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Parameters 2.7.15—2.7.18, Underload protection:
General
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 5Hz
(the underload time counter is stopped).
The torque values for setting the underload curve are set in percentage which refers to the nominal torque
of the motor. The motor's name plate data, the parameter Motor nominal current and the drive's nominal
current I
are used to find the scaling ratio for the internal torque value. If other than nominal motor is used
L
with the drive, the accuracy of the torque calculation decreases.
2.7.15
Underload protection
0 = No response
1 = Warning
2 = Fault, stop mode after fault according to parameter 2.1.9
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
The torque limit can be set between 10.0—150.0 % x T
This parameter gives the value for the minimum torque allowed when the output frequency is
above the field weakening point. See Figure 1- 22.
If you change the parameter 2.1.6 (Motor
nominal current) this parameter is
automatically restored to the default value.
4
Description of parameters
Figure 1- 22. Setting of minimum load
Honeywell
.
nMotor
Torque
Par. 2.7.16
Par. 2.7.17
Underload area
Fieldweakening
5 Hz
point par. 2.6.3
f
NX12k65