interpoles.

So do the big Kostov motors, and the classic aircraft starter-generators.

--
First they ignore you; then they mock you; then they fight you; then you
win. -- Mahatma Gandhi
--
Lee A. Hart http://www.sunrise-ev.com/LeesEVs [hidden email]

_______________________________________________
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Re: Advancing Motor Timing pros/cons/ accel efficiency

Jeff Major
In reply to this post by gtyler54
Hi George,

http://kostov-motors.com/files/productattachments/04c1adb9b9b14801dea33e5ecd0c3e44_F18B2.pdf 


See the wiring diagram and connection note on that drawing.

Large forklift trucks were common applications requiring interpole DC series wound motors due to the reversing direction duty and plug reversing even though the voltage and RPM were low by today's EV motor standards.

I have an old postal Jeep with a 96V system, 11 inch series wound DC  motor with interpoles and a SCR controller with regeneration.  It is direct drive (motor to rear differential) therefore uses contactor field switching for reversing the motor.

Regards,

Jeff M



----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List' <[hidden email]>
Cc:
Sent: Friday, November 9, 2012 1:51 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Are there any examples of series motors with interpoles on internet?

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 3:04 p.m.
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hello George,

Interpole series motors are used for reversing applications and where
dynamic, plug, or (dare I say it?) regenerative braking is used.  Brush
advance doesn't work in these spots. 

Interpoles in shunt and compound motors work better than the brush advance
because they vary strength with load and the sweet spot for commutation
varies with load.

Contrary to what your referenced article says and what you state, interpoles
do not counteract armature reaction.  Compensating or pole face winding do. 
And interpoles do not shift (rotate) the main field flux.  The interpole by
virtue of the mmf from the comm coil (interpole winding) manipulates the
flux in a small interpolar region where the neutral plane was before it was
shifted by the armature reaction.  This may seem picky.  But that is because
most here are concerned with series motors where armature reaction is not a
big factor in performance.  With shunt machines, armature reaction can cause
serious loss of torque or regulation.  There you will find interpoles do
nothing to counteract this and they must use compensating windings and
sometimes series field windings.

Regards,

Jeff M



----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List'
<[hidden email]>
Cc:
Sent: Tuesday, November 6, 2012 6:30 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

I found a pretty good explanation that will help those who have never looked
at this before,
http://www.cedengineering.com/upload/DC%20Generators%20and%20Motors.pdf

page 1-9 talks about interpoles etc. I think the important thing is, the
reaction of the flux and the amount of brush advance needed is not directly
influenced by RPM. It is directly related to current in the armature,
reading this document we can see why. Only thing, I have limited experience
with DC motors, last course I did on them was in the '60's. I have never
seen or heard of a SERIES DC motor with interpoles, in a way, the normal
poles are like interpoles because they are also in series. My reasoning
tells me that if you advance the brush timing the right amount the timing
should be right at all loads, currents and RPM's? In a shunt motor they are
in series so that as the current increases and rotates the flux path they
turn it straight again, and as this is caused by the current the current
through the interpoles, varying with this current produces the right amount
of counter rotation to correct it as the current varies.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 5:16 a.m.
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hi Mark,

As JJ says, the torque loss is offset by RPM increase as happens with field
weakening, so it is not a direct hit on efficiency.  The efficiency curve
will be altered with brush advance (and with field weakening).  At some load
points it may increase a bit and other loads decrease.  Proper advance
should not result in significantly lower motor efficiency.  Going too far
with advance or retardation may result in adverse effects on the efficiency
by actually shifting shorted coils (those being commutated) under the main
field flux.

And I told you that advance compensates for altered commutation due to high
current, high voltage and/or high RPM.  In your case, it is not 3000 RPM I
would be concerned about, it is the system voltage and current limit.  You
said it was drilled for 12 degrees, right?  Off hand, I think about half
that would be better for you.  If you're smelling or hearing the brush arc
going uphill, I'd give it that 6 degrees.

Regards,

Jeff M



________________________________
From: Mark Hanson <[hidden email]>
To: "[hidden email]" <[hidden email]>
Sent: Tuesday, November 6, 2012 9:55 AM
Subject: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency


Hi Jeff etc;
Yes, my previous experience with Prestolite and a tranny is neutral is
best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral when
installing it so it always has run in neutral.  I would think that 20%
reduced torque with a given current means 20% *less* efficiency and a bad
thing.  My max RPM's is 3K (with 4-speed tranny) so I'm certainly not
running this motor very fast where i think advanced timing would be needed. 
So I'm inclined to leave it alone as i don't see how advancing the timing
for 3K rpm operation would have a positive effect (at that speed) and have a
negative effect starting off.
Best Regards,mark
Message: 8
Date: Mon, 5 Nov 2012 10:33:14 -0800 (PST)
From: Jeff Major <[hidden email]>
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
To: Electric Vehicle Discussion List <[hidden email]>
Message-ID:
<[hidden email]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Mark,

Brushes arc primarily due to voltage, current and RPM.? Any, or
combinations, can cause excessive arcing when too high.? I personally think
that most times the advance is too far.? But if that is where it is drilled,
I'd do it for the voltage you're running.

Advancing the brushes weakens the field in effect and therefore reduces the
torque per amp of the motor while increasing the RPM per amp.? On a 4 pole
motor, if you rotate (advance) the brushes 90 degrees, you reverse
rotation.? 45 degrees would give you zero torque.? So you lose about 2
percent per degree.? That is just an approximation because it is not
linear.? But it is not unreasonable to expect 20 percent lower torque at a
given current with a 12 degree advance.

The other thing is:? What is your starting point?? Was your motor set on
neutral when installed?? I recall you doing test on the Prestolite motor
assuming it was neutral to start and it was manufactured with a 4.5 degree
advance.

Most cases will benefit from the advanced brushes and improved commutation
even at the expense of torque if you have the transmission.? Just use a
lower gear.? If you don't run a transmission, think hard about it because
reverse on the motor with advanced brushes can be damaging.

See ya,

Jeff M
                         
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_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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Re: Advancing Motor Timing pros/cons/ accel efficiency

gtyler54
Thanks, well, that’s definitely one! I was thinking that an interpole is in
series with the armature, so is the field, so there is no real difference.
You may as well just have a bigger field winding with some brush advance.
        I see the "interpoles" aid the field in one direction and buck it in
the other, so the motor will run faster in one direction than the other.
fairly simple, but operation is different to a shunt motor interpoles as the
field angle does not change with current, well with a shunt motor and
interpoles it does not either but it would without them.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Saturday, 10 November 2012 2:08 p.m.
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hi George,

http://kostov-motors.com/files/productattachments/04c1adb9b9b14801dea33e5ecd
0c3e44_F18B2.pdf 


See the wiring diagram and connection note on that drawing.

Large forklift trucks were common applications requiring interpole DC series
wound motors due to the reversing direction duty and plug reversing even
though the voltage and RPM were low by today's EV motor standards.

I have an old postal Jeep with a 96V system, 11 inch series wound DC  motor
with interpoles and a SCR controller with regeneration.  It is direct drive
(motor to rear differential) therefore uses contactor field switching for
reversing the motor.

Regards,

Jeff M



----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List'
<[hidden email]>
Cc:
Sent: Friday, November 9, 2012 1:51 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Are there any examples of series motors with interpoles on internet?

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 3:04 p.m.
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hello George,

Interpole series motors are used for reversing applications and where
dynamic, plug, or (dare I say it?) regenerative braking is used.  Brush
advance doesn't work in these spots. 

Interpoles in shunt and compound motors work better than the brush advance
because they vary strength with load and the sweet spot for commutation
varies with load.

Contrary to what your referenced article says and what you state, interpoles
do not counteract armature reaction.  Compensating or pole face winding do. 
And interpoles do not shift (rotate) the main field flux.  The interpole by
virtue of the mmf from the comm coil (interpole winding) manipulates the
flux in a small interpolar region where the neutral plane was before it was
shifted by the armature reaction.  This may seem picky.  But that is because
most here are concerned with series motors where armature reaction is not a
big factor in performance.  With shunt machines, armature reaction can cause
serious loss of torque or regulation.  There you will find interpoles do
nothing to counteract this and they must use compensating windings and
sometimes series field windings.

Regards,

Jeff M



----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List'
<[hidden email]>
Cc:
Sent: Tuesday, November 6, 2012 6:30 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

I found a pretty good explanation that will help those who have never looked
at this before,
http://www.cedengineering.com/upload/DC%20Generators%20and%20Motors.pdf

page 1-9 talks about interpoles etc. I think the important thing is, the
reaction of the flux and the amount of brush advance needed is not directly
influenced by RPM. It is directly related to current in the armature,
reading this document we can see why. Only thing, I have limited experience
with DC motors, last course I did on them was in the '60's. I have never
seen or heard of a SERIES DC motor with interpoles, in a way, the normal
poles are like interpoles because they are also in series. My reasoning
tells me that if you advance the brush timing the right amount the timing
should be right at all loads, currents and RPM's? In a shunt motor they are
in series so that as the current increases and rotates the flux path they
turn it straight again, and as this is caused by the current the current
through the interpoles, varying with this current produces the right amount
of counter rotation to correct it as the current varies.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 5:16 a.m.
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hi Mark,

As JJ says, the torque loss is offset by RPM increase as happens with field
weakening, so it is not a direct hit on efficiency.  The efficiency curve
will be altered with brush advance (and with field weakening).  At some load
points it may increase a bit and other loads decrease.  Proper advance
should not result in significantly lower motor efficiency.  Going too far
with advance or retardation may result in adverse effects on the efficiency
by actually shifting shorted coils (those being commutated) under the main
field flux.

And I told you that advance compensates for altered commutation due to high
current, high voltage and/or high RPM.  In your case, it is not 3000 RPM I
would be concerned about, it is the system voltage and current limit.  You
said it was drilled for 12 degrees, right?  Off hand, I think about half
that would be better for you.  If you're smelling or hearing the brush arc
going uphill, I'd give it that 6 degrees.

Regards,

Jeff M



________________________________
From: Mark Hanson <[hidden email]>
To: "[hidden email]" <[hidden email]>
Sent: Tuesday, November 6, 2012 9:55 AM
Subject: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency


Hi Jeff etc;
Yes, my previous experience with Prestolite and a tranny is neutral is
best.  The Warp "Impulse 9" was sent advanced but I moved it to neutral when
installing it so it always has run in neutral.  I would think that 20%
reduced torque with a given current means 20% *less* efficiency and a bad
thing.  My max RPM's is 3K (with 4-speed tranny) so I'm certainly not
running this motor very fast where i think advanced timing would be needed. 
So I'm inclined to leave it alone as i don't see how advancing the timing
for 3K rpm operation would have a positive effect (at that speed) and have a
negative effect starting off.
Best Regards,mark
Message: 8
Date: Mon, 5 Nov 2012 10:33:14 -0800 (PST)
From: Jeff Major <[hidden email]>
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency
To: Electric Vehicle Discussion List <[hidden email]>
Message-ID:
<[hidden email]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Mark,

Brushes arc primarily due to voltage, current and RPM.? Any, or
combinations, can cause excessive arcing when too high.? I personally think
that most times the advance is too far.? But if that is where it is drilled,
I'd do it for the voltage you're running.

Advancing the brushes weakens the field in effect and therefore reduces the
torque per amp of the motor while increasing the RPM per amp.? On a 4 pole
motor, if you rotate (advance) the brushes 90 degrees, you reverse
rotation.? 45 degrees would give you zero torque.? So you lose about 2
percent per degree.? That is just an approximation because it is not
linear.? But it is not unreasonable to expect 20 percent lower torque at a
given current with a 12 degree advance.

The other thing is:? What is your starting point?? Was your motor set on
neutral when installed?? I recall you doing test on the Prestolite motor
assuming it was neutral to start and it was manufactured with a 4.5 degree
advance.

Most cases will benefit from the advanced brushes and improved commutation
even at the expense of torque if you have the transmission.? Just use a
lower gear.? If you don't run a transmission, think hard about it because
reverse on the motor with advanced brushes can be damaging.

See ya,

Jeff M
                         
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Re: Advancing Motor Timing pros/cons/ accel efficiency

Jeff Major
George,

Interpoles do nothing to the main field.

Jeff M




----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List' <[hidden email]>
Cc:
Sent: Saturday, November 10, 2012 4:46 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Thanks, well, that’s definitely one! I was thinking that an interpole is in
series with the armature, so is the field, so there is no real difference.
You may as well just have a bigger field winding with some brush advance.
    I see the "interpoles" aid the field in one direction and buck it in
the other, so the motor will run faster in one direction than the other.
fairly simple, but operation is different to a shunt motor interpoles as the
field angle does not change with current, well with a shunt motor and
interpoles it does not either but it would without them.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Saturday, 10 November 2012 2:08 p.m.
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hi George,

http://kostov-motors.com/files/productattachments/04c1adb9b9b14801dea33e5ecd
0c3e44_F18B2.pdf 


See the wiring diagram and connection note on that drawing.

Large forklift trucks were common applications requiring interpole DC series
wound motors due to the reversing direction duty and plug reversing even
though the voltage and RPM were low by today's EV motor standards.

I have an old postal Jeep with a 96V system, 11 inch series wound DC  motor
with interpoles and a SCR controller with regeneration.  It is direct drive
(motor to rear differential) therefore uses contactor field switching for
reversing the motor.

Regards,

Jeff M



----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List'
<[hidden email]>
Cc:
Sent: Friday, November 9, 2012 1:51 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Are there any examples of series motors with interpoles on internet?

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Jeff Major
Sent: Wednesday, 7 November 2012 3:04 p.m.
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

Hello George,

Interpole series motors are used for reversing applications and where
dynamic, plug, or (dare I say it?) regenerative braking is used.  Brush
advance doesn't work in these spots. 

Interpoles in shunt and compound motors work better than the brush advance
because they vary strength with load and the sweet spot for commutation
varies with load.

Contrary to what your referenced article says and what you state, interpoles
do not counteract armature reaction.  Compensating or pole face winding do. 
And interpoles do not shift (rotate) the main field flux.  The interpole by
virtue of the mmf from the comm coil (interpole winding) manipulates the
flux in a small interpolar region where the neutral plane was before it was
shifted by the armature reaction.  This may seem picky.  But that is because
most here are concerned with series motors where armature reaction is not a
big factor in performance.  With shunt machines, armature reaction can cause
serious loss of torque or regulation.  There you will find interpoles do
nothing to counteract this and they must use compensating windings and
sometimes series field windings.

Regards,

Jeff M



----- Original Message -----
From: George Tyler <[hidden email]>
To: 'Jeff Major' <[hidden email]>; 'Electric Vehicle Discussion List'
<[hidden email]>
Cc:
Sent: Tuesday, November 6, 2012 6:30 PM
Subject: RE: [EVDL] Advancing Motor Timing pros/cons/ accel efficiency

I found a pretty good explanation that will help those who have never looked
at this before,
http://www.cedengineering.com/upload/DC%20Generators%20and%20Motors.pdf

page 1-9 talks about interpoles etc. I think the important thing is, the
reaction of the flux and the amount of brush advance needed is not directly
influenced by RPM. It is directly related to current in the armature,
reading this document we can see why. Only thing, I have limited experience
with DC motors, last course I did on them was in the '60's. I have never
seen or heard of a SERIES DC motor with interpoles, in a way, the normal
poles are like interpoles because they are also in series. My reasoning
tells me that if you advance the brush timing the right amount the timing
should be right at all loads, currents and RPM's? In a shunt motor they are
in series so that as the current increases and rotates the flux path they
turn it straight again, and as this is caused by the current the current
through the interpoles, varying with this current produces the right amount
of counter rotation to correct it as the current varies.
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