Eaton Cutler-Hammer SLX9000 Series, User Manual

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SLX9000 Adjustable Frequency Drives User Manual
MN04003020E For more information visit: www.eaton.com
9-29
January 2009
Underload Protection
2.7.14 Maximum stall frequency ID712
The frequency can be set between 1-fmax (par. 2.1.2).
For a stall event to occur, the output frequency must have remained below this limit.
The purpose of the motor underload protection is to ensure that there is load on the
motor when the drive is running. If the motor loses its load, there might be a
problem in the process, e.g. a broken belt or a dry pump.
Motor underload protection can be adjusted by setting the underload curve with
parameters 2.7.16 (Field weakening area load) and 2.7.17 (Zero frequency load), see
below. The underload curve is a squared curve set between the zero frequency and
the field weakening point. The protection is not active below 5 Hz (the underload
time counter is stopped).
The torque values for setting the underload curve are set in percentage of nominal
torque of the motor. The motor’s nameplate data, the parameter Motor nominal
current and the drive’s nominal current I
L
are used to find the scaling ratio for the
internal torque value. If other than nominal motor is used with the drive, the
accuracy of the torque calculation decreases.
2.7.15 Underload protection ID713
0 No response
1 Warning
2 Fault, stop mode after fault according to parameter 2.1.12
3 Fault, stop mode after fault always by coasting
If tripping is set active, the drive will stop and activate the fault stage.
Deactivating the protection by setting the parameter to 0 will reset the underload
time counter.
2.7.16 Underload protection, field weakening
area load
ID714
The torque limit can be set between 10.0 and 150.0% x T
nMotor
.
This parameter gives the value for the minimum torque allowed when the output
frequency is above the field weakening point. See
Figure 9-22 .
If you change the parameter 2.1.9 (Motor nominal current), this parameter is
automatically restored to the default value.