Re: [CAD_CAM_EDM_DRO] Re: LARGE DC MOTOR speed control question

Grangers has DC speed controls of all sizes. Also most Electrical supply
outlets, and most all motor repair shops. They will be rated for HP, and
also 90 or 180 volt motors. The internal controls you will be looking for
are Min speed control, Max speed control. They have provision for an
external pot for the actual speed control, but most have a speed pot mounted
on the panel for the operator to use. The other internal control you want is
IR COMP. (compensation). This is the control that allows the motor to
maintain a reasonable constant voltage/speed with a change of loads. Too
little compensation and the voltage (RPM) sags under an increased load, too
much and the voltage (RPM) surges as the load increases. The correct setting
will allow the motor to maintain a constant voltage (RPM), under a load
change, within the constraints of the motor size, and the load.
When you set the RPM dial on a Sherline, you are actually setting the voltage
applied to the motor, and indirectly the RPM. If the control has built in IR
COMP. It will maintain that VOLTAGE (RPM) under a changing load.
bill