Parameter Reference D-147
AC30 series Variable Speed Drive
Scale Setpoint
Parameters::Motor Control::Scale Setpoint
This function defines 100% speed in RPM.
Functional Description
The Drive is commanded to run the motor at a certain speed, which is derived from various sources, such as comms, analog inputs, commands from
the keypad, etc. All these speed commands are expressed as a percentage. The percentage is referenced to this parameter. So, for example, if
this parameter is set to 3000 rpm, and the user commands 100% speed, then the motor should turn at 3000rpm.
However, the user must be aware of what this parameter means for different control options:
- For vector control (both for PMAC and IM) for 100% demand the motor will provide the actual shaft speed of the value that
is set in this parameter.
- For V/Hz control (IM only) for 100% demand the actual shaft speed will be the value set in this parameter less than the slip
of the motor. So, in order to achieve rated speed at rated torque in V/Hz mode, the user should put in this parameter an
RPM value that is corresponding to the base frequency of the motor with the number of pole pairs taken into account, or in
other words, ‘100% Speed in RPM’ should be set to synchronous speed. (For example, a 50Hz, 4 pole induction motor, with
rated speed of 1450RPM, should have its ‘100% Speed in RPM’ value set to 1500. This will ensure that in V/Hz mode when
the motor is loaded with rated load the actual speed of the shaft will be 1450 RPM!)
This parameter also represents the maximum speed available, since (apart from a small allowance for process trims) the speed commands are not
allowed to exceed 100%.
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