SV9000 Motor Pump Enhanced Protection Application Page 39 (60)
7.12 Stall time
The time can be set between 2.0—120 s.
This is the maximum allowed time for a stall stage. There is an internal up/down counter to
count the stall time. See figure 6.2-22. If the stall time counter value goes above this limit
the protection will cause a trip (see parameter 7.10).
Stall time counter
Time
Stall
No Stall
Trip/Warning
Par. 7.10
Trip area
Par. 7.12
Figure 6.2-22: Counting the Stall Time
7.13 Maximum stall frequency
The frequency can be set between 1—f
max
(par. 1.2).
In a stall state, the output frequency is smaller than this limit. See figure 6.2-21.
Parameters 7.14—7.17, Underload protection
General
The purpose of 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 dry pump.
Motor underload protection can be adjusted by setting the underload curve with
parameters 7.15 and 7.16. The underload curve is a squared curve set between zero
frequency and the field weakening point. The protection is not active below 5Hz (the
underload counter value is stopped). See figure 6.2-23.
The torque values for setting the underload curve are set in percentage of the nominal
torque of the motor. The motor's name plate data, parameter 1.13, the motor's nominal
current and the drive's nominal current I
CT
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.
7.14 Underload protection
Operation:
0 = Not in use
1 = Warning
2 = Fault
Tripping and warning will display the same message code. 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 to zero.
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