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Xeno wrote:
That's what I thought shorting the armature was doing.
Shorting the armature causes the energy to be dissipated in the
armature. Since the resistance of the armature isn't that high, it takes
a while.
On 28/05/2017 12:57 PM, Xeno wrote:
On 28/05/2017 12:50 PM, Sylvia Else wrote:
On 28/05/2017 11:50 AM, Phil Allison wrote:
Stupider than Anyone Else wrote:
---------------------------------
Putting a reverse voltage on it will stop it faster,
** So will sticking a screwdriver in with the rotor.
The point remains that extracting the energy and storing it is gonna
be a SLOWER way of braking the rotor.
The issue is the rate at which energy can be extracted. Whether the
energy is stored or dissipated is irrelevant. The higher the reverse
voltage the faster the blade will stop, and the faster the energy is
extracted.
The design issue is then how to provide the reverse voltage, and what
to do with the energy.
Sylvia.
That's what I thought shorting the armature was doing.
Shorting the armature causes the energy to be dissipated in the
armature. Since the resistance of the armature isn't that high, it takes
a while.
Sylvia.
On 27/05/17 23:19, Phil Allison wrote:
Clifford the FUCKWIT Chirping Cricket wrote:
and who was told NOT to reply
---------------------------------------------
Pumping the energy back into the battery may be a convenient way of
dealing with it - otherwise it would have to be dissipated as heat
- but
I doubt it's worth doing for the sake of the recovered energy.
Worth doing if only to make the blade stop quickly.
** Wot fucking ASSININE CRAP !!!!!!!!!!!!
The blade will stop WAAAAAYYYY faster if you DO NOT DO THAT !!!!
Do you fucking know ANY engineering, electronics or electrical
theory at ALL??
Do not try to reply.
The answer has been obvious for DECADES.
WAT?
There's energy in the rotating blade.
If you remove the energy, it stops faster.
** FFS - it will stop way FASTEST if the energy is dumped.
NOT recovered & STORED !!!
You know nothing trolling maggot.
Ok, but a dead short doesn't necessarily do that, as you know.
You need somewhere other than armature resistance to dump the
energy, and the battery is a reasonable place, assuming that
the armature is sufficiently high-Q to get it there. If not,
just short it.
How would *you* dump the energy?
On 28/05/2017 1:36 PM, Sylvia Else wrote:
On 28/05/2017 12:57 PM, Xeno wrote:
On 28/05/2017 12:50 PM, Sylvia Else wrote:
On 28/05/2017 11:50 AM, Phil Allison wrote:
Stupider than Anyone Else wrote:
---------------------------------
Putting a reverse voltage on it will stop it faster,
** So will sticking a screwdriver in with the rotor.
The point remains that extracting the energy and storing it is gonna
be a SLOWER way of braking the rotor.
The issue is the rate at which energy can be extracted. Whether the
energy is stored or dissipated is irrelevant. The higher the reverse
voltage the faster the blade will stop, and the faster the energy is
extracted.
The design issue is then how to provide the reverse voltage, and what
to do with the energy.
Sylvia.
That's what I thought shorting the armature was doing.
Shorting the armature causes the energy to be dissipated in the
armature. Since the resistance of the armature isn't that high, it
takes a while.
Sylvia.
Instant dead stop on a car's wiper motor.
On 28/05/2017 1:36 PM, Sylvia Else wrote:
On 28/05/2017 12:57 PM, Xeno wrote:
On 28/05/2017 12:50 PM, Sylvia Else wrote:
On 28/05/2017 11:50 AM, Phil Allison wrote:
Stupider than Anyone Else wrote:
---------------------------------
Putting a reverse voltage on it will stop it faster,
** So will sticking a screwdriver in with the rotor.
The point remains that extracting the energy and storing it is
gonna be a SLOWER way of braking the rotor.
The issue is the rate at which energy can be extracted. Whether the
energy is stored or dissipated is irrelevant. The higher the
reverse voltage the faster the blade will stop, and the faster the
energy is extracted.
The design issue is then how to provide the reverse voltage, and
what to do with the energy.
Sylvia.
That's what I thought shorting the armature was doing.
Shorting the armature causes the energy to be dissipated in the
armature. Since the resistance of the armature isn't that high, it
takes a while.
Sylvia.
Instant dead stop on a car's wiper motor.
On 28/05/2017 7:58 AM, Clifford Heath wrote:
On 27/05/17 23:04, Xeno wrote:
On 27/05/2017 8:48 PM, Clifford Heath wrote:
On 27/05/17 19:49, Phil Allison wrote:
Clifford Heath the Chirping Cricket wrote:
-------------------------------------------
Pumping the energy back into the battery may be a convenient
way of dealing with it - otherwise it would have to be
dissipated as heat - but
I doubt it's worth doing for the sake of the recovered energy.
Worth doing if only to make the blade stop quickly.
** Wot fucking ASSININE CRAP !!!!!!!!!!!!
The blade will stop WAAAAAYYYY faster if you DO NOT DO THAT !!!!
Do you fucking know ANY engineering, electronics or electrical
theory at ALL??
Do not try to reply.
The answer has been obvious for DECADES.
WAT?
There's energy in the rotating blade.
If you remove the energy, it stops faster.
Pointless maybe, but how is that hard to understand?
With DC motors there are easier ways to get one to stop quickly when
it's turned off. Your car's wiper motor does that.
No, it doesn't. Regeneration requires more than just going
open or short circuit.
It's simple and it's easy to incorporate. It's regenerative braking
but you are not pumping
energy back into the battery so no complications there.
Perhaps you can explain what you think "regeneration" means?
Because you certainly don't mean what everyone else means by it!
In this case, it serves to retard the motion of the armature. Works
very well on wiper motors - stops them dead. Isn't that the aim here -
stopping a motor quickly?
How would *you* dump the energy?
**AFAIK, some drills (and possibly other tools) apply a small reverse
current into the motor, when the trigger is released.
You can test the *instant effect* by isolating the shorting wire. YouOnce upon a time on usenet Xeno wrote:
On 28/05/2017 1:36 PM, Sylvia Else wrote:
On 28/05/2017 12:57 PM, Xeno wrote:
On 28/05/2017 12:50 PM, Sylvia Else wrote:
On 28/05/2017 11:50 AM, Phil Allison wrote:
Stupider than Anyone Else wrote:
---------------------------------
Putting a reverse voltage on it will stop it faster,
** So will sticking a screwdriver in with the rotor.
The point remains that extracting the energy and storing it is
gonna be a SLOWER way of braking the rotor.
The issue is the rate at which energy can be extracted. Whether the
energy is stored or dissipated is irrelevant. The higher the
reverse voltage the faster the blade will stop, and the faster the
energy is extracted.
The design issue is then how to provide the reverse voltage, and
what to do with the energy.
Sylvia.
That's what I thought shorting the armature was doing.
Shorting the armature causes the energy to be dissipated in the
armature. Since the resistance of the armature isn't that high, it
takes a while.
Sylvia.
Instant dead stop on a car's wiper motor.
Which is going trhough a reduction gearbox which also adds 'stopping power'
(as does the drag of the blade on the screen).
In fact 'instant' is relative. As it's at the end of it's stroke the motor
could actually move for several degrees of arc (or even revolutions before
the reduction 'box') but it not be obvious at the wiper due to the reduction
and then the play in the 'crankshaft' bushing at direction-change.
On 28/05/2017 11:02 AM, Phil Allison wrote:
Putting a reverse voltage on it will stop it faster,
On 2017-05-28, Sylvia Else <sylvia@not.at.this.address> wrote:
On 28/05/2017 11:02 AM, Phil Allison wrote:
Putting a reverse voltage on it will stop it faster,
true.
and since the current is in the opposite direction to the voltage,
false. ( see "back EMF" )
energy is being pumped into whatever is presenting the voltage.
nope.
you get electric braking, but not electric energy recovery
In general motors are like capacitors, energy goes in and out as
currents and is stored as a voltage (called back emf) in a permanent
magnet motor back emf is proportional to the spin speed and direction.
On 2017-05-28, Sylvia Else <sylvia@not.at.this.address> wrote:
On 28/05/2017 11:02 AM, Phil Allison wrote:
Putting a reverse voltage on it will stop it faster,
true.
and since the current is in the opposite direction to the voltage,
false. ( see "back EMF" )
No, whilst you can stop a DC motor very quickly by briefly reversing theOn 28/05/2017 11:02 AM, Phil Allison wrote:
Clifford the FUCKWIT Chirping Cricket wrote more CRAP.
---------------------------------------------
Pumping the energy back into the battery may be a convenient way of
dealing with it - otherwise it would have to be dissipated as
heat - but
I doubt it's worth doing for the sake of the recovered energy.
Worth doing if only to make the blade stop quickly.
** Wot fucking ASSININE CRAP !!!!!!!!!!!!
The blade will stop WAAAAAYYYY faster if you DO NOT DO THAT !!!!
Do you fucking know ANY engineering, electronics or electrical
theory at ALL??
Do not try to reply.
The answer has been obvious for DECADES.
WAT?
There's energy in the rotating blade.
If you remove the energy, it stops faster.
** FFS - it will stop way FASTEST if the energy is dumped.
NOT recovered & STORED !!!
You know nothing trolling maggot.
Ok, but a dead short doesn't necessarily do that, as you know.
** Shorting the armature is exactly how to stop the rotor FAST.
FOAD.
.... Phil
Putting a reverse voltage on it will stop it faster, and since the
current is in the opposite direction to the voltage, energy is being
pumped into whatever is presenting the voltage.
On 27/05/17 23:19, Phil Allison wrote:
Clifford the FUCKWIT Chirping Cricket wrote:
and who was told NOT to reply
---------------------------------------------
Pumping the energy back into the battery may be a convenient way of
dealing with it - otherwise it would have to be dissipated as heat
- but
I doubt it's worth doing for the sake of the recovered energy.
Worth doing if only to make the blade stop quickly.
** Wot fucking ASSININE CRAP !!!!!!!!!!!!
The blade will stop WAAAAAYYYY faster if you DO NOT DO THAT !!!!
Do you fucking know ANY engineering, electronics or electrical
theory at ALL??
Do not try to reply.
The answer has been obvious for DECADES.
WAT?
There's energy in the rotating blade.
If you remove the energy, it stops faster.
** FFS - it will stop way FASTEST if the energy is dumped.
NOT recovered & STORED !!!
You know nothing trolling maggot.
Ok, but a dead short doesn't necessarily do that, as you know.
You need somewhere other than armature resistance to dump the
energy, and the battery is a reasonable place, assuming that
the armature is sufficiently high-Q to get it there. If not,
just short it.
How would *you* dump the energy?
No, whilst you can stop a DC motor very quickly by briefly reversing the
battery voltage applied to the motor (and thereby reversing the
direction of current flow in the motor, (to which the torque developed
is pretty much proportional)), doing so will extract yet more energy
from the battery rather than recharging it.
If you want to stop the
motor whilst recovering some of the energy then you have to reverse the
sign of the current (compared to when the motor is running) and leave
the voltage with the same sign as when it is running (but with a lower
magnitude that ramps down, ideally to zero). If you change the sign of
both the current and the voltage, then their product, the power, would
not change sign, i.e. power would continue to flow from the battery to
the motor (and until the motor reverses rotation, that power all ends up
just heating the motor).
The same applies to brushless motors, it is just more complicated to
explain.
It wasn't meant to entertain you. I was just pointing out that reversingChris Jones wrote:
------------------
No, whilst you can stop a DC motor very quickly by briefly reversing the
battery voltage applied to the motor (and thereby reversing the
direction of current flow in the motor, (to which the torque developed
is pretty much proportional)), doing so will extract yet more energy
from the battery rather than recharging it.
** No fooling ????
What you will also do is cause severe damage to the commutator by causing a monstrous current surge simultaneous with a segment to segment over-voltage.
If you have ever got away with such looney abuse, the DC supply employed must have been wimpy.
If you want to stop the
motor whilst recovering some of the energy then you have to reverse the
sign of the current (compared to when the motor is running) and leave
the voltage with the same sign as when it is running (but with a lower
magnitude that ramps down, ideally to zero). If you change the sign of
both the current and the voltage, then their product, the power, would
not change sign, i.e. power would continue to flow from the battery to
the motor (and until the motor reverses rotation, that power all ends up
just heating the motor).
** Pure gobbledegook.
The same applies to brushless motors, it is just more complicated to
explain.
** I'm asleep already ...
The design issue is then how to provide the reverse voltage, and what
to do with the energy.
Sylvia.
That's what I thought shorting the armature was doing.
Shorting the armature causes the energy to be dissipated in the
armature. Since the resistance of the armature isn't that high, it takes
a while.