# [EVDL] Series DC emergency braking possibility for two added parts.



## EVDL List (Jul 27, 2007)

Hello Dennis,

My first EV back in 76 made by the Electric Fuel Propulsion Co. in Troy, 
Mich. use a Cable Form motor controller made for industrial electric 
machines normally in the 144 volt range. It was modified for 180 vdc using 
large heat sinking resistors to reduce the 180 volt battery pack to 144 
volts.

This unit initially came with dynamic braking which is reversing the 
direction of the motor using a 4 pole 600 amp contactor or using two 2-pole 
contactors that is mechanically and electrically interlock together. Also 
there was another 600 amp contactor that switch in a very large 0.25 to 0.50 
power resistor that is use for resistance braking which I still have today. 
This resistor measures about 18 inches long and is a 12 inches square. This 
resistor is normally use in load banks for testing electrical machines.

Same type of unit is use for reversing a EV using a smaller 3 inch diameter 
resistor that is 16 inches long. Also the free wheeling diode had to be 
switch out and another one switch in the reverse direction.

They first tested this dynamic braking setup in full violent emergency stop 
mode. There is actually a settings mode in the accelerator control that is 
label violent, high, standard and soft accelerator and braking.

They first tested this braking action in violent which broke out a threaded 
bolt section in the motor coupler. In the most violent mode, the positive 
voltage is disconnected from the motor communtator and the negative voltage 
is disconnected from the motor field.

Then the positive voltage is connected to the field and the negative 
connected to the communtator. The field and communtator is still connected 
in series.

In the not so violent mode using the normal or softer braking mode, the 
resistor is inserted in the negative voltage between the negative of the 
controller and the communtator. The resistor is so large, that it had to be 
hang below the front bumper. On a braking test from 92 mph, it glow red 
which I though it make a good heater source.

Never use it, need a larger EV to be able to install all this equipment.

Roland








----- Original Message ----- 
From: "Dennis Miles" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Monday, September 24, 2012 2:12 AM
Subject: [EVDL] Series DC emergency braking possibility for two added parts.


> I thought of this Sunday night and I would prefer asking you-all for a
> comment or two before experimenting and destroying a motor. Or putting 
> some
> fast wear on brushes.
> I propose using a high current relay (Contactor) under control of a dash
> mounted switch with a protective cover, to "Short out the armature
> connections" from one to the other, leaving the field connected to the
> motor controller output, then, in case of a hydraulic braking system
> failure (I have experienced one before and using the mechanical "Emergency
> brake" is very hard to control to a safe stop.) Instead I would in case 
> of
> foot brake failure merely lift the accelerator pedal to cut power to the
> motor, but the car does not slow down, so with the above parts added, open
> cover and flip switch activating the relay(Contactor) to short out the
> armature, then slowly press the accelerator producing "Plug Braking" 
> action
> but with motor controller allowing a measure of control and thus bring the
> EV to a safe stop. Pullover into a safe location and call a flatbed truck
> car hauler to carry the EV home to the shop and fix the hydraulic brakes. 
> I
> do not think this would be a safe method for everyday use but I have 4-way
> flashers and I use them only once a year or less. But. when needed they 
> are
> there.
> -- 
> Regards,
> * Dennis *(EVprofessor)* Miles*
> *(863)944-9913* (phone noon to midnight E.S.T.)
> * reply to [email protected]*
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## EVDL List (Jul 27, 2007)

Thanks, Roland,
You have had so many interesting EV adventures and your sharing them
with us is wonderful. I always read your posts.
I expect trying my simple short out the armature method could easily
"Smoke"the armature unless braking was very gently applied but smoke is
better than a collision with another vehicle or a big tree. (Both in repair
dollars and minimizing injury of occupants.)
Regards,* Dennis *(EVprofessor)* Miles*
*(863)944-9913* (phone noon to midnight E.S.T.)
* reply to [email protected]*
+++++++++++++++++++++++++++++++++++++++


> Roland Wiench <[email protected]> wrote:
> 
> > Hello Dennis,
> >
> ...


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## EVDL List (Jul 27, 2007)

> On 24 Sep 2012 at 10:33, Roland Wiench wrote:
> 
> > My first EV back in 76 made by the Electric Fuel Propulsion Co. in
> > Troy, Mich. use a Cable Form motor controller ... in the 144 volt
> ...


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## EVDL List (Jul 27, 2007)

> David Roden wrote:
> 
> > On 24 Sep 2012 at 10:33, Roland Wiench wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

Roland, am I confused? you said, *"In the most violent mode, the
positive voltage is disconnected from the motor commutator and the negative
voltage is disconnected from the motor field.*
*Then the positive voltage is connected to the field and the
negative connected to the commutator. The field and commutator is still
connected in series."*
That being the situation the motor would continue to run in the same
direction, to reverse a series motor one reverses either the field OR the
armature but not both... (I didn't teach that wrong for twenty years, did
I?)
Could anyone tell me if they have tried the circuit as I described it for
controlled motor braking?
Regards,* Dennis *(EVprofessor)* Miles*
*(863)944-9913* (phone noon to midnight E.S.T.)
* reply to [email protected]*
+++++++++++++++++++++++++++++++++++++++++


> Roland Wiench <[email protected]> wrote:
> 
> > Hello Dennis,
> >
> ...


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