Rockwell Automation 1398-DDM-xxx ULTRA 100 Series Drives Installation Manual - Manual (Page 267)

Publication 1398-5.2 – PDF 1997
Creating Custom Motor Files D-13
Rating Parameters
Continuous Torque
Continuous torque specifies the rated current of the motor in peak
Amps. (Note: Continuous torque is peak Amps, rather than rms.) The
drive uses the continuous torque current value in its motor thermal
protection software. The drive generates a fault if the square of the
actual current, after passing through a low pass filter, exceeds the
square of the continuous torque current value. The square is used
because the power dissipation in the motor is approximated as I
2
R
losses. The continuous torque value may be in the range from 0.0078
to 255.9922 Amps.
Some manufacturers specify the rated current of a motor in rms Amps.
To convert from rms Amps to peak Amps, use the formula:
Occasionally a manufacturer specifies only the rated torque, and does
not include the rated current specification. In such a case, the rated
current can be computed using the rated 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:
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:
Intro
1 Amps Amps(rms)
⋅ = ⋅
1 414 .
Intro
I 1.1
rated torque in N m
K RATED
T
= ⋅
⋅
Intro
1 Amps Amps(rms)
⋅ = ⋅
1 414 .