KSB PumpDrive 2 - Electrical Motor Protection by Overvoltage;Undervoltage Monitoring; Stop Due to Overcurrent; Dynamic Overload Protection by Speed Limitation

8 Commissioning/Shutdown
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PumpDrive 2
8.8.2.2 Electrical motor protection by overvoltage/undervoltage monitoring
The frequency inverter monitors the mains voltage. If it falls below 380 V -10 % or
exceeds 480 V +10%, this results in tripping and an alert is output. The alert must be
acknowledged before the drive can be restarted.
8.8.2.3 Stop due to Overcurrent
NOTE
Should the Overcurrent and Short Circuit faults occur, the frequency inverter is
automatically reset (after 2s – 4s - 6s). If the fault still cannot be acknowledged,
the frequency inverter switches off for safety reasons, and fault messages A5 (Short
circuit)/A9 (Overcurrent) and A6 (Hardware fault) are output. The combination of
these faults indicates to the operator that all components of the system and their
electrical connections must be thoroughly checked. The frequency inverter can only
be restarted with a voltage reset after the fault present has been rectified.
If the Max. Motor Current in % of Nominal Motor Current (3-3-7-1) limit value is
exceeded by 5%, the partially self-acknowledging Overcurrent alert is output that
causes the motor to be stopped. The drive remains disabled as long as this event is
active. The Motor Disabled status is displayed on the control panel.
8.8.2.4 Dynamic Overload Protection by Speed Limitation
The frequency inverter is equipped with current sensors that record and limit the
motor current. When the defined overload limit is reached, the speed is lowered to
reduce the power (I²t control). The frequency inverter then no longer operates in
closed-loop control mode but maintains the operative function at a lower speed.
Based on the values set in the I²t Triggering Characteristic (3-3-7-5) and the Max.
Motor Current in % of Nominal Motor Current (3-3-7-1) parameters, a dynamic time
period is calculated during which the motor may be operated at a current higher
than the Nominal Motor Current (3-2-1-4) until I²t control takes over. The more the
motor exceeds its nominal current, the faster the I²t control mode is activated.
The first time dynamic overload protection (I²t counter=0) is activated and the
motor current is at 110% of the nominal motor current (3-2-1-4), it will take
60seconds (3-3-7-5) for I²t control to take over as defined in the default factory
settings. If the overload current is below the maximum motor current, the dynamic
time period calculated is extended by a corresponding amount. If the motor
continues to operate at its nominal current following operation in overload mode,
the I²t control mode remains active. If the current drops to a value below the nominal
current of the motor (3-2-1-4), the I²t counter is reset. This process can take up to
10minutes, depending on the current at which the motor is currently operating.
As soon as I²t control is activated, the Dynamic Overload Protection warning is
displayed. This warning is self-acknowledging and is reset when I²t control is
deactivated.
When the I²t stop speed (3-3-7-6) is undershot, the partially self-acknowledging
Dynamic Overload Protection alert is output and the motor is stopped. The motor is
disabled. After the I²t threshold value is undershot, the motor restarts after a
maximum disable time of 10seconds has lapsed, depending on the size of the motor.
Table63: Parameters for dynamic overload protection by speed limitation
Parameter Description Possible settings Refers to Factory setting
3-2-1-4 Nominal Motor Current
Nominal current of motor as per
name plate
0.00 ... 150.00 A - Dependent on size
3-3-7-1 Max. Motor Current in % of
Nominal Motor Current
Setting the maximum motor current
permissible
0 ... 150 % 3-2-1-4 110 %