Rockwell Automation 1398-DDM-xxx ULTRA 100 Series Drives Installation Manual - Manual (Page 261)

Publication 1398-5.2 – PDF 1997
Creating Custom Motor Files D-7
The denominator units of the required torque constant are peak Amps,
rather than rms Amps. To convert the torque constant from units of N-
m/Amp(rms), use the formula:
Many Allen-Bradley motors specify the torque constant in units of N-
m/rmsA/phase. In this case, in addition to conversion from rms Amps
to peak Amps, the value needs to be multiplied by three because it has
been defined as “per phase”.
If a motor operates with trap drives, the torque constant is specified as
a “square wave” torque constant. However, ULTRA 100 Series drives
are sinusoidal drives and the torque constant must be specified as a
“sine wave” torque constant or “sinusoidal” torque constant. To
convert between sinusoidal torque constants and square wave torque
constants, usually a factor of 5-10% is required. The motor
manufacturer should be able to specify the sinusoidal torque constant,
even if it is not shown in the data sheet.
J
M
(Inertia)
The rotor inertia specifies the inertia of the motor, not including the
load, and is required in units of Kg-cm
2
. The inertia can be in the
range of 0.0156 to 1023.9844 Kg-cm
2
.
The conversion formulas between Kg-cm
2
, Kg-m
2
, in-lb-s
2
, and
oz-in-s
2
are:
K
E
(Back EMF)
The back-EMF is the peak value of the line-to-line sinusoidal EMF
generated at 1000 RPM, and is required in units of Volts/KRPM or
Volts/1000 RPM. The back-EMF value can be in the range of 0.0039
to 255.9961 Volts/KRPM.
Note that the required value is a peak value, rather than an rms value.
To convert the back-EMF from units of Volts(rms)/kRPM, use the
formula:
Intro
1
Newton meter
Amp
0.707
Newton meter
Amp(rms)
⋅
=
⋅
Intro
1 Kg cm 0.0001 Kg m
1
1129.85
in lb s
1
70.6155
oz in s 2 2 2 2 ⋅ ⋅ = ⋅ ⋅ = ⋅ ⋅ ⋅ = ⋅ ⋅ ⋅
Intro
1
Volts
1000 RPM
Volts(rms)
1000 RPM
⋅ = ⋅
1 414 .