Rockwell Automation 1398-DDM-xxx USE MNL/ULTRA 200 DIG.SERVO.DR - Manual (Page 276)

Publication 1398-5.0 – October 1998
D-12 Creating Custom Motor Files
Peak Torque
The peak or maximum torque specifies the maximum current
capability of the motor in peak Amps. (Note: This is peak Amps,
rather than rms.) The drive uses the maximum torque value to limit
the current applied to the motor. At run-time, the instantaneous current
of the drive is limited to the minimum of this value, the drive’s peak
rating, the analog current limit inputs, and the software current limits.
The maximum torque value can be in the range from 0.0078 to
255.9922 Amps.
Some manufacturers specify the maximum current of a motor in rms
Amps. To convert from rms Amps to peak Amps, use the formula:
Occasionally a manufacturer specifies only the maximum
instantaneous torque, and does not include the maximum current
specification. In such a case, the peak current can be computed using
the peak torque and the torque constant. A factor of 1.1 is included to
allow for degradation of the torque constant at high temperatures, etc.
The formula, assuming the torque constant has already been converted
to N-m/A(peak), is given by:
Thermal Time Constant
The thermal time constant check box indicates if a valid thermal time
constant exists for the motor. If this check box is not selected, the
motor thermal protection software is disabled.
Enabling of the motor thermal protection software is recommended,
even if the thermal time constant is not known. This software feature
significantly reduces the chance of damage to the motor, even when
the motor has an integral thermostat.
The thermal time constant value, also known as the cool down time
constant, identifies how fast the motor winding temperature dissipates
heat. The value is entered in seconds. The thermal time constant value
can be in the range from 1 to 65535 seconds.
Intro
1 Amps Amps(rms)
⋅ = ⋅
1 414 .
Intro
I 1.1
maximum torque in N m
K
PEAK
T
= ⋅
⋅