Re: [CAD_CAM_EDM_DRO] dc spindle motor control.

jeff35m_73068 wrote:

>I am working on a fuji electric dc spindle motor. This is on a large
>Makino vertical mill, that had a 3000c control.
>
>I would like to increase the speed of this motor. Would simply
>increasing the voltage do this? This spindle motor was connected to a
>fanuc 3000c controler(which is all missing). The motor itself has 5
>wires coming from it. 3 from the armature area, and 2 from the
>fields. The motor runs the best with the fields connected in series
>with the armature. Is anyone familure with this type of motor
>control? What did this 3rd wire do? ty jeff
>
>

I can't tell what the 3rd wire is for. It may be a safety ground (is it
green, or green/yellow?) Or, it may be a connection for commutating poles.
You say it runs best in series wound connection. If that is compared with
not connecting the field at all, that is no surprise. But, that will
give HORRIBLE
speed regulation under load. Also, since this is most likely designed for
shunt field connection, it is not likely to perform well at all under
load in series field
connection. You can tell by measuring the field resistance. It will
either be
under one Ohm, if actually designed for series operation, or tens of Ohms if
designed for shunt. Does it have a specification plate?

Generally, for shunt operation, you can run the field at a higher current
for low-speed, high-torque operation, and reduce field current for
high-speed, low-torque. It acts just like a gear shift.

Jon