Interroll Drum motor series i, S, S/A, D
Options and accessories
Version 4.1 (06/2015) en-US
Translation of original instruction manual
65
Asynchronous drum motors with frequency inverters
f / Hz
Operating frequency [Hz] 5
10 15 20 25 30-50 55 60 65 70 75 80
Available motor torque in %
Rated motor
frequency
50 Hz
80 85 90 95 100 100
91 83 77 71
60 Hz
75 80 85 90 95 100
100 100 92 86 80 75
Value 1: Based on a rated motor frequency of 50 Hz (50-Hz motors should be operated only up
to 70 Hz in the speed range under field control.)
Value 2: Based on a rated motor frequency of 60 Hz (60-Hz motors should be operated only up
to 80 Hz in the speed range under field control.)
The torque dependency depicted in the figure above is expressed as P = T x
ω
. With a reduced
operating frequency of below 20/24 Hz, the motor torque is reduced by changing heat
dissipation conditions. The power loss dissipation is a result of the oil quantity, in contrast to
standard ventilated motors. For frequencies starting at 80 ... 85 / 95 100 Hz, the curve for the
output torque does not have a hyperbolic shape, but is instead replaced with a quadratic
function which is the result of the effect of the pull-out torque and the voltage. The output/
frequency characteristics of most frequency inverters supplied with 3 x 400 V / 3 x 460 V can
be parameterized to 400 V / 87 Hz in order to connect motors with 230 V / 50 Hz. This may
create further losses in the motor and lead to its overheating if the motor is dimensioned with
insufficient power reserves.
•
Clock frequency:
A high clock frequency leads to a better utilization factor of the motor.
Optimum frequencies are 8 or 16 kHz. Parameters such as smooth running test quality
(motor is running smoothly) and noise development are also affected positively by high
frequencies.
•
Voltage increase:
Interroll motor windings are dimensioned for a rated voltage increase
rate of 1 kV/μs. If a frequency inverter generates a steeper voltage increase, motor chokes
must be installed between frequency inverter and motor. But since all drum motors from
Interroll run in an oil bath, the risk of overheating or damage of the motor due to large
voltage increase rates is extremely low. Contact your local Interroll dealer about the need
for motor chokes.
Torque dependent on
input frequency
Frequency inverter
parameters
