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Discussion Starter · #1 ·
First thank you everybody for answering my dumb questions.
My first is on a motor rated at 24 volts and 200 amps. I am going to try and run 72 volts and
want to know if I should run 12 volts on the field or the 72 volts.
My second is does the field current change with the load on the motor?
My last is can you check the condition of insulation in motor with meter?
Rick Prentiss
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Discussion Starter · #2 ·
Your question doesn't make sense.

If it's a series motor, then the field should be wired in series with the
armature. You might apply 72V to the combination, but the field has such
a low resistance that it typically only drops a couple volts.

You can't apply 12V to the field unless you seperate it from the armature,
in which case it's no long a series motor, and applying 12V to the field
of a typical series motor is WAY to much, the field will draw thousands of
amps (assuming your battery can source that much) and quickly melt down.

> First thank you everybody for answering my dumb questions.
> My first is on a motor rated at 24 volts and 200 amps. I am going to try
> and run 72 volts and
> want to know if I should run 12 volts on the field or the 72 volts.
> My second is does the field current change with the load on the motor?
> My last is can you check the condition of insulation in motor with meter?
> Rick Prentiss
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>


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Discussion Starter · #3 ·
Hi Rick,

Comments inserted:

--- [email protected] wrote:

> First thank you everybody for answering my dumb
> questions.
> My first is on a motor rated at 24 volts and 200
> amps. I am going to try and run 72 volts and
> want to know if I should run 12 volts on the field
> or the 72 volts.

No. A series motor means the armature (A1 & A2) is
connected in series with the field (S1 & S2). So, for
example, S1 and A1 are connected together, then S2 and
A2 are connected to the 72 volt source.

> My second is does the field current change with the
> load on the motor?

Yes, in the series motor, the armature and field
current are the same, and depend on the load.

> My last is can you check the condition of insulation
> in motor with meter?

Yes, but should not be necessary. You can use a
simple ohm meter and check resistance from terminals
to motor case. Should be a very large resistance. If
it is a very low resistance, like a few ohms, then
there may be a ground in the motor. Motor shops use a
device called a megger to do this, which will apply a
high voltage and read the megohms.

Hope this helps.

Jeff M

> Rick Prentiss


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