--- Zeke Yewdall <
[email protected]> wrote:
> Unless I'm mistaken, standard motor controllers will
> not work very
> well with a shunt or sepex motor (like an aircraft
> generator
> essentially is), unless you use a separate power
> supply for the field.
> I'm not sure exactly what yours is like, but it
> should have four
> terminals on it, not just two like a typical series
> motor. My big GE
> sepex motor has four -- two for the field and two
> for the armature.
>
> The options as I understand them are --
>
> 1) use a controller made for a sepex motor
> http://www.electrofit-zapi.com/hfcontsepex.htm the
> Sem3 for 96 volts
> 400 amps might be useful for you.... These apply
> full field voltage,
> while chopping the armature voltage, then when
> armature voltage
> reaches 100%, they start chopping the field voltage
> to increase the
> RPM's that way. I have been unable to find any
> controllers rated at
> higher than 96 volts 400amps though. And I want
> about 120 to 144
> volts and around 600 amps for mine.
>
> 2) Use a fixed field voltage of much lower than the
> armature voltage,
> and use a conventional chopper controller on the
> armature -- sounds
> like that's working out pretty well for Michael's.
>
> 3) Apply full armature voltage, and full field
> voltage to start with
> (and use a clutch, probably), and then slowly reduce
> field voltage to
> increase motor RPMs. This is what I think I'll do
> with mine to begin
> with -- the previous owner of the motor said it
> worked well for him.
> If it doesn't work out, I'll switch to 2).
>
> Z
>
>
>
> On 7/31/07, Phelps <
[email protected]> wrote:
> > Upp sent this to the wrong address last time..
> Better late
> >
> > Roland wrote
> > > > > Motors are inductive loads, where the ampere
> will rise with increase
> > > > > voltage
> > > > >
> > > > > Unlike resistance loads as a heater, where
> if you have a 240 v heater
> > > > > Element at 8 amps, it will become 4 amps at
> 120 v.
> > > > >
> > > > > A motor that it windings are rated for 240 v
> may use 10 amps where A
> > Motor
> > > > > Has its windings rated for 120 V may use 20
> amps for the same hp. But
> > > > > using
> > > > > Different voltages on the same windings
> rated for some other voltage
> > The
> > > > > Ampere may increase as follows:
> > > > >
> > > > > Here is the results of a 180 VDC motor test
> I did using different
> > Voltages
> > > > > At no load:
> > > > >
> > > > > Battery Pack Actual Volts Amperes Rpm
> > > > >
> > > > > 12 12.6 5 634
> > > > > 18 18.9 6 1013
> > > > > 24 25.4 6.2 1390
> > > > > 30 31.8 6.4 1773
> > > > > 36 37.8 6.6 2143
> > > > > 42 44.5 6.8 2521
> > > > > 48 51.2 7.0 2985
> > > > > 54 57.5 7.5 3270
> > > > > 60 63.7 8 3715
> > > > >
> > > > > There is a maximum voltage and ampere rating
> you can go over on a
> > Motor.
> > > > > This is call the Service Factor (SF). If
> 115V motor has a rated SF of
> > 115%
> > > > > And the motor has a ampere rating of 200
> ampere for continuous running
> >
> >
> > > > > then
> > > > >
> > > > > 200A x 1.15 = 230 amps. The 115V motor can
> run on 115V x 1.15 = 132.25
> >
> > V.
> > > > >
> > > > > On the label for the motor, there should be
> a Service Factor which may
> >
> > Say
> > > > > SF 1.25 for a DC motor. I don't why the ADC
> and Warp motors do not
> > Have
> > > > > Motor label that list the specifications of
> the motor.
> > > > >
> > > > > My General Electric motor does. It list the
> DC motor as 165 volts at
> > 175
> > > > > Amps at 32 HP with a SF of 1.25 meaning the
> over voltage can be about
> > 208
> > > > > Volts and the over ampere can be 218 amperes
> continuous.
> > > > >
> > > > > Roland
> >
> > Therefore what I need to know is .
> > If I chooses to go with 72 volts on my 30volt
> rated motor hoping to use less
> >
> > Than half the amps to do the same job .. Will that
> really be what I get??
> > According to the above maybe not..
> >
> > However..
> >
> > Am I missing that some controllers actually
> decrease and control the
> > Actually amps delivered to the motor?
> > As I was told earlier here . They don't change the
> amount of amps .. Just
> > That amount of time that the amps are applied to
> the motor.. Or are some
> > Controllers different in that since.. ..
> > So if I understand what I am herring.. Then also
> if the actually amps are
> > Not changed .. If I open my controller up full to
> achive max speed the
> > Amount of amps will not be decreased and my poor
> motor will die If the amps
> > Raise and double when I raise the volts that I am
> considering to make my car
> >
> > With 72 instead do 30volts..
> >
> > Tanks Mitchell
> >
> >
>
>
